Understanding the local environment of Sm3+ in doped SrZrO3 and energy transfer mechanism using time-resolved luminescence: a combined theoretical and experimental approach

A combined experimental and theoretical study on the photoluminescence (PL) properties of strontium zirconate (SZ) and Sm3+ doped SZ nanostructures is presented in this work. SZ and Sm3+ doped SZ is synthesized by a gel-combustion route and characterized systematically using X-ray diffraction (XRD), transmission electron microscopy (TEM), photoluminescence (PL) spectroscopy, and electron paramagnetic resonance (EPR) experimental techniques. PL studies on nanocrystalline SZ show strong violet-blue and weak orange-red emission under excitation wavelength at 243 nm. An EPR study shows the presence of oxygen vacancy in SZ nanocrystals. Combined emission, EPR studies and theoretical calculations brings out the possible reason for multicolor emission in SZ nanocrystals. The results of the PL spectroscopy measurement imply that the Sm3+ emissions, which originated from the (4)G(5/2) -> H-6(J) (J = 5/2, 7/2, 9/2, and 11/2) intra-4f transitions of Sm3+ ions, are due to the indirect excitation of the Sm3+ ions through an energy transfer process from electron-hole pairs generated in the SZ hosts. Based on combined experimental and theoretical studies, a possible mechanism for PL of undoped and Sm3+-doped SZ is proposed.