The temperature-frequency behaviour of the permimivily d(T, f) and m[S(T. f)] (20-300 K, 120 Hz-9 MHz), EPR, optical absorption and luminescence of KTaO3, nominally pure and weakly doped (0.1 ~1 % Li: 0.01 wt% Cr; 3 wt% Cu; I wi% Fe; 0.1 wt% Li+O.l wt% CI and 0.1 wt% L i t 0 . l wt% Crt0.02 wt% Cu) were studied. Below 70 K, in all doped samples, dielecuic dispersion CCCUIS, with m[S(T)l maxima positions obeying rhc universal Arhenius law with activation energy A = 1000 * 50 K. This is associared with local ordering in the dipoledipole Clusters containing reorienting defect pairs of various kinds, with correlations due to interaction via t h e m soft mode.
The optical absorption spectra of SrO : Ni crystals are investigated in the visible and near infrared region. Two kinds of Ni2+ centres (I and 11) are found which can be completely and reversibly eonverted into each other by annealing in oxygen atmosphere and in vacuum. Models of centre J and I1 are proposed. Centre I is a n isolated KiZt ion on (111) off-centre position. Centre I1 is a Xi?+ ion on (110) off-centre positionassociated with a n oxygen ion on the nearest interstitial position.
Mcc;lexouamr onTmecKHe cnempbr nornoueamx KpmcTaJrnoB SrO : pl'i B B H A H M O~ PI EIH-npeapauram~wec~ OAHH B npyroii B ~~B H C H M O C T H OT yc~~oskiii 0Txm-a o6pa3ua. IIIpemo-@palrpaCHOii 06JIacTRX CIIeKTpa. 0 6~a p y m e~o ABa THna UeIITpOB (I EI 11) Ni2+, 06pa~11110 XieHbI MOneJIH UeHTpOB 112 11. UeHTp 1 IIpeACTaBJReT C O 6 O a H3OJIHpOBaHHbIa HOH xi", PaBHOBeCHOe IIOJIOXeHHe KOTOpOrO CMeweHO 113 KaTEIOHHOrO y3JIa BAOJIb HanpaB,TtHHR (111). UeHTp 11 -3TO IXOH Ni2+, CMeUeHHbIa IIO (110), PflJIOILI C KOTOpbIM paCn0nOmeH MemROJ' 3eJIbHbIa H O H KPICJIOPOna.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.