First-Principles Investigation Of Paramagnetic Centers In P2o5 Based Glasses

We present a first-principles investigation of paramagnetic centers in P2O5 based on the calculation of electron paramagnetic resonance (EPR) parameters (g-tensor and Fermi contacts). Calculations of the EPR parameters for the P-1 configuration in crystalline o'(P2O5) support the previous attribution of the P-1 to a P-defect structurally analogous to the Si-E' center. As far as concerns the P-1 center in glassy P2O5, the present work suggests the possible occurrence of another configuration besides the analogue of the Si-E' center. Such an alternative P1 center configuration is likely to be relevant for those P2O5 based glasses featuring a considerable fraction of Q(1) and Q(2) tetrahedral units besides the Q(3) unit which dominates the structure of pure P2O5.