The phase composition, structure, and hydrolytic durability of sodium-aluminum-(iron)-phosphate glassy materials doped with lanthanum, cerium, europium, and gadolinium oxides

Sodium-aluminum-(iron)-phosphate glasses containing lanthanum, cerium, europium, and gadolinium (Ln) oxides were examined by X-ray diffraction, infrared spectroscopy, and X-ray photoelectron spectroscopy. Phase composition of the quenched and annealed materials was determined. It has been shown that introduction of up to ~ 5 wt% Ln oxides to sodium-aluminum-phosphate (SAP) and sodium-aluminum-iron-phosphate (SAIP) baseline compositions did not cause their devitrification at quenching (except the La-bearing glass) and did not offer significant impact on their structure and hydrolytic durability. All the Lns studied are present in a trivalent form. After annealing the SAP-based glasses were partly devitrified with segregation of aluminophosphate, sodium-aluminophosphate, Ln- (monazite) and Na/Ln phosphate phases while in the Ln-bearing SAIP glasses sodium-iron orthophosphate and monazite were found. Devitrification at annealing reduced hydrolytic durability of glasses by factors of 5 to 10 as compared to the quenched samples (glasses).