Dielectric-related R-zero-phonon emission line shift of Cr³⁺ in SrTiO₃:Ca

Luminescence of Cr3+centres in Sr1-xCaxTiO3(x=0-0.12) reveals an unusual"dielectric relatedtemperature shift of the R lines, which correlates well with reciprocal dielectric permittivity behaviour and depends on the character of the phase transitions. The position of the R lines shifts to higher energies with Ca addition. Results obtained are attributed to interaction of the impurity centres with the soft TO1 branch, structural changes and random fields, which are inherent in Sr1-xCaxTiO3.