Results of Mn, Fe, Co, and Cu admixture EPR spectra studies in PLZT and PMN ceramics are discussed. The spectra of Mn, Fe, and Co ions with dominating absorption at geff = 2.0 and 4.3 are proposed due to d5 (S = 5/2) configurations (Mn2+, Fe3+, Co4+). The latter can be used as probes disclosing specific features (glass‐like behaviour) of the structures. The Jahn‐Teller ions (Mn3+, Fe4+, Co5+, Cu2+) are responsible for the dopant effect, e.g., the shift of the ε(T) maximum to higher temperatures. The microscopic nature of differences of the dopant effect in PLZT and PMN materials and in the Mn → Fe → Co sequence is analyzed.

This is the first presentation of optical absorption and luminescence emission and excitation spectra of transparent PLZT 10/65/35 (Pbo,,Lao,,Zro,,,Tio,3,03) and PLZT 8/65/35 ( P b o ,~z L a~,~~Z r " ,~s T i~, 3 s 0 3 ) ferroelectric ceramics, both undoped and doped with Cr,O,. Undoped samples exhibit a band gap absorption a t 77 K near 365 nm and broad-band luminescence peaked at 610 nm, which is attributed to self-trapped exciton emission of Ti3 ' 0 , oxygen deficient complexes. The newly arising absorption, excitation and emission spectra of Cr,03-doped PLZT are ascribed to transitions of Cr3+ and C r 5 + in octahedral positions. The temperature dependence of the inhomogeneously broadened R line luminescence of Cr3+ (*E, -+ 4A,,), peaked at Y 13610 cm-at 77 K in PLZT 8/65/35, reveals a line split in the vicinity of 183 K. This is tentatively attributed to an unknown low-temperature lattice reconstruction or to a phase transition.Die optischen Absorptions-, Emission-und Anregungs-Spektren der Lumineszenz von transparenten, undotierten und mit C r , 0 3 dotierten PLZT 10/65/35 (Pbo,9Lao,lZro,,,Tio,3s03) und 8/65/35 (Pbo,~2Lao,osZro,,sTio,3 503) ferroelektrischen Keramiken wird erstmals prasentiert. Die undotierten Proben zeigen bei 77 K Bandkantenabsorption in der Nahe von 365 nm und Breitband-Lumineszenz mit einem Maximum bei 610 nm, fur welche die ,,self-trapped'' Exzitonencmission der SauerstoffdefizitKomplexe Ti3 +Ox verantwortlich ist. Die zusiitzlichen Absorptions-, Anregungs-und Emission-Banden im mit Cr,O, dotierten PLZT gehoren zu Ubergangen der Cr3+-und Crs+-Ioncn in oktaederischen Positionen. Die Temperaturabhangigkeit der inhomogen verbreiterten R-Linien-Lumineszenz dcs Cr3 + ('E, + 4A,,) mit Maximum 13610 cm-' bei 77 K im PLZT 8/65/35 zcigt eine Linienaufspaltung in der N i h e von 183 K. Dieser Effekt wird vorlaufig einer unbekannten Tieftcmperatur-Gitterrekonstruktion beziehungsweise einem Phasenuhergang zugeschrieben.

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EPR spectra of PMN ceramics doped with 0.1 mol% Fez@ were recorded at T = 100 K and 7 = 475 K and were amibuted to Pe3+ ions in positions with different local symmetries. Three types of Fe3+ paramagnetic centres of rhombic, axial and cubic symmetry in avenge and individual low-symmetry fiuchlations were described by spin Hamiltonians with distributed constaots. The other type of centre at T = 100 K was found to retain the pure cubic symmetry of ideal homogeneous regions. The superhyperfine inemtion between Fe3+ and neighbouring "Pb nuclei is 4 mT. The mechanisms by which the paramagnetic centre symmetry is decreased involves a contribution from the ation disorder in 8 sites and a temperaturedependent contribution of lattice distortions in p o h regions The oxygen sublattice shift was estimated.