Synthesis and exploration of intricate optical and thermal attributes of Sm³⁺ doped novel borate phosphors

This paper focuses on the structural, morphological, luminescence and temperature-dependent emission properties of novel Sm³⁺ doped CaB₂O₄(CBO- Sm) phosphors synthesized via solid-state reaction route. The structural analysis showed the orthorhombic crystal structure and unaltered phase of the host even upon doping with Sm³⁺ ions. Diffuse reflectance established the characteristic peaks of Sm³⁺, and the sample has an optical band gap of 3.85 eV. The emission spectra have 4 different peaks at 568 nm, 603 nm, 648 nm, and 709 nm under 404 nm excitation. The highest intense peak observed at 603 nm showed quenching beyond 0.75 mol% of dopant concentration, owing to dipole-dipole energy transfer. The reddish-orange emission has high purity with a CCT value around 1760 K. The temperature-dependent luminescence analysis proved nearly stable emission CBO- Sm phosphors even at 170 °C with high activation energy. Thus, synthesized samples are suitable for thermal sensing and optoelectronic device applications.