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.

Dielectric properties of I-III-VI2-type ternary chalcopyrite semiconductors, including linear and second order nonlinear optical susceptibilities at 10.6 mm, have been quantitatively studied from the chemical bond viewpoint. Contributions from each type of constituent chemical bond, i.e., I u VI and III u VI bonds, to the total linear and nonlinear optical properties of these compounds at 10.6 mm have been theoretically determined. The chemical bond method quantitatively expresses the trends in the dielectric properties of these compounds, which is helpful for carrying out modeling of their properties.

On the basis of the bond valence model, an approach is established to determine the dopant occupancy in the lithium niobate (LN) crystallographic frame. The dopant location can be easily assigned by comparing the deviation of its normal and calculated valence states, when such a dopant is arbitrarily placed in both Li+ and Nb5+ sites, respectively. Further, the parameter Global Instability Index is used to characterize the structural instability of doped LN crystals. The dopant occupancy in the LN crystallographic frame and its interaction with the LN matrix are quantitatively understood by the structural stability. Calculated threshold values of various dopants are further obtained in the present work.