Static and dynamic Jahn-Teller effects in Cu (super 2+) oxysalt minerals

摘要: The details of Jahn-Teller distorted Cu (super 2+) phi 6 (phi : O 2-) , OH -) H 2 O) octahedral geometries in oxysalt minerals are examined. Usually the octahedron is (4+2)-distorted, although both (2+4)-distorted and holosymmetric octahedra have been reported mineral structures. To a first order, theorem indicates that either (4+2) or (2+4) distortion equally likely to occur, apparent conflict with dominance (4+2)-distorted octahedra; this requires an extension theorem. Examination structures shows there no conclusive evidence octahedron. presence volborthite KCu 3 (OH) [(ASO 4 )H(ASO )], (2+2+2)-distorted bayldonite cyanochroite attributed dynamic effect, rather than static usual most persuasive example true occurs structure demesmaekerite.