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McNicholas, Kyle M. "Characterization of Native Point Defects in Barium Strontium Titanate / Strontium Titanate Heterostructures". The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1337970955.
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Wu, Wenzhong. "Low Temperature Sintering Semiconductive Barium Strontium Titanate". FIU Digital Commons, 2007. http://digitalcommons.fiu.edu/etd/76.
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Low temperature sintering has become a very important research area in ceramics processing and sintering as a promising process to obtain grain size below 100nm. For electronic ceramics, low temperature sintering is particularly difficult, because not only the required microstructure but also the desired electronic properties should be obtained. In this dissertation, the effect of liquid sintering aids and particle size (micrometer and nanometer) on sintering temperature and Positive Temperature Coefficient Resistivity (PTCR) property are investigated for Ba1-xSrxTiO3 (BST) doped with 0.2-0.3mol% Sb3+ (x = 0.1,0.2,0.3,0.4 and 0.5). Different sintering aids with low melting point are used as sintering aids to decrease the sintering temperature for micrometer size BST particles. Micrometer size and nanometer size Ba1-xSrxTiO3 (BST) particles are used to demonstrate the particle size effect on the sintering temperature for semiconducting BST. To reduce the sintering temperature, three processes are developed, i.e. 1 using sol-gel nanometer size Sb3+ doped powders with a sintering aid; 2 using micrometer size powders plus a sintering aid; and 3 using nanometer size Sb3+ doped powders with sintering aids. Grain size effect on PTCR characteristics is investigated through comparison between micrometer size powder sintered pellets and nanometer size powder sintered pellets. The former has lower resistivity at temperatures below the Curie temperature (Tc) and high resistivity at temperatures above the Curie temperature (Tc) along with higher ñmax/ñmin ratio (ñmax is the highest resistivity at temperatures above Tc, ñmin is the lowest resistivity at temperatures below Tc), whereas the latter has both higher ñmax and ñmin. Also, ñmax/ñmin is smaller than that of pellets with larger grain size. The reason is that the solid with small grain size has more grain boundaries than the solid with large grain size. The contribution z at room temperature and high temperature and a lower ñmax/ñmin ratio value.
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Fardin, Ernest Anthony, i efardin@ieee org. "Barium Strontium Titanate Thin Films for Tunable Microwave Applications". RMIT University. Electrical and Computer Engineering, 2007. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20080104.135507.
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There has been unprecedented growth in wireless technologies in recent years; wireless devices such as cellular telephones and wireless local area network (WLAN) transceivers are becoming ubiquitous. It is now common for a single hardware device, such as a cellular telephone, to be capable of multi-band operation. Implementing a dedicated radio frequency (RF) front-end for each frequency band increases the component count and therefore the cost of the device. Consequently, there is now a requirement to design RF and microwave circuits that can be reconfigured to operate at different frequency bands, as opposed to switching between several fixed-frequency circuits. Barium strontium titanate (BST) thin films show great promise for application in reconfigurable microwave circuits. The material has a high dielectric constant which can be controlled by the application of a quasi-static electric field, combined with relatively low losses at microwave frequencies. Tunable microwave components based on BST-thin films have the potential to replace several fixed components, thereby achieving useful size and cost reductions. This thesis is concerned with the growth and microwave circuit applications of BST thin films on c- and r-plane sapphire substrates. Sapphire is an ideal substrate for microwave integrated circuit fabrication due to its low cost and low loss. Electronically tunable capacitors (varactors) were fabricated by patterning interdigital electrode structures on top of the BST films. High capacitance tunabilities of 56% and 64% were achieved for the films grown on c-plane and r-plane sapphire, respectively, at 40 V bias. A novel electronically tunable 3 dB quadrature hybrid circuit was also developed. Prototypes of this circuit were initially implemented using commercial varactor diodes, in order to validate the design. An integrated version of the coupler was then fabricated using BST varactors on c-plane sapphire. The results achieved demonstrate the potential of sapphire-based BST thin films in practical microwave circuits.
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Price, Tony S. "Nonlinear Properties of Nanoscale Barium Strontium Titanate Microwave Varactors". Scholar Commons, 2012. http://scholarcommons.usf.edu/etd/4390.
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Barium strontium titanate thin film varactors have been widely investigated for the purpose of creating tunable front-ends for RF and microwave systems. There is an abundance of literature observing the capacitance-voltage behavior and methods on improving tunability. However, there is a lack of thorough investigations on the nonlinear behavior, specifically the third order intermodulation distortion, and the parameters that impact it. There is also a research void that needs to be filled for nanoscale barium strontium titanate varactors as nanotechnology becomes increasingly prevalent in the design of RF and microwave components.
This work aims to advance the understanding of nonlinear properties of barium strontium titanate varactors. Temperature and voltage impacts on the third order intermodulation distortion products of BST varactors are observed by two-tone measurements. The material properties of the films are correlated with the nonlinear behavior of the varactors. Additionally, size reduction capabilities are shown by fabricating planar barium strontium titanate interdigital varactors with nanoscale size gaps between the electrodes. Modeling techniques are also investigated.
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Yue, Hailing. "Design and Optimization of Barium Strontium Titanate Ferroelectric Varactors". University of Dayton / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1348779036.
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Chien, Hsin-I. "Microfabrication of barium strontium titanate BaxSr(1-x)TiO3". Thesis, London South Bank University, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.618692.
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Balu, Venkatasubramani. "Barium strontium titanate thin film capacitors for high-density memories /". Digital version accessible at:, 1999. http://wwwlib.umi.com/cr/utexas/main.
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Pan, Kuan-Chang. "Ferroelectric Barium Strontium Titanate Thin-Film Varactor Based Reconfigurable Antenna". University of Dayton / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1323453777.
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Tombak, Ali. "Radio Frequency Applications of Barium Strontium Titanate Thin Film Tunable Capacitors". NCSU, 2000. http://www.lib.ncsu.edu/theses/available/etd-20001129-002144.
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TOMBAK, Ali. Radio Frequency Applications of Barium Strontium Titanate Thin Film Tunable Capacitors. (Under the supervision of Amir S. Mortazawi).Properties of thin film barium strontium titanate (BST) based capacitors for RF and microwave components were studied. The capacitors were measured for their tunability, loss tangent, frequency dependence of dielectric permittivity, and behavior at large RF signal amplitudes. A nonlinear equivalent circuit model for tunable BST capacitors was developed. Analysis of a tunable low pass filter fabrication using BST capacitors along with its intermodulation distortion measurements was given. Several simulations for bandpass filters were performed. Furthermore, a periodically loaded coplanar waveguide phase shifter utilizing the BST capacitors was designed.
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Gurumurthy, Venkataramanan. "Barium Strontium Titanate films for tunable microwave and acoustic wave applications". [Tampa, Fla.] : University of South Florida, 2007. http://purl.fcla.edu/usf/dc/et/SFE0002089.
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Ketkar, Supriya Ashok. "Synthesis, Characterization and Applications of Barium Strontium Titanate Thin Film Structures". Scholar Commons, 2013. http://scholarcommons.usf.edu/etd/4700.
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Barium Strontium Titanate (BST) based ferroelectric thin film devices have been popular over the last decade due to their versatile applications in tunable microwave devices such as delay lines, resonators, phase shifters, and varactors. BST thin films are promising candidates due to their high dielectric constant, tunability and low dielectric loss. Dielectric-tunable properties of BST films deposited by different deposition techniques have been reported which study the effects of factors, such as oxygen vacancies, film thickness, grain size, Ba/Sr ratio, etc. Researchers have also studied doping concentrations, high temperature annealing and multilayer structures to attain higher tunability and lower loss. The aim of this investigation was to study material properties of Barium Strontium Titanate from a comprehensive point of view to establish relations between various growth techniques and the film physical and electrical properties.
The primary goal of this investigation was to synthesize and characterize RF magnetron sputtered Barium Strontium Titanate (Ba1-xSrxTiO3), thin film structures and compare their properties with BST thin films deposited by sol-gel method with the aim of determining relationships between the oxide deposition parameters, the film structure, and the electric field dependence. In order to achieve higher thickness and ease of fabrication, and faster turn around time, a `stacked' deposition process was adopted, wherein a thin film (around 200nm) of BST was first deposited by RF magnetron sputtering process followed by a sol-gel deposition process to achieve higher thickness. The investigation intends to bridge the knowledge gap associated with the dependence of thickness variation with respect to the tunability of the films. The film structures obtained using the three different deposition methods were also compared with respect to their analytical and electrical properties. The interfacial effect on these `stacked' films that enhance the properties, before and after annealing these structures was also studied.
There has been significant attention given to Graphene-based supercapacitors in the last few years. Even though, supercapacitors are known to have excellent energy storage capability, they suffer from limitations pertaining to both cost and performance. Carbon (CNTs), graphene (G) and carbon-based nanocomposites, conducting polymers (polyaniline (PANI), polypyrrole (PPy), etc.) have been the fore-runners for the manufacture of supercapacitor electrodes. In an attempt to better understand the leakage behavior of Graphene Polyaniline (GPANI) electrodes, BST and BST thin films were incorporated as constituents in the process of making supercapacitor electrodes resulting in improved leakage behavior of the electrochemical cells. A detailed physical, chemical and electrochemical study of these electrochemical cells was performed.
The BST thin films deposited were structurally characterized using Veeco Dektek thickness profilometer, X-ray diffraction (XRD), Scanning electron microscopy (SEM) and atomic force microscopy (AFM) techniques. The interfacial structural characterization was carried out using high-resolution transmission electron microscopy (HRTEM). This investigation, also presents noncontact electrical characterization of BST films using Corona Kelvin metrology (C-KM).
The `stacked' BST thin films and devices, which were electrically tested using Corona Kelvin metrology, showed marked improvement in their leakage characteristics over both, the sputtered and the sol-gel deposited counterparts. The `stacked' BST thin film samples were able to withstand voltages up to 30V positive and negative whereas, the sol-gel and sputtered samples could hold only up to a few volts without charge leaking to reduce the overall potential. High frequency, 1GHz, studies carried out on BST thin film interdigitated capacitors yielded tunability near 43%.
Leakage barrier studies demonstrated improvement in the charging discharging response of the GPANI electrochemical electrodes by 40% due to the addition of BST layer.
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Alema, Fikadu Legesse. "Multicomponent Doped Barium Strontium Titanate Thin Films for Tunable Microwave Applications". Diss., North Dakota State University, 2014. https://hdl.handle.net/10365/27258.
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In recent years there has been enormous progress in the development of barium strontium titanate (BST) films for tunable microwave applications. However, the properties of BST films still remain inferior compared to bulk materials, limiting their use for microwave technology. Understanding the film/substrate mismatch, microstructure, and stoichiometry of BST films and finding the necessary remedies are vital. In this work, BST films were deposited via radio frequency magnetron sputtering method and characterized both analytically and electrically with the aim of optimizing their properties.
The stoichiometry, crystal structure, and phase purity of the films were studied by varying the oxygen partial pressure (OPP) and total gas pressure (TGP) in the chamber. A better stoichiometric match between film and target was achieved when the TGP is high (> 30 mTorr). However, the O2/Ar ratio should be adjusted as exceeding a threshold of 2 mTorr in OPP facilitates the formation of secondary phases. The growth of crystalline film on platinized substrates was achieved only with a lower temperature grown buffer layer, which acts as a seed layer by crystallizing when the temperature increases.
Concurrent Mg/Nb doping has significantly improved the properties of BST thin films. The doped film has shown an average tunability of 53%, which is only ~8 % lower than the value for the undoped film. This drop is associated with the Mg ions whose detrimental effects are partially compensated by Nb ions. Conversely, the doping has reduced the dielectric loss by ~40 % leading to a higher figure of merit. Moreover, the two dopants ensure a charge neutrality condition which resulted in significant leakage current reduction. The presence of large amounts of empty shallow traps related to NbTi localize the free carriers injected from the contacts; thus increase the device control voltage substantially (>10 V).
A combinatorial thin film synthesis method based on co-sputtering of two BST sources doped with Mg/Nb and Ce, respectively, was applied. The composition and the dielectric properties of the deposited film were correlated and the optimal concentration of dopants corresponding to high tunability and low dielectric loss was determined in a timely fashion.
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Ditum, Caroline Mary. "The fabrication and characterisation of barium strontium titanate ceramics and films". Thesis, University of Birmingham, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.273739.
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Baylis, Samuel Andrew. "Tunable patch antenna using semiconductor and nano-scale Barium Strontium Titanate varactors". [Tampa, Fla.] : University of South Florida, 2007. http://purl.fcla.edu/usf/dc/et/SFE0001970.
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Sarma, Kumaravinotha N. Sanmugaratna. "Barium strontium titanate thin film based multi-layer structures for microwave application". Thesis, London South Bank University, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.506714.
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O'Neill, D. "Growth and properties of barium strontium titanate thin films and multilayer stacks". Thesis, Queen's University Belfast, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.396217.
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Lookman, Akeela. "Phase transition behaviour and metastability in barium strontium titanate thin film capacitors". Thesis, Queen's University Belfast, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.426708.
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Grattan, Lesley Jane. "Investigation of thickness effects on the dielectric constant barium strontium titanate thin films". Thesis, Queen's University Belfast, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.396079.
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Momose, Shun. "Spectroscopic Study on Metalorganic Chemical Vapor Deposition Mechanisms of Barium Strontium Titanate Films". 京都大学 (Kyoto University), 2002. http://hdl.handle.net/2433/149807.
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Vemulapalli, Sreekanth. "Design Of Tunable Band Pass Filter Using Barium Strontium Titanate (BST) Thin Films". University of Dayton / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1304697174.
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Manavalan, Sriraj G. "Structural and electrical properties of barium strontium titanate thin films for tunable microwave applications". [Tampa, Fla.] : University of South Florida, 2005. http://purl.fcla.edu/fcla/etd/SFE0001155.
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Alsaei, Jawad. "Theory and simulation of electronic and optical properties of thin film barium strontium titanate". Thesis, Imperial College London, 2015. http://hdl.handle.net/10044/1/28579.
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In this thesis, we investigate, from first-principles, various means by which the energy gaps and the refractive index of BaTiO$_3$, SrTiO$_3$ and Ba$_{x}$Sr$_{1-x}$TiO$_3$ may be tuned, including epitaxial strain, alloying, and anionic doping. We start by discussing some limitations in the experimental spectroscopic ellipsometry technique that could affect the reliability of the measured optical spectra. Then, we investigate the effects of strain and alloying on the energy gaps of these materials. Interesting features in the gaps are observed as a function of strain, where it decreases and increases for small and high strains, respectively. These features are correlated with the spontaneous polarization of the system, whose behaviour is sensitive to the value of strain. The polarization also affects the behaviour of the bandgap of Ba$_{x}$Sr$_{1-x}$TiO$_3$ as a function of Sr content, which shows a non-monotonic trend. On the other hand, the refractive index of Ba$_{x}$Sr$_{1-x}$TiO$_3$ shows similar features with strain and alloying to those of the bandgaps. Strain is found to induce a decrease of up to $\sim 8\%$ in the refractive index and a birefringence of up to $\sim0.14$, whereas alloying has a smaller effect. Ferroelectric distortions are found to have a major role in decreasing the index, where much less effect is observed when they are inhibited. However, we show that the refractive index is insensitive to the ordering of Sr atoms in Ba$_{x}$Sr$_{1-x}$TiO$_3$. Finally, we investigate the effect of F and N codoping in BaTiO$_3$. The refractive index is sensitive to the atomic ordering of the dopant atoms, which prefer to be aligned in linear chains of F$-$Ti$-$N. The component of the index along the chain shows a dramatic increase with respect to pure BaTiO$_3$, while the other components are almost unaffected. Also, we show that the index can be further tuned by strain and doping concentration.
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Demydov, Dmytro V. "Nanosized alkaline earth metal titanates : effects of size on photocatalytic and dielectric properties". Diss., Manhattan, Kan. : Kansas State University, 2006. http://hdl.handle.net/2097/177.
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Kim, Dongsu. "Monolithic Analog Phase Shifters Based on Barium Strontium Titanate Coated Sapphire Substrates for WLAN Applications". Diss., Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/5211.
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The objective of this research is to implement monolithic analog phase shifters based on barium strontium titanate (BST) coated sapphire substrates for IEEE 802.11b wireless local area network (WLAN) applications. It has been known that several BST thin film properties such as high relative permittivity, electric field dependence, fast polarization response, relatively low loss, and high breakdown field, allow for miniaturization and high performance of analog phase shifters. Before attempting to implement BST phase shifters, coplanar waveguides (CPWs) and interdigital capacitors (IDCs) based on various BST compositions and thicknesses have been developed and characterized to capitalize on the electrical properties of BST thin films.
Based on the characteristics of BST thin films, two design topologies have been studied to implement phase shifters. The first topology is a reflection-type structure. The reflection-type phase shifter composed of a 3-dB coupler and two identical reflective terminations has provided a large phase shift with a relatively low insertion loss. The second topology is an all-pass network structure. The all-pass network phase shifter consists of only lumped elements so that one can shrink in size of devices. The total chip area of the all-pass network phase shifter is only 2.6 mm * 2.2 mm with a loss figure-of-merit (FOM) of more than 69 deg/dB at 2.4 GHz. This is the smallest size and the best performance obtained to date for BST phase shifters in the 2.4 GHz band and comparable or even better than the state of the GaAs MMIC phase shifters. The nonlinear response of the all-pass network phase shifter also was investigated with two-tone intermodulation distortion (IMD) measurement. Furthermore, the all-pass network phase shifter was studied to ascertain a design to ensure minimum performance variation over a range of temperature and to determine which BST composition performed best in the face of temperature variations.
Compact beamforming networks (BFNs) for WLAN systems using client-based smart antennas have been demonstrated to validate the feasibility of BST technology for WLAN applications. The two-element BFNs have been shown to increase throughput and network capacity by rejecting interference.
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Tam, Dickson Tai Shun. "An investigation on effect of Mn-doping on dielectric property of barium strontium stannate titanate". access abstract and table of contents access full-text, 2005. http://libweb.cityu.edu.hk/cgi-bin/ezdb/dissert.pl?msc-ap-b21175135a.pdf.
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Thesis (M.Sc.)--City University of Hong Kong, 2005.At head of title: City University of Hong Kong, Department of Physics and Materials Science, Master of Science in materials engineering & nanotechnology dissertation. Title from title screen (viewed on Sept. 4, 2006) Includes bibliographical references.
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Yeung, Kwok Fai. "An investigation on effect of Mn-doping on dielectric property of barium strontium stannate titanate". access abstract and table of contents access full-text, 2005. http://libweb.cityu.edu.hk/cgi-bin/ezdb/dissert.pl?msc-ap-b21175317a.pdf.
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Thesis (M.Sc.)--City University of Hong Kong, 2005.At head of title: City University of Hong Kong, Department of Physics and Materials Science, Master of Science in materials engineering & nanotechnology dissertation. Title from title screen (viewed on Sept. 4, 2006) Includes bibliographical references.
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Pena, Piedad. "Stoichiometry and Deposition Temperature Dependence of the Microstructural and Electrical Properties of Barium Strontium Titanate Thin Films". Thesis, University of North Texas, 1998. https://digital.library.unt.edu/ark:/67531/metadc279410/.
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Barium Strontium Titanate (BST) was deposited on Pt/ZrO2 / SiO2/Si substrates using liquid source metal organic chemical vapor deposition. A stoichiometry series was deposited with various GrII/Ti ratios (0.658 to 1.022) and a temperature series was deposited at 550 to 700°C. The thin films were characterized using transmission electron microscopy.
Both series of samples contained cubic perovskite BST and an amorphous phase. The grain size increased and the volume fraction of amorphous phase decreased with increasing deposition temperature. The electrical and microstructural properties improved as the GrII/Ti ratio approached 1 and deteriorated beyond 1. This research demonstrates that BST thin films are a strong candidate for future
MOS transistor gate insulator applications.
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Saha, Sanjib. "Study Of Pulsed Laser Ablated Barium Strontium Titanate Thin Flims For Dynamic Random Access Memory Applications". Thesis, Indian Institute of Science, 2000. http://hdl.handle.net/2005/208.
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The present study describes the growth and characterization of pulsed laser ablated Bao.sSro.sTiOs (BST) thin films. Emphasis has been laid on the study of a plausible correlation between structure and property in order to optimize the processing parameters suitably for required application. An attempt has been made to understand the basic properties such as, origin of dielectric response, charge transfer under low and high-applied electric fields across the BST capacitor and finally the dielectric breakdown process.
Chapter 1 gives a brief introduction on the application of ferroelectric thin films in microelectronic industry and its growth techniques. It also addresses the present issues involved in the introduction of BST as a capacitor material for high-density dynamic random access memories. Chapter 2 outlines the motivation for the present study and briefly outlines the research work involved.
Chapter 3 describes the experimental procedure involved in the growth and characterization of BST thin films using pulsed laser ablation technique. Details include the setup design for PLD growth, material synthesis for the ceramic targets, deposition conditions used for thin film growth and basic characterizations methods used for study of the grown films.
Chapter 4 describes the effect of systematic variation of deposition parameters on the physical and electrical properties of the grown BST films. The variation in processing conditions has been found to directly affect the film crystallinity, structure and morphology. The change observed in these physical properties may also be correlated to the observed electrical properties. This chapter summarizes the optimal deposition conditions required for growing BST thin films using a pulsed laser ablation technique.
Microstructure of BST films has been categorized into two types: (a) Type I structure, with multi-grains through the film thickness, for amorphous as-grown films after high temperature annealing (exsitu crystallized), and (b) columnar structure (Type II) films, which were as-grown well-crystallized films, deposited at high temperatures.
The ac electrical properties have been reviewed in detail in Chapter 5. Type I films showed a relatively lower value of dielectric constant (e ~ 426) than Type II films with dielectric constant around 567. The dissipation factors were around 0.02 and 0.01 for Type I and Type II films respectively. The dispersion in the frequency domain characteristics has been quantitatively explained using Jonscher's theory. Complex impedance spectroscopy employed showed significant grain boundary response in the case of multi-grained Type I films while negligible contribution from grain boundaries has been obtained in the case of columnar grained Type II BST films. The average relaxation time r obtained from the complex impedance plane plots show almost three orders higher values for Type I films. The obtained results suggest that in multi-grained samples, grain boundary play a major role in electrical properties. This has been explained in accordance to a model proposed on the basis of depleted grains in the case of Type I films where the grain sizes are smaller than the grain boundary depletion width.
Chapter 6 describes the dc leakage properties of the grown BST thin films and the influence of microstructure on the leakage properties. It was evident from the analysis of the graph of leakage current against measurement temperature, that, the observed leakage behavior in BST films, can not be attributed to a single charge transport mechanism. For Type I films, the Arrhenius plot of the leakage current density with 1000/T exhibits different regions with activation energy values in the range of 0.5 and 2.73 for low fields (2.5kV/cm). The activation energy changes over to 1.28 eV at high fields (170 kV/cm). The obtained values agree well with that obtained from the ac measurements, thus implying a similarity in the origin of the transport process. The activation energy value in the range of 0.5 eV is attributed to the electrode/film Schottky barrier, while the value in the range of 2.73 eV is due to deep trap levels originating from Ti+3 centers. The value in the range of 1.28 eV has been attributed to oxygen vacancy motion. Similar results have been obtained from the Arrhenius plot of the leakage current for Type II films. In this case, only two different activation energy values can be identified in the measured temperature and applied electric field range. At low fields the activation energy value was around 0.38 eV while at high fields the value was around 1.06 eV. These values have been identified to be originating from the electrode/film Schottky barrier and oxygen vacancy motion respectively. Thus a complete picture of the charge transport process in the case of BST thin film may be summarized as comprising of both electronic motion as well as contribution from oxygen vacancy motion.
The effect of electrical stress on the capacitance-voltage (C-V) and the leakage current has been analyzed in Chapter 7. From the change in the zero bias capacitance after repeated electron injection through the films the values of the electronic capture cross-section and the total trap density for Type I and II films have been estimated. The results showed higher values for Type I film in comparison to Type II films. The difference has been attributed to the presence of grain boundaries and a different interface in the case of Type I films when compared to Type II films where the absence of grain boundaries is reflected in the columnar microstructure. A study of the time-dependent-dielectric-breakdown (TDDB) characteristics under high fields for Type I and Type II films showed higher endurance for Type I film. On the other hand space-charge-transient characteristics have been observed in the case of Type II films at elevated temperature of measurement. Mobility and activation energy values extracted from the transient characteristics are found to be in the range of 1 x 10~12 cm2 /V-sec and 0.73 eV respectively, suggesting a very slow charge transport process, which has been attributed to the motion of oxygen vacancies. An overall effect of electrical stress suggested that oxygen vacancy motion can be related to the observed resistance degradation and TDDB, which has been further enhanced by the combination of high temperature and high electric fields.
Chapter 8 deals with the effect of intentional doping in the BST films. The doping includes Al at the Ti-site, Nb in the Ti-site and La at the Ba/Sr-site. The effect of doping was observed both on the structure and electrical properties of the BST films. Acceptor doping of 0.1 atomic 7c Al was found to decrease the dielectric constant as well as the leakage current. For higher concentration of acceptor-dopant, the leakage current was found to increase while showing space-charge-transient in the TDDB characteristics, again suggesting the effect of increased concentration of oxygen vacancies. Donor doping using 2 atomic % La and Xb significantly improved the leakage as well as the TDDB characteristics by reducing the concentration of oxygen vacancies. A further procedure using graded donor doping in the BST films exhibits even better leakage and TDDB properties. An unconventional, graded doping of donor cations has been carried out to observe the impact on leakage behavior, in particular. The leakage current measured for a graded La-doped BST film show almost six orders of lower leakage current in comparison to undoped BST films, while endurance towards breakdown has been observed to increase many-fold.
Chapter 9 highlights the main findings of the work reported in this thesis and lists suggestions for future work, to explore new vistas ahead.
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Ernst, Eric Michael. "Hydrothermal conversion of diatom frustules into barium titanate based replicas". Thesis, Atlanta, Ga. : Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/24687.
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Thesis (M. S.)--Materials Science and Engineering, Georgia Institute of Technology, 2008.Committee Chair: Sandhage, Kenneth H.; Committee Co-Chair: Snyder, Robert L.; Committee Member: Sanders, Thomas H.
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Nadouf, Mohammed. "Synthese et etude de poudres submicroniques de titanate de baryum et de ses solutions solides avec le strontium". Université Louis Pasteur (Strasbourg) (1971-2008), 1986. http://www.theses.fr/1986STR13129.
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On etudie les solutions solides entre titanate de baryum et titanate de strontium. Deux methodes de synthese de ces perovskites sont abordees : la methode ceramique classique, ou l'on fait reagir des solides a haute temperature, et la methode oxalique qui fait intervenir la preparation d'un sel mixte que l'on decompose a basse temperature. Les relations entre la nature des sels des oxydes, le ph de precipitation, la temperature de reaction ou de precipitation et les caracteristiques structurales et proprietes physiques des ceramiques frittees sont etudiees
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Brown, Dustin Anthony. "Novel Approaches to Ferroelectric and Gallium Nitride Varactors". University of Dayton / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1398902436.
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Zhang, Qingteng. "Properties of Ferroelectric Perovskite Structures under Non-equilibrium Conditions". Scholar Commons, 2012. http://scholarcommons.usf.edu/etd/4422.
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Ferroelectric materials have received lots of attention thanks to their intriguing properties such as the piezoelectric and pyroelectric effects, as well as the large dielectric constants and the spontaneous polarization which can potentially be used for information storage. In particular, perovskite crystal has a very simple unit cell structure yet a very rich phase transition diagram, which makes it one of the most intensively studied ferroelectric materials. In this dissertation, we use effective Hamiltonian, a first-principles-based computational technique to study the finite-temperature properties of ferroelectric perovskites. We studied temperature-graded
(BaxSr1-x )TiO3 (BST) bulk alloys as well as the dynamics of nanodomain walls (nanowalls) in Pb(ZrxTi1-x )O3 (PZT) ultra-thin films under the driving force of an AC field. Our computations suggest that, for the temperature-graded BST, the polarization responds to the temperature gradient (TG), with the "up" and "down" offset observed in polarization components along the direction of TG, in agreement with the findings from experiments. For the nanowalls in PZT, the dynamics can be described by the damped-harmonic-oscillator model, and we observed a size-driven transition from resonance to relaxational dynamics at a critical thickness of 7.2 nm. The transition originates from the change in the effective mass of a nanowall as a film thickness increases. Some of the findings may find potential applications in various devices, such as thermal sensors, energy converters, or novel memory units.
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Podpirka, Adrian Alexander. "Studies on Synthesis, Structural and Electrical Properties of Complex Oxide Thin Films: Ba1-xSrxTiO3 and La2-xSrxNiO4". Thesis, Harvard University, 2012. http://dissertations.umi.com/gsas.harvard:10247.
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High performance miniaturized passives are of great importance for advanced nanoelectronic packages for several applications including efficient power delivery. Low cost thin film capacitors fabricated directly on package (and/or on-chip) are an attractive approach towards realizing such devices. This thesis aims to explore fundamental frequency dependent dielectric and insulating properties of thin film high-k dielectric constant in the perovskite and perovskite-related complex oxides. Throughout this thesis, we have successfully observed the role of structure, strain and oxygen stoichiometry on the dielectric properties of thin film complex oxides, allowing a greater understanding of processing conditions and polarization mechanisms. In the first section of the thesis, we explore novel processing methods in the conventional ferroelectric, barium strontium titanate, \(Ba_{1-x}Sr_xTiO_3 (BST)\), using ultraviolet enhanced oxidation techniques in order to achieve improvements in the dielectric properties. Using this method, we also explore the growth of BST on inexpensive non-noble metals such as Ni which presents technical challenges due to the ability to oxidize at high temperatures. We observe a significant lowering of the dielectric loss while also lowering the process temperature which allows us to maintain an intimate interface between the dielectric layer and the metal electrode. The second section of this thesis explores the novel dielectric material, Lanthanum Strontium Nickelate, \(La_{2-x}Sr_xNiO_4 (LSNO)\), which exhibits a colossal dielectric response. For the first time, we report on the colossal dielectric properties of polycrystalline and epitaxial thin film LSNO. We observe a significant polarization dependence on the microstructure due to the grain/grain boundary interaction with charged carriers. We next grew epitaxial films on various insulating oxide substrates in order to decouple the grain boundary interaction. Here we observed substrate dependent dielectric properties associated with induced strain. We also observe, due to the p-type carriers in LSNO, pn junction formation when grown epitaxially on the conducting oxide degenerate n-type Nb-doped \(SrTiO_3\). Finally we explore the growth mechanism of epitaxial LSNO as a function of high oxygen content. Due to the ability for LSNO to take in interstitial oxygen, a reoriented growth is observed at a critical thickness, thereby allowing us to vary anisotropy as a function of deposition conditions.Engineering and Applied Sciences
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Peelamedu, Ranganathan Ravip. "Effects of Deposition Temperature and Post Deposition Annealing on the Electrical Properties of Barium Strontium Titanate Thin Film for Embedded Capacitor Applications". Master's thesis, University of Central Florida, 2004. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2951.
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A higher degree of system level integration can be achieved by integrating the passive components into semiconductor devices, which seem to be an enabling technology for portable communication and modern electronic devices. Greater functionality, higher performance and increase in reliability can be achieved by miniaturizing and reducing the number of components in integrated circuits. The functional potential of small electronic devices can be enormously increased by implementing the embedded capacitors, resistors and inductors. This would free up surface real estate allowing either a smaller footprint or more silicon devices to be placed on the same sized substrate. This thesis focuses on the effect of deposition temperature and post deposition annealing (PDA) in different gas ambient on the electrical properties of sputter deposited ferroelectric Barium Strontium Titanate (Ba0.5St0.5) TiO3 thin film capacitors. Approximately 2000A of Barium Strontium Titanate (BST) thin film was deposited at different substrate temperatures (400,450,500 and 550[degrees]C) on cleaned silicon substrates. These BST films were then annealed separately in 100% N2, 100% O2 and 10% O2 + 90% N2 at 575[degrees]C in sputtering machine (PVD anneal) and a three zone annealing Lindberg furnace. The objective of this thesis was to compare the effect of PDA on the electrical properties of BST films deposited at different substrate temperatures between PVD annealing and furnace annealing. For this work, tantalum thin film was used as top and bottom electrode to fabricate the capacitors. BST thin film capacitors were fabricated and characterized for leakage current and dielectric breakdown. Roughness study on pre and post annealed BST films were done using optical profilometer. The capacitors were tested using HP impedance analyzer in the frequency range from 10Hz through 1 MHz. From the experiments, 100% O2 annealed furnace annealed BST thin film seem to have better dielectric constant, higher breakdown voltage and nominal capacitance density.M.S.E.E.
Department of Electrical and Computer Engineering
Engineering and Computer Science
Electrical Engineering
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Wang, Shu. "Experimental Investigation of New Inductor Topologies". University of Dayton / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1460733373.
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Sun, Jingyu. "Carbon nanotube growth on perovskite substrates". Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:2b77fe9b-7313-49b2-b490-70574b4af565.
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This thesis reports on the chemical vapour deposition (CVD) growth of carbon nanostructures (mainly carbon nanotubes (CNTs)) on perovskite oxide surfaces with the aid of various catalysts. Two types of perovskite oxide, single crystal SrTiO3 (001) and polycrystalline BaSrTiO3, have been used as catalyst supports (in metal-catalyst-involved CVD routes) or as catalysts (via metal-catalyst-free CVD routes) for the growth of carbon nanostructures. In metal-catalyst-involved cases, SrTiO3 (001) single crystal has been proven, for the first time, to serve as a substrate for the growth of CNTs. Fe and Ni catalysts can be tailored in a controllable manner on SrTiO3 (001) surfaces prior to the CNT synthesis, forming truncated pyramid shaped nanocrystals with uniform size distributions. The growth of vertically aligned CNT carpets was realised with the aid of Fe on SrTiO3 (001) surfaces, and it was further found that the CNTs grow via a base growth model. Furthermore, it is possible to grow helical carbon nanostructures on BaSrTiO3 substrates by introducing a Sn catalyst into the system. The synthesised helical carbon nanostructures follow a tip growth mode, where the structural and chemical aspects of catalyst particles gave rise to a wide range of carbon morphologies. CNTs were also grown on single crystal SrTiO3 (001) and polycrystalline BaSrTiO3 substrates via metal-catalyst-free routes. The surface-roughness-tailored growth of CNTs was surprisingly achieved on a series of engineered SrTiO3 (001) surfaces, where a correlation between the surface roughness/morphology of the substrates and the relevant catalytic activity was revealed. The growth of CNTs arises because the catalyst fabrication methods lead to the formation of SrTiO3 asperities with nanoscale curvatures, over which the CNTs are generated throughout a lift-off process. Facet-selective growth of CNTs was observed on polycrystalline BaSrTiO3 surfaces, where BaSrTiO3 (110) facets lead to the growth of CNTs on them, whereas the (001) facets result in no growth at all. This observation was further analysed in the content of the adsorption and diffusion of carbon species on distinct BaSrTiO3 facets, before reaching the conclusion that the formation of CNTs occurs through a metal-free, stack-up process driven by the assembly of the carbon fragments.
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Spatz, Devin. "Optimization of BST Thin Film Phase Shifters for Beam Steering Applications". University of Dayton / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1493299280169257.
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Midy, Jean. ""Etude de la croissance du titanate de baryum et de strontium en couches minces et de ses propriétés électriques sur une large gamme de fréquence"". Phd thesis, Université de Valenciennes et du Hainaut-Cambresis, 2012. http://tel.archives-ouvertes.fr/tel-00739398.
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Le titanate de baryum et de strontium (BaSrTiO3) est un matériau diélectrique de synthèse à forte permittivité possédant la propriété d'être accordable lorsqu'il est soumis à un champ électrique. Ceci est lié à sa structure cristalline à maille perovskite. Son intégration dans des dispositifs capacitifs est donc prometteuse pour l'industrie de la microélectronique. Il est déposé en couches minces par pulvérisation cathodique à partir de cibles pressées à froid au sein du laboratoire. L'étude de la croissance du matériau, dopé ou non, et de ses propriétés électriques à 100 khz ont permis d'envisager une montée en fréquence. Les évolutions de la permittivité diélectrique complexe et de l'accordabilité du matériau ont ainsi pu être étudiées sur un dispositif spécifique dans une gamme de fréquences allant de 1 à 60 ghz. L'utilisation d'un logiciel de simulation numérique par éléments finis (ELFI) dans le cadre de l'étude à haute fréquence permet de remonter aux caractéristiques propres du matériau, et ainsi d'interpréter plus finement les résultats issus de l'étude en basse fréquence. L'ensemble des connaissances acquises permet finalement de développer des dispositifs à capacité variable qui sont actuellement en cours d'élaboration au sein du laboratoire.
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Kumar, Manish. "High density and high reliability thin film embedded capacitors on organic and silicon substrates". Thesis, Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/26655.
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Thesis (M.S.)--Materials Science and Engineering, Georgia Institute of Technology, 2009.Committee Chair: Tummala Rao; Committee Member: Pulugurtha Raj; Committee Member: Wong C P. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Cure, David. "Reconfigurable Low Profile Antennas Using Tunable High Impedance Surfaces". Scholar Commons, 2013. http://scholarcommons.usf.edu/etd/4659.
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This dissertation shows a detailed investigation on reconfigurable low profile antennas using tunable high impedance surfaces (HIS). The specific class of HIS used in this dissertation is called a frequency selective surface (FSS). This type of periodic structure is fabricated to create artificial magnetic conductors (AMCs) that exhibit properties similar to perfect magnetic conductors (PMCs). The antennas are intended for radiometric sensing applications in the biomedical field. For the particular sensing application of interest in this dissertation, the performance of the antenna sub-system is the most critical aspect of the radiometer design where characteristics such as small size, light weight, conformability, simple integration, adjustment in response to adverse environmental loading, and the ability to block external radio frequency interference to maximize the detection sensitivity are desirable.
The antenna designs in this dissertation are based on broadband dipole antennas over a tunable FSS to extend the usable frequency range. The main features of these antennas are the use of an FSS that does not include via connections to ground, their low profile and potentially conformal nature, high front-to-back radiation pattern ratio, and the ability to dynamically adjust the center frequency. The reduction of interlayer wiring on the tunable FSS minimizes the fabrication complexity and facilitates the use of flexible substrates.
This dissertation aims to advance the state of the art in low profile tunable planar antennas. It shows a qualitative comparison between antennas backed with different unit cell geometries. It demonstrates the feasibility to use either semiconductor or ferroelectric thin film varactor-based tunable FSS to allow adjustment in the antenna frequency in response to environment loading in the near-field. Additionally, it illustrates how the coupling between antenna and HIS, and the impact of the varactor losses affect the antenna performance and it shows solutions to compensate these adverse effects. Novel hybrid manufacturing approaches to achieve flexibility on electrically thick antennas that could be transitioned to thin-film microelectronics are also presented.
The semiconductor and ferroelectric varactor-based tunable low profile antennas demonstrated tunability from 2.2 GHz to 2.65 GHz with instantaneous bandwidths greater than 50 MHz within the tuning range. The antennas had maximum thicknesses of λ/45 at the central frequency and front to back-lobe radiation ratios of approximately 15dB. They also showed impedance match improvement in the presence of a Human Core Model (HCM) phantom at close proximity distances of the order of 10-20 mm. In addition, the use of thin film ferroelectric Barium Strontium Titanate (BST) varactors in the FSS layer enabled an antenna that had smaller size, lower cost and less weight compared to the commercially available options.
The challenging problems of fabricating robust flexible antennas are also addressed and novel solutions are proposed. Two different types of flexible antennas were designed and built. A series of flexible microstrip antennas with slotted grounds which demonstrated to be robust and have 42% less mass than typically used technologies (e.g., microstrip antennas fabricated on Rogers® RT6010, RT/duroid® 5880, etc.); and flexible ferroelectric based tunable low profile antennas that showed tunability from 2.42 GHz to 2.66 GHz using overlapping metallic plates instead of a continuous ground plane. The bending test results demonstrated that, by placing cuts on the ground plane or using overlapping metallic layers that resemble fish scales, it was possible to create highly conductive surfaces that were extremely flexible even when attached to other solid materials. These new approaches were used to overcome limitations commonly encountered in the design of antennas that are intended for use on non-flat surfaces.
The material presented in this dissertation represents the first investigation of reconfigurable low profile antennas using tunable high impedance surfaces where the desired electromagnetic performance as well as additional relevant features such as robustness, low weight, low cost and low complexity were demonstrated.
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Pelegrini, Marcus Vinicius. "Deposição e caracterização de filmes de titanato de estrôncio e bário (Ba0,5Sr0,5(TiO3)) visando a sua utilização na fabricação de defasadores variáveis operando em 60 GHZ". Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/3/3140/tde-26082016-154730/.
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Este trabalho, realizado junto ao Grupo de Novos Materiais e Dispositivos (GNMD) pertencente ao Laboratório de Microeletrônica (LME) da Universidade de São Paulo, teve como objetivo correlacionar algumas propriedades físico-químicas de filmes finos de Ba1-XSrxTiO3 (BST), obtidos pela técnica de pulverização catódica reativa (sputtering), com os parâmetros de deposição, visando a fabricação de defasadores inteligentes operando em 60 GHz. Propriedades como cristalinidade e composição química foram estudadas e relacionadas com o tipo de substrato sobre o qual os filmes finos de BST foram depositados, e com os diversos parâmetros de deposição variados. Foi observada uma forte influência dos parâmetros de deposição, principalmente da temperatura e do tipo de substrato, na cristalinidade dos filmes. Os filmes depositados sobre cobre são mais cristalinos do que aqueles depositados sobre Si. Já a composição química dos filmes não variou significativamente, mantendo-se próxima à do alvo de sputtering utilizado, independentemente do substrato ou das condições de deposição. As propriedades elétricas dos filmes fabricados foram extraídas de capacitores de placas paralelas construídos utilizando o BST como dielétrico linear. As curvas de capacitância vs tensão a 1 MHz destes capacitores permitiram determinar uma variação de tunabilidade de até 44 %, para uma permissividade elétrica relativa de 310, valores estes compatíveis com aqueles encontrados na literatura. As propriedades elétricas dos filmes produzidos permitiram projetar um defasador de 1,3 mm2, com uma figura de mérito de 30º/dB para uma defasagem de 360º.This work, performed at the New Materials and Devices Group (GNMD) of the Microelectronics Laboratory of the Polytechnic School of the University of São Paulo, has the objective to correlate reactive sputtered-BST thin films to its deposition parameters, aiming to produce a 60 GHz tunable phase shifter. Thin film crystallinity and stoichiometry were correlated with sputtering deposition parameters and the type of substrate. A strong influence of the sputtering parameters was observed on BST crystallinity, mainly the temperature and the type of substrate. Thin films on copper are more crystalline than on Si (100). The stoichiometry, on the other hand, did not change as function of the deposition parameters or the substrate in both cases. The thin films electrical properties were obtained by capacitance vs voltage measurements, with the BST as linear dielectric of a parallel plate capacitor. The capacitors 1 MHz C-V characterization showed tunabilities as high as 44%, for an electrical permittivity of 310. These properties allowed a phase shifter project, resulting a 1,3 mm2 device with a figure of merit of 30 º/dB for 360 º phase shift.
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Rutkowski, Mitchell M. "Growth Parameter Dependence and Correlation of Native Point Defects and Dielectric Properties in BaxSr1-xTiO3 Grown by Molecular Beam Epitaxy". The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1366299175.
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Horikawa, Tsuyoshi. "A study of advanced integrated semiconductor device and process technologies for data storage and transmission". 京都大学 (Kyoto University), 2016. http://hdl.handle.net/2433/215222.
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Kim, Jang-Yong. "Processing and On-Wafer Test of Ferroelectric Film Microwave Varactors". Doctoral thesis, Stockholm : Information and Communication Technology (ICT), Kungl. Tekniska högskolan (KTH), 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4226.
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Shen, Ya. "BST-Inspired Smart Flexible Electronics". Doctoral diss., University of Central Florida, 2012. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5492.
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The advances in modern communication systems have brought about devices with more functionality, better performance, smaller size, lighter weight and lower cost. Meanwhile, the requirement for newer devices has become more demanding than ever. Tunability and flexibility are both long-desired features. Tunable devices are 'smart' in the sense that they can adapt to the dynamic environment or varying user demand as well as correct the minor deviations due to manufacturing fluctuations, therefore making it possible to reduce system complexity and overall cost. It is also desired that electronics be flexible to provide conformability and portability. Previously, tunable devices on flexible substrates have been realized mainly by dicing and assembling. This approach is straightforward and easy to carry out. However, it will become a “mission impossible” when it comes to assembling a large amount of rigid devices on a flexible substrate. Moreover, the operating frequency is often limited by the parasitic effect of the interconnection between the diced device and the rest of the circuit on the flexible substrate. A recent effort utilized a strain-sharing Si/SiGe/Si nanomembrane to transfer a device onto a flexible substrate. This approach works very well for silicon based devices with small dimensions, such as transistors and varactor diodes. Large-scale fabrication capability is still under investigation. A new transfer technique is proposed and studied in this research. Tunable BST (Barium Strontium Titanate) IDCs (inter-digital capacitors) are first fabricated on a silicon substrate. The devices are then transferred onto a flexible LCP (liquid crystalline polymer) substrate using wafer bonding of the silicon substrate to the LCP substrate, followed by silicon etching. This approach allows for monolithic fabrication so that the transferred devices can operate in millimeter wave frequency. The tunability, capacitance, Q factor and equivalent circuit are studied. The simulated and measured performances are compared. BST capacitors on LCP substrates are also compared with those on sapphire substrates to prove that this transfer process does not impair the performance. A primary study of a reflectarray antenna unit cell is also conducted for loss and phase swing performance. The BST thin film layout and bias line positions are studied in order to reduce the total loss. Transferring a full-size BST-based reflectarray antenna onto an LCP substrate is the ultimate goal, and this work is ongoing at the University of Central Florida (UCF). HFSS is used to simulate the devices and to prove the concept. All of the devices are fabricated in the clean room at UCF. Probe station measurements and waveguide measurements are performed on the capacitors and reflectarray antenna unit cells respectively. This work is the first comprehensive demonstration of this novel transfer technique.ID: 031001474; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Adviser: Xun Gong.; Co-adviser: Parveen Wahid.; Title from PDF title page (viewed July 15, 2013).; Thesis (Ph.D.)--University of Central Florida, 2012.; Includes bibliographical references (p. 129-144).
Ph.D.
Doctorate
Electrical Engineering and Computer Science
Engineering and Computer Science
Electrical Engineering
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Nadouf, Mohammed. "Synthèse et étude de poudres submicroniques de titanate de baryum et de ses solutions solides avec le strontium". Grenoble 2 : ANRT, 1986. http://catalogue.bnf.fr/ark:/12148/cb37599956b.
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Vykoukalová, Tereza. "Příprava a vlastnosti feroelektrických keramických materiálů". Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2012. http://www.nusl.cz/ntk/nusl-230401.
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The aim of the work was a processing of ceramic material based on BST for ferroelectric application. Wet chemical techniques based on precipitations and sol-gel methods with ultrasound, hydrothermal or mechanochemical treatment supporting deaglomeration and reducing particle growth were used for BST ceramic powder synthesis. Suitable powders were selected by the evaluation of particle morphology, size and agglomeration, from these powders BST bulk ceramic with defined phase composition and morphology applicable for ferroelectric applications was prepared. It was found, that the most suitable method for preparation of phase pure and nanosized BST powder was sol-gel synthesis with solvothermal treatment (200 °C/48 h). Ceramic with relative density of 85 % TD and with the average grain size of about 1, 22 µm was prepared by pressing and sintering of the powder synthesized by the sol-gel method.
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(7027682), Matthew J. Michie. "GRAIN GROWTH RATE TRANSITIONS IN BARIUM STRONTIUM TITANATE". Thesis, 2019.
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Understanding grain growth in dielectric ceramics is essential to controlling the electrical and mechanical properties necessary to produce ceramic capacitors and sensors. The effect of alloying barium titanate with strontium titanate on the equilibrium crystal shape was investigated in order to determine possible impacts on grain growth. The equilibrium crystal shape was studied through three experimental methods to identify possible changes in grain boundary energy or anisotropy with changing composition.
The first method was by imaging intergranular pores to observe faceting behavior and relative interfacial energies. Intergranular pores were reconstructed to determine the relative surface energies of the identified facets. The second method was to perform atomic force microscopy on surface facets to collect topography data. The topography data was combined with orientation data obtained by EBSD analysis from the same region, and used to calculate the normal vector of the surface facets. These datasets were plotted in a stereographic projection to study the faceting anisotropy. The third method involved collecting EBSD orientation data and images of surface faceting behavior. The surface faceting behavior of each grain was categorized by type of facet and plotted on a stereographic projection at the corresponding orientation. This allowed for the analysis of faceting transitions and the differentiation of faceted and continuous regions of the equilibrium crystal shape. The analysis of faceting behavior across compositions has implications on grain growth of the barium titanate/strontium titanate system.
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陳坤源. "Preparationand characterization of films and gels of barium titanate and strontium titanate". Thesis, 1988. http://ndltd.ncl.edu.tw/handle/66695120755301975476.
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LIU, YI-ZHENG, i 劉依政. "The PTCR properties of (barium-lead-strontium) titanate ceramics". Thesis, 1991. http://ndltd.ncl.edu.tw/handle/04603668200751545314.
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