Добірка наукової літератури з теми "Relaxeur ferroélectriques"
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Статті в журналах з теми "Relaxeur ferroélectriques":
Ravez, J., and A. Simon. "Le premier relaxeur ferroélectrique oxyfluoré." physica status solidi (a) 159, no. 2 (February 1997): 517–22. http://dx.doi.org/10.1002/1521-396x(199702)159:2<517::aid-pssa517>3.0.co;2-o.
Ravez, Jean, and Annie Simon. "Ferroélectriques classiques ou relaxeurs dérivés de BaTiO3." Comptes Rendus de l'Académie des Sciences - Series IIB - Mechanics-Physics-Chemistry-Astronomy 325, no. 8 (October 1997): 481–86. http://dx.doi.org/10.1016/s1251-8069(97)89450-x.
Papet, P. "Effets de la taille des grains sur les propriétés diélectriques du relaxateur ferroélectrique Pb(Mg1/3Nb2/3)O3." Journal de Physique III 4, no. 7 (July 1994): 1189–96. http://dx.doi.org/10.1051/jp3:1994194.
Дисертації з теми "Relaxeur ferroélectriques":
Tellier, Jenny. "Sur les phases d'Aurivillius : études structurales et transitions de phases." Limoges, 2006. https://aurore.unilim.fr/theses/nxfile/default/dd157e3d-cbb2-4ec9-95b3-2e5100ed9b30/blobholder:0/2006LIMO0019.pdf.
Aurivillius phases, with general formula (Bi2O2)2+(Am-1BmO3m+l)2- can be ferroelectric or relaxor materials. They display orthorhombic symmetry at room temperature and tetragonal at high temperature. Structural study of ferroelectric and relaxor compounds at room temperature show that relaxors' structure is legs distorted than that of ferroelectrics. Their fluorite slabs are independent and contain non-bismuth cations. Disorder in relax ors is showed using TEM analysis. It leads to local variations of structure which can be responsible for relaxor behaviour. Phase transition study cannot be carried out systematically for such compounds. The case of SrBi2Ta2O9, SrBi2Nb2O9 and Bi4Ti2,8Cr0,2O12 is considered, and additional information is given about other Aurivillius phases
Laulhé, Claire. "Structure locale dans un ferroélectrique relaxeur : BaTi(1-x)Zr(x)O3." Phd thesis, Grenoble INPG, 2007. http://tel.archives-ouvertes.fr/tel-00196922.
Aydi, Abdelhedi. "Élaboration et caractérisations diélectriques de céramiques ferroélectriques et/ou relaxeur de formule MSnO3-NaNbO3(M = Ba,Ca)." Bordeaux 1, 2005. http://www.theses.fr/2005BOR12964.
The present work reports the elaboration process and physical investigation of ceramics belonging to the chemical systems NaNbO3-(Ba, Ca)SnO3. These materials are terefore free of lead and all poisonous elements in order to answer to the protective norms of the environment. The studied systems presnt some continuous solid solutions between the NaNbO3 antiferroelectric phase - that becomes easily ferroelectric by low rate substitutions and the paraelectric stannate phase. Two different dielectric behavior have been evidenced : ferroelectric and relaxor. According to the whole of studies done during this work one can confirm that caionic substitutions in the A site either in the B site of a perovskite ABO3 can modifiy the dielectric properties of the material. The introduction of Sn4+ cation in B sites favours a relaxor effect. The transition temperature should be modulatedd by varying the rate of cationic substitution. One can get so relaxor materials close to room temperature
AYDI, Abdelhedi. "Elaboration et caractérisations diélectriques de céramiques ferroélectriques et/ou relaxeur de formule MSnO3-NaNbO3(M=Ba,Ca)." Phd thesis, Université Sciences et Technologies - Bordeaux I, 2005. http://tel.archives-ouvertes.fr/tel-00009068.
Guerville, François de. "Films minces et superréseaux à base du ferroélectrique BaTiO3 et du relaxeur BaTi0,68Zr0,32O3 : élaboration, études par diffraction de rayons X et par spectroscopie Raman : modélisation des domaines ferroélectriques dans les films minces et les superréseaux." Amiens, 2008. http://www.theses.fr/2008AMIE0113.
This work deals with lead-free ferroelectric oxide thin films and superlattices, studied both experimentally (elaboration/characterization) and by modelling. In the experimental part, we have elaborated thin films and superlattices based on ferroelectric BaTiO3 and relaxor BaTi0. 68Zr0. 32O3 by pulsed laser deposition on MgO substrate buffered by La0. 5Sr0. 5CoO3. These samples were then studied by X ray diffraction and Raman spectroscopy in order to determine their structure, to estimate the stress therein and to evidence structural phase transitions. In superlattice, BaTiO3 layers show a quadratic ferroelectric structure with a1/a2 domains whereas BaTi0. 68Zr0. 32O3 layers are perpendicularly deformed to substrate plane. Dislocations appearance beyond a 260 Å critical period seems to relax these stresses. Against all expectations, superlattices Raman spectra have thinner lines than in films. We have attributed this phenomenon to a Ti4+ ion disorder decrease on the BaTiO3 perovskite structure B site. Temperature studies seem to show phase transition absence for BaTiO3 layers in superlattice. In addition, we have simulated thermodynamic and electric behaviour of ferroelectric domains in thin film and in ferroelectric/paraelectric superlattice. For this, we have modelled polarization profile taking into account finite size and interface effects, from 0 Kelvin to beyond phase transition temperature. We have shown nanometric thickness films properties are substantially modified by gradual polarization profile in these domains ; dielectric constant temperature evolution suits experimental behaviour observed around phase transition
Hentati, Mouhamed Amin. "Effets des inhomogénéités locales et des contraintes extérieures sur les propriétés diélectriques et structurales des monocristaux PZN-x%PT." Phd thesis, Châtenay-Malabry, Ecole centrale de Paris, 2013. http://tel.archives-ouvertes.fr/tel-01003354.
Dorcet, Vincent. "Etude de la relation entre structure et propriétés des pérovskites pseudo-cubiques du système Na0,5Bi0,5TiO3 – BiFeO3." Limoges, 2008. https://aurore.unilim.fr/theses/nxfile/default/add20181-deb8-407a-94b4-82709f0b469f/blobholder:0/2008LIMO4002.pdf.
The perovskite type compounds of the solid solution (1-x)Na0. 5Bi0. 5TiO3 (NBT) – xBiFeO3 (BF) were studied by transmission electron microscopy and impedance spectroscopy in order to decipher the origin of their dielectric and ferroelectric properties. The solid solution presents two distinct domains. Close to NBT (x < 0. 5), a first phase transition from the rhombohedral ferroelectric low temperature phase to an original orthorhombic one revealed for the first time, is achieved through a modulated phase that accounts for the antiferroelectric and the relaxor behaviours of NBT. The orthorhombic phase then evolves to a tetragonal one by a diffuse phase transition leading to a paraelectric state. Above x = 0. 5, the compounds behave as “normal” ferroelectrics. The relaxor behaviour is here due to the occurrence of oxygen vacancies arising as a consequence of the mix valence of iron atoms
Hornebecq, Virginie. "Nouveaux tantalates ferroélectriques de type bronze quadratique de tungstène : de la structure aux propriétés physiques." Phd thesis, Université Sciences et Technologies - Bordeaux I, 2000. http://tel.archives-ouvertes.fr/tel-00003498.
Aoujgal, Ahmed. "Etude des propriétés physico-chimiques et électroniques de matériaux ferroélectriques sous forme de céramiques et de films minces en vue d'applications radiofréquences et microondes." Littoral, 2010. http://www.theses.fr/2010DUNK0285.
The main objective of this work is to design, implement and optimize tunable materials for electronic applications at high frequencies. The easiest component to build on this study is the tunable capacitor with a voltage which can then be integrated into microwave devices such as tunable or reconfigurable resonators, filters, antennas. . . Etc. The capacitor can be either thin film or ceramic-based. To produce such components we must use materials which must have low dielectric loss, high dielectric permittivity, high tunability and stability of the resonant frequency of the capacitor with the temperature. For this, we conducted a detailed study of classical and relaxor ferroelectric materials in order, firstly to optimize the synthesis conditions, and secondly to improve their electrical properties for radiofrequencies and microwave applications. We have studied ferroelectric materials with perovskite phase, namely barium titanate strontium (BST) which is a classical ferroelectric and barium zirconium (BZT) which according to its composition can be a classical ferroelectric or relaxor ferroelectric and the derivatives of BaZr0. 1Ti0. 9O3 obtained by substituting bismuth and zinc-niobium respectively at A and B sites of the perovskite phase. We also synthesized and characterized the pyrochlore phase materials of bismuth zinc niobate, with composition of Bi1. 5ZnNb1. 5O7. The studies we have done range from the development of these materials in the form of ceramics and thin films, followed by characterizations to determine their physico-chemical properties, structural dielectric and ferroelectric in a range wide of frequencies and temperature
Castagnos, Anne-Marie. "Les relaxeurs ferroélectriques BaTi0,65 Zr0,35 O3 et Pb(1-x)BixMg(1+x)3Nb(2-x)/3O3(0< ou égalx." Toulouse 3, 2002. http://www.theses.fr/2002TOU30197.
Dielectric relaxation (frequency dispersion of the dielectric permittivity) is explained by the impossibility for the polar order to establish at long range. In PbMg1/3Nb2/3O3, this is attributed to a complex nanostructure where a local chemical order (ordering of the cations on the B site) coexists with a local polar order due to correlations of atomic displacements. These correlations expand up to a temperature known as freezing point, where they block. The Pb lone pair also plays a role in relaxation. In order to specify the role of each component, we have synthesised and studied the following relaxors. .