Sol-gel preparation and electrical behaviour of Ln: YAG (Ln = Ce, Nd, Ho, Er)

A sol-gel method has been developed to prepare pure yttrium aluminum garnet Y3Al5O12 (YAG), and rare-earth substituted (Ce-Y3Al5O12, Nd-Y3Al5O12 Ho-Y3Al5O12, and Er-Y3Al5O12) samples. The XRD patterns of the polycrystalline powders sintered at 1000 ?C showed the formation of monophasic garnet materials. The micro-structural features in the polycristalline samples were studied by scanning electron microscopy. A homogeneous distribution of rare-earth do pants in the YAG lattice was achieved in all of the cases. Electrical conductivity measurements were also performed on the compacts of sol-gel derived Ln-YAG samples. In contrast to the expected dielectric behavior, the conducting properties of the examined specimens indicate metallic behavior with the resistivity increasing gradually with increasing temperature.

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Dielectric and varistor properties of rare-earth-doped ZnO and CaCu3Ti4O12 composite ceramics

Journal of Advanced Dielectrics ◽

10.1142/s2010135x1350001x ◽

2013 ◽

Vol 03 (01) ◽

pp. 1350001 ◽

Cited By ~ 6

Author(s):

Huafei Lu ◽

Yuanhua Lin ◽

Jiancong Yuan ◽

Cewen Nan ◽

Kexin Chen

Keyword(s):

Rare Earth ◽

Sol Gel ◽

Nonlinear Coefficient ◽

Composite Ceramic ◽

Dielectric Behavior ◽

Composite Ceramics ◽

High Dielectric Permittivity ◽

Doped Zno ◽

Co Precipitation ◽

High Dielectric

To investigate the multi-functional ceramics with both high permittivity and large nonlinear coefficient, we have prepared rare-earth Tb -and- Co doped ZnO and TiO 2-rich CaCu3Ti4O12 (TCCTO) powders by chemical co-precipitation and sol–gel methods respectively, and then obtained the TCCTO/ ZnO composite ceramics, sintered at 1100°C for 3 h in air. Analyzing the composite ceramics of the microstructure and phase composition indicated that the composite ceramics were composed of the main phases of ZnO and CaCu3Ti4O12 (CCTO). Our results revealed that the TCCTO/ ZnO composite ceramics showed both high dielectric and good nonlinear electrical behaviors. The composite ceramic of TCCTO: ZnO = 0.3 exhibited a high dielectric constant of ~210(1 kHz) with a nonlinear coefficient of ~11. The dielectric behavior of TCCTO/ ZnO composite could be explained by the mixture rule. With the high dielectric permittivity and tunable varistor behaviors, the composite ceramics has a potential application for the higher voltage transportation devices.

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The Effect of Stabiliser’s Molarity to the Growth of ZnO Nanorods

Defect and Diffusion Forum ◽

10.4028/www.scientific.net/ddf.312-315.99 ◽

2011 ◽

Vol 312-315 ◽

pp. 99-103 ◽

Cited By ~ 5

Author(s):

Zuraida Khusaimi ◽

Mohamad Hafiz Mamat ◽

Mohd Zainizan Sahdan ◽

Norbani Abdullah ◽

Mohamad Rusop

Keyword(s):

Sol Gel ◽

Zno Nanorods ◽

Structural Features ◽

Zinc Nitrate ◽

Molar Ratio ◽

Nitrate Hexahydrate ◽

X Ray Diffraction ◽

X Ray ◽

Wet Chemical ◽

Gel Preparation

A wet chemical approach, originating from sol-gel preparation, was adopted with the intention to develop a low-temperature benign method of preparation. ZnO nanorods are successfully grown in an aqueous medium. The precursor, zinc nitrate hexahydrate (Zn(NO3)2.6H2O), is stabilized by hexamethylene tetraamine (HMTA). The effect of changing the molarity of HMTA to the structural orientation of ZnO nanorods is investigated. X-ray diffraction of the synthesized ZnO shows hexagonal zincite structure. The structural features of the nanocrystalline ZnO were studied by SEM. Structural features, surface morphology and differences in lattice orientation are seemingly influenced by varying the Zn2+: HMTA molar ratio. The formation of ZnO nanorods with blunt and sharp tips is found to be significantly affected by this ratio.

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Electrical Conductivity of Molten DyCl3-NaCl and DyCl3-KCl Systems: An Approach to Structural Interpretations of Rare Earth Chloride Melts

Zeitschrift für Naturforschung A ◽

10.1515/zna-2017-0250 ◽

2017 ◽

Vol 72 (12) ◽

pp. 1105-1112

Author(s):

Yasuhiko Iwadate ◽

Takahiro Ohkubo

Keyword(s):

Rare Earth ◽

Type Equation ◽

Structural Features ◽

Rare Earth Chloride ◽

Chloride Melts ◽

Electrical Conductivities ◽

Increasing Temperature ◽

Melt Composition ◽

Relationship Of ◽

The Relationship

AbstractElectrical conductivities (κs) of molten DyCl3-NaCl and DyCl3-KCl systems were estimated by measuring the impedances of each mixture melt at any temperature and/or frequency. The molar volumes (Vms) were measured by dilatometry and represented as a polynomial empirical equation of temperature and composition. Due to both the properties, the molar conductivities (Λms) were calculated and their temperature and/or composition dependences were discussed from the standpoint of structural features as well. The κs increased curvilinearly with increasing temperature across the whole composition ranges. This trend was also applied to the Λms which was fitted by an Arrhenius-type equation. The relationship of Λms with melt composition was studied and the Λms were found to decrease with increasing composition of DyCl3. These findings were interpreted based on the results of structural science so far reported, and finally, the relationship between Λms and the structures of pure rare earth chloride melts was discussed.

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Sol-gel preparation and characterization of non-substituted and Sr-substituted lanthanum cobaltates

Open Chemistry ◽

10.2478/s11532-008-0045-0 ◽

2008 ◽

Vol 6 (3) ◽

pp. 456-464 ◽

Cited By ~ 8

Author(s):

Sigute Cizauskaite ◽

Aivaras Kareiva

Keyword(s):

Sol Gel ◽

Structural Features ◽

Synthesis Temperature ◽

Heating Time ◽

X Ray Diffraction ◽

Phase Purity ◽

X Ray ◽

Gel Preparation ◽

Temperature Heating

AbstractThis paper reports on the results concerning the sol-gel preparation and characterization of Sr-substituted perovskite lanthanum cobaltates La1−xSrxCoO3−δ (x = 0.0, 0.25, 0.5 and 0.75). The metal ions, generated by dissolving starting materials in diluted acetic acid were complexed by 1,2-ethanediol to obtain the precursors for the non-substituted and Sr-substituted LaCoO3. The influence of the synthesis temperature, heating time and the amount of substituent on the phase purity of La1−xSrxCoO3−δ were investigated. The phase transformations, composition and micro-structural features in the gels and polycrystalline samples were studied by thermal analysis (TG/DTA), infrared spectroscopy (IR), powder X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM).

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Synthesis of lead-based 1212 and 3212 superconductors by an aqueous sol-gel method

Open Chemistry ◽

10.2478/s11532-009-0025-z ◽

2009 ◽

Vol 7 (3) ◽

pp. 362-368 ◽

Cited By ~ 1

Author(s):

Giedre Nenartaviciene ◽

Ramunas Skaudzius ◽

Rimantas Raudonis ◽

Aivaras Kareiva

Keyword(s):

Sol Gel ◽

Xrd Analysis ◽

Structural Features ◽

Complexing Agents ◽

X Ray Diffraction ◽

X Ray ◽

Resistivity Measurements ◽

Ceramic Samples ◽

Xrd Patterns ◽

Sol Gel Synthesis

AbstractThe aqueous sol-gel synthesis technique for the preparation of (Pb,Sr)Sr2(Y,Ca)Cu2O7±x (Pb-1212) and (Pb2,Cu)Sr2(Y,Ca)Cu2O8±x (Pb-3212) superconductors using two different complexing agents, namely 1,2-ethanediol and tartaric acid was studied. The phase transformations, composition and micro-structural features in the polycrystalline samples were studied by powder X-ray diffraction analysis (XRD), infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). XRD analysis of the ceramic samples obtained by calcination of Pb-Sr-Y-Ca-Cu-O acetate-glycolate precursor gels in air, for 10 hours at 800°C and at 825°C, showed the presence of homogeneous Pb-1212 and Pb-3212 crystallites as major phases. The XRD patterns of the ceramics obtained from Pb-Sr-Y-Ca-Cu-O acetate-tartrate precursor gels, however, showed multiphasic character. The critical temperature of superconductivity (TC (onset)) observed by resistivity measurements were found to be 91 K and 75 K for Pb-1212 and Pb-3212 samples, respectively.

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Rare earth (Eu3+, Tb3+) centered composite gels Si–O–M (M=B, Ti) through hexafluoroacetyl-acetone building block: Sol–gel preparation, characterization and photoluminescence

Materials Research Bulletin ◽

10.1016/j.materresbull.2011.08.015 ◽

2011 ◽

Vol 46 (12) ◽

pp. 2515-2522 ◽

Cited By ~ 9

Author(s):

Chang Wang ◽

Bing Yan

Keyword(s):

Rare Earth ◽

Building Block ◽

Sol Gel ◽

Composite Gels ◽

Gel Preparation

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Synthesis and Antimicrobial Activity of Fe:TiO2 Particles

Journal of Nano Research ◽

10.4028/www.scientific.net/jnanor.56.28 ◽

2019 ◽

Vol 56 ◽

pp. 28-38 ◽

Cited By ~ 4

Author(s):

Uraiwan Werapun ◽

Jaraslak Pechwang

Keyword(s):

Anatase Phase ◽

Sol Gel ◽

Rutile Phase ◽

Antibacterial Activities ◽

X Ray Diffraction ◽

X Ray ◽

Ft Ir ◽

Xrd Patterns ◽

Increasing Temperature ◽

Scanning Electron

TiO2 and iron-doped TiO2 were synthesized by sol-gel method. TiO2 and 0.5 %mol Fe:TiO2 were calcined at 500 and 800 °C for 3 h. The synthesized particles were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), UV-VIS diffuse reflectance spectrophotometry (UV/DRS), scanning electron microscopy (SEM) and scanning electron microscope-energy dispersive X-Ray analysis (SEM-EDX). The XRD patterns of all samples that were calcined at 500 °C showed only anatase phase. On increasing temperature from 500 to 800 °C, the anatase phase transformed to rutile phase. For 0.5 %mol Fe:TiO2, pseudobrookite (Fe2TiO5) phase was observed at 800 °C. The particles that contained rutile showed higher antibacterial activities against E.coli, B. subtilis, and S. aureus than anatase phase, under fluorescent irradiation.

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Synthesis and Characterization of Monodispersed Rare-earth Ion Doped CeO2 Coated on SiO2 Spheres

MRS Proceedings ◽

10.1557/proc-1074-i10-36 ◽

2008 ◽

Vol 1074 ◽

Author(s):

Pandurangan Muralidharan ◽

Seung Hwan Jo ◽

Hyun Wook Lee ◽

Do Kyung Kim

Keyword(s):

Heat Treatment ◽

Rare Earth ◽

Sol Gel ◽

Rare Earth Ion ◽

Uniform Size ◽

Tem Analysis ◽

Xrd Patterns ◽

Photoluminescence Studies ◽

Sio2 Spheres

ABSTRACTCore–shell microspheres of monodispersed SiO2 coated with rare-earth ion doped CeO2 (Eu3+ Sm3+ Dy3+) were prepared through a sol-gel method and followed by heat treatment at 800 °C for 4 h. XRD patterns revealed the crystal structures of the doped CeO2 coated on amorphous SiO2 sphere as a shell subsequent to heat treatment at 800 °C. SEM and TEM analysis indicated the microstructures of the coating and uniform size distributions of microspheres. Photoluminescence studies showed that the luminescent property had significant influence depending on different dopant ions and the thickness of the shell coated on SiO2 spheres.

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