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Kozuka, Hiromitsu; Kajimura, Masahiro; Hirano, T.; Katayama, Kentaro

doi:10.1023/a:1008780120351

Cited by 123 publications

(54 citation statements)

References 2 publications

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“…The micro-crack between grains on the sol-gel derived films are due to the condensation reaction and to the collapse of pores under the heat treatment. 34 The film microstructure is affected by the annealing procedure, e.g., by annealing temperature, time, heating rate, etc. In turn, film microstructure influences the SMT properties.…”

Section: Resultsmentioning

confidence: 99%

Spectroscopic analysis of phase constitution of high quality VO2 thin film prepared by facile sol-gel method

Fan

Chen

et al. 2013

AIP Advances

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VO2 thin films with large-area were prepared on Al2O3 substrates by a simple sol-gel method. After an annealing treatment under low vacuum condition, all the VO2 films showed a preferred growth direction and exhibited excellent semiconductor-metal transition (SMT) characteristics. The structure and electrical properties of the obtained VO2 films were investigated systematically. Raman spectra, X-ray diffraction and X-ray absorption spectra measurements pointed out that the VO2 film on ${\rm A}{\rm l}_{\rm 2} {\rm O}_{\rm 3} ( {{\rm 10}\overline {\rm 1} {\rm 0}})$Al2O3(101¯0) substrate showed a M1 phase instead of M2 phase as reported in previous studies. Based on the experiment results, it was suggested that the strained structure of oriented VO2 films could be a mechanism for the formation of the intermediate M2 phase, whereas it is difficult to access the pure M2 phase of undoped VO2 films. VO2 film on ${\rm A}{\rm l}_{\rm 2} {\rm O}_{\rm 3} \left( {{\rm 10}\overline {\rm 1} {\rm 0}} \right)$Al2O3101¯0 substrate showed a lower SMT temperature compared to VO2 film on Al2O3 (0001), which can be mostly attributed to the differences of both lattice mismatch and thermal stress. The present results confirm and make clear the relevance of the substrate orientation in the growth of VO2 film and their different contributions to the SMT characteristics in vanadate systems.

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Section: Resultsmentioning

confidence: 99%

Spectroscopic analysis of phase constitution of high quality VO2 thin film prepared by facile sol-gel method

Fan

Chen

et al. 2013

AIP Advances

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“…18 3 ) by spincoating at a spinning rate of 3440 rpm. The gel lms thus prepared were heated successively at 100to 700 C, where 10 min heattreatment was conducted at each temperature.…”

Section: Eects Of the Processing Parametersmentioning

confidence: 99%

On Ceramic Thin Film Formation from Gels: Evolution of Stress, Cracks and Radiative Striations

Kozuka

2003

J. Ceram. Soc. Japan

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There are still several problems to be scientically solved for thegconventionalh solgel ceramic coating technique to be utilized in industrial scale. Based on the recognition, the author's group studied the stress evolution and crack formation in gelderived lms and the evolution of radiative striations in spincoating lms. Possible modication of the solgel technique has also been made for realizing thicker lms via non cycled deposition. First, the residual stress was measured on alkoxidederived silica and titania lms deposited on silica glass substrate. The residual stress increased with increasing heattreatment tempera ture due to densication. It was demonstrated that the stress in lms is not a simple function of the dier ence in thermal expansion coecient between the lm and the substrate, but is greatly aected by the processing parameters including the amount of water for hydrolyzing alkoxides and the kinds of the chelat ing agents. Second, in situ observation was conducted on silica and titania gel lms deposited on single crystal silicon substrates. Macroscopic cracking occurred in the heatingup stage, suggesting that the cracks are formed by tensile stress generated in lms due to densication. Also, such cracking was found to occur at lower temperatures when the lms are thick or heated at lower rates. Third, expecting that organic polymers with amide groups like polyvinylpyrrolidone (PVP) can promote structural relaxation and can sup press stress evolution on heating, PVPassisted solgel thin lm deposition was proposed. Incorporating PVP in coating solutions, crackfree ceramic thin lms including BaTiO 3 , PZT and BaBi 4 Ti 4 O 15 lms over submicron or micron in thickness could be prepared via noncycled deposition. Finally, radiative striations were quantitatively evaluated by surface roughness measurement, and the eects of the processing parameters on striation evolution were studied. The height and spacing of striations were found to be in creased with decreasing spinning rate and with increasing sol viscosity. Striations were also found to be formed even without the rotation of the substrate, suggesting that the substrate rotation is not a necessary condition for evolution of striations. On the assumption that the mechanism of the evolution of striations is the same irrespective of the presence or absence of the substrate rotation, in situ observation of the evolu tion of striations was conducted on a sol layer placed on a stationary substrate. It was observed that stria tions are formed on solvent evaporation after the sol was spread, not on proceeding of the sol front towards the outer.

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“…A possible alternative to producing high quality and of BaTiO 3 :Er 3+ films is to incorporate PVP (polyvinylpirrolidone: as rheological agent FW: 360000) during the solgel synthesis process. 15,16) However, its effect in the morphological and luminescent properties is unclear; therefore, the present work studies, by means of three different experimental procedures, the effect of molar ratio and PVP on morphology and photoluminescent properties of Er-doped BaTiO 3 sol gel thin films. Table 1.…”

Section: Introductionmentioning

confidence: 99%

Effect of Starting Materials on the Morphological and Optical Properties of Er Doped BaTiO<sub>3</sub> Nanocrystalline Films

Hernández¹,

García-Murillo²,

Romo³

et al. 2013

Mater. Trans.

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Erbium (5%mol) doped BaTiO 3 films were prepared using different metallic precursors: barium acetate, titanium butoxide and isopropoxide with different molar ratios. Three different experimental methodologies (A, B and C) were proposed in order to obtain optical quality thick films incorporating polyvinylpyrrolidone (PVP) as a rheological agent at the sol stage. In all cases, Er doped BaTiO 3 films were deposited in silica quartz substrates. The morphology was controlled by means of the incorporation of the chelating agent and water molar ratios. Through the three different synthesis routes, Er:BaTiO 3 films presented mainly the cubic phase, as observed by X-ray diffraction. The films presented a homogeneous and crack-free surface of cross-linked particles. Photoluminescent results show that the highest intensity emission of the Er 3+ ( 4 S 3/2 ¼ 4 I 15/2 ) was obtained from Er:BaTiO 3 film prepared using C methodology, which could be associated with the film's thicknesses.

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Untitled

Cited by 123 publications

References 2 publications

Spectroscopic analysis of phase constitution of high quality VO2 thin film prepared by facile sol-gel method

Spectroscopic analysis of phase constitution of high quality VO2 thin film prepared by facile sol-gel method

On Ceramic Thin Film Formation from Gels: Evolution of Stress, Cracks and Radiative Striations

Effect of Starting Materials on the Morphological and Optical Properties of Er Doped BaTiO<sub>3</sub> Nanocrystalline Films

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