INVESTIGATION OF CHROMIUM IMPURITIES CHARGE-STATE AND CHEMICAL-BONDS IN PLZT CERAMIC

The results of the first observation of Pb-207 NMR spectra both in pure PLZT and doped by chromium are reported. The observed NMR spectra peculiarities were shown to be dependent on lanthanum and chromium content, and connected with a distribution of chemical shift tenser values and their principal axis directions. The ESR spectra were measured in PLZT with Cr for the first time. The spectra were shown to be those of Cr3+, Cr5+ and Ti3+ their intensities being dependent on the La content. It was shown that with increasing La concentration the reduction of Cr5+ to Cr3+ and disappearance of Ti3+ took place. The relative intensity of Cr3+ and Cr5+ in the ESR spectra was supposed to be proportional to the volume of PZT regions in PLZT samples. It follows both from ESR and NMR measurements that for lanthanum concentrations higher than 4.5% there are no local PZT regions in PLZT. The role of the obtained data for the appearance of dipole glass state is discussed.