• Jia-Hu Ouyang

      Articles written in Bulletin of Materials Science

    • Synthesis and characterization of nano-sized Ba𝑥Sr1–𝑥SO4 (0 ≤ 𝑥 ≤ 1) solid solution by a simple surfactant-free aqueous solution route

      Yu-Feng Li Jia-Hu Ouyang Yu Zhou Xue-Song Liang Ji-Yong Zhong

      More Details Abstract Fulltext PDF

      A facile aqueous solution route has been employed to synthesize Ba𝑥Sr1–𝑥SO4 (0 4 𝑥 ≤ 1) solid solution nanocrystals at room temperature without using any surfactants or templates. The as-synthesized products were characterized by means of X-ray diffraction (XRD), X-ray fluorescence spectrometer (XRF), scanning electron microscopy (SEM), and differential scanning calorimetry–thermogravimetry (DSC–TG). The Ba𝑥Sr1–𝑥SO4 solid solution nanocrystals exhibit an orthorhombic structure and an ellipsoidal-shaped morphology with an average size of 80–100 nm. The lattice parameters of Ba𝑥Sr1–𝑥SO4 solid solution crystals increase with increasing x value. However, they are not strictly coincident with the Vegard’s law, which indicates that the as-obtained products are non-ideal solid solutions. The Ba𝑥Sr1–𝑥SO4 solid solution nanocrystals have an excellent thermal stability from ambient temperature to 1300°C with a structural transition from orthorhombic to cubic phase at about 1111°C.

    • Heat capacity measurements on Yb𝑥Gd2–𝑥Zr2O7 (𝑥 = 0, 1, 2) ceramics by differential scanning calorimetry

      Zhan-Guo Liu Jia-Hu Ouyang Yu Zhou

      More Details Abstract Fulltext PDF

      Yb𝑥Gd2–𝑥Zr2O7 (𝑥 = 0, 1, 2) ceramics were pressureless-sintered using ceramic powders acquired by chemical-coprecipitation and calcination methods. Heat capacities of Yb𝑥Gd2–𝑥Zr2O7 were measured with a heat flux-type differential scanning calorimetry in the temperature range of 298–1200 K. At 298 K, the heat capacities of Gd2Zr2O7, YbGdZr2O7 and Yb2Zr2O7 were 214, 221 and 230 J.K-1 mol-1, respectively.

    • Electrical conductivity and chemical stability of BaCe0.8−𝑥A𝑥Gd0.2O3−𝛿 (A = In, Zr, Ta; 𝑥 = 0, 0.1) ceramics

      Xiao-Ming Liu Yi-Jing Gu Zhan-Guo Liu Jia-Hu Ouyang Fu-Yao Yan Jun Xiang

      More Details Abstract Fulltext PDF

      BaCe0.8−𝑥A𝑥Gd0.2O3−𝛿 (A = In, Zr, Ta; 𝑥 = 0, 0.1) ceramics were synthesized by solid-state reaction method. Microstructure and electrical properties of BaCe0.8−𝑥A𝑥Gd0.2O3−𝛿 ceramics were investigated by means of X-ray diffraction (XRD), scanning electron microscopy (SEM) and complex impedance analysis at intermediate temperatures of 573–1073 K in different atmospheres. BaCe0.8Gd0.2O3−𝛿, BaCe0.7In0.1Gd0.2O3−𝛿 and BaCe0.7Zr0.1Gd0.2O3−𝛿 ceramics exhibit a single cubic perovskite structure. BaCe0.7In0.1Gd0.2O3−𝛿 ceramic has the highest conductivity of 4.6 × 10-2 S.cm-1 in air at 1073 K. BaCe0.7In0.1Gd0.2O3−𝛿 and BaCe0.7Zr0.1Gd0.2O3−𝛿 ceramics exhibit an excellent chemical stability against boiling water. Indium is a suitable doping element to promote the sintering densification and to enhance both electrical conductivity and chemical stability of Gd-doped BaCeO3 at operating temperatures.

  • Bulletin of Materials Science | News

    • Editorial Note on Continuous Article Publication

      Posted on July 25, 2019

      Click here for Editorial Note on CAP Mode

© 2017-2019 Indian Academy of Sciences, Bengaluru.