Factors influencing values of A or 10 Dq

The inverse fifth-power dependency of crystal field splitting on metal-oxygen distance expressed in eq. (2.17) is of fundamental importance in transition metal geochemistry, particularly in mineral physics at high pressures and interpretations of visible to near-infrared spectra of minerals. Thus, the A °= R 5 relationship, eq. (2.17), is referred to frequently in later chapters. 

The second method for estimating the value of A is from plots of thermodynamic data for series of similar compounds of transition elements. This method is discussed further in chapter 7. 

Certain generalizations may be made about factors that influence the magnitude of A or 10 Dq, values of which depend on individual cations, types of anions or ligands, interatomic distances, pressure and temperature variations, and symmetries of ligand environments. 

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