First-Principles Investigation of Paramagnetic Centers in P2 O5 Based Glasses

Abstract

We present a first-principles investigation of paramagnetic centers in P<inf>2</inf> O<inf>5</inf> based on the calculation of electron paramagnetic resonance (EPR) parameters (g -tensor and Fermi contacts). Calculations of the EPR parameters for the P<inf>1</inf> configuration in crystalline $o $(P<inf>2</inf> O<inf>5</inf>) support the previous attribution of the P<inf>1</inf> to a P-defect structurally analogous to the Si-${E }$ center. As far as concerns the P<inf>1</inf> center in glassy P<inf>2</inf> O<inf>5</inf>, the present work suggests the possible occurrence of another configuration besides the analogue of the Si-${E }$ center. Such an alternative P<inf>1</inf> center configuration is likely to be relevant for those P<inf>2</inf> O<inf>5</inf> based glasses featuring a considerable fraction of Q<inf>1</inf> and Q<inf>2</inf> tetrahedral units besides the Q<inf>3</inf> unit which dominates the structure of pure P<inf>2</inf> O<inf>5</inf>.