A study of color centers produced in quartz by x-radiation.

Abstract

Z-cut sections of natural quartz crystals were colored to saturation by x-irradiation from a beryllium window x-ray tube. The crystal sections were decolored by heating and recolored by further x-radiation. The same optical transmissions, at saturation, were obtained when the energy distribution of the x-ray beam was the same but were different when different voltages were applied to the x-ray tube. The heat treatment used in removing the color from quartz does not affect the value of the optical transmission when recolored by x-radiation to saturation. It was observed that in every case the rate of coloration was greater after the section had been cleared and re-irradiated than when the color was being produced for the first time. If the heat treatment is restricted to an amount barely sufficient to remove the coloration, then the rate follows the same curve on successive irradiation cycles. If the crystal section is baked for a longer period of time than that stated above, the rate decreases and approaches that of fresh quartz. The change in rate of coloration of quartz is governed by the immediately preceding heat treatment employed in removing the color centers. No “memory” of previous heat treatments appears to be present.