A study of electron paramagnetic resonance and optical absorption in calcium chromium phosphate glasses containing praseodymium

This paper reports on the EPR and optical absorption studies of Cr3+ ions i n praseodymium calcium chromium phosphate glasses. The effect of concentrat ion of Cr3+ ions and rare earth oxide praseodymium on resonance signals hav e been studied. The temperature dependence of EPR signals was studied. The intensity of the resonance signals increases with decrease of temperature w hereas the linewidths are found to be independent of temperature. The coupl ing constant J between Cr3+ ion pairs was calculated. The crystal-field par ameters and optical band gap energy were evaluated. From the results, the v alues of the optical band gap energy are found to depend quite sensitively on added chromium content. It is observed that the crystal-field at the Cr3 + ion site becomes weak with increase in praseodymium content. The theoreti cal values of optical basicity were also evaluated. (C) 1998 Elsevier Scien ce S.A. All rights reserved.