The relationship among the composition, structure and selected properties for five series of silver phosphate glasses containing 0, 5, 10, 15 and 20wt% Fe$_2$O$_3$ has been investigated. The synthesized glasses have been characterized using different experimental techniques. X-ray diffraction studies revealed that the glasses are amorphous in nature. IR spectral studies have shown the presence of characteristic P–O–P linkages of linear phosphate chains,presence of O–P–O units in the phosphate tetrahedral and the formation of P–O–Fe bonds in the doped glass. It is also confirmed that due to doping of Fe$_2$O$_3$, loosening of glassy structure occurred and the glass became more disordered. Differential scanning calorimetric (DSC) studies revealed that glass transition temperature increased with Fe$_2$O$_3$ concentration. Scanning electron microscopic studies have shown that Fe$_2$O$_3$ doping modifies the microstructures of the glass and at lower concentration of dopant, a nanostructure is obtained. Electrical conductivity measurements from 303 to 373 K in a frequency range from 100 Hz to 5 MHz have indicated that all glasses are ionic conductors with Ag$^+$ ions as the charge carrier. Fe$_2$O$_3$ doping in silver phosphate glass increased the electrical conductivities. Results have shown that dielectric constants increased with the increase of temperature at all the frequencies; a.c. and d.c. conductivities have been separated and a Cole–Cole plot is also drawn. Dielectric losses in all the glasses decreased with frequency at a particular temperature. It is found that Ag$_2$O–P$_2$O$_5$ glass doped with 5wt% Fe$_2$O$_3$ gives high OCV value and the doped glass can be used as an electrolyte for solid-state batteries.

Crystalline chromium-doped Y$_{0.50}$Gd$_{0.50}$BO$_3$ with vaterite structure was synthesized by the calcination of gel from the reaction of yttrium borate, gadolinium borate, boric acid and propylene oxide at 900°C for 4 h. Orthoborates containing 10 and 20 mol% chromium-doped samples were successfully obtained and characterized by various techniques. Photoluminescent studies were performed for the doped samples. The optical bandgap of chromium-doped samples falls in the visible region making the material more viable for photocatalytic activities. The sample was used as a photocatalyst for photodegradation of methylene blue dye. Y$_{0.50}$Gd$_{0.50}$BO$_3$ and chromium-doped samples showed good magnetic properties, as they are antiferromagnetic in nature. To the best of our knowledge, the vaterite form of chromiumdoped Y$_{0.50}$Gd$_{0.50}$BO$_3$ has been synthesized for the first time.