Preparation of Mullite Whiskers from Powder of Topaz Pure and Doped with Rare Earths

Renato Reis Monteiro; Antônio Claret Soares Sabioni

doi:10.4028/www.scientific.net/MSF.798-799.189

Paper Titles

Microstructural and Colour Analysis of CuCrO₂ Delafossite Obtained by Gelatin Method
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Synthesis, Characterization and Ionic Conductivity of Fully Stabilized Zirconia Obtained from Core-Shell Type Structures
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Synthesis and Characterization of Zirconium Oxide Systems with Yttrium Rich Rare Earth Concentrate Additives
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Synthesis of Gadolinium Doped Ceria Ceramic Powder by Polymeric Precursor Method (Pechini)
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Preparation of Mullite Whiskers from Powder of Topaz Pure and Doped with Rare Earths
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Effect of LiF and CaO Additions on MgAl₂O₄ Dynamic Behavior
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Effects of the Addition of Ions Barium on the Structural and Electrical Properties of PZT Ceramic
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Nanostructured Co₃O₄ Oxide for Low Temperature Ethanol Oxidation
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Effect of the Iron Doping on the Thermal Decomposition of the Polymeric Precursor for the Titanium Dioxide Powder Synthesis
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HomeMaterials Science ForumMaterials Science Forum Vols. 798-799Preparation of Mullite Whiskers from Powder of...

Preparation of Mullite Whiskers from Powder of Topaz Pure and Doped with Rare Earths

Abstract:

Mullite whiskers were obtained by thermal decomposition of powders of natural topaz, pure and doped with 3 and 5% in weight of La₂O₃ and Y₂O₃, at the temperatures of 1300 and 1400^°C, for 1h, in air. Pure and doped mullite whiskers showed a molar ratio Al₂O₃: SiO₂ close to 2:1, rich in alumina. The aspect ratio (AR) of whiskers varies with dopant concentrations and temperatures. The ARs for pure whiskers were 28 and 31.5, at the temperatures of 1300 and 1400°C, respectively, showing no glassy phase. For the doped whiskers, there were observed a reduction in the ARs, ranging from 14.13 to 16.10 (3 and 5% La₂O₃) and from 6.32 to 7.35 (3 and 5% Y₂O₃), for the temperatures of 1300 and 1400°C, respectively. The Y₂O₃ was not entirely incorporated, and part of it formed Y₂Si₂O₇ and Y₂O₃_-_δ, with δ = 0.33 according to quantitative X-ray diffraction analysis (XRD analysis) with the presence of small amount of vitreous phase.