Zhao-Hui Han

Controllable synthesis of nanocrystalline CdS with different morphologies and particle sizes by a novel solvothermal process

Nanocrystalline CdS with different morphologies and particle sizes was obtained via a novel solvothermal reaction between cadmium salts such as Cd(NO 3 ) 2 ·4H 2 O or CdSO 4 ·8/3H 2 O and thiourea (Tu) at relatively low temperature. It is found that solvents play an important role in controlling the morphology and particle sizes of the nanocrystalline CdS product. The effect of solvents, anions of the cadmium salt, the molar ratio of Tu to the cadmium salt, and temperature on the morphology, particle sizes and phase of nanocrystalline CdS products has been investigated.

A new low temperature one-step route to metal chalcogenide semiconductors: PbE, Bi2E3 (E=S, Se, Te)

A solvothermal reaction of metal oxalates such as PbC2O4 , Bi2(C2O4)3 with E (E=S, Se, Te) in organic solvents at relatively low temperature (120–160 °C) produces crystalline PbS, PbSe, PbTe, Bi2S3 , Bi2Se3 , and Bi2Te3 :PbC2O4+Esolvent

Hydrothermal crystal growth and characterization of cerium hydroxycarbonates

Abstract Orthorhombic and hexagonal CeOHCO 3 crystals were grown by a hydrothermal method. X-ray diffraction, scanning electron microscopy and optical spectroscopy were used to characterize the samples. The orthorhombic phase was formed prior to the hexagonal phase following an increase in temperature. The two phases correspond to different morphologies and luminescent performance. Orthorhombic CeOHCO 3 crystals are shuttle-like while hexagonal CeOHCO 3 is butterfly-like, and the former displays a much stronger luminescence than the latter.

Hydrothermal preparation and characterization of rod-like ultrafine powders of bismuth sulfide

Abstract Uniform rod-like ultrafine powders of Bi 2 S 3 with a diameter of 40 nm and a length of up to 150 nm have been successfully prepared by the hydrothermal treatment of an alkaline sol (pH = 8.0–10.0) from BiCl 3 and Na 2 S·9H 2 O with EDTA as complexing agent at relatively low temperature. Powder X-ray diffraction (XRD) pattern indicated that the product was pure orthorhombic Bi 2 S 3 phase with cell constants a = 11.138, b = 11.290, and c = 3.980 A. The optimum condition for crystallization of amorphous Bi 2 S 3 is hydrothermal treatment at 100–150°C for 6 to 12 h. The X-ray photoelectron spectra and infrared (IR) spectra confirmed that the product was of high purity.

A simple solvothermal route to copper chalcogenides

Abstract Using copper(I) chloride, sodium oxalate and elemental chalcogen, copper chalcogenide powders were synthesized through a simple solvothermal route. Pseudocubic Cu 1.80 S and orthorhombic Cu 31 S 16 single phases synthesized in ethylenediamine (En) are made up of polyhedral particles, cubic Cu 2− x Se synthesized in pyridine (Py) was irregular in shape, while Cu 1.75 Te synthesized in distilled water appeared to be spherical. Other chalcogenides were also formed under different conditions.

An organic solution method for crystal growth of tin chalcogenides with special morphologies

Tin chalcogenides with different morphologies were prepared from stannous oxalate and chalcogen through one step using ethylenediamine as the solvent. Orthorhombic SnS and orthorhombic SnSe crystals are plate like and rod like, whereas cubic SnTe particles are much smaller and appear to be spherical. Taking SnSe as a representative, the formation mechanism of these crystals was discussed.

Ethanothermal reactions to crystalline lithium ferrites

Abstract Using ethanol as the solvent, chemical reactions of ferric chloride and lithium hydroxide were studied under heated conditions. Crystallized β-LiFe5O8 and α-LiFeO2 were produced from the starting materials of different molar ratios. Owing to the incompleteness of reactions that occurred in the organic medium, an equilibrium between the two lithium ferrite phases was discovered. The reason for excess lithium source material for α-LiFeO2 was made clear by analyzing the chemical processes to the lithium ferrite.

Hydrothermal synthesis and characterization of La1-xCexOHSO4 phosphors

Abstract Monoclinic La 1− x Ce x OHSO 4 compounds (0⩽ x ⩽1) were hydrothermally synthesized from mixed rare earth nitrates and thiourea at moderate temperature. The crystals grown are all flake-like in morphology and display room temperature ultraviolet luminescence. The mean dimension of the crystals turns smaller, and the luminescent intensity turns stronger following the increase of cerium content in the phosphor compounds.

Preparation of late transition metal selenides with different morphologies in ethylenediamine

A series of late transition metal selenides were prepared within 180°C in ethylenediamine. Both anhydrous and hydrous starting materials could be used as long as the reducing oxalates were involved. As-prepared FeSe2, CoSe2, NiSe2, and Cu2−xSe crystallites were rod-like, disc-like, octahedral, and plate-like, respectively. Sulfides and tellurides of these late transition metals with different morphologies may also be synthesized by this preparative method.