Local Structure Studies of Ti for SrTi¹⁶O₃ and SrTi¹⁸O₃ by Advanced X-ray Absorption Spectroscopy Data Analysis

Abstract

Strontium titanate is a model quantum paraelectric in which in the region of dominating quantum statistics the ferroelectric instability is inhibited due to nearly complete compensation of the harmonic contribution into ferroelectric soft mode frequency by the zero-point motion contribution. The enhancement of atomic masses by the substitution of ¹⁸O for ¹⁶O decreases the zero-point atomic motion and low-T ferroelectricity in SrTi¹⁸O₃ is realized. In this study we report on the local structure of Ti in SrTi¹⁶O₃ and SrTi¹⁸O₃ by Ti K-edge extended x-ray absorption fine structure measurements in temperature range 6 – 300 K.

Keywords:

• Strontium titanate; quantum paraelectric; isotopic effect; X-ray absorption spectroscopy; local atomic structure; phase transitions

Acknowledgments

The authors thank Dr. Olivier Mathon from ESRF and Dr. Edmund Welter from DESY for assistance during the beamtimes, and Dr. Alexei Kuzmin for fruitful discussions and feedback.

Funding

This work has been supported by the Latvian Science Council grant no. 402/2012. The work was supported in part from large infrastructure SAFMAT Project CZ.2.13/3.1.00/22132, P108/12/1941 of GACR and PP RAS “Quantum mesoscopic and disordered systems”.