<span style="font-size:15.0pt;mso-bidi-font-size:16.0pt;mso-bidi-font-weight:bold" lang="EN-US">Effect of crystallite size on electron spin resonance of Gd³⁺ and luminescence of Eu³⁺ doped in La₆WO₁₂ </span>

Abstract

Nano-sized Eu³⁺ and Gd³⁺ doped lanthanum tungstates of composition La_6-xLn_xWO₁₂ (Ln = Eu, Gd; 0 ≤ x ≤ 0.2) are prepared by sol-gel complexation method. These samples are characterized by powder X-ray diffraction (XRD). The average crystallite size is calculated from the XRD using Scherer’s equation. The electron spin resonance (ESR) spectrum of Gd³⁺ doped lanthanum tungstate (La₆WO₁₂) gives characteristic “U” type spectrum. The luminescence spectrum of Eu³⁺ doped La₆WO₁₂ gives characteristic ⁵D₀→⁷F_n (<i style="mso-bidi-font-style:normal">n</i> = 0 to 4) bands due to trivalent europium ions. The intensity of ⁵D₀→⁷F₂ transition decreases with increase in the sintering temperature due to depletion of surface Eu³⁺ ions. The intensity of ⁵D₀→⁷F₂ sintered at 700°C has highest intensity and may have laser applications.