A structural study of the perovskite series CaTi{sub 1{minus}2x}Fe{sub x}Nb{sub x}O{sub 3}
- Lakehead Univ., Thunder Bay, Ontario (Canada). Dept. of Geology
An X-ray powder diffraction study of the series CaTi{sub 1{minus}2x}Fe{sub x}Nb{sub x}O{sub 3} is presented. The series comprises orthorhombic perovskites (Pbnm, a {approx} b {approx} {radical}2a{sub p}, c {approx} 2a{sub p}, Z = 4) in the range 0 {le} x {le} 0.3, and monoclinic perovskites (P2{sub 1}/n, a {approx} b {approx} {radical}2a{sub p}, c {approx} 2a{sub p}, {beta} {ne} 90{degree}, Z = 4) in the range 0.4 {le} x {le} 0.5. The structure of the orthorhombic members is derived from the cubic aristotype by octahedral rotation a{sup {minus}}a{sup {minus}}c{sup +}. The structural distortion in the monoclinic members involves octahedral rotation and short-range cation ordering at the B-site (4c and 4d). In the series CaTi{sub 1{minus}2x}Fe{sub x}Nb{sub x}O{sub 3}, the unit-cell parameters and degree of octahedral rotation increase with x. The [111]{sub p} tilt angle increases from 16.1{degree} in CaTiO{sub 3} to 17.6--18.9{degree} in CaFe{sub 1/2}Nb{sub 1/2}O{sub 3} (for the NbO{sub 6} and FeO{sub 6} octahedra, respectively). In contrast to previous studies, here the diffraction pattern of the end-member CaFe{sub 1/2}Nb{sub 1/2}O{sub 3} is interpreted to exhibit splitting of the hkl and h0l lines indicative of a monoclinic derivative of the CaTiO{sub 3}-type structure.
- OSTI ID:
- 651122
- Journal Information:
- Journal of Solid State Chemistry, Vol. 138, Issue 2; Other Information: PBD: Jul 1998
- Country of Publication:
- United States
- Language:
- English
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