Pradosh Prakash Sahay

This study explores the synthesis of ZnO nanoparticles through a solution‐combustion route, examining their structural, photoluminescent, and photocatalytic properties upon introducing Sm as a dopant. All synthesized samples display a hexagonal wurtzite structure, with crystallite sizes between 55 and 73 nm. Field‐emission scanning electron microscopy reveals significant sample morphological variation. Diffuse reflectance spectroscopy indicates that doping with Sm³⁺ results in a slight decrease in the bandgap energy. The photoluminescence (PL) emission spectra at excitation wavelengths of 325, 350, and 390 nm show broad emission bands spanning from the violet to the green regions of the visible spectrum, attributed to defects in ZnO. Additionally, the PL intensity increases with Sm doping up to 2 mol% Sm, after which it declines. The photocatalytic degradation efficiency improves upon Sm doping up to 3 mol% and thereafter decreases.

This paper investigates the synthesis of Ce³⁺ and Eu³⁺ doped, as well as co-doped ZnO nanoparticles using the solution combustion route. The nanoparticles exhibit a hexagonal wurtzite structure of ZnO with crystallite sizes ranging from 19 to 22 nm. Structural parameters, including lattice constants, bond lengths, and bond angles, are evaluated. Morphological diversity is observed in field-emission scanning electron microscopy images. The diffuse reflectance spectroscopy results reveal an energy band gap of 3.20 eV for undoped ZnO nanoparticles. The energy band gap value slightly decreases for Eu-doped ZnO and certain (Ce, Eu) co-doped ZnO nanoparticles. Photoluminescence (PL) excitation peaks are attributed to energy levels of native defects in the ZnO band gap, along with f–d and f–f transitions of rare-earth ions (Ce³⁺, Eu³⁺). The PL emission spectra under different excitation wavelengths (350 nm, 394 nm, and 465 nm) display varied peak positions. ZnO co-doped with 0.96 mol% of Ce³⁺ and 0.92 mol% of Eu³⁺ emerges as a promising material for luminescence applications, exhibiting a significant increase in green emission intensity. Consequently, this study represents a novel contribution to the field of ZnO-based luminescent materials.

This paper presents a research investigation into the synthesis of vanadate oxides M₃(VO₄)₂ (M: Mg or Zn) using the solution combustion method and investigates their structural, photoluminescence, and photocatalytic properties after introducing cerium (Ce) as a dopant. The resulting synthesized samples all display an orthorhombic crystalline structure with crystallite sizes ranging from 71 to 110 nm. Morphological diversity among the samples is revealed through field‐emission scanning electron microscopy (FESEM) imagery. Diffuse reflectance spectroscopy discloses that the introduction of Ce³⁺ as a dopant leads to an increase in the band gap energy. Notably, when excited at a wavelength of 340 nm, the photoluminescence emission intensity reaches its peak across all samples. This intensity undergoes enhancement due to Ce³⁺ doping, causing a slight shift toward shorter wavelengths attributable to the augmented band gap resulting from the dopant. Markedly, among the investigated materials, Ce³⁺‐activated Mg₃(VO₄)₂ stands out with the most pronounced emission intensity, positioning it as a highly promising luminescent material. Additionally, the incorporation of Ce³⁺ has a positive effect on the photocatalytic performance of Mg₃(VO₄)₂, resulting in notable improvement.

Solution combustion synthesized ZnO nanoparticles that were Ce doped, Dy doped or co‐doped at varying dopant concentrations were characterized for their microstructural, optical, and photoluminescence (PL) characteristics. The synthesized nanoparticles matched the standard hexagonal wurtzite structure of ZnO. The lattice fringes in the high‐resolution transmission electron micrographs and the bright spotty rings in the selected area electron diffraction patterns authenticated the high crystallinity of the nanoparticles. The diffuse reflectance spectroscopy resolved the energy bandgap for the undoped ZnO as 3.18 eV, which decreased upon doping and co‐doping. A sharp narrow ultraviolet emission peak at ~398 nm that originated from excitonic recombination was found in the PL spectra of the nanoparticles. The visible emission peaks in the PL spectra were assigned to the f–d and f–f electron transitions of Ce³⁺ and Dy³⁺ ions, respectively, in addition to different native defects in ZnO. The visible emissions (blue, yellow, and red) improved upon (Ce, Dy) co‐doping, therefore (Ce, Dy) co‐doped ZnO nanoparticles can be considered a promising luminescent material for the development of energy‐saving light sources.

Dy‐doped Y₂O₃ nanoparticles were synthesized by solution combustion route with urea as fuel, and their microstructural features were analyzed by X‐ray diffraction (XRD) and high‐resolution transmission electron microscopy (HRTEM). The XRD study confirms the formation of a pure cubic phase of Y₂O₃, with the maximum textural coefficient along the (2 2 2) plane for the Dy‐doped samples. The lattice fringes in the HRTEM image and the bright spotty rings in the selected area electron diffraction (SAED) pattern reveal the highly crystalline nature of the nanoparticles. From the diffuse reflectance spectroscopy, using Kubelka‐Monk theory, the direct bandgap energy is estimated to be 5.61 eV for the undoped Y₂O₃, which is found to decrease upon Dy³⁺ doping. The room‐temperature excitation spectra of the nanoparticles recorded at 575 nm emission wavelength comprise several excitation bands corresponding to the f‐f transitions of Dy³⁺ ions in the host lattice. The photoluminescence spectra of the nanoparticles excited at the wavelength of 350 nm comprise three visible emission peaks at 477 nm (blue), 573 nm (yellow), and 666 nm (red). It has been concluded that the 0.5 mol% Dy‐doped Y₂O₃ nanoparticles are the potential candidate to be used for solid‐state luminescent device applications.