Optical properties of zinc bismuth phosphate glass

Abstract Optical properties were studied on ternary zinc bismuth phosphate glasses, which have two distinct glass-forming regions; low-P 2 O 5 region and high-P 2 O 5 region. Orthophosphate and isolated phosphate structures are dominant in the former region and metaphosphate and pyrophosphate structures are dominant in the latter region. Refractive index of the low-P 2 O 5 glass ( n d  > 1.82) was relatively higher than that of the high-P 2 O 5 glass ( n d 2 O 5 for the high-P 2 O 5 glass were almost the same as those for the low-P 2 O 5 glass. The factor of Bi 2 O 3 of the low-P 2 O 5 glass was, however, smaller than that of the high-P 2 O 5 glass, although the refractive index of the former was higher than that of the latter. The discrepancy between the refractive index and the factor of Bi 2 O 3 was due to the molar volume of glasses, that is, the refractive index was affected by the packing density much more than the molar refraction in zinc bismuth phosphate glasses. Absorption edge and reflection peak of the low-P 2 O 5 glass were situated at lower energies than those of the high-P 2 O 5 glass, which was consistent with the difference in resonance energy of the wavelength dispersion of the factor of Bi 2 O 3 in molar refraction. The existence of a Raman band at 160 cm −1 in the low-P 2 O 5 glass, which was not observed in the high-P 2 O 5 glass, suggested the difference in the Bi O bonding state between two glasses.