Production and properties of high purity TeO sub(2)-ZnO-Na sub(2)O-Bi sub(2)O sub(3) and TeO sub(2)-WO sub(3)-La sub(2)O sub(3)-MoO sub(3) glasses

High-purity TeO sub(2)-ZnO-Na sub(2)O-Bi sub(2)O sub(3) and TeO sub(2)-WO sub(3)-La sub(2)O sub(3)-MoO sub(3) glasses were produced by melting the high-purity oxides mixtures in platinum or gold crucible at 800 degree C in hermetic chamber in the purified oxygen atmosphere. The content of limiting impurities in the produced initial oxides and glasses, the optical properties as well as the stability to crystallization were investigated. The optical fibers were produced from high-purity tellurite glasses with losses at the level of several hundreds of dB/km. The total content of 3d-transition metals in the glasses was not more than 1 ppm wt and content of hydroxyl groups corresponded to the absorption level of 0.001-0.002 cm super(-1) at [approx]3 mu m. The absorption band, monotonically increasing with the increase in MoO sub(3) content, was observed in dry TeO sub(2)-WO sub(3)-La sub(2)O sub(3)-MoO sub(3) glasses with the maximum at about 3.7 mu m.