Sam Solomon

Optical properties of nanocrystalline HfO2 synthesized by an auto-igniting combustion synthesis

Abstract The optical properties of nanocrystalline HfO2 synthesized using a single-step auto-igniting combustion technique is reported. Nanocrystalline hafnium oxide having particle size of the order 10–15 nm were obtained in the present method. The nanopowder was characterized using X-ray diffraction, Fourier transform infrared and Fourier transform Raman spectroscopic studies. All these studies confirm that the phase formation is complete in the combustion synthesis and monoclinic phase [P21/c(14)] of HfO2 is obtained without the presence of any impurities or additional phases. The powder morphology of the as-prepared sample was studied using transmission electron microscopy and the results were in good agreement with that of the X-ray diffraction studies. The optical constants such as refractive index, extinction coefficient, optical conductivity and the band gap were estimated from UV–vis spectroscopic techniques. The band gap of nanocrystalline HfO2 was found to be 5.1 eV and the sample shows a broad PL emission at 628 nm. It is concluded that the transitions between intermediate energy levels in the band gap are responsible for the interesting photoluminescent properties of nanocrystalline HfO2.

Structural, dielectric and optical characterization of BaMoO4 nano powder synthesized through an auto-igniting combustion technique

Nanocrystalline BaMoO4 was synthesized through auto-ignited combustion technique. The X-ray diffraction studies of BaMoO4 nanoparticles reveals that the as-prepared powder is single phase, crystalline, and has tetragonal structure. The average particle size of the as-prepared powder from transmission electron microscopic is found to be 22nm. The thermal stability of the nano powder was examined using thermo gravimetric analysis and differential thermal analysis. The band gap determined from absorption spectra is 3.20eV.Photoluminescence spectra of the samples shows green emission peak. The dielectric constant and loss factor of the sample at 1 MHz is found to be 9.75 and 1.38×10−2 at room temperature.

Electrical and optical properties of nanocrystalline RE–Ti–Nb–O6 (RE = Ce, Pr, Nd and Sm) electronic material

Nano-crystalline RETiNbO6 (RE = Ce, Pr, Nd and Sm) is successfully synthesized through the solution combustion technique. The XRD analysis revealed that the materials have orthorhombic aeschynite structure with space group Pnma. The particle size determined from XRD and TEM shows that the samples are nano-crystalline. Structure is confirmed by the analysis of FT-Raman, the fourier transform infrared spectra and surface morphology by SEM micrograph. The optical properties, dielectric characteristics at radio frequency range and complex impedance of the system are also studied. Percentage of rare earth in each compound, sintering temperature and density achieved are calculated. The UV–Vis spectra show that the materials can be used as a protective material from UV radiation due to high absorbance in that region. These compounds show strong emission in violet and green regions in the photoluminescence spectrum. The compounds are useful in communication systems due to low dielectric loss and high dielectric constant. The high ionic conductivity suggests that the material can be used as electrolyte in solid oxide fuel cells.

Enhanced infrared transmission characteristics of microwave-sintered \(\hbox {Y}_{2}\hbox {O}_{3}\)–\(\hbox {MgO}\) nanocomposite

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Synthesis of strontium zirconate as nanocrystals through a single step combustion process

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Impedance and modulus spectroscopic studies on 40PrTiTaO6 + 60YTiNbO6 ceramic composite

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Structural, spectroscopic and dielectric investigations on Ba8Zn(Nb6−xSbx)O24 microwave ceramics

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