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5 Materials Science Poland

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Silicon oxide nanowires and spheres grown by hydrothermal deposition

100%

Pei L. Z.

tom Vol. 27, No. 1

339--347

Silicon oxide nanowires and spheres were prepared via a simple hydrothermal deposition using silicon powder as the starting material. Field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), energy dispersive spectra (EDS) and high-resolution transmission electron microscopy (HRTEM) were used to observe the structure and morphologies of the products. The results show that the average diameter of silicon oxide nanowires with an amorphous structure is about 500 nm, and that smooth silicon oxide spheres have a definite diameter distribution ranging from several hundred nanometers to several micrometers. The growth process of the silicon oxide nanowires and spheres is discussed.

Synthesis and formation process of zirconium dioxide nanorods

51%

Pei L. Z. , Xie Y. K. , Pei Y. Q. , Yuan C. Z.

Materials Science Poland

2013

tom Vol. 31, No. 2

186--192

Crystalline zirconium dioxide nanorods have been prepared by a simple hydrothermal process using zirconium hydroxide as the zirconium raw material. Zirconium dioxide nanorods are composed of monoclinic zirconium dioxide phase, which has been confirmed by the X-ray diffraction analysis. Electron microscopy observations show that the zirconium dioxide nanorods have a single crystal structure, with the rod diameter of less than 100 nm and length of 1 – 2 m. Hydrothermal temperature and reaction time play essential roles in the formation and growth of the zirconium dioxide nanorods. Nucleation and crystal growth process are proposed to explain the formation and growth of the zirconium dioxide nanorods.

Fabrication of core-shell Ge-GeO2 nanoneedles

45%

Pei L. Z. , Zhao H. S. , Tan W. , Yu H. Y. , Zhang Q. F.

tom Vol. 28, No. 1

77--84

Core-shell Ge-GeO2 nanoneedles were prepared by a hydrothermal deposition using Ge and GeO2 as starting materials. The samples were characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, transmission electron microscopy and high-resolution transmission electron microscopy. The results demonstrate that the length of the samples with typical needle structure is higher than 10 žm. The obtained nanoneedles are composed of single crystalline Ge with diamond cubic structure and amorphous oxide outer layers. An explanation of the formation and growth of Ge nanoneedles is proposed, and is based on the metallic-catalyst vapour-liquid-solid and oxide-assisted growth mechanisms.

Preparation of Ni/MgO catalysts for carbon nanofibres by a self-propagating low temperature combustion process

45%

Zhang Y. , Tang Y. H. , Zhang E. L. , Lin L. W. , Pei L. Z.

tom Vol. 28, No. 4

764--772

Ni/MgO catalysts were prepared using nitrate salt and citric acid in various ratios by the sol-gel selfpropagating, low temperature combustion process. The products were characterized by the scanning electron microscopy, X-ray diffraction, thermogravimetric analysis and differential scanning calorimetry. The results show that Ni/MgO catalyst precursors of various particle sizes can be obtained by controlling the amount of citric acid. The catalytic activity of Ni/MgO decreases as the calcination temperature increases, owing to the difficulty of the NiO reduction. The mechanism of formation of Ni/MgO catalysts has also been proposed. Self-propagation combustion has great advantage of occurring at low temperatures, and the Ni/MgO is a suitable catalyst for low cost preparation of carbon nanofibres.

Dependence of growth conditions on copper germanate nanowires and their electrochemical characteristics

32%

Pei L. Z. , Pei Y. Q. , Yang Y. , Dong Y. P. , Wang S. B. , Fan C. G. , Duan T. , Zhang Q.

Materials Science Poland

2011

tom Vol. 29, No. 4

241--247

Copper germanate (CuGeO3) nanowires have been synthesized by the hydrothermal deposition process using GeO2 and copper foil as the resource as well as the deposition substrate. The factors including hydrothermal temperature, pressure and duration of the process were investigated in order to analyze the processing parameters that control the formation process, morphology and size of the nanowires. The dependence of the nanowires properties on the growth conditions shows that the CuGeO3 nanowires can be synthesized in a large range of different hydrothermal parameters from 400 C to 250 hydrothermal pressure has an important effect on the formation and growth of the CuGeO3 nanowires. The CuGeO3 nanowires exhibit good electrochemical cyclic voltammetry characteristics owing to offering many advantages in sensing applications including their small size, high aspect ratio and conductance.