Spontaneous strain of conductive strontium titanate Sr₁₋ _x La _x TiO₃ measured by using X-ray topographic domain contrast

Author： Ozaki T. Kusunose K. Yamaguchi H. Kajiwara K. Chikaura Y.

Publisher： Taylor & Francis Ltd

ISSN： 0141-1594

Source： Phase Transitions: A Multinational Journal, Vol.84, Iss.9-10, 2011-09, pp. : 837-842

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Abstract

We have measured the spontaneous strain c/a − 1 of the antiferrodistortive phase transition in the conductive strontium titanates Sr₁₋ _x La _x TiO₃ with x = 0, 0.005, 0.010, and 0.050 by using X-ray topographic domain contrast. We have found that the substitution of a small amount of La³⁺ ions into SrTiO₃ leads to the large increase of the phase transition temperature T _a, the saturated spontaneous strain (c/a − 1)_s, and the saturated order parameter Φ _s. The values of T _a and (c/a − 1)_s of Sr_0.95La_0.05TiO₃ are twice as large as those of SrTiO₃. These findings indicate that the large increase of T _a, (c/a − 1)_s and Φ _s are not caused by the doped conduction electrons, but by the crystal structure change, due to the substitution of La³⁺ ions into Sr²⁺ sites.