Microwave-assisted synthesis of Mn-doped CuO nanoparticles: Multi-model XRD investigation of Mn-induced lattice distortion, defect engineering, and structural and optical properties correlations

Pure and Mn-doped CuO nanoparticles were synthesized using a microwave-assisted precipitation method followed by annealing at 400 ° C. XRD analysis confirmed the monoclinic CuO structure without secondary phases. The average crystallite size obtained using the Debye-Scherrer method decreased from 29 nm for pure CuO to 25 nm for Mn-doped CuO, while the lattice parameters increased from a = 4.6619 Å, b = 3.0737 Å, and c = 5.1757 Å to a = 4.7202 Å, b = 3.1083 Å, and c = 5.2304 Å, respectively. The microstrain increased from 0.07028 × 10⁻³ to 0.08120 × 10⁻³ , indicating increased lattice distortion after Mn incorporation. EDS analysis showed an Mn concentration of 3.18 at%. UV-Vis analysis revealed a shift in the absorption maximum from 359 to 372 nm, while the optical transmittance increased from approximately 32–55%. Photoluminescence measurements showed enhanced red emission intensity around 629 nm after Mn incorporation. These results demonstrate that Mn incorporation modifies the structural, defect-related, and optical properties of CuO nanoparticle.