Abstract
The ${\rm ZnO} {-} {{\rm ZrO}_2}$ nanocomposites were prepared using varying concentrations of ${{\rm Ho}^{3 +}}$ ions through the solution combustion method. Zirconium butoxide and zinc nitrate were used as the precursor solutions with citric acid as a fuel. The synthesis was done at a low temperature of 80°C and then the samples calcined at 600°C for 2 h, before characterization. Rietveld refinement revealed that the nanocomposite consisted of wurtzite zinc oxide, mixed with cubic and tetragonal zirconia phases. Scanning electron microscopy images show dispersed small polygonal crystals within a spongy matrix for lower ${{\rm Ho}^{3 +}}$ concentrations, while samples with higher dopant ratios featured larger crystals mixed with rods. The UV spectra had absorption edges from 400 nm with a dopant-dependent energy band gap ranging between 2.78 and 3.04 eV. The nanocomposites exhibited an initial violet emission that varied through blue into the green region, depending on the ${{\rm Ho}^{3 +}}$ doping concentration. Dipole–dipole interaction was found to be responsible for the luminescence quenching within the nanocomposite material.
© 2020 Optical Society of America
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