Synthesis and Photoluminescent Property of \(\text{MgO:Cr}^{3+}\) Powders

Abstract

MgO:Cr³⁺ powders with different dopant contents have been synthesized by sol-gel method using the following precursors: magnesium nitrate (Mg(NO₃)₂), chrome nitrate (Cr(NO\(_3\))\(_3\)), and citric acid. The effect of the Cr\(^{3+}\) concentration and heat-treating temperature on structural and optical properties of the synthesized samples has been studied. For the samples with the low Cr³⁺-dopant concentrations or low heat-treating temperature, the photoluminescent (PL) spectra consist of sharp lines assigned to the \(^2\)E \(\to\) \(^4\)A\(_2\) transition of ions Cr³⁺ in perfect octahedral symmetry sites. But for the samples with the high Cr\(^{3+}\)-dopant concentrations and undergone high heat-treating temperature, the PL spectra appear a broad emission bands, which is assigned to the \(^4\)T\(_1\to ^4\)A\(_2\) transitions within the Cr\(^{3+}\) ions in the MgO orthorhombic symmetry crystal field.