CATALYTIC EFFECTS OF AG2O ADDITIVES ON MICROSTRUCTURE AND RECRYSTALLIZATION IN BORATE GLASSES

摘要

A substitution of Ag2O for B2O3 in a 35BaO-25Fe(2)O(3)-(40 - x) B2O3-xAg(2)O, x = 0.0, 0.5, 1.0 and 3.0, glass series modifies the B2O3 network and changes infrared frequencies in the 1600-600 cm(-1) region. Four bands at 1440, 1280, 1180 and 1120 cm(-1) appear in glass containing no Ag2O additive. On adding the Ag2O, the 1120 cm(-1) band (which belongs to the BO3 --> BO4 modified group in the B2O3 network) no longer appears, and the other three bands (belonging to the B-O stretching vibrations in the interconnected boroxol rings) shift 15-40 cm(-1) to higher frequencies expected in the reduced structural defects of BO3 --> BO4 modified groups and non-bridging oxygens. This modified glass crystallizes (at 500-850 degrees C) into acicular BaFe12O19 microcrystals of a higher coercivity of similar to 5000 Oe, suitable for high energy-density magnets and other devices. [References: 22]