Impurities of Bi2WO6 formed during the hydrothermal process under a wide range of acid–base conditions (from 1.5 M HNO3 to 0.5 M NaOH) were qualitatively analyzed and accurately quantified for the first time.
在广泛的酸碱条件下(从1.5 M HNO3到0.5 M NaOH),水热过程中形成的Bi2WO6杂质进行了首次定性分析和精确定量。
Nitrate anion-mediated morphology control of Bi5O7NO3 and its photocatalytic activity
作者:Longzhu Zhang、Lingjun Chou、Xinheng Li
DOI:10.1039/c3ce41875h
日期:——
Different morphologies of a material often show different performance. Four different morphologies of Bi5O7NO3 including microflowers, nanowires, nanoribbons and nanosheets have been controllably synthesized by simply increasing concentration of precursor bismuth nitrate in a hydrothermal method without adding any surfactant or template. Those morphologies have revealed a dramatic difference in rhodamine B (RhB) photocatalytic activity. The nanosheets showed much better photocatalytic activity than the nanowires and the nanoribbons while the microflowers showed very poor activity. In our control experiments where we partially substituted Bi(NO3)3 for Zn(Ac)2, Zn(NO3)2, and KNO3 respectively, we have found that the formed morphologies were very closely related to nitrate anions. This explicitly proves that the nitrate anion plays a crucial role in determining the morphologies. Guided by atomic model, nitrate anion-mediated oriented attachment mechanism is proposed on the basis of our experimental results. Our finding that nitrate anions favoured the formation of nanosheets would benefit the synthesis of nanosheets at a lower cost. Our study provides a simple and economic way for preparing good candidates for potential applications in solar energy conversion.
Lead-free ferroelectric Na0.5Bi0.5TiO3 (NBT), 0.94Na(0.5)Bi(0.5)TiO(3)-0.06BaTiO(3) (NBT-6BT) and (Na0.5Bi0.5)(0.94)Ba-0.06(Nb0.05Ti0.95)O-3 (Nb-NBBT6) ceramics were synthesized via a multi-ionic sol-gel method process. The effects of Nb on the structural, dielectric and ferroelectric properties were studied. Doped Nb ions distributed uniformly in the Nb-NBBT6 ceramics and shrank the grain sizes of Nb-NBBT6. All NBT, NBT-6BT and Nb-NBBT6 ceramics consisted of the rhombohedral phase and the tetragonal phase according to XRD Rietveld refinements. The dielectric constants of the Nb-NBBT6 ceramics were improved compared to NBT and NBT-6BT below 200 degrees C. The introduction of Nb ions enhanced the dielectric stability, and the temperature difference between two dielectric peaks increased from 153 degrees C for NBT to 197 degrees C for Nb-NBBT6. The remnant polarization (P-r) of Nb-NBBT6 ceramics decreased, but the reduced E-c of 7.01 kV/cm and the maximum polarization of 40.79 mu C/cm(2) (90 kV/cm) revealed the enhanced ferroelectric property. The temperature-dependent ferroelectric hysteresis loops of Nb-NBBT6 ceramics (65-150 degrees C) exhibited the largest energy-storage density (W) of 0.399 J/cm(3) at 90 degrees C.
Kodoma, Hiroshi, Journal of Solid State Chemistry, 1994, vol. 112, p. 27 - 30
作者:Kodoma, Hiroshi
DOI:——
日期:——
Kodoma, Hiroshi, Journal of Solid State Chemistry, <hi>1994</hi>, vol. 112, p. 27 - 30