EPR study of V2O5–P2O5–Li2O glass system

$${x\hbox{V}_{2}\hbox{O}_{5}\cdot(100-\hbox{x})[\hbox{P}_{2}\hbox{O}_{5}\cdot\hbox{Li}_{2} \hbox{O}]}$$ glass system, with 0  <  x $${\le }$$ 50 mol%, was prepared and investigated by EPR method. For low content of V2O5 all the spectra present a hyperfine structure typical for isolated V4+ ions. With the increasing of V2O5 content, the EPR absorption signal showing hyperfine structure is superposed by a broad line without hyperfine structure characteristic for clustered ions. At high V2O5 content, the vanadium hyperfine structure disappears and only the broad line can be observed in the spectra. Spin Hamiltonian parameters g $$\Vert $$ , g $${\bot}$$ , A $$\Vert $$ , A $${\bot}$$ , dipolar hyperfine coupling parameters, P, and Fermi contact interaction parameters, K, have been calculated.The composition dependence of line widths of the first two absorptions from the parallel band and of the broad line characteristic to the cluster formations was also discussed.