Experimental charge density distribution and its correlation to structural and optical properties of Sm3+ doped Nd2O3 nanophosphors

Pure and Sm3+ doped Nd2O3 nanophosphors were synthesized using modified Pechini method. The phase formation with symmetry of the sample is confirmed by the Rietveld refinement of the powder Xray diffraction (PXRD) data. The surface morphology and the crystallite size were examined using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) and the results confirmed that the synthesized particles are in nanosize. The energy-dispersive X-ray (EDX) analysis was done to confirm the purity of the sample. The optical properties of the sample were studied using ultraviolete-visible range (UV-Vis) spectroscopic analysis and photoluminescence studies. The calculated band gap of the synthesized Nd2O3 was found to be higher than that of bulk Nd2O3. The photoluminescence (PL) of the prepared samples reveals that doping with Sm3+ ion has influenced the optical properties. Quantitative investigation on charge density distribution was done by analysing the 3-dimensional and 2-dimensional charge density maps drawn along the bonding directions. The maximum entropy method (MEM)/Rietveld analysis was used for the first time to analyse the charge density in the chosen system. Charge density arrangement in the unit cell is correlated to the analysed photoluminescent (PL) properties. The spectral behaviour of the samples has been explained through charge ordering which are verified using experimental data obtained. The studies on these materials have shown that these nanophosphors will provide promising application for near-ultraviolet light-emitting diodes (n-UV-LEDs). (C) 2017 Chinese Society of Rare Earths. Published by Elsevier B.V. All rights reserved.