
%0 Journal Article
%A Glaum, R 
%A Hitchman, MA 
%T On the Bonding Behaviour of Transition Metal Ions in Inorganic Solids&#8212;Optical and Epr Spectroscopic Studies on Anhydrous Phosphates and Phosphate-Silicates of Ti<sup>3+</sup>
%J Australian Journal of Chemistry
%D 1996/11/01
%V 49
%N 11
%P 1221-1228
%K 
%R https://doi.org/10.1071/CH9961221
%U https://www.publish.csiro.au/paper/CH9961221 
%X TiPO4 (green), Ti4P6Si2O25 (purple-red) and TiP3O9 (blue) show a remarkable variety of colours . We compare the results of optical and e.p.r. spectroscopic measurements on these compounds with d-electron energy levels for Ti3+ obtained by using the angular-overlap model. Thus, a unified set of angular-overlap model bonding parameters for the description of the spectroscopic behaviour of Ti3+ in anhydrous phosphates can be derived. The &#963;-interaction was assumed to depend on the nth power of the Ti-O bond distance, and it was found that optimum agreement with experiment occurred with n = -4.5. For the correct reproduction of the experimentally observed ground-state splittings it is necessary to allow for anisotropic &#960;-bonding interactions between titanium and the oxygen ligands linking Ti-O coordination polyhedra. 
