Bismuth and lead oxides codoped boron phosphate glasses for Faraday rotators

Abstract New magneto-optical vitreous materials were obtained by melting-quenching technique comprising wet route raw materials preparation. The glass has the following composition in oxide mol. %: 10 Li 2 O, 9 Al 2 O 3 , 5 ZnO, (35; 20; 50) B 2 O 3 , (35; 50; 20) P 2 O 5 , 3 Bi 2 O 3 , 3 PbO, phosphorus and boron oxide being the vitreous network formers. It was also prepared a similar reference glass composition but without Bi 2 O 3 and PbO. Optical and structural characterization by ultraviolet-visible (UV–Vis), Fourier Transform Infrared (FTIR) and Raman Spectroscopy of the bulk glasses showed a transmission over 90%, metaphosphate structure of glass together with Q 2 boron oxide units and P–O‒B bonds. The mechanical parameters, hardness ( H ), Young's modulus ( E ) and fracture toughness ( K IC ) of boron phosphate glasses, evaluated by micro- and nanoindentation techniques, demonstrated mostly higher values in comparison with those for alumino-phosphate glasses due to mixed boro-phosphate network. Thermal behavior was investigated by Differential Scanning Calorimetry (DSC) putting in evidence the vitreous transition temperature which decreases with about 45 °C when Bi and Pb oxides were added and two crystallization effects. The diamagnetic character of a highly transparent Bi and Pb oxide co-doped boron phosphate glass was confirmed by ellipsometry, and the glass presented high magneto-optical properties at the top of the commercial bulk products.