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  • 1
    Electronic Resource
    Electronic Resource
    Structural Evolution in Sol–Gel-Derived Yttrium Aluminum Garnet–Alumina Precursor Fibers (2002)
    Westerville, Ohio : American Ceramics Society
    Journal of the American Ceramic Society 85 (2002), S. 0 
    Details
    ISSN: 1551-2916
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A sol leading to a eutectic Al2O3–Y3Al5O12 composition was spun into fibers. These fibers were dried and pyrolyzed between 200° and 850°C in a nitrogen or water-vapor atmosphere. Pyrolysis in nitrogen resulted in dense, amorphous fibers with considerable residual carbon content. In water vapor, fibers also remained amorphous, but organics were almost completely removed. The loss of organics created micropores that grew as the pyrolysis temperature increased. The amorphous fiber structures were examined by nitrogen adsorption, helium pycnometry, and transmission electron microscopy. Young's moduli of the pyrolyzed fibers were measured, and porosities of the fibers were calculated from both nitrogen-adsorption data and elastic behavior. Sintering tests showed the best sinterability for fibers pyrolyzed in water vapor to 385°–500°C.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1151-2916.2002.tb00535.x
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  • 2
    Electronic Resource
    Electronic Resource
    Densification and Crystallization of Lead Titanate Aerogels (1997)
    Westerville, Ohio : American Ceramics Society
    Journal of the American Ceramic Society 80 (1997), S. 0 
    Details
    ISSN: 1551-2916
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Crack-free monolithic lead titanate (PbTiO3, or PT) aerogels were prepared via a sol-gel process and drying in supercritical carbon dioxide. The material was characterized by thermogravimetric analysis, dilatometry, helium pycnometry, and X-ray diffraction. Skeletal densification was the main reason for the observed shrinkage of the heat-treated porous material at temperatures 〈450°C. The transition (at temperatures of 500°-600°C) from an amorphous state to the crystalline (tetragonal) PT was accompanied by significant particle coarsening, as revealed by transmission electron microscopy. Nitrogen adsorption measurements confirmed that crystallization was preceded by the formation of interparticle necks.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1151-2916.1997.tb03168.x
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  • 3
    Electronic Resource
    Electronic Resource
    Powders, Fibers, Thin Films and Aerogels: Sol-Gel-Derived Piezoelectric Materials (2002)
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 224-226 (June 2002), p. 613-618 
    Details
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/46/transtech_doi~10.4028%252Fwww.scientific.net%252FKEM.224-226.613.pdf
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  • 4
    Electronic Resource
    Electronic Resource
    Coating of Polymer Surfaces by Liquid Phase Deposition of TiO〈sub〉2〈/sub〉: A Biologically-Inspired Approach (2006)
    s.l. ; Stafa-Zurich, Switzerland
    Advances in science and technology Vol. 45 (Oct. 2006), p. 1246-1251 
    Details
    ISSN: 1662-0356
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Natural Sciences in General , Technology
    Notes: The coating of polymer surfaces with ceramics up to now is basically only accomplishableby vacuum-based technologies such as sputtering, because the thermal load is low compared toother methods such as sol-gel processing. Since the investment costs for the equipment required areconsiderably high and the coating is limited to line-of sight deposition, simple and cost-effectiveprocessing routes are sought.In all higher organisms inorganic materials are synthesized at ambient temperatures under physiologicalconditions. Therefore the study of biomineralization processes has gained considerable academicattention in the last decades. One of the key features of inorganic material deposition in vitois the interaction between supersaturated solutions and specifically modified surfaces.Following this paradigm so-called bio-inspired approaches can be developed which go beyond thecurrent limitations of synthetic techniques. One example is the mineralization of planar polymersurfaces with TiO2 at 50oC. Using polystyrene latex particles as templates, all four stagescommonly found in natural biomineralization can be emulated in a completely artificial system
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/42/transtech_doi~10.4028%252Fwww.scientific.net%252FAST.45.1246.pdf
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  • 5
    Electronic Resource
    Electronic Resource
    Lead Zirconate-Titanate Films Prepared from Soluble Powders (1998)
    Springer
    Journal of sol gel science and technology 13 (1998), S. 827-831 
    Details
    ISSN: 1573-4846
    Keywords: sol-gel ; thin films ; ferroelectricity ; lead zirconate titanate (PZT)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Precursor powders for Pb(Zr1 − xTix) O3 (PZT) thin films were produced by the reaction of zirconium-and titanium-n-propoxides with acetylacetone and lead acetate trihydrate. The subsequent complete removal of volatile components yielded powders that can be handled in air. The powders are indefinitely stable under ambient conditions. High molarity (〉2m) coating sols were prepared by dissolution of the precursor powders in mixtures of 1,3-propanediol, triethanolamine (TEA) and water. Excess amounts of lead to compensate lead loss during firing were easily introduced into these solutions. The deposition of these sols on steel substrates and firing at 600°C yielded PZT films. Many physical parameters like film thickness, morphology and electrical performance could be influenced by choice of the solvent mixture composition and oxide content of the sols. Depending on the preparation dielectric permittivities, εr of up to 840 were measured at 1 kHz. By hysteresis measurements at 50 Hz and a field amplitude of 50 V/μm a remanent polarization of about 40 μC/cm2 and coercivity of about 8 V/μm was obtained. The films were stable against dielectric breakdown up to 70V/μm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008694417169
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  • 6
    Electronic Resource
    Electronic Resource
    Development of Ferroelectric Aerogels (1999)
    Springer
    Journal of sol gel science and technology 16 (1999), S. 173-182 
    Details
    ISSN: 1573-4846
    Keywords: PZT ; aerogels ; sol-gel ; sintering
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract For ultrasonic applications in gases porous piezoelectric transducers with low acoustic impedances are required. Highly porous piezoceramics can be prepared by sol-gel processing, supercritical drying and subsequent firing. These PT and PZT aerogels are obtainable as crystalline monoliths with porosities up to 70 vol%. In this paper the influence of sol-gel-synthesis, stoichiometry, drying conditions and heat treatment on the material properties are reviewed. Lowering the coercive field strength by dopants is necessary in order to facilitate the polarization of highly porous PZT-ceramics. New results show that the introduction of 2 mol% neodymium is possible in the sol-gel synthesis of the aerogel precursor. Most structural properties of the resulting PbNd0.02Zr0.53Ti0.47O3 aerogels are similar to those of the undoped material.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008733826408
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  • 7
    Electronic Resource
    Electronic Resource
    PZT Aerogels: Sol-Gel Derived Piezoelectric 3-3 Composites (2000)
    Springer
    Journal of sol gel science and technology 19 (2000), S. 145-148 
    Details
    ISSN: 1573-4846
    Keywords: sol-gel ; aerogels ; ferroelectrics ; lead zirconate titanate ; PZT
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Ultrasonic transducers with low acoustic impedances are required for applications in gaseous media. In porous piezoelectrics the pore volume acts as a second medium of a solid-gas composite and thus lowers the overall acoustic impedance. Lead zirconate titanate (PbZr.53Ti.47O3, PZT) aerogels were prepared by sol-gel processing and supercritical drying in isopropanol. Prefiring at 400°C in air and subsequent thermal treatment in saturated PbO-atmosphere results in phase transformation to PZT (perovskite phase), grain growth and aerogel densification. In this paper the densification of this new class of piezoelectric material at temperatures above 600°C is described. Porosities were measured as a function of sintering time and temperature. Changes in the microstructure were characterized by scanning electron microscopy. Dielectric measurements are presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008755414899
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  • 8
    Electronic Resource
    Electronic Resource
    Inorganic Thin Films Prepared from Soluble Powders and Their Applications (2000)
    Springer
    Journal of sol gel science and technology 19 (2000), S. 473-477 
    Details
    ISSN: 1573-4846
    Keywords: sol-gel ; precursor chemistry ; thin films ; soluble powders
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Sol-gel processing has proved to be a useful method for the preparation of a wide range of inorganic thin films. However, gelation or precipitation of coating solutions and thus limited shelf-life have been drawbacks for the industrial application of this technology. Soluble powders of various compositions can be prepared from modified metal alkoxides commonly employed in sol-gel processing. Even though these powders contain a considerable amount of organic moieties they can be stored indefinitely under ambient conditions, thus diminishing shelf life problems. Redissolution in polar organic solvents, solvent mixtures or even water yields ready-to-use coating solutions. Coating solutions for the preparation of titania (TiO2), zirconia (ZrO2) and lead zirconate titanate (PbTi x Zr1−x O3, PZT) films have been synthesized by this method. Thickness, microstructure and properties of the resulting films can be varied by modification of the solvent, the coating procedure and thermal treatment. Inorganic thin films for various applications have been prepared.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008711916658
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  • 9
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    Nucleation and Growth of TiO2Thin Films on Modified Polystyrene Surfaces (2003)
    American Chemical Society
    Details
    Publication Date: 2003-09-01
    Print ISSN: 0897-4756
    Electronic ISSN: 1520-5002
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by American Chemical Society
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  • 10
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    Organic−Inorganic Hybrid Structure of Calcite Crystalline Assemblies Grown in a Gelatin Hydrogel Matrix:  Relevance to Biomineralization (2002)
    American Chemical Society
    Details
    Publication Date: 2002-11-01
    Print ISSN: 0897-4756
    Electronic ISSN: 1520-5002
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by American Chemical Society
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