Gangqiang Yang

Effects of concentration of chloride anion on the morphology and microstructure of precipitates from lead nitrate solutions

Lead nitrate mixed with alkali in solution generates insoluble precipitates. The morphology and microstructure of the precipitates are dramatically influenced by the chloride anion concentration in the lead nitrate precursor solution. To intensively investigate the effect of the chloride anion concentration, we performed a series of controllable experiments with different concentrations of chloride anions (the concentration ratios of Pb2+ : Cl− = 1 : 0, 1 : 0.2, 1 : 0.5, 1 : 1, 1 : 2, and 1 : 3 in the solution) at different solution temperatures of 90 and 80 °C. The results reveal that, with the increasing concentration of chloride anions, the colour of the precipitates changes from yellow to red and finally to white; the morphology of the precipitates changes from plate-like to rod-like; the crystal structure of the precipitates changes from β-PbO to a mixture of β- and α-PbO (or α-PbO), and finally to lead hydroxide. These results suggest that adding chloride could lead to the formation of rod-like morphology and simultaneously could restrain the dehydration of Pb(OH)2.

SYNTHESIS OF β-PbO MICRO-OCTAHEDRONS BY ELECTRODEPOSITION

A simple and effective electrochemical deposition method to fabricate lead oxide micro-octahedrons is reported. Unlike previous reports in which the current densities of electrochemical deposition were normally not more than 5 mA/cm2 and resulted in the deposition of lead flakes, the current densities in our process were improved to more than 15 mA/cm2 which results in the deposition of lead oxide micro-octahedrons. Our results indicated that well-shaped lead oxide micro-octahedrons could form at current densities in the range of 15–25 mA/cm2.

Piezoelectric ZnO Nanorod Arrays by Hydrothermal Reaction

ZnO nanorod arrays were grown on Zn substrates by an inexpensive and facile hydrothermal reaction at low temperature of 95°C. 0.1 M ZnCl2 was used as a precursor was dissolved in 100 ml of deionized water, and 2ml ammonia solution (25%) was added to the solution, it enable easily obtained arrayed ZnO nanorods. Morphology and microstructure of the ZnO nanorods was characterized. Precision impedance analyzer and quasi-static d33 measurer were employed to analyze the micro-area piezoelectric property. The resonant frequency and the piezoelectric constant of ZnO nanorod arrays are 1.09 MHz and 17 pm/V, respectively.