Results 271 to 280 of about 45,325 (317)
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Structure and Dynamics of Perovskite-Type Crystals
physica status solidi (b), 1968AbstractThe connection between Landau's theory of phase transitions and the lattice‐dynamical theory of a displacive transition in a crystal is discussed. At a second‐order displacive transition the frequency of one normal mode becomes zero. By investigating the displacements of the atoms from special positions of the lattice for a number of crystals ...
W. Cochran, A. Zia
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Methane combustion on perovskites-based structured catalysts
Catalysis Today, 2000Abstract LaMnO 3 perovskites supported on La stabilised γ-Al 2 O 3 and MgO have been prepared and characterised as methane combustion catalysts. XRD analysis, BET surface area results and H 2 TPR measurements have all revealed the presence of significant interaction between the perovskite and the alumina based support, which becomes very strong ...
S Cimino +4 more
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Synthesis and Structure of Perovskite ScMnO3
Inorganic Chemistry, 2013The rare-earth manganites RMnO3 (R = rare earth) are a class of important multiferroics with stable hexagonal structures for small R ion radius (Sc, Lu, Yb, ...). Metastable perovskite phases of these systems possess intriguing electronically driven electrical polarization, but the synthesis of the perovskite phase for the end member ScMnO3 system has ...
Haiyan, Chen +7 more
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Defect Structure of Nonstoichiometric Perovskite
Japanese Journal of Applied Physics, 1989The Po2 dependance on electrical conductivity and the oxygen diffusion in non-stoichiometric BaTiO3 and (Ba, Ca) TiO3 ceramics were investigated. It is confirmed that the electrical conductivity of A-site-excess specimen at high temperature is decreasing with decrease of oxygen pressure.
Hidenobu Kondou +3 more
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Optical modes of the perovskite structure
Journal of Physics and Chemistry of Solids, 1963Abstract The optical modes of the perovskite structure are characterized by the displacements of five inequivalent sublattices. The motion of these sublattices is completely determined by seven sublattice couplings. Neglecting the three smallest couplings, three of the remaining couplings can be determined from the observed optical frequencies of ...
R.I. Joseph, B.D. Silverman
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Spin and structural transitions in AlFeO3 and FeAlO3 perovskite and post-perovskite
Physics of the Earth and Planetary Interiors, 2010Abstract We extend the field of investigation of the perovskite to post-perovskite phase transition from the Earth's lowermost mantle with a study of the double substitution Mg + Si = Al + Fe. For this we use an advanced formalism within the density functional theory, the planar augmented wavefunction method, to investigate the perovskite and post ...
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Structural origin of relaxor perovskites
Journal of Physics and Chemistry of Solids, 1996Abstract Relaxor behavior of a diffuse phase transition and large frequency dispersion requires a small and broadly distributed activation barrier for interstate transitions. This can best be realized in a relatively random environment that apparently is provided by many complex perovskites, including those containing Pb. On the other hand, while the
Chen I-Wei, Li Ping, Wang Ying
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On the Structure of BaTl0.5Sb0.5O3: An Ordered Perovskite
Journal of Solid State Chemistry, 1997Abstract The structure of BaTl0.5Sb0.5O3has been investigated by powder X-ray diffraction. The profile refinement shows that the structure is of the (NH4)3FeF6-type, having a high degree of ordering between Tl and Sb, with the space groupFm 3 mand lattice parametera=8.3809(1) A.
W.T. Fu, D.J.W. IJdo
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Perovskite: The Electrically Active Structure
Ferroelectrics, 2009Metal oxides that have particularly strong electrical responses very frequently have the perovskite structure, or incorporate elements of that structure into more complex arrangements. These include ferroelectrics, piezoelectrics, and superconducting oxides. These structures often involve alternating layers in coherent, intergrowth patterns. It will be
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Defect structure in perovskite titanates
Current Opinion in Solid State and Materials Science, 1996Abstract Recent results have been obtained on the defect chemistry of perovskite ferroelectrics and have been applied to polarization fatigue in thin film ferroelectric memories, in other words the loss of switchable polarization after repeated switching cycles.
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