Proceedings of the 13th international conference on defects in insulating materials - icdim 96 vol:239- pages:15-18
In search for the microscopic nature of the tunneling states (TS), which dominate the ''anomalous'' low-temperature properties of amorphous solids, neutron irradiated quartz turned out to be very interesting as a model for the glassy state: by varying the neutron dose, a gradual transition from a crystalline to an amorphous material can be obtained which allows a comparison between the induced structural damage and the ''glassy'' properties at low temperature. Recently we developed a microscopic model for the TS in neutron irradiated quartz: chains of coupled SiO4 tetrahedra which transform from one (alpha(1)) to the other configuration (alpha(2)) in alpha-quartz. On the other hand studies of the TS after heat treatment showed that annealing could induce changes of the typical ''glassy'' distribution of the relaxation times of the TS. Here we present new data and a further analysis of annealing studies in neutron irradiated quartz. The influence of increasing the neutron dose is studied for different frequencies. It is found that when the dose approaches the threshold dose for transformation, after heat treatment, to the amorphous phase, annealing does not influence the distribution of the relaxation times of the TS like it does for lower doses.