Abstract:
A “covalency contraction” parameter, Rv, is defined as the ratio of the until cell volume of a transition metal compound MmXn relative to the unit cell volume of MgmXn. This parameter is found to be proportional to the electronegativity of X and thus inversely proportional to the degree of covalence of the M-X bond. The paraemter Rv explains the relative differences in cell volumes (V) for certain pairs of isotopic compounds, e.g., V(FeO) is larger than V(MgO), but V(Fe2GeS4) is smaller than V(Mg2GeS4). Similar but smaller variations in Rv occur in ternary oxides MxYyOz and can be traced to the covalence of the Y-O bond. Approximately linear relationships exist between Rv and spin-transfer coefficients determined for Ni2+, Co2+ and Mn2+ from magnetic resonance and neutron diffraction methods, and between Rv and the Mössbauer isomer shift for Fe2+. The differences in spin transfer observed for MnO and MnCO3are consistent with the differences in Rv for the two compounds.
To download the article click on the link below:
http://link.springer.com.ololo.sci-hub.cc/chapter/10.1007/BFb0116567
0 Comments