Temperature and composition dependent structural investigation of the defect perovskite series Sr1−xTi1−2xNb2xO3, 0≤x≤0.2
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Date
2010-09
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Publisher
Elsevier
Abstract
The crystal structure of the defect perovskite series Sr1−xTi1−2xNb2xO3 has been investigated over a range of temperatures using high-resolution synchrotron X-ray diffraction, neutron diffraction and electron diffraction. Three distinct regions were observed: 0<x≤0.125 was a solid solution of Sr1−xTi1−2xNb2xO3 with minor SrTiO3 intergrowth, 0.125<x≤0.2 was a pure Sr1−xTi1−2xNb2xO3 solid solution adopting the cubic perovskite type structure (Pm3¯m) and for x>0.2 Sr0.8Ti0.6Nb0.4O3 and Sr3TiNb4O15 formed a two phase region. The cubic structure for Sr0.8Ti0.6Nb0.4O3 was stable over the temperature range 90–1248 K and the thermal expansion co-efficient was determined to be 8.72(9)×10−6 K−1. Electron diffraction studies revealed diffuse scattering due to local scale Ti/Nb displacements and slightly enhanced octahedral rotations that did not lead to long range order. The octahedral rotations were observed to ‘lock-in’ at temperatures below ~75 K resulting in a tetragonal structure (I4/mcm) with anti-phase octahedral tilting about the c-axis. © 2010, Elsevier Ltd.
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Keywords
Perovskite, Crystal structure, Defects, Thermal expansion, Solid solutions, Phase transformations
Citation
Brant, W. R., Schmid, S., Gu, Q., Withers, R. L., Hester, J., & Avdeev, M. (2010). Temperature and composition dependent structural investigation of the defect perovskite series Sr1−xTi1−2xNb2xO3, 0≤x≤0.2. Journal of Solid State Chemistry, 183(9), 1998-2003. doi:10.1016/j.jssc.2010.06.002