Physical, optical and radiative properties of CaSO4-B2O3-P2O5 glasses doped with Sm3+ ions

Trivalent rare earth ions doped borosulfophosphate glasses are in high demand owing to their several unique attributes that are advantageous for applications in diverse photonic devices. Thus, Sm3+ ion doped calcium sulfoborophosphate glasses with composition of 25CaSO4-30B2O3-(45−x)P2O5-xSm2O3 (where x = 0.1, 0.3, 0.5, 0.7 and 1.0 mol%) were synthesized using melt-quenching technique. X-ray diffraction confirmed the amorphous nature of the prepared glass samples. Differential thermal analyses show transition peaks for melting temperature, glass transition and crystallization temperature. The glass stability is found in the range 91 °C to 116 °C which shows increased stability with addition of Sm2O3 concentration. The Fourier transform infrared spectral measurements carried out showed the presence of vibration bands due to PO linkage, BO3, BO4, PO4, POP, OPO, SOB, and BOB unit. Glass density showed increase in value from 2.179 to 2.251 g cm−3 with increase in Sm2O3 concentration. The direct, indirect band gap and Urbach energy calculated were found to be within 4.368-4.184 eV, 3.641-3.488 eV and 0.323-0.282 eV energy ranges, respectively. The absorption spectra revealed ten prominent peaks centered at 365, 400, 471, 941, 1075, 1228, 1375, 1477, 1528 and 1597 nm corresponding to 4D3/2,6H5/2→4I11/2,6P3/2, 6F11/2, 6F9/2, 6F7/2, 6F5/2, 6F3/2, 6H15/2 and 6F1/2 transitions respectively. Photoluminescence spectra monitored at the excitation of 398 nm exhibits four emission bands positioned at 559, 596,643 and 709 nm corresponding to 4G5/2→6H5/2, 6H7/2, 6H9/2 and 6H11/2 transitions respectively. The nephelauxetic parameters calculated showed good influence on the local environment within the samarium ions site and the state of the SmO bond. The Judd-Ofelt intensity parameters calculated for all glass samples revealed that Ω6 > Ω4 > Ω2. The emission cross-section and the branching ratios values obtained for 4G5/2→6H7/2 transition indicate its suitability for LEDs and solid-state laser application.