Synthetic, structural, and magnetic studies of strontium copper(II) borates with the composition Sr{sub 1-x}M{sub x}Cu{sub 2}(BO{sub 3}){sub 2}, M = Ba or Ca
- Stockholm Univ. (Sweden)
Studies of the new type of alkaline earth copper(II) borates, represented by SrCu{sub 2}(BO{sub 3}){sub 2}, have been performed by high temperature techniques. In the parent structure of SrCu{sub 2}(BO{sub 3}){sub 2}, the strontium content can be partially substituted by calcium or barium. A series of such phases with the composition Sr{sub 1-x}M{sub x}Cu{sub 2}(BO{sub 3}){sub 2} where M = Ca or Ba and O {le} x < 0.4 have been prepared. X-ray powder photographs verify that these phases are isostructural to SrCu{sub 2}(BO{sub 3}){sub 2}. The crystal structure of Sr{sub 1-x}M{sub x}Cu{sub 2}(BO{sub 3}){sub 2} can be regarded as consisting of slightly puckered layers with the composition [CuBO{sub 3}]{sup {minus}} stacked along [001], with eight coordinated alkaline earth atoms located between the layers. Estimated bond valence sums for all atoms indicate normal bond length distributions in the structure. The structure possesses a pseudo-mirror symmetry but the deviations (<0.2 {angstrom}) from this symmetry (space group I4/mmm) are statistically high significant. The substitution of strontium for smaller calcium or larger barium atoms has a pronounced effect on the interlayer separation. Measured magnetic susceptibilities of SrCu{sub 2}(BO{sub 3}){sub 2} indicate a transition to an antiferro-magnetic state below 14 K.
- OSTI ID:
- 508642
- Journal Information:
- Journal of Solid State Chemistry, Vol. 113, Issue 1; Other Information: PBD: Nov 1994
- Country of Publication:
- United States
- Language:
- English
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