Structure prototypes perovskite

First-principles calculations of formation energies of point defects were made on BaTiOs [723,724] and NaNbOs [725] crystals. Among the various fundamentally and technologically important oxides, SrTiOs is a simple structural prototype for many perovskites, in which the detailed investigation of native and dopant defects can lay the theoretical groundwork that can be applied to structurally and chemically more complex perovskite materials [726]. 

Figure 3.19 The structure of a prototypical perovskite ABO3. A and B cations are shown as large grey and small black spheres respectively...

The basic perovskite structure ABX3 forms the prototype for a wide range of other structures related to it by combinations of topological distortions, substitution of the A, B and X ions, and intergrowth with other structure types. These compounds exhibit a range of magnetic, electrical, optical, and catalytic properties of potential application in solid state physics, chemistry, and materials science. 

Perovskites have the general formula, ABX3, with SrTiCb being a prototype. They contain a framework structure containing corner-sharing TiC>6 octahedra with the A cation in twelve coordinate interstices.384,385 Several hundred oxides have this struc... 

Figure 22 Structures of members of the perovskite related series /4n5n03 + 2. (a) BaZnp4, the prototype of the A 2B20i (n = 2) oxides, and (b) Ca2Nb207 and other A B Oia. oxides in = 4)...

Here, R is the radius of the ions, and the subscripts A, B and O represent the corresponding ions in ABO3. This factor serves as a structure parameter to describe the extent of distortion of the perovskite structure from the ideal cubic prototype due to mismatch between the A-O and B-O bond lengths. Figure 2.10 shows the relationship of AHj n. the heat of formation of ABO3 from oxide precursors, to the perovskite tolerance factor, t. As indicated in Fig. 2.10, the stability of the perovskite structure increases as the tolerance factor increases towards 1, because... 

Barium titanate (BaTi03) is the prototype ferroelectric material. It has the ideal perovskite structure above 120°C. At temperatures below 120°C the small cation (Tf" ) shifts... 

Figure 93 Basic structural types of cuprate superconductors, (a) Perovskite structure (cubic) (b) Infinite- layered structure (tetragonal) (c) Rocksalt prototype structure (reduced cell) (d) Composite layer between infinite layer and rocksalt building blocks.

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