The crystal structure of the B-site ordered complex perovskite Sr(Yb0.5Nb0.5)O3.
The room-temperature crystal structure of the B-site ordered complex perovskite strontium ytterbium niobate, Sr(Yb(0.5)Nb(0.5))O(3) [monoclinic, Z = 2, P2(1)/n (set 2), a = 5.79095 (8), b = 5.82210 (7), c = 8.20358 (12) Å, beta = 90.126 (1) degrees, with final R(wp) = 0.0595, R(Bragg) = 0.0203 for the neutron profile and R(wp) = 0.0832, R(Bragg) = 0.0193 for the X-ray profile, respectively], was determined by X-ray powder diffraction, high-resolution neutron powder diffraction and transmission electron microscopy. This compound shows a slight triclinic distortion from the prototype doubled cubic perovskite cell as a result of an a(-)a(-)c(+)-type oxygen octahedral tilting distortion. It is also shown that the site ordering of the different species of B-site cations, Yb(3+) and Nb(5+), inherently leads to a difference between the volumes of the YbO(6) and NbO(6) octahedra. This volume difference is shown to inevitably inhibit the rigid rotation of octahedra.
Department of Materials Science and Engineering, Korea Advanced Institute of Science and Engineering, Taejon, Korea.
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