Temperature dependent PAC studies with the rare earth 172Lu in ZnO

In a first attempt to measure the temperature dependence of the electric field gradient at the site of 172Lu/172Yb in ZnO a large jump in the quadrupole interaction frequency was observed between measurements at room temperature and 200 °C. Above 200 °C the frequency only changed very little. In order to understand this unusual behaviour we prepared another sample and studied the temperature range between room temperature and 200 °C in more detail. The results obtained previously could be confirmed. The new data show a smooth increase of the quadrupole interaction frequency from about 146 MHz at room temperature to almost 390 MHz at 400 °C. This behaviour is likely to be due to the influence of the rare earth's partially filled 4f shell.