Crystal Chemistry, Optical Spectroscopy and Crystal Field Calculations of Co3TeO6 and Solid Solutions Co3–xZnxTeO6. Issue 38 (4th October 2018)

• Record Type: Journal Article
• Authors: Reichartzeder, Dominik; Wildner, Manfred; Weil, Matthias; Ivanov, Sergey; Stash, Adam; Chen, Yu‐Sheng
• Is Part Of: European journal of inorganic chemistry. Issue 38(2018)
• Page Start: 4221
• Page End: 4233
• Publication Date: 2018-10-04
• Subjects: Solid‐state structures -- X‐ray diffraction -- UV/Vis spectroscopy -- Crystal‐field calculations -- Tellurate solid solutions; Chemistry, Inorganic -- Periodicals; Organometallic chemistry -- Periodicals; Bioinorganic chemistry -- Periodicals; Solid state chemistry -- Periodicals; 546
• DOI: 10.1002/ejic.201800701
• Languages: English
• ISSNs: 1434-1948

Abstract

Abstract : Solid solutions Co3– x Zn x TeO6 ( x = 0–3) were prepared both in polycrystalline and single‐crystalline form using solid state reactions and chemical vapour transport reactions, respectively. Miscibility between the isotypic end members was established over the complete range ( C 2/ c, Z = 12, a ≈ 14.85, b ≈ 8.83, c ≈ 10.34 Å, β ≈ 93°). Crystal structure determinations, performed on basis of single crystal laboratory X‐ray (at 295 K) and synchrotron (at 10 and 100 K) data of Co3 TeO6 and selected solid solutions, revealed no structural phase transition and allowed a detailed insight into the Co → Zn substitution mechanism. The coordination polyhedra of the five crystallographically independent M 2+ cations are distorted octahedra (for three cations), one distorted tetrahedron and one distorted square pyramid. With increasing Zn content the polyhedral distortions increase, and the preference of the Zn 2+ cation for the tetrahedral coordination becomes distinctive. Optical absorption and diffuse reflectance spectroscopy reveal extraordinary strong crystal field absorption effects, over wide x ranges predominantly governed by Co 2+ in the single tetrahedral and one strongly acentric distorted octahedral site. Superposition Model crystal field calculations yield intrinsic and power‐law exponent parameters in general agreement with previous data for Co 2+ . The five cation sites show comparatively high crystal field strengths at generally very low interelectronic repulsion parameters, indicating prominent covalent contribution to Co–O bonding in Co3– x Zn x TeO6 solid solutions. Abstract : Solid solutions between Zn3 TeO6 and multiferroic Co3 TeO6 show strong polyhedral changes along the series, in spite of very similar cation sizes of Co and Zn. The evolution of structural chances and their impact on optical properties are followed by X‐ray diffraction down to 10 K and optical spectroscopy, both performed on single crystals and polycrystalline material. Structure‐property relationships are analysed by crystal field Superposition Model calculations.