ANOMALOUS CRYSTAL CHEMISTRIES OF THE IN-111 ]CD-111 AND HF-181-]TA-181 PROBES IN RUTILE TIO2 STUDIED USING PERTURBED-ANGULAR-CORRELATION SPECTROSCOPY

We have used perturbed-angular-correlation (PAC) spectroscopy to measure nuclear-electric-quadrupole interactions at the Ti site in ceramic samples of rutile TiO2. To investigate differences in the probe crystal chemistry, we used two chemically different PAC probes, In-111 --> Cd-111 and Hf-181 --> Ta-181, and we measured the temperature dependences of the electric-field-gradient parameters, V(zz), eta, and delta over a temperature range from 290 to 1300 K. The results of these PAC measurements are compared to the results of Ti-47, Ti-49 nuclear-magnetic-resonance measurements. Significant differences are found in the temperature dependences of V(zz) and eta that cannot be explained in terms of simple considerations such as ionic size and charge. These effects are discussed in terms of differences in directional bonding that the PAC probes could exhibit.