Teses / dissertações sobre o tema "Ag₂Te"
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Kfouri, Charbel el. "Système Ag-As-Te diagramme de phases et matériaux vitreux /". Grenoble 2 : ANRT, 1988. http://catalogue.bnf.fr/ark:/12148/cb37614640f.
Texto completo da fonteAl, Hokayem Karen. "Synthèse électrochimique de nanostructures à base de tellure pour la conversion thermoélectrique". Electronic Thesis or Diss., Université de Lorraine, 2022. http://www.theses.fr/2022LORR0315.
Texto completo da fonteAmong the thermoelectric materials, tellurium has a high positive Seebeck coefficient (500 μV/K) at room temperature but with a relative high thermal conductivity (3 W/m.K). Nanostructuring is a solution to improve thermoelectric performances, as the lattice part of the thermal conductivity can be independently lowered. In this work, we synthesized self-standing Te nanostructures by electrodeposition technique, taking advantage of the templating properties of ionic liquids solvents. Single crystalline hexagonal nanostructures were systematically obtained with a preferential orientation along the [001] direction. By varying the conditions of electrodeposition, the size of nanostructures can be tuned. Finally, nanorods of 52 ± 11 nm in diameter and less than 300 nm long were grown by applying a small charge density. Tellurium nanorods were used as precursors of an additional synthesis step. Indeed, by simple redox reaction in Ag(I) or Cu(II) aqueous solution, Te nanostructures have been transformed into single crystalline nanorods Ag2+xTe and Cu1.75Te respectively. In the last part of the work, we tried to incorporate these nanostructures as well as graphene quantum dots in conductive polymer in order to realize flexible hybrid films. The latter should combine the interesting thermoelectric properties of the nanostructures and the low thermal conductivity as poly(3-hexylthiophene) (P3HT)
EL, KFOURI CHARBEL. "Contribution a l'etude du systeme binaire ag-as-te : diagramme de phases et materiaux vitreux". Paris 6, 1988. http://www.theses.fr/1988PA066225.
Texto completo da fontePerlt, Susanne. "Microstructure Analyses and Structure-Property Relationships of Ag(1-x)Pb(18)Sb(1+y)Te(20)". Doctoral thesis, Universitätsbibliothek Leipzig, 2013. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-114865.
Texto completo da fonteEddike, Driss. "Contribution à l'étude des systèmes Ag-Cu-Tl-Te et Cu-Bi-Se caractérisation thermoélectriques des matériaux /". Grenoble 2 : ANRT, 1987. http://catalogue.bnf.fr/ark:/12148/cb37604801w.
Texto completo da fontePerlt, Susanne [Verfasser], Thomas [Gutachter] Höche e Kornelius [Gutachter] Nielsch. "Microstructure Analyses and Structure-Property Relationships of Ag(1-x)Pb(18)Sb(1+y)Te(20) / Susanne Perlt ; Gutachter: Thomas Höche, Kornelius Nielsch". Leipzig : Universitätsbibliothek Leipzig, 2013. http://d-nb.info/1238367240/34.
Texto completo da fonteRoberts, Jordan. "Telluride mineralogy at the Deer Horn Au-Ag-Te-(Bi-Pb-W) deposit, Lindquist Peak, west-central British Columbia : implications for the generation of tellurides". Thesis, University of British Columbia, 2017. http://hdl.handle.net/2429/63390.
Texto completo da fonteScience, Faculty of
Earth, Ocean and Atmospheric Sciences, Department of
Graduate
Holder, David S. "Geological and geochemical controls for epithermal Au-Ag-Te (Pb-Zn) mineralisation at Coranda-Hondol and the Brad-Sacaramb basin mineral district of western Romania". Thesis, Kingston University, 2016. http://eprints.kingston.ac.uk/37305/.
Texto completo da fonteDjiba, Aliou [Verfasser], e Ulrich [Akademischer Betreuer] Bismayer. "Porphyrische Cu-Mo-Au-Re und epithermale Au-Ag-Te Vererzungen der Insel Limnos, nordöstliche Ägäis, Griechenland : Mineralogie-Mineralchemie der hydrothermalen Alterationen und damit verbundene Vererzungen / Aliou Djiba ; Betreuer: Ulrich Bismayer". Hamburg : Staats- und Universitätsbibliothek Hamburg, 2019. http://d-nb.info/1196296103/34.
Texto completo da fonteBruneau, Jean Michel. "Étude et réalisation de disques optiques ré-inscriptibles à changement de phase". Université Joseph Fourier (Grenoble ; 1971-2015), 1998. http://www.theses.fr/1998GRE10050.
Texto completo da fonteNai-Wei, Chang, e 張乃薇. "Konjac Films Containing Au/Ag-Te Nanotubes as Antibacterial Wound Dressings". Thesis, 2014. http://ndltd.ncl.edu.tw/handle/gsv854.
Texto completo da fonte國立臺灣海洋大學
食品科學系
102
Konjac glucomannan (KGM) had good swelling, water vapour transmission, non-cytotoxicity as well as provided wound healing on rat. However, it had not antibacterial property, so wound could not avoid infecting from bacterium. The aim of this study was to prepare KGM film which coupled into antibacterial agent, ‘gold/silver tellurium nanotube (Au/Ag-Te NT)’ for KGM film. We evaluated the Au/Ag-Te NT KGM film for antibacterial properties, cytotoxicity, blood clotting and wound healing. Au/Ag-Te NT produced Reactive oxygen species (ROS). The structure of Au/Ag-Te NT was rod shape composed by Ag/Te and a circle granule Au on the middle area, element analysis revealed that Au formed on the middle area. The X-ray diffraction (XRD) study revealed the major crystal facets for Au/Ag-Te NT at [101], [220] and [221]. The antibacterial test suggested when concentration of Au/Ag-Te NT KGM film higher than 3.40 μg/cm2 showed a good antibacterial property for Staphylococcus aureus and Pseudomonas aeruginosa, and in vitro test revealed that concentration lower than 3.40 μg/cm2 showed a good biocompatibility for L-929 mouse fibroblasts and HaCaT human keratinocyte, while cells attached Au/Ag-Te NT KGM film by pseudopodia. Au/Ag-Te NT KGM film also promoted blood clotting from clotting assay. In addition, Au/Ag-Te NT added did not influence physical properties of KGM film. In vivo test showed that Au/Ag-Te NT KGM film provided a significant higher percentage of wound closure compared with untreated control group and commercial dressing group in the 3rd , 7th and 10th day. Furthermore, histological examination demonstrated significantly advanced granulation tissue, angiogenesis and collagen formation in the 7th, 14th and 21st day. Histologic section revealed the granulation tissue and angiogenesis for Au/Ag-Te NT KGM film at early stage of wound healing in the 3rd and 5th day. These results suggested that Au/Ag-Te NT KGM film had good antibacterial property, biocompatibility, also promoted blood clotting and wound healing. It could be applied as a potential material of wound dressing.
邱國峻. "Phase equilibria and liquidus projection of thermoelectric Ag-Sn-Te alloys". Thesis, 2012. http://ndltd.ncl.edu.tw/handle/91584058465062117914.
Texto completo da fonteShen, Jun. "Untersuchungen in ternären chalkogenhaltigen Systemen Ag-Ga-Te und Sn-Sb-Se". Doctoral thesis, 2003. https://repositorium.ub.uni-osnabrueck.de/handle/urn:nbn:de:gbv:700-2003021919.
Texto completo da fonteLi, Cheng Tang, e 李丞唐. "Electromigration and thermoelectric transport properties of Ag-doped Bi-Sb-Te systems". Thesis, 2016. http://ndltd.ncl.edu.tw/handle/37625598679098543952.
Texto completo da fonte國立清華大學
材料科學工程學系
104
Bismuth telluride based compounds have been widely employed in commercial thermoelectric cooling/generation devices owing to their decent thermoelectric properties near room temperature regime. Some trace elements, such as iodine, silver and copper, are commonly added to modulate transport properties of bismuth telluride based compounds. In addition, the figure of merit of thermoelectric materials can be effectively promoted by electrical stressing. In this study, Ag elements were driven into a piece of Bi0.5Sb1.5Te3 sample in contact to a silver foil when applying a high density of electric current at elevated temperature. We demonstrate that Ag concentration profile can be tailored unidirectionally by electrical stressing. The evolution of Ag concentration profile was measured by energy dispersive spectroscopy and modeled based on an electromigration-enhanced diffusion mechanism. It is found that the supersaturated Ag may react with excess Te by forming Ag2Te secondary phase near the grain boundaries. With continuous electrical stressing, Ag2Te will be decomposed by hole wind force. These Ag elements migrate from anode side to cathode side of the Bi0.5Sb1.5Te3 sample under an electric field and a hole wind driving force simultaneously. Due to multiple Ag defect sites, such as interstitials, Sb lattice and grain boundaries, Ag atoms may migrate through different paths and lead to a superposition of different diffusion pockets. A physical mechanism is proposed to explain the evolution of Ag concentration profiles in the electrically stressed Bi0.5Sb1.5Te3 compounds. The effects of electrical stressing and Ag doping on the defect mechanism and thermoelectric transport properties of Bi0.5Sb1.5Te3 compounds are investigated.
Huang, Yen-Chun, e 黃彥鈞. "A study of interfacial reaction between molten Sn-Ag solder and Te substrate". Thesis, 2009. http://ndltd.ncl.edu.tw/handle/76539270100174568164.
Texto completo da fonte國立清華大學
材料科學工程學系
97
Telluride-based thermoelements can react with Sn-contained solders and form SnTe intermetallic compounds that may deteriorate electrical and mechanical properties of soldered junctions. In addition to the diffusion barrier approach, chemical composition of the solder alloys could be adjusted to suppress or decrease the rate of SnTe formation. In this study the effects of Ag addition (0.1, 1, 3.5, 5 wt.%) in pure Sn on the interfacial reaction between molten solder and Te substrate is explored. It is found that the thickness of SnTe compound is reduced after soldering reaction when more than 1 wt.% Ag is added into Sn solder. For an identical time of 300 minutes, the SnTe thickness is decreased from 570 �慆 for a pure Sn and Te reaction to only 11 �慆 for a Sn-Ag alloy and Te reaction. The suppression of SnTe compound formation is associated with the presence of Ag3Te2 and Ag2Sn3Te5 ternary compounds that are located in between the SnTe compound and the Te substrate. However, the rate at which SnTe initially forms is enhanced as the formation of SnTe originates from two different sources: byproduct of molten solder and Te substrate (Ag3Te2 and SnTe) and excess SnTe when Ag3Te2 further reacts with Sn in the solder (Ag2Sn3Te5 and SnTe). When the thickness of SnTe remains essentially constant, SnTe undergoes a conservative ripening, resulting in surface roughening. Based on top-view scanning electron microscopy micrographs, it is calculated that SnTe particles size increase approximately with the cube root of reaction time.
Chen, Yi-Ming, e 陳怡名. "Effect of Ag,Cu Doping on Erasable Phase-Change Sb-Te Thin Films". Thesis, 1997. http://ndltd.ncl.edu.tw/handle/40367923400714872310.
Texto completo da fonte國立臺灣大學
材料科學與工程學研究所
85
Evaporated binary chalcogenide Sb-Te thin films withAg(0 ∼11.4 at%), Cu(0∼10.8 at%) addition were investigated. The crystallization process of these (Sb-Te)-based amorphous films were investigated by isothermally treated at 100℃, 200℃and 300℃, respectively.The structure of these alloy films was confirmed by X-ray diffraction(XRD), Tx and Tm were mea- sured by differential scanning calorimetry(DSC), and the microstructures were observed by transmission electron microscopy(TEM). The reflectivities of these films were measured by spectrophotometer. We found that all of the as-deposited films had an amorphous structure with many naro-crystallines particles, and the crystallization temperature (Tc) of Ag8.3Sb34.9Te56.8 and Cu10.8Sb33.2Te56.0 were more than125℃,172℃, respectively. It indicates that doping Ag or Cu can improve the room temp- erature stability of Sb-Te alloy films. The contrast ratio of as-deposited Ag3.2Sb35.8Te61.0 and Cu4.1Sb37.4Te58.5 are more than 42% and 37% after isothermally treated at 300℃. It indicates that these compositions will be suitable for phase change optical recording materials.
Kuo, Po-Wei, e 郭柏瑋. "Properties of hot-pressed Bi-Sb-Te compounds with non-uniform Ag doping". Thesis, 2013. http://ndltd.ncl.edu.tw/handle/93368320939100611493.
Texto completo da fonte國立清華大學
材料科學工程學系
101
Thermoelectric materials that can convert thermal energy to electric energy and vice versa have been applied in applications of waste-heat recovery and refrigeration. In most thermoelectric devices, the directions of temperature gradient and electric field are the same. In this research, a longitudinal temperature gradient introduces a lateral electric field, which is called transverse Seebeck effect, has been found in hot-pressed Bi0.4Sb1.6Te3 sample with non-uniform Ag doping. The property of uncoupling heat flow and electric flow directions may provide ideas of developing different device applications. The thermoelectric properties of both Ag-doped and non-doped Bi-Sb-Te samples have been determined experimentally. The transverse Seebeck effect has been found in non-uniform Ag doping sample with asymmetric transverse voltage in hot side and cold side by a self-designed transverse Seebeck measurement apparatus. The experimental and simulation results shows that transverse Seebeck effect should have been referred to different voltage drops between Ag-doped region and non-doped region. Asymmetric transverse voltage may be related to larger charged carrier flow at high temperature side, which has been expressed as an empirical term jemp in simulation. The experimental and simulation results have applied a preliminary model of transverse thermoelectric effect specimen fabrication. The transverse Seebeck coefficient has reached 120 μV/K in simulation.
Wu, Chen-Chi, e 吳鎮吉. "Thermoelectric transport properties of Bi-Te based thin films with Ag overlaid junction structure". Thesis, 2014. http://ndltd.ncl.edu.tw/handle/40204414808667052315.
Texto completo da fonte國立清華大學
材料科學工程學系
102
Bismuth telluride has been considered as a promising candidate for thin-film thermoelectric (TE) devices due to its superior thermoelectric properties at room temperature regime. Generally, a good thermoelectrics requires a large Seebeck coefficient, a high electrical conductivity and a low thermal conductivity, which can be achieved by optimization of carrier concentration. In this study, both P-type Bi-Sb-Te and N-type Bi-Se-Te thin films were deposited on polyimide substrates by RF magnetron sputtering. A step-like Ag overlayer was evaporated partially on top of the TE films using e-gun deposition. Silver atoms were driven into the TE films by thermal annealing to form a non-uniform doping profile. The research goal is to investigate the effect of Ag doping on thermoelectric transport properties of P- and N-type Bi-Te thin films. The results show that Ag elements have non-uniform distributions in both in-plane and out-of-plane directions of TE thin films. The Ag doping results in 4.7 times increase of carrier concentration in P-type films and 1.75 times increase in N-type films. It suggests that AgSb acceptor-like defects provide large amount of hole carriers in P-type films, while the excessive Te atoms occupy Bi site by forming TeBi donor-like defects counterbalances the contribution of AgBi defects in N-type films. The scanning Seebeck results reveal an asymmetric Seebeck effect in the P-type films. The P-type films with Ag doping achieve a maximum Seebeck coefficient of 285 µV/k, an output current of 5.41 µA and a power density of 10.5 nW/cm2 when heat flows in the direction from high to low doping region of P-type films with a distance between two probes of 5.3 mm. The N-type films with Ag doping do not show obviously asymmetric effect, which is likely attributed to small difference in carrier concentration between doped and non-doped region.
郭文源. "Study on cyclability and stability of Ag-In-Sb-Te material based compact disc". Thesis, 2000. http://ndltd.ncl.edu.tw/handle/92580191875885542994.
Texto completo da fonteCho, Yen-Te, e 卓岩德. "Phase Diagrams of Ternary Ag–Ga–Te System and Thermoelectric Properties of Chalcopyrite AgGaTe2". Thesis, 2016. http://ndltd.ncl.edu.tw/handle/98085113923638142501.
Texto completo da fonte國立中山大學
材料與光電科學學系研究所
104
Thermoelectricity converts waste heat into electricity directly and reversibly. Ag-Ga-Te ternary system is a promising thermoelectric system, mainly due to the p-type chalcopyrite AgGaTe2. The peak zT(figure-of-merit) value of AgGaTe2 is around 1.2 at the region of 600-800oC. Phase diagram provides materials’ fundamental information, and is important for understanding the phase relations and controlling the microstructures. However, for the Ag-Ga-Te system, only limited information is available. This study is keen to determine the phase relations of Ag-Ga-Te system at 650oC,including: (1) experimentally determine the isothermal section of Ag-Ga-Te system at 650oC by thermally annealing ternary Ag-Ga-Te alloys, (2) experimentally determine the liquidus projection of Ag-Ga-Te system by directly air-cooling or water-quenching ternary Ag-Ga-Te alloys (3) synthesize ternary Ag-Ga-Te alloys with specific composition and measure the thermoelectric properties such as Seebeck coefficient, electrical resistivity and thermal conductivity at elevated temperatures. The homogeneity region of the ternary compound AgGaTe2 at 650oC as well as its primary solidification region are mapped. Moreover, the liquidus projection of Ag-Ga-Te system contains two miscibility gaps that originated from its constituent Ag-Te and Ga-Te systems, and is found to be divided by primary solidification phases Ag2Te, AgGaTe2 and Ag2Ga.
Wang, Cha-Han, e 王嘉宏. "Study on cyclability and Stability of Ag-In-Sb-Te material base phase change disc". Thesis, 2001. http://ndltd.ncl.edu.tw/handle/91855890706240981281.
Texto completo da fonte國立清華大學
電子工程研究所
89
Base on the repeatable、convenient、high storage capacity,and the low cost cause of the mass mass production,the phase change optic disc already become the major high storage capacity media, obviously. And recently, the DVD system was developed very fast,the high storage density was the major trend of the phase change optic disc. The Ge-Sb-Te material system can’t follow this trend, this is also why we choose the Ag-In-Sb-Te material system. But the Ag-In-Sb-Te material system was found the cyclability only have 103 times, evident that this system’s cyclability is lower than former system’s. According to literatures, the reason of cyclability can’t be promoted were very mush, and we aimed at the phase segregation of Te, to study how the improve this problem. We try to used the way whose address in literatures, when sputtering the Ag-In-Sb-Te target mixed the nitrogen gas, promoted the Te and N bond together. The fetter force would confine Te not to segregated self, to achieve our purpose. More advance, we didn’t use the RF power in Sputter chamber to decompose nitrogen, we decompose the nitrogen molecule directly by microwave outside the chamber, attempt to decompose the nitrogen molecule become atomic nitrogen to promote the bonding probability and it’s efficiency. We using the results of DSC analysis to operated by Kissinger equation to prove the method of Microwave enhance N2 atoms increase the activation energy of recroding layer approximately 0.3~0.6 eV, and the Absorbance results of FTIR measure to prove the Te-N bond increase. In cyclability, a four layer structure of the phase chage disc used in the analysis is polycarbonate substrate / ZnS:SiO2 100nm / Ag-In-Sb-Te 200nm / ZnS:SiO2 180nm/ Al-Cr 100nm. The results of the disc dynamic test also observe our Microwave enhance N2 atoms method was 3times than the RF enhance N2 molecule method at cyclability.
Lu, Shih-Liang, e 古士良. "Study on Ag-In-Sb-Te optical phase change recording material for erasable optical disk". Thesis, 1999. http://ndltd.ncl.edu.tw/handle/95561921919930111898.
Texto completo da fonte國立清華大學
物理學系
87
Aiming to obtain high density of directly overwritable optical discs, the optical phase change material has been studied. Ag-In-Sb-Te multinary alloy is one of the most investigated materials as phase change recording media. In this work, all films were deposited by R. F. magnetron sputtering. Ag-In-Sb-Te recording film was sandwiched between two ZnS 80 — SiO2 20 at % layers. And the layer structure of the phase change disc used in the experiment is polycarbonate substrate / ZnS:SiO2 115 nm / Ag-In0Sb-Te 20 nm / ZnS:SiO2 15 nm / Al 120 nm which is determined by optical and thermal simulation.The composition of the Ag-In-Sb-Te alloy films was measured by inductively coupled plasma atomic emission spectroscopy (ICP-AES), and the crystalline temperature of the thin films was analyzed by differential scanning calorimetry (DSC). Characterization of the crystalline structure had been performed using X-ray diffraction analysis and scanning electron microscopy. The optical properties were determined using optical spectrometer in the wavelength range from 400 to 850 nm. A higher carrier-to-noise ratio was obtained. The results indicates that Ag-In-Sb-Te based optical phase change discs could be a promising candidate for high density rewritable disc system.
Chien, Chia-Hua, e 錢佳華. "The synthesis and thermoelectric properties of Bi-Sb-Te nanowire and Ag doped SnSe nanocrystals". Thesis, 2017. http://ndltd.ncl.edu.tw/handle/g7nm34.
Texto completo da fonte國立清華大學
工程與系統科學系
106
Thermoelectric applications have attracted increasing interest recently due to its capability of converting waste heat into electricity without hazardous emissions. Compare with the bulk materials, many researches have been able to experimentally reveal that physical properties were different in low dimensional materials. In nanoscale, the enhancement of the thermoelectric efficiency by the reduction of lattice thermal conductivity (κph) due to phonon blocking. In addition, tuning the position of Femi level to achieve the optimum power factor (σα2) by doping concentration effect is another strategy to improve the zT value. In this thesis, we have synthesized the high quality and large-scale nanomaterials based on the mentioned concept and divided into two systems to investigate the thermoelectric properties. In the first part, the thermoelectric properties of a Bi0.8Sb1.2Te2.9 nanowire (NW) were in-situ studied as it was trimmed from 750 down to 490 and 285 nm in diameter by a focused ion beam. While electrical and thermal conductivities both indubitably decrease with the diameter reduction, the two physical properties clearly exhibit different diameter dependent behaviors. The much lower thermal conductivities were observed as compared with the theoretical prediction of Callaway model. The consequence indicates that in addition to the size effect, extra phonon scattering of defects created by Ga ion irradiation was attributed to the reduction of thermal conductivities. The size dependence of Seebeck coefficient and figure of merit (zT) show the maximum at 750 nm, then decrease linearly with size decrease. The study not only provides the thoroughly understanding of the size and defect effects on the thermoelectric properties but also proposes a possible method to manipulate the thermal conductivity of NWs via ion irradiation. In the second part, A two steps, surfactant-free solution growth process was utilized to synthesize p-type Ag doped SnSe nanocrystals in gram quantities. The formation mechanism of SnSe nanocrystals studied by the high resolution transmission electron microscopy. A clear phase transition near 800 K was discovered in the temperature dependence of thermal conductivity. The thermoelectric properties of SnSe pellets prepared by spark plasma sintering, exhibit a significant increase of zTmax (0.8 at 850 K) in the 3 % Ag doped SnSe. The zTmax value is about 40 % higher than that of the prinstine SnSe. The consequence is mainly attributed to the enhancement of carrier concentration and power factor by Ag doping. Our results demonstrate that this facile chemical method is amenable to fabricate high quality SnSe nanocrystals and might also be applied to other anisotropic crystalline materials.
Shen, Jun [Verfasser]. "Untersuchungen in ternären chalkogenhaltigen Systemen Ag-Ga-Te und Sn-Sb-Se / eingereicht von Jun Shen". 2001. http://d-nb.info/97038033X/34.
Texto completo da fonteLin, Yu-Chu, e 林育竹. "Thermoelectric properties of Bi-Sb-Te and thermal conductance of Au-X-Al2O3(X=Ag,In)". Thesis, 2012. http://ndltd.ncl.edu.tw/handle/94360169401489861673.
Texto completo da fonte國立中央大學
物理研究所
100
Thermal property plays an important role in the characteristic of bulk materials, the measurement is necessary to understand the underlying physics that leads to certain phenomena. However, the accurate measurement and characterization of thermal property of bulk materials can pose many challenges. In order to improve and modify the measurement of thermal property, two investigations of different region have been reported in this thesis. A thermal rectifier is the heat transfer analog to the familiar electrical diode. And thermal rectification is very interest because of its potential to open up new ground for the control of heat transport. In the first study, the thermal rectification in a two–terminal bulk material has been measured. We have prepared pure metal, Au, and polycrystalline insulator, Al2O3, as the two-terminal bulk material which glued with Ag paste and ductile indium wire. Hereby, we made an experimental system (steady state method) which is essentially a measurement of the heat flow through the sample to detect the thermal rectification. The observed thermal conductance of Au-X-Al2O3 (X=Ag, In) in the forward and reverse direction is no rectifying effect with the temperature difference of 10 K between heat baths. We have calculated thermal rectification using thermal conductivity data and found that the calculation is in discordancy with experimental data. In the second study, thermoelectric materials have great potential for use in solid-state power generation and cooling devices. These devices have numerous advantages over conventional methods, but they are not widely used today is because of the poor efficiency. Much of the effort in the thermoelectric field has been directed at improving the efficiency of thermoelectric devices. In order to improve the efficiency of these devices, solid understanding on the properties of the materials from which they are made is required. This usually involves extensive measurement of the thermal and electrical properties of the material. In many cases, the measurement of characteristics of bulk materials is necessary to understand the underlying physics the leads to certain phenomena. Measurement of the properties of bulk material often involves working with specific samples because of synthesis of bulks materials. The measurement of the thermal conductivity of the specific size samples has been a little bit formidable challenge for many years due to the low thermal conductance and the low mechanical strength of the sample. One of the methods developed to address this problem is the steady state method. The steady state method was modified and the results and description of the modified technique are presented in this thesis. Improvements were made to the sample stage and measurement system. The system was evaluated with standards to confirm the validity of the measurements. Investigation of thermoelectric material, the thermal conductivity of CuxBi0.5Sb1.5Te3 (x=0.01) at room temperature is 1.25 W/m-K by steady state method. In addition, the Seebeck coefficient measurement was already established, and the sample stage and measurement are similar to the steady state method. However, our research included an investigation of all properties of thermoelectric materials of CuxBi0.5Sb1.5Te3, and the figure of merit (ZT) has been reported.
吳欣潔. "Phase equilibria, microstructures and thermoelectric properties of the quaternary Pb-Ag-Sb-Te thermoelectric material system". Thesis, 2012. http://ndltd.ncl.edu.tw/handle/01320463603103743597.
Texto completo da fonte國立清華大學
化學工程學系
101
Thermoelectric material has been recognized as a promising candidate in the application of sustainable energy. The quaternary Pb-Ag-Sb-Te system has attracted much attention because it contains high-zT AgPb18SbTe20 (zT>2 at 800K), PbTe and AgSbTe2. The phase stability, microstructural evolution and resultant electrical/thermal transport properties of quaternary Pb-Ag-Sb-Te and the constituent systems (Ag-Sb-Te, Pb-Sb-Te and Ag-Pb-Te) are investigated. The liquidus projections of both ternary Ag-Pb-Te and Pb-Sb-Te systems are constructed. In particular, the Ag-Pb-Te ternary-eutectic alloy, with composition of Ag-4.3at%Pb-62.6at%Te, forms a partially aligned nano-sized lamellar microstructure, which comprises both the PbTe and Ag5Te3 phases, and an additional dotted PbTe of 200-600nm. This particular ternary-eutectic alloy is unidirectionally solidified using the Bridgman method, resulted in a nanostructured composite with an extremely low thermal conductivity(κ) of 0.3 W/mK and a zT peak of 0.41 at 400K. The phase diagrams of ternary Ag-Sb-Te system are constructed as well, including the 400℃ and 250℃ isothermal sections and the liquidus projection. The ternary AgSbTe2 is stabilized at 400℃ but not at 250℃, with homogeneity region of 49.0-53.0at%Te and 28.0-30.0at%Sb. The nano-scaled microstrucutre and crystal structures of the non-stoimeteric AgSbTe2 are analyzed by the transmission electron microscope (TEM). In particular, an ordered array of nano-wire microstructure, comprising a 200nm Ag2Te and a matrix of AgSbTe2+δ-Sb2Te, was resulted from a Class I reaction: L=AgSbTe2+Ag2Te+δ-Sb2Te with liquid composition of Ag-40at%Sb-36.0at%Te at 496.5℃. To understand and guide production of uniform bulk samples of this composite, the liquidus projection of quaternary Pb-Ag-Sb-Te system at 36.0at%Te isoplethal section is constructed experimentally using quenched samples. High-resolution transmission electron microscopy (TEM) confirms that these three phases are simultaneously present at the nanometer scale. Furthermore, unidirectional solidification experiments of the ternary eutectic alloy using the Bridgman method are carried out to examine the alloy's solidification behaviors. Pb-alloyed AgSbTe2 (PbxAg20Sb30-xTe50, x=3,4,5 and 6) are also unidirectionally solidified using the modified Bridgman method. The as-solidified 5at%Pb and 6at%Pb alloys, which exhibit high phase purity of AgSbTe2, contain grain-boundary inhomogeneity and nano-precipitates of δ-Sb2Te, leading to an extremely low thermal conductivity (κ) of 0.3-0.4 W/mK. A peak zT of 0.7-0.8 is found in as-solidified 5at% specimen at 425K. However, after annealing at 673K, the zT peak of 5at%Pb(annealed) decreases to 0.4, presumably due to increase in grain size and decrease in inhomogeneity.
Perlt, Susanne. "Microstructure Analyses and Structure-Property Relationships of Ag(1-x)Pb(18)Sb(1+y)Te(20)". Doctoral thesis, 2012. https://ul.qucosa.de/id/qucosa%3A11961.
Texto completo da fonteLai, Hung-Chung, e 賴宏忠. "Effects of Silver Content on the Phase Stability and Optical Properties of Ag-In-Sb-Te Recording Material". Thesis, 2004. http://ndltd.ncl.edu.tw/handle/40786426739252678875.
Texto completo da fonte國立成功大學
材料科學及工程學系碩博士班
92
This study aims to prepare Ag-In-Sb-Te amorphous thin films with various Ag contents by sputtering and investigates the effect of Ag content on the phase stability and optical properties. In order to evaluate the phase stability of amorphous films, differential Scanning Calorimeter(DSC) is applied to examine the exothermic behavior of crystallization under different heating rates. Also, the Kissinger method is used to calculate the activation energy for crystallization. The results show that an increase in Ag content causes a higher activation energy, and thus makes the crystallization process more difficult. This implies that increasing Ag content can improve the phase stability of Ag-In-Sb-Te amorphous films. The results of phase analysis by X-ray diffraction show that after the crystallizing heat treatment held at different temperatures (160 oC、180 oC、200oC、250 oC、300 oC), the microstructure of the Ag-In-Sb-Te films is a mixture of Sb and small amount of AgInTe2. Notably, AgInTe2 can not be detected in the 6 Ag and 13Ag specimens suffering the heat treatment at 200oC. Optical properties of the films with amorphous and crystallized states are also investigated. The results indicate the reflectivity of the amorphous of 6Ag and 13Ag films are similar but 8Ag specimen is lower others, however, those of the crystallized films decreases in turn from 6Ag, 8Ag and 13 Ag. Therefore, reflectivity contrast of the 8Ag sample is greater than that of the 6Ag specimen, which is in turn greater than that of the 13Ag specimen. From the aforementioned properties, this study proposes that the Ag-In-Sb-Te thin film with the Ag content of 8 at%, which possesses appropriate phase stability and superior optical performance, is recommended for application as the recording material for CD-RW disc.
張莨鈞. "Liquidus projections of the Se-Sb-Te ternary thermoelectric material system and the Ag-In-Se ternary solar energy material system". Thesis, 2014. http://ndltd.ncl.edu.tw/handle/99501915147636745847.
Texto completo da fonteLakshmi, K. P. "Studies on Si15Te85-xGex and Ge15Te85-xAgx Amorphous Thin Films for Possible Applications in Phase Change Memories". Thesis, 2013. http://etd.iisc.ac.in/handle/2005/3359.
Texto completo da fonteLakshmi, K. P. "Studies on Si15Te85-xGex and Ge15Te85-xAgx Amorphous Thin Films for Possible Applications in Phase Change Memories". Thesis, 2013. http://etd.iisc.ernet.in/2005/3359.
Texto completo da fonte