Spectroscopic characteristics of Sm³⁺ doped alkaline earth potassium titanium phosphate glasses

193-196The paper reports on the preparation and characterization of Sm3+ doped alkaline earth potassium titanium phosphate (RKTP) glasses with molar composition of 24(NaPO3)6 + 30KH2PO4 + 25TiO2 + 20RCl2 + 1Sm2O3 (R=Mg, Ca & Sr). Optical absorption spectra in the UV-VIS-NIR region reveal twelve absorption bands and are assigned to different transitions arising from the 6H5/2 ground state. The energy level structure of Sm3+ (4f5) has been analyzed using the free-ion Hamiltonian model. The root mean square deviations between the experimental and calculated energies of Sm3+ doped MgKTP, CaKTP and SrKTP glasses are 44, 35 and 56 cm-1 respectively and are comparable with the earlier reports. By measuring the areas under the absorption peaks, the experimental oscillator strengths are calculated and the phenomenological JO-intensity parameters (Ω2, Ω4 and Ω6) have been determined with the help of least-squares fitting approach. These parameters exhibit a similar trend as Ω2>Ω6>Ω4 in all the three glasses. The evaluated JO parameters are then used to calculate the excited 4G5/2 level radiative properties such as radiative transition probabilities (AR), branching ratios (βR) and lifetimes ( R). The emission spectra recorded by exciting with 476 nm shows four peaks at 563, 599, 649 and 714 nm and are assigned to 4G5/2 → 6H5/2, 6H7/2, 6H9/2, 6H11/2 respectively. The experimentally observed decay profiles of the 4F5/2 level of Sm3+ are found to be single exponential yielding the lifetimes ( mes) 2330, 1750 and 2320 μs in MgKTP, CaKTP and SrKTP glasses respectively, which are comparable with the calculated lifetimes ( R) obtained from the Judd-Ofelt theory