The nuclear quadrupole interaction at 111Cd and 181Ta sites in anatase and rutile TiO2: A TDPAC study

TL;DR

This study investigates the nuclear quadrupole interactions at 111Cd and 181Ta sites in anatase and rutile TiO2 using TDPAC, revealing differences in electric field gradients and asymmetry parameters that relate to lattice positions and charge states.

Contribution

The paper provides detailed measurements of quadrupole interactions in TiO2 polymorphs, offering new insights into local atomic environments using TDPAC techniques.

Findings

Quadrupole interaction frequencies differ significantly between anatase and rutile.

Anatase shows negligible quadrupole interaction for 111Cd, indicating unperturbed sites.

Rutile exhibits distinct quadrupole parameters consistent with literature values.

Abstract

The nuclear quadrupole interaction of the I=5/2 state of the nuclear probes 111Cd and 181Ta in the anatase and rutile polymorphs of bulk TiO2 was studied using the time differential perturbed angular correlation (TDPAC). The fast-slow coincidence setup is based on the CAMAC electronics. For anatase, the asymmetry of the electric field gradient was eta=0.22(1) and a quadrupole interaction frequency: 44.01(3) Mrad/s was obtained for 181Ta. For rutile, the respective values are eta=0.56(1) and quadrupole frequency=130.07(9) Mrad/s. The values for rutile match closely with the literature values. In case of the 111Cd probe produced from the beta decay of 111Ag, the quadrupole interaction frequency and the asymmetry parameter for anatase was negligible. This indicates an unperturbed angular correlation in anatase. On the other hand for rutile, the quadrupole frequency is 61.74(2) Mrad/s and the asymmetry is 0.23(1) for 111Cd probe. The results have been interpreted in terms of the surrounding atom positions in the lattice and the charge state of the probe nucleus.