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Mingmei Wu

Publications and source records attributed to Mingmei Wu.

5 recordsLinked to original sources
PubMed2006

Hexagonal and prismatic nanowalled ZnO microboxes.

We hereby report hydrothermal syntheses of new microstructures of semiconducting ZnO. Single-crystalline prismatic ZnO microboxes formed by nanowalls and hexagonal hollow microdisks closed by plates with micron-sized inorganic fullerene-like structures have been made in a base-free medium through a one-step hydrothermal synthesis with the help of n-butanol (NB). Structures and morphologies of the products were confirmed by results from powder X-ray diffraction and scanning electron microscopy. NB has been found to play a crucial role in the growth of these hollow structures. It is indicated that these hollow ZnO crystals were grown from redissolution of interiors. These ZnO microboxes exhibit a band emission in the visible range, implying the possession of a high content of defects.

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PubMed2004

Hydrothermal synthesis of prismatic NaHoF(4) microtubes and NaSmF(4) nanotubes.

A new example of tubular materials based on sodium rare-earth tetrafluorides, NaHoF(4) and NaSmF(4), has been fabricated by a simple hydrothermal method. In addition, an unusual nanotube with a perfect couple of an outer prismatic shell with an inner concentric prismatic nanorod at the center is found. According to the architectures of various products, the general growth mechanism of these tubes is proposed.

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PubMed2003

Kinetically controlled synthesis of wurtzite ZnS nanorods through mild thermolysis of a covalent organic-inorganic network.

The high-temperature (over 1020 degrees C) polymorph of ZnS, wurtzite ZnS, has been successfully prepared through a low-temperature (180 degrees C) hydrothermal synthesis route in the presence of ethylenediamine (en). The effects of en concentrations, reactant concentrations, reaction temperatures, and reaction times on crystal structures and shapes of ZnS have been investigated. We have demonstrated that the wurtzite ZnS showing rodlike morphology can be kinetically stabilized in the presence of en, especially at a high reactant concentration under appropriate hydrothermal conditions. Besides phase evolution of ZnS from hexagonal to cubic, morphological transformation from nanorods to nanograins has also been observed in the present investigation. Nanograins of phase-pure cubic ZnS, the thermodynamically stable polymorph, are easily prepared, and no hexagonal ZnS nanorods are detected in "pure" water, i.e., in the absence of en molecules. The above investigations indicate that the controlled fabrication of wurtzite ZnS nanorods is due to a mediated generation of the lamellar phase, ZnS.0.5en, a covalent organic-inorganic network based on ZnS slabs, and to its subsequent thermolysis in aqueous solution. The controlled growth of wurtzite ZnS nanorods and sphalerite ZnS nanograins provides us an opportunity to structurally modulate physical properties. These wurtzite ZnS nanorods display narrower and stronger blue emission than sphalerite ZnS nanograins.

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PubMed2002

Physical stability vs. chemical lability in microporous metal coordination polymers: a comparison of [Cu(OH)(INA)]n and [Cu(INA)2]n: INA = 1,4-(NC5H4CO2).

Two microporous copper isonicotinate polymers [Cu(OH)(INA)] and [Cu(INA)2] have been formed hydrothermally in good yield and purity; each have 1D channels of ca. 4 x 6 A dimension, but with quite different hydrophilicities; both frameworks retain structural integrity to above 200 degrees C, however whilst [Cu(OH)(INA)] is also chemically stable, [Cu(INA)2] is highly labile and readily transforms to the molecular complex [Cu(INA)2(H2O)4] in water at room temperature.

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