Optical response characteristics & radiation shielding properties of Sm3+ ions activated tungsten alkali borate glasses for visible laser & radiation shielding applications

Abstract

Trivalent samarium oxide doped Tungsten Alkali Borate (TAB) glasses were synthesized by melt-quenching technique and their structural and luminescence properties were studied. The amorphous nature of prepared TAB glass was confirmed by XRD. The presence of various borate functional groups was identified from Raman Spectra. The optical band gap energies evaluated from absorption spectra were found to be 2.24, 2.25, 2.28, 2.30, 2.34 and 2.36 eV increased with the increase of Sm³⁺ ion concentration. The JO parameters were found to be high (Ω₂ = 85.6 × 10⁻²², Ω₄ = 242 × 10⁻²² & Ω₆ = 313 × 10⁻²²) for TABSm1.0 glass. These parameters were then employed to assess the radiative properties of the significant fluorescent transitions ⁴G_5/2 → ⁶H_5/2, ⁴G_5/2 → ⁶H_7/2 and ⁴G_5/2 → ⁶H_9/2 of TABSm glasses. From the PL decay spectra experimental lifetimes calculated and found to be 1224, 1198, 1137, 928, 688 and 596 μs decreased due to energy transfer between neighbouring Sm³⁺ ions. Highest quantum efficiency about 92% observed for TABSm1.0 glass compared to other TABSm glasses. The CIE colour chromaticity coordinates obtained for TABSm1.0 glass - (0.58, 0.41) also confirmed the reddish-orange emission. Many shielding characteristics like “Mass Attenuation coefficient (MAC), Effective Atomic Number (Z_eff), Half Value Layer (HVL), Tenth Value Layer (TVL), Mean Free Path (MFP), Equivalent Atomic Number (Z_eq), and Exposure build-up factor” were evaluated to understand the shielding capacity of present glasses. It was found that TABSm2.5 glass possesses higher values of the radiation shielding parameters which make the TABSm2.5 glass suitable for radiation shielding applications.