Investigation of ZnO-P₂O₅ Glasses Containing Variable Bi₂O₃ Contents Through Combined Optical, Structural, Crystallization Analysis and Interactions with Gamma Rays

Optical absorption spectra of prepared undoped zinc phosphate glass together with samples containing additional Bi₂O₃ (2.5, 5, 10, 15%) were measured within the range 200–1100 nm before and after gamma irradiation. The spectrum of the undoped glass reveals strong UV absorption which is related to the presence of trace ferric ions (Fe ³⁺) present as unaviodable impurities within theraw materials. Bi₂O₃-containing glasses show an additional broad band near the visible band centered at about 464 nm which is attributed to the absorption of Bi ³⁺ ions. Gamma irradiation is observed to cause extension of the UV absorption of the undoped and the sample containing low 2.5% Bi₂O₃. The broad visible band due to Bi ³⁺ is not affected by gamma irradiation indicating some shielding behavior due to the presence of heavy massive Bi ³⁺ ions. Infrared absorption spectra of the studied glasses reveal vibrational bands due mainly to metaphosphate groups which show interference with the vibrations due to the introduction of Bi–O bonding groups (as BiO₆, BiO₃ or P–O–Bi) specially with the increase of Bi₂O₃. The crystallization behavior is discussed in relation to the phase separation concept and ionic potential of the Zn ²⁺ ions together with the depolymerization effect of Bi₂O₃ to convert metaphosphate to pyrophospahte and the formation of a crystalline bismuth phosphate phase.