It is true that gallium ferrite has orthorhombic Crystal structure. But I have usually seen that ABO3 type compounds have perovskite structure. So why the difference?
It is true that some compounds having the ABO3 stoichiometry (or chemical formula) show the perovskite-type structure; but one should not confuse a structure type with a chemical formula. Otherwise, even nitric acid, HNO3 (and many other compounds) could also be called "perovskites"..., which does not make any sense.
It depends on the proportions of the ions radius . For the perovskite structure so called tollerance factor (1/(2^0.5))*(RA+RO)/(RB+RO) should be between 0.8 and 1.1.
Dear Vishesh Saxena
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A perovskite is any material with the same type of crystal structure as calcium titanium oxide (CaTiO3), known as the perovskite structure, or
XIIA2+VIB4+X2−3 with the oxygen in the face centers.
The general chemical formula for Perovskite compounds is ABX3, where 'A' and 'B' are two cations of very different sizes, and X is an anion that bonds to both.
The 'A' atoms are larger than the 'B' atoms. The ideal cubic-symmetry structure has the B cation in 6-fold coordination, surrounded by an octahedron of anions, and the A cation in 12-fold cuboctahedral coordination. The relative ion size requirements for stability of the cubic structure are quite stringent, so slight buckling and distortion can produce several lower-symmetry distorted versions, in which the coordination numbers of A cations, B cations or both are reduced. Natural compounds with this structure are perovskite, loparite, and the silicate perovskite bridgmanite.
In the idealized cubic unit cell of such a compound, type 'A' atom sits at cube corner positions (0, 0, 0), type 'B' atom sits at body centre position (1/2, 1/2, 1/2) and oxygen atoms sit at face centred positions (1/2, 1/2, 0). (The diagram shows edges for an equivalent unit cell with A in body centre, B at the corners, and O in mid-edge).
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This was copied from:
https://en.wikipedia.org/wiki/Perovskite_(structure)
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