Boron nitride whiskers with a special structure have been synthesized by a thermal reaction process. The as-prepared BN whiskers have a length of tens of micrometers and a mean diameter of 500 nm. High-resolution TEM analysis shows that the as-prepared BN whiskers can be described as a nanofiber-interweaved network. Infrared and electron energy loss spectra reveal that the BN whiskers are composed of both

A novel self-assembled microstructure, nestlike Mg5(CO3)4(OH)2

Malachite (Cu2(OH)2CO3) with a hierarchical sphere-like architecture has been successfully synthesized via a simple and mild hydrothermal route in the absence of any external inorganic additives or organic structuredirecting templates. Powder X-ray diffraction, scanning electron microscopy, and Fourier transmission infrared spectrometry are used to characterize various properties of the obtained malachite samples. The hierarchical malachite particles are uniform spheres with a diameter of 10-20

The bond valence model is employed to calculate the bond strength of constituent chemical bonds formed between growth units in both potassium dihydrogen phosphate (KDP) and ammonium dihydrogen phosphate (ADP) crystals, with the aim to predict and control the crystal shape. After calculating and comparing the relative growth rates of all selected planes, which are related to the crystallographic structure and chemical bond strength, the natural morphology of both KDP and ADP can be conveniently deduced. To check the calculated results, the crystallites of KDP and ADP are grown under different growth conditions; their morphologies accord well with our theoretical calculations. Meanwhile, the influence of ethanol anti-solvent on crystal morphology is microscopically interpreted, which alters the crystal morphology by changing the supersaturation of the growing solution and influencing the bonding process. When ethanol is added into the growing solution, the crystal shape becomes slender.

A novel spontaneous ion replacement route based on the solubility difference as the driving force to synthesize a number of metal oxides has been established. We present a comprehensive study on the ion replacement reaction for chemical synthesis of micro-and nanostructured Mn2O3, ZnO, CuO, CdO, Al2O3, and CaO samples. This novel approach described herein is derived from the solubility difference between two carbonate salts, in which a metal cation can be driven from one liquid phase into another solid phase in the solution system. The resulting metal carbonate salts are initially formed and subsequently calcined to form highly crystallined metal oxides. The variation of pH values, reaction temperature, and reagent shapes can vary the solubility of these two carbonate salts, which thus changes the final morphology of metal oxides. The present work makes a progress to simply and mildly synthesize metal oxides with various morphologies, due to the fact that materials with a desired morphology are a key engineering step toward their shape-dependent chemical and physical properties.

The origin of nonlinearity in KTiOPO4 was investigated quantitatively from the chemical bond viewpoint. All constituent chemical bonds in this crystal were considered and their contributions to the total linearity and nonlinearity were quantitatively determined. Calculated results agree satisfactorily with experimental data in both signs and numerical values. These results show us that TiO6 groups and P(1)O4 groups have relatively larger linear contributions and the nonlinearity derives from KOx (x58,9) groups and P~2!O4 groups.

A novel and quantitative study on structure-property relationships has been carried out in urea crystal, based on the dielectric theory of complex crystals and the modified Levine bond charge model, mainly from the chemical bond viewpoint. For the first time, it was treated like this, and the bond parameters and linear and nonlinear characteristics of constituent chemical bonds were presented quantitatively. The theoretical result agrees satisfactorily with the experimental datum and can reasonably explain the nonlinear origin of urea crystal, that is, the C-N bond in the conjugated system of bonds OWCrN-H. At the same time, the novel method should be a useful tool toward the future development of the search for new nonlinear optical (NLO) materials in the organic crystal field.