Novel features of Sr1−xCaxTiO3 phase diagram: Evidence for competing antiferroelectric and ferroelectric interactions

Abstract

Structural and dielectric evidences are advanced to show that the Sr1−xCaxTiO3(SCT) system undergoes an antiferroelectric (AFE) phase transition in the composition range 0.18 ≤x≤0.40. Stabilization of the AFE phase, instead of the ferroelectric (FE) phase known for 0<x< 0.12, is shown to be intimately linked with the nonpolar antiferrodistortive phase transitions driven by the R and M point instabilities preceding the AFE transition. It is proposed that the disorder and frustration introduced by CaTiO3 substitution in the incipient FE matrix of SrTiO3 leads to the smearing of the ε ′(T) response in SCT for 0.002<x<0.12 akin to dipole glasses and relaxor ferroelectrics. © 2000 The American Physical Society.