NaNbO3 crystals dispersed in a B2O3 glass matrix – Structural characteristics versus electrical and dielectrical properties

Graça, M.P.F.; Silva, M.G. Ferreira da

doi:10.1016/j.solidstatesciences.2008.07.010

Cited by 44 publications

(27 citation statements)

References 33 publications

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“…, and Ho 3+ [5][6][7][8]. However the high phonon energy of borate is not detrimental to Sm 3+ and Eu 3+ normal 4f transition, and sometimes it can accel-erate the relaxation processes, which is necessary and beneficial for visible emission [9].…”

Section: +mentioning

confidence: 99%

“…Borate glass is considered to be a suitable optical material because of its special properties [7,8], but its application is restricted due to its high phonon energy. Unlike borate, tellurite and heavy metal oxides glasses are characterized by its low phonon energy which make them an excellent candidate for efficient infrared and upconversion visible emission in Er 3+ , Tm…”

Section: Introductionmentioning

confidence: 99%

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Electrical, dielectric and structural properties of borovanadate glass systems doped with samarium oxide

Graça

Fawzy

Badr

et al. 2011

Phys. Status Solidi C

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Glasses doped with rare earth (RE) ions are widely studied due to the numerous applications of these systems (active media for solid state lasers, optical telecommunication, non‐linear optical materials, electro‐optic devices, etc.). Boron trioxide, B2O3, is a known glass forming oxide with a relative low melting temperature. The addition of a transition metal oxide, such as V2O5, promotes the exhibition of semiconducting properties making these promising systems for several technological applications, such that ones involved in solar energy conversion devices. It is known that alkali borovanadate glasses, like alkali borate glasses themselves, are ionically conducting materials. Despite their importance there are only few studies on these glasses reported on literature. Thus, the alkali‐borovanadate glass system constitutes a family with high interest from the electrical and dielectric point of view. The effect of the increment of alkali quantity in the electrical and dielectric response of these glasses and the physical/structural explanation are questions which will be addressed. In this work, the transparent glass samples with molar composition 0.01Sm2O3‐0.99[0.85B2O3‐(0.15‐x)Li2O‐xV2O5] with x = 0, 0.1, 0.2, 0.35, 0.5 and 2 (mol%) were prepared by conventional melting technique. The prepared samples were fully characterized using different experimental techniques such as, differential thermal analysis (DTA), X‐ray diffraction (XRD), electrical and dielectric measurements. The samples structure, electrical and dielectric properties as a function of vanadium ions content was explored and discussed (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Section: +mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Electrical, dielectric and structural properties of borovanadate glass systems doped with samarium oxide

Graça

Fawzy

Badr

et al. 2011

Phys. Status Solidi C

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“…In addition, the existence of non-symmetric maximum for M´´ confirms that there is a relaxation time distribution. Moreover, the M´´ maximum shifts to higher frequencies when the measurement temperature rises from 100 K to 400 K which reveals a decrease in the relaxation time, indicating a easier depolarization associated with the thermal activated process [14][15][16]. Figure 7 depicts the magnetic hysteresis (M-H) loops of the heat treated 1%Fe 2 O 3 -99% SiO 2 sample at 1400 o C derived at 300 K and 5 K. As we can see, the saturation magnetization for 5 K is almost 2.5 times larger than that at 300 K, however, our experience in the same sample heat treated at 1200 o C showed that there is higher magnetization saturation in both 5 K and 300 K which can be attributed to the surface spin induced by silica coating resulted from inhomogeneous distribution of magnetic nanoparticles in SiO 2 shells.…”

Section: Methodsmentioning

confidence: 99%

Effect of iron on the dielectric properties of silicate glasses prepared by sol‐gel

Salehizadeh

Graça

2014

Phys. Status Solidi C

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The sol‐gel method is a very flexible route for producing sieving matrix such as SiO2 with pore radii in nanoscale region to embed oxide particles like Fe2O3. In this work, iron oxide nanoparticles embedded in a SiO2 glassy matrix prepared by the sol‐gel method have been investigated as a function of Fe/Si ratio. Different composition of dried gels with 1, 2, 10 and 20 mol% of Fe2O3 in the SiO2 matrix were heat‐treated (HT) in air, at temperatures from 400 ºC up to 1400 °C. The structure and morphology of the obtained glasses and glass‐ceramics were studied by X‐ray powder diffraction (XRD), Raman spectroscopy and scanning electron microscopy (SEM). Impedance spectroscopy measurements and magnetic characterization were performed as function of temperature and the results are related with the microstructure. The X‐ray diffraction patterns showed that increasing the amount of Fe2O3 oxide promotes the formation of crystalline phases, in particular silicate phases. The increase of the heat‐treatment temperature has a similar behavior. The electrical and dielectric properties were related with these structural modifications and with the sample morphology. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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“…The analytical background, used in the electrical data analysis, is described elsewhere [23][24][25].…”

Section: Methodsmentioning

confidence: 99%

“…The ln(r dc ) vs 1/T (Fig. 3) graph was used to calculate the dc activation energy (E a(dc) ) [21,[23][24][25][26][27][28]. The results show a decrease of the E a(dc) with the rise of the heat-treatment temperature (Table 1).…”

Section: Intensity (Arb Units)mentioning

confidence: 99%

Dielectric spectroscopy of LiNbO3 and TmNbO4 nanocrystals embedded in a SiO2 glass matrix

Silva

Sombra

Graça

2010

Journal of Non-Crystalline Solids

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NaNbO3 crystals dispersed in a B2O3 glass matrix – Structural characteristics versus electrical and dielectrical properties

Cited by 44 publications

References 33 publications

Electrical, dielectric and structural properties of borovanadate glass systems doped with samarium oxide

Electrical, dielectric and structural properties of borovanadate glass systems doped with samarium oxide

Effect of iron on the dielectric properties of silicate glasses prepared by sol‐gel

Dielectric spectroscopy of LiNbO3 and TmNbO4 nanocrystals embedded in a SiO2 glass matrix

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