Local Symmetry of Cu~(2+) Ions in Sodium Silicate Glasses from Data of EPR Spectroscopy

摘要

Sodium silicate glasses with a constant ratio of oxide concentrations (mol %) SiO_2/Na_2O = 2.4 and with copper ions introduced in the form of CuO (from 1 to 10 mol %) are studied by the EPR method.The shape and width of the EPR line of copper ions are analyzed,and the spin-Hamiltonian parameters g_||,g_(perpendicular),A_||,and A_(perpendicular) are determined by simulating the EPR spectrum and comparing the simulated and experimental spectra.The EPR spectrum of copper ions (1 mol %) is characterized by the parameters g_|| = 2.35,g_(perpendicular) = 2.065,Ay = 135 x 10~(-4) cm~(-1),A_(perpendicular) = 7 x 10~(-4) cm~(-1),and DELTAH= 25 G.An analysis of this spectrum shows that the nearest environment of the Cu~(2+) ion has the shape of an elongated octahedron.The EPR spectrum of the sodium silicate glass containing 10 mol % Cu is a superposition of the spectrum of an octahedral complex (g_|| = 2.35,g_(perpendicular) = 2.075,A_|| =135 x 10~(-4) cm~(-1),DELTAH = 40 G) and the spectrum of a cluster (g_|| = 2.35,g_(perpendicular) = 2.15,A_|| = 135 x 10~(-4) cm~(-1) DELTAH = 50 G).