Nuclear Quadrupole Relaxation in Ge-As-Se Chalcogenide Glasses

(75)As nuclear quadrupole resonance (NQR) spin-spin (T(2)) and spin-lattice (T(1)) relaxation time measurements have been performed in glasses of the Ge-As-Se system as a function of average coordination number (r) over bar. The results for T(2) indicate that in compositions with high (r) over bar the inhomogeneities in the local structure increase and clustering effects lead to nanoscale phase separation. There is evidence of the indirect interaction of As atoms (J-coupling) in these compositions. The spin-lattice relaxation occurs through "spin diffusion" when inhomogeneities in the spin system environment lead to the distribution of relaxation rates. We suggest that T(1) measurements can provide a probe of the network rigidity in some glasses. [DOI: 10.1143/JJAP.47.8166]