Synthesis, Raman and X-ray diffraction investigations of rubidium-doped Gd1.8Ti2O6.7 pyrochlore oxide via a sol–gel process

Garbout, A.; Bouattour, S.; Rego, A.M. Botelho do; Ferraria, Ana Maria; Kolsi, A. W.

doi:10.1016/j.jcrysgro.2007.03.021

Cited by 36 publications

(14 citation statements)

References 25 publications

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“…The values of K are 0.89 and 0.94 for a spherical particle with cubic symmetry crystallites determined by integral breadth and FWHM, respectively [29,30]. K can take an approximate value of one in both situations [31].…”

Section: Sample Characterizationmentioning

confidence: 99%

Experimental investigation and model development for thermal conductivity of α-Al2O3-glycerol nanofluids

Sharifpur

Ntumba

Meyer

et al. 2017

International Communications in Heat and Mass Transfer

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A B S T R A C TIn order to investigate the effect of nanoparticle volume fraction, nanoparticle size and temperature on the thermal conductivity of glycerol based alumina (α-Al 2 O 3 ) nanofluids, a set of experiments were carried out for temperature ranging from 20°C to 45°C. The nanofluids contained α-Al 2 O 3 nanoparticles of three different sizes (31 nm, 55 nm and 134 nm) were prepared by two-step method at volume fractions ranging from 0.5% to 4%. The experimental results show that α-Al 2 O 3 -glycerol nanofluids have substantially higher thermal conductivity than the base fluid and the maximum enhancement of the relative thermal conductivity was 19.5% for the case of 31 nm at 4% volume fraction. The data analyses indicated that the volume fraction and size of the nanoparticles have significant effects on the thermal conductivity ratio (TCR) of Al 2 O 3 -glycerol nanofluids, while the temperature has almost no significant effect on the data for range of this study. At room temperature, the effective thermal conductivity remains almost constant for 50 h at 4% volume fractions. The comparison of the obtained experimental data and predictions from some existing theoretical and empirical models reveals that the thermal conductivity ratio and its trend could not be accurately explained by the models in open literature. Consequently, a new empirical correlation based on the experimental data has been developed in this study.

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Section: Sample Characterizationmentioning

confidence: 99%

Experimental investigation and model development for thermal conductivity of α-Al2O3-glycerol nanofluids

Sharifpur

Ntumba

Meyer

et al. 2017

International Communications in Heat and Mass Transfer

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“…For quantification purposes, the following sensitivity factors were used: Ti 2p -1.8, O 1s -0.66 and C 1s -0.25. Other details on data acquisition and treatment were as published elsewhere [21]. Some studies dedicated to the determination of the relation between Ti 3+ /Ti 4+ states for the samples annealed in situ in ultrahigh vacuum (10 −9 mbar) were done using XPS setup with a PHI 5600ci spectrometer at the Leibniz Institut für Werkstoffkunde, Dresden.…”

Section: Xps Composition Controlmentioning

confidence: 99%

An improvement of photocatalytic activity of TiO2 Degussa P25 powder

Bessergenev

Mateus

Rego

et al. 2015

Applied Catalysis A: General

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a b s t r a c tThe photocatalytic activities of Degussa P25 powders annealed at various temperatures in vacuum and air were studied together with investigations of their compositions by XPS, of their crystal structures by XRD and of their specific surface areas by BET. It is shown that the photocatalytic activity of P25 powders was remarkably enhanced after vacuum annealing; the kinetic coefficient can be raised by 75% during annealing at 400 • C. It is obvious that this enhancement is not related to the adhesion ability of the P25 powders.

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“…A nonstoichiometry in Gd x Ti 2 O 7−δ was 1.72 < x < 2 [22]. In addition, it was found that the presence of Rb + dopant in Gd 1.8 Ti 2 O 6.7 leads to an increase of the ionic conductivity [23].…”

Section: Introductionmentioning

confidence: 99%

Sol–gel synthesis, structure characterization and Raman spectroscopy of Gd2−2xBi2xTi2O7 solid solutions

Garbout

Bouattour

Kolsi

2009

Journal of Alloys and Compounds

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Synthesis, Raman and X-ray diffraction investigations of rubidium-doped Gd1.8Ti2O6.7 pyrochlore oxide via a sol–gel process

Cited by 36 publications

References 25 publications

Experimental investigation and model development for thermal conductivity of α-Al2O3-glycerol nanofluids

Experimental investigation and model development for thermal conductivity of α-Al2O3-glycerol nanofluids

An improvement of photocatalytic activity of TiO2 Degussa P25 powder

Sol–gel synthesis, structure characterization and Raman spectroscopy of Gd2−2xBi2xTi2O7 solid solutions

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