LUMINESCENCE AND OPTICAL-ABSORPTION IN NOMINALLY PURE AND CR-DOPED PLZT CERAMICS

This is the first presentation of optical absorption and luminescence emission and excitation spectra of transparent PLZT 10/65/35 (Pb0.9La0 .1Zr0.65Ti0.3503) and PLZT 8/65/35 (Pb0.92La0.08Zr0.65Ti0.35O3) ferroe lectric ceramics, both undoped and doped with Cr2O3. Undoped samples e xhibit a band gap absorption at 77 K near 365 nm and broad-band lumine scence peaked at 610 nm, which is attributed to self-trapped exciton e mission of Ti3+Ox oxygen deficient complexes. The newly arising absorp tion, excitation and emission spectra of Cr2O3-doped PLZT are ascribed to transitions of Cr3+ and Cr5+ in octahedral positions. The temperat ure dependence of the inhomogeneously broadened R line luminescence of Cr3+ (2Eg --> 4A2g), peaked at almost-equal-to 13610 cm-1 at 77 K in PLZT 8/65/35, reveals a line split in the vicinity of 183 K. This is t entatively attributed to an unknown low-temperature lattice reconstruc tion or to a phase transition.