Trends of the Ionic Conductivity of Cation-Doped Barium Zirconates

• Main Authors: hsuan chih Chang, 張軒誌
• Other Authors: Jenghan Wang
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/33126448820116878320

碩士 === 國立臺灣師範大學 === 化學系 === 98 === 　　Trends of the ionic conductivity of BaZr1-xMxO3, (M = In3+, Y3+, Yb3+, Dy3+, Gd3+, Sm3+, Nd3+, La3+) have been experimentally and computationally examined in this work. Experimentally, the powder with different dopant ratios , 2%, 5%, 10% and 20%, has been initially synthesized by GNP (glycine nitrate process) method, and it physical and chemical properties have been examined by XRD, SEM, EDX and ICP-Mass (Inductively coupled plasma mass spectrometry). The synthesized powder is further pressurized and sintered at different temperatures, 1250, 1450 and 1600 oC and heating period, 5, 10 and 40 hours, to form BaZr1-xMxO3 pellets for the conductivity tests in various atomspheres: dry N2, dry H2, wet air and wet H2. Computationally, formation energies of oxygen vacancy V_o^(..) and proton defect OH_o^' and enthalpy of V_o^(..) migration, proton hopping and OH_o^' diffusion of the doped BaZrO3 have been systematically examine by the means of density functional theory (DFT) calculation. 　　Based on the experimental and computational works, the results show that the ionic conductivity will increase as the dopant ratio raises and the sinter period decreases. The sinter temperature has limited effect on the conductivity. From the chemical aspect, the conductivity is systematically influenced by the ionic radius of the doped cation. The small radius of the dopant results a better conductivity from the experimental measurement and lower enthapy in the DFT calculation.