Absorption Spectra of Solid (Polycrystalline) and Liquid (Melt) Compounds of Bivalent Cobalt

Abstract

Measurements are made of the visible spectra of pure CoCl2, CoBr2 polycrystalline layers, and CoCl26H2O and CoBr26H2O monocrystals between 77 and 1050 °K. A good degree of correspondence is established between the spectral components of polycrystalline CoCl2 and CoBr2. The spectra of the two hydrates also show similarities which lead to the conclusion that the first coordination sphere around Co++ at 77 °K has an octahedral‐type symmetry with two halide ions and four water molecules. Modification of the CoCl2 and CoBr2 spectra when passing from the solid to liquid phase (melt) is also investigated. This indicates a transformation from octahedral to tetrahedral symmetry.

Electrical Conductivity of Molten Cobalt Dibromide + Potassium Bromide Mixtures

“…Works involving cobalt(II) bromide are rather rare. [13][14][15][16][17] To our knowledge, neither the electrical conductivity of the pure CoBr 2 nor those of the CoBr 2 (1) + KBr (2) mixtures have been reported. In this work, we measured electrical conductivity of CoBr 2 and of CoBr 2 (1) + KBr (2) mixtures at high temperature with the purpose to obtain data concerning phase transitions and transport properties in this system.…”

Low‐Temperature Spectra of Some CsCl:CoCl2 Samples

“…The experimental technique was e s s e n t i a l l y the same as that used previously (4). The absorption c e l l , i.e.…”

“…(We did n o t find any structure data for CsCoC13.) Comparing the spectra of CsCoC13 and pure CoCl2, which is well known to have octahedral symmetry (4,6 ) , one may observe two differences: ooncerning the resolution (worse for CsCoC13) and the position of the absorption bands (the group between 17000 and 21000 cm" is s h i f t e d towards t h e red by a mean value of 150 cm" f o r CsCoC13), indicating a s l i g h t decrease o f t h e c r y s t a l f i e l d . A l l measured s p e c t r a f o r intermediary concentrations (5, 19, 81%) a r e combinations o f t h e above mentioned basic spectra.…”