Ba₂Zn₂La₄O₁₀:Sm³⁺: A novel orange–red emitting nanophosphor with high color purity for WLEDs applications

Ba₂Zn₂La_4(1−x)O₁₀:4xSm³⁺ (0.5–6 mol%) nanophosphor series synthesized successfully via solution combustion approach were crystallized into tetragonal lattice (I4/mcm (140) space group symmetry). The qualitative and quantitative phase information was obtained by performing Rietveld refinement technique. Morphological studies were carried out via scanning and transmission electron microscopy (SEM & TEM) observations. The energy-gap values for Ba₂Zn₂La₄O₁₀(5.58 eV) and Ba₂Zn₂La_3.88Sm_0.12O₁₀(5.42 eV) powder samples were determined from diffuse reflectance (DR) studies. The near ultra-violet (NUV) excitation (λ_ex = 410 nm) of Sm³⁺-doped nanophosphors revealed strong reddish-orange (603 nm) emission accredited to ⁴G_5/2→⁶H_7/2 (most prominent) transition. The Blasse’s relation provided critical distance (16.39 Å) for energy transfer process amid adjacent activator centres and shortlisted the actual interaction type (dipole–quadrupole) behind concentration quenching behaviour. Non-radiative relaxation rate (78.7701 s^− 1), radiative lifetime (1.61 ms) and quantum efficiency (89%) of ⁴G_5/2 emitting state were obtained by detailed analysis of fluorescence decay curves of Ba₂Zn₂La_4(1−x)O₁₀:4xSm³⁺ series. Furthermore, the CIE chromaticity diagram provides strong reddish-orange luminescence in visible region, which displays the auspicious applications of Ba₂Zn₂La₄O₁₀:Sm³⁺ nanophosphor in NUV-based white LEDs.