Analysis of charge—orbital ordering in compounds with mixed valence

Abstract

Analysis of Charge-Orbital Ordering in Compoundswith Mixed Valence BY G. V. IONOVA (a) , E. P. MAHAROV (b), 0. M. PACHEV (b), and 5. P. IONOV (c) Orbital and charge ordering in transition element compounds are considered and a theoretical model is established. Special emphasis is given to the divalent compounds of Cu2+, Ag2', Au2+ and the trivalent compounds of Pd3+ and Pt3+. It is shown that spatial orbital ordering takes place in cornpounds with strong intracentre correlations (Cut+, &2+, Mn3+) and that strong intercentre correlation results in charge ordering on orbitals or centres (Ag2+, Au2+, Pd3+, and Pt3+). Real systems and lattice distortions caused by spatial and charge ordering are discussed. B cTaTbe paccMoTpeHo Op6HTaJIbHOe M a a p~n o~o e ynopHnosesHe B coemiHeHmx nepe-XOLIHbIX 3JIeMeHTOB H 06cyxneaa TeOpeTH9eCKaH MOaeJIb TaKOrO yIlOpHHOseHElH. Oco6oe BHHMaHMe YHeJIHeTCH LIByXBaJIeHTHbIM COeHHHeHBHM cUZt, Ag2+ H AU2' a TaKlfEe TpeX-BaJIeHTHblM COeAMHeHkl HM Pd3+ H pt3+. nOKa3aH0, 9TO B COeAHHeHHH C CBJIbHbIMH OHHO-UeHTPOBbIMH KOppeJIH4HfiMH (CU", Cr2+ H MnS+) MOWeT H M W b MeCTO IlpOCTpaHCTBeHHOe ynOpHHOYeHI?e nbIpO9HblX Op6MTaJIefi (dzz-z2 I.I dZaPy:), a B COeLIkiHeHMHX C CElJIbHbIMA ABYXUeHTPOBbIMH KOppeJIHUHHMH (Ag2+, AU", Pda+ M Pt3+) HMeeT MeCTO 3apHJlOBOe LICKPlfEeHAH B HHX, 06yCJIOBJIeHHbIe npOCTpaHCTBeHHblM I? 3apHHOBbIM ynOpHHO9eHHeM.ynopmoseHMe Ha UeHTpax w op6n~ax. 0 6 c y m n a m~c~ peamHwe cmTeMbI M pellreTosHbIe