In this work we have carried out a first-principles investigation of intrinsic paramagnetic point defects in P2O5 and in Na2O-P2O5 glasses as representative of alkali phosphate glasses. Glass models were generated by combining classical molecular dynamics and Monte Carlo simulations, and validated by comparing their corresponding structure factor with available x-ray and neutron scattering experiments. We have used density functional theory to calculate the Electron Paramagnetic Resonance parameters for a large set of paramagnetic oxygen-vacancy configurations. Our investigation, also by unveiling the effect of the local environment and disorder on the hyperfine tensor, leads us to propose a new model for the debated P3 center. In particular we establish the occurrence of two variants, which we name Pa3 and Pb3 centers.
COBISS.SI-ID: 6176973
In this work we studied, by means of ab-initio calculations, paramagnetic centers in P2O5 glass and crystal. In particular, our calculations of the EPR parameters for the P1 configuration in crystalline o’(P2O5 ) support the previous attribution of the P1 to a P-defect structurally analogous to the Si-E' center. As far as concerns the P1 center in vitreous P2O5 , this work has suggested the possible occurrence of other relevant configurations, besides the one analogue of the Si-E' center, important in phosphate glasses that, besides foundamental Q3 unit, have a a considerable fraction of Q1 and Q2 tetrahedral units.
COBISS.SI-ID: 5476603