Abstract:
The project was approved 'in its final form in March 1997 and initiated in May, 1997. The main instruments to be used i.e. the Spectrophotometer was ordered in May but the L.C. (Letter of Credit for the purchase of the instrument) could not be opened till December, 1997 due to the lengthy bank formalities. The instrument was received and installed in August, 1998. Meantime the materials (chemicals) for the fabrication of the germanate glasses i.e. GeO2, BaO, TiO were ordered from abroad and purchased in October, 1998. The delay was due to the negotiations on the high price for Ge02- the main glass forming material. The furnace to be used to prepare the samples had to be upgraded to meet the high temperature (about 1500C) requirements for preparing the germanate glasses. Three samples with different compositions were successfully fabricated till April, 1999. By this time, accessories to be used with the spectrophotometer i.e. the stabilizer and the printers were arranged. The prepared samples were then measured using the spectrophotometer for optical absorption in the uv-visible range 190 - 1100 nm or wavelength. The optical gap was evaluated using the Mott and Davis theory from these measurements. The value of the gap lies between 3.475 and 3.662 eV for different samples with different compositions.
