UNIQUE PHYSICAL-PROPERTIES AND FRAGILITY OF 50CUO(X)-50P(2)O(5) GLASSES

50CuO(x)-50P(2)O(5) glasses with different copper valence states (0 < Cu+/(Cu2+ + Cu+) < 0.61) were prepared by adding glucose during glass melting, and some physical properties and fragility of these glasses w ere examined. The density of 50CuO(x)-50P(2)O(5) glasses decreases lin early with increasing Cu+ content from 3.18 to 3.01 g/cm(3). Although the glass transition temperature decreases with increasing Cu+ content from 437 to 196 degrees C, the viscosity and the activation energy fo r viscous flow also decrease with increasing Cu+ content. From the con cept of fragility, it was found that 50CuO(x)-50P(2)O(5) supercooled l iquids become strong with increasing Cu+ content due to the formation of strong Cu+-O bonds. The properties of 50CuO(x)-50P(2)O(5) glasses w ere compared with those of xNaO(0.5)-(50-x)MgO-50P(2)O(5) glasses, and the results suggest that the former glasses exhibit unique properties and fragility due to a unique coordination state of Cu+.