Perturbed Angular Correlation studies in SrTiO3 single crystals

The quadrupole hyperfine interactions of Cd-111/In-111 probe nuclei in sing le-crystalline SrTiO3 perovskite samples were investigated using Perturbed Angular Correlation spectroscopy. Three electric field gradients were detec ted and their fractions and hyperfine parameters were measured in the tempe rature range from 26 to 700 K. The fraction f(0) having a vanishing quadrup ole frequency, as expected for Cd-111 on substitutional sites in a cubic la ttice, starts to develop around 300 K and reaches 100% at 700 K. Two well-d efined EFG's having closely lying quadrupole frequencies and asymmetry para meters of omega(Q1) = 49.1(3) Mrad/s, eta(1) = 0.10(2) and omega(Q2) = 51 8 (3) Mrad/s, eta(2) = 0.12(2), at room temperature, were identified in the t emperature range from 250 to 530 K, and their (100) orientation in the latt ice was determined. They are associated with electronic defects at the prob e atoms.