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Ahlawat R.,Ch Devi Lal University
International Journal of Applied Ceramic Technology

Gd(NO3)3·6H2O and TEOS were used as precursors and obtained powdered form of Gd2O3:SiO2 nanocomposite. The as-prepared sample was annealed at 773 K and 1173 K and characterized by XRD, TEM, UV-Vis spectra, and PL. The average nanocrystallite size was found of the order of ~27 nm using well-known Debye-Scherer's equation. From the UV-Vis spectra, it was shown that the position of absorption peak has been shifted toward the higher wavelength side with temperature. In the PL spectra, the broad emission band has been observed at 583 nm along with weak bands at 516, 526, and 556 nm. © 2015 The American Ceramic Society. Source

Ahlawat R.,Ch Devi Lal University
International Journal of Applied Ceramic Technology

Gd(NO3)3.6H2O and TEOS were used as precursors and obtained Gd2O3:SiO2 ceramic powder having different concentration of Gd2O3 as 2.2, 2.8, 3.4, and 4.0 wt % using solgel process. The powdered samples were annealed at 500°C and 900°C temperatures and characterized by XRD, FTIR, SEM, and TEM. In X-ray diffraction, cubic phase of Gadolinium oxide is reported only for the annealed samples having higher concentration (3.4 & 4.0 wt %) of Gd2O3. SEM and TEM results further confirm that the surface morphology of the microstructures depend on the temperature and concentration. © 2014 The American Ceramic Society. Source

Y2O3:SiO2 powder was synthesized by a sol-gel method, using hydrous yttrium nitrate and hydrous silicon oxide as precursors and HCl as a catalyst. The dried samples were submitted to multi-step annealing schedule in air without applying pressure. A simple four-step annealing schedule with a final stage of about 900 °C for 6.0 h was followed. The samples of Y2O3:SiO2 nanocomposites were obtained with well defined size and shape. Structural changes of the nanocomposites were investigated by XRD, FTIR and TEM. Multi-step annealing scheme with different ramp rates and incubation times allows recovery-relaxation processes within the boundaries and leading to a concomitant linear increase of crystallite size and densification. Almost fully dense quasi-spherical cubic-yttria nanopowder has been demonstrated with an average grain size distribution of 10-40 nm; can be uniformly dispersed in silica matrix. © 2015 Elsevier Ltd. and Techna Group S.r.l. All rights reserved. Source

Aghamkar R.P.,Ch Devi Lal University
Journal of Optoelectronics and Advanced Materials

Y (NO3)3.4H2O and TEOS were used as precursors and powdered form of Y2O3:SiO2 binary oxide was prepared by sol gel process. The powdered sample was annealed at 750°C temperature and characterized by X-ray diffraction, Fourier transforms infrared spectroscopy and transmission electron microscopy. The sample analyzed by FTIR and TEM confirmed the grain size dependency on sintering temperature. Cubic structure of yttrium oxide nanocrystallite with average size ~ 21 nm was obtained at 750 °C (6h) along with crystalline silica. Source

SiO2:RE2O3 [RE = Y, Gd] powder were prepared by wet chemical technique and the prepared binary oxides annealed at 500 °C and 900 °C. The crystalline structure, phase transformation, and surface morphologies of as-prepared and annealed samples were investigated by XRD and TEM. The normal transmission was measured using FTIR spectroscopy. Optical properties have been studied with UV-Vis spectroscopy and PL study. XRD results shows that the as prepared samples of SiO2:RE2O3 [RE = Y, Gd] powder has mixed phases of RE(NO3)3 and Si(OH)3. However, cubic rare earth oxide phase alone is found for annealed samples. The strain values are calculated from W-H plot for annealed samples. TEM micrograph shows that the samples are composed of individual spherical nanocrystallites at 500 °C and aggregated nanocrystallites at 900 °C. From the UV-Vis spectra, it is found that the position of the absorption peak is shifted toward the higher wavelength side when annealing temperature is increased. In the PL spectra, the broad emission bands are observed between 570-600 nm and the presence of O-Si-O (silica) and metal oxide is confirmed by FTIR spectra. © 2015 Elsevier B.V. Source

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