Impurity-induced Polar States in SrTiO3 Quantum Paraelectric

TL;DR

This study investigates impurity-induced polar states in SrTiO3-based crystals, quantifying short- and long-range polar contributions and developing a method to analyze their effects on optical properties.

Contribution

It introduces a new approach to calculate short-range polarization contributions from light refraction data in impurity-doped SrTiO3 crystals.

Findings

Quantified short- and long-range polar contributions in SrTiO3 crystals.

Developed a method to analyze impurity-induced polar ordering via optical measurements.

Compared the roles of short- and long-range order in impurity-induced polarization.

Abstract

Short and long range impurity-induced polar ordering in Sr1-xCaxTiO3 with x = 0.014 (SCT-1.4) and SrTi(16O0.0318O0.97)3 (STO-18) single crystals were investigated and discussed on the basis of the light refraction temperature dependences measurements. For SCT-1.4 the temperature dependences of the morphic birefringence and dielectric hysteresis loops were measured. Within the optical indicatrix perturbation approach a method for calculation from polar contributions to the refraction of light of short-range polarization contribution Psh originated by spatial fluctuations is developed for the systems with the coexistence of long and short range polar ordering. The magnitudes and temperature dependences of Psh and long-range spontaneous polarization Ps have been determined in SCT-1.4 and STO-18. The results allowed to characterize quantitatively and to compare contributions of short (Psh) and long (Ps) range ordering in the formation of impurity-induced polar phase in SrTiO3.