Growth Of ZnS Crystals Research Articles

Mechanism study on the sulfidation of ZnO with sulfur and iron oxide at high temperature

The mechanism of ZnO sulfidation with sulfur and iron oxide at high temperatures was studied. The thermodynamic analysis, sulfidation behavior of zinc, phase transformations, morphology changes, and surface properties were investigated by HSC 5.0 combined with FactSage 7.0, ICP, XRD, optical microscopy coupled with SEM-EDS, and XPS. The results indicate that increasing temperature and adding iron oxide can not only improve the sulfidation of ZnO but also promote the formation and growth of ZnS crystals. Fe2O3 captured the sulfur in the initial sulfidation process as iron sulfides, which then acted as the sulfurizing agent in the late period, thus reducing sulfur escape at high temperatures. The addition of carbon can not only enhance the sulfidation but increase sulfur utilization rate and eliminate the generation of SO2. The surfaces of marmatite and synthetic zinc sulfides contain high oxygen due to oxidation and oxygen adsorption. Hydroxyl easily absorbs on the surface of iron-bearing zinc sulfide (Zn1−xFexS). The oxidation of synthetic Zn1−xFexS is easier than marmatite in air.

Optical and Structural Investigations of Manganese Doped ZnS/SiO2 Core-Shell Nanostructure

The paper reports room temperature synthesis of wurtzite type manganese doped ZnS nanostructures via colloidal technique. The reaction procedure found to play an important role in the crystal growth of ZnS . Surface encapsulation of ZnS by silica ( SiO 2) provides effective approach for uniform coating, where 3-Mercaptopropyl Tri methoxysilane (MPS) has been used for silica source as a capping molecule. The obtained silica coated ZnS nanocrystals were well dispersed with hexagonal wurtzite structure of core-shell particles size of about 15 nm. Aggregation of these nanoparticles has been promoted to special shaped structures, which are crystals of 8H wurtzite with prominent pyramidal morphology with curved faces. Growth phenomena of this wurtzite polytype of homologous series 8H is based on screw dislocations and exhibited optimal photoluminescence (PL) spectra.

Zinc blende versus wurtzite ZnS nanoparticles: control of the phase and optical properties by tetrabutylammonium hydroxide.

The influence of tetrabutylammonium hydroxide on the phase composition (cubic zinc blende versus hexagonal wurtzite) of ZnS nanoparticles was studied. The ZnS nanoparticles were prepared by a microwave-assisted solvothermal method, and the phase structure and optical properties along with the growth process of ZnS nanoparticles were studied. We report XRD, FE-SEM, EDXS, UV-vis and PL measurements, and first-principles calculations based on TDDFT methods in order to investigate the structural and electronic properties and the growth mechanism of ZnS nanostructures. The effects as well as the merits of microwave heating on the process and characteristics of the obtained ZnS nanostructures and their performance are reported.

Composite polymeric particles with ZnS shells

We report on a preparation of hybrid particles with polymeric cores and ZnS shells. Two types of monodisperse sterically stabilized polystyrene particles with hydroxyl-terminated PEG chains (PS/PEGMA) or β-diketone groups (PS/AAEM) on the surface have been prepared and characterized. Formation of ZnS layer on the surface of submicron particles has been studied by SEM and EDX. Deposition of ZnS on the surface of PS/PEGMA particles is not uniform and leads to formation of ‘raspberry’ morphology with rough surface. It has been found that presence of β-diketone groups on the particle surface leads to formation of well-defined ZnS layers. It has been assumed that such effect is due to the complexation of Zn cations by β-diketone groups leading to nucleation and growth of ZnS crystals on the polymer particle surface. Polymeric particles were completely covered with ZnS if the loaded amount of inorganic material was higher then 40wt%. The thickness of ZnS layer on the particle surface can be easily varied by changing the ZnS load (in present study maximal thickness of the ZnS shell was 70nm). It has been found that increase of the ultrasound power leads to considerable increase of the ZnS deposition on the particle surface without strong changes of the particle morphology. Hybrid particles have been investigated with XRD technique and their optical properties were studied by UV-spectroscopy. The colloidal stability of obtained particles was studied by separation analyser. Sedimentation experiments indicate that colloidal stability of obtained composite particles depends strongly on loaded ZnS amount and pH value of the aqueous medium. It has been found that highest sedimentation velocities (or maximum of instability) were determined by ZnS loads, which provide complete coverage of the particle surface. Increase of the ZnS layer thickness led to better stability of hybrid particles in aqueous medium.

Crystal growth of ZnS and ZnSe by chemical transport using NH 4Cl as a transport agent

Crystal growth of ZnS and ZnSe has been carried out by chemical transport using NH 4Cl as a transport agent. Single crystals of both compounds with cubic zinc-blende structure have been obtained. The transport rate depended proportionally on the undercooling, but not markedly on the amount of NH 4C1 added. The electrical resistivity of the as-grown crystals was of the order of 10 8–10 9 ohm cm. Crystal growth of solid solutions, Zn(S x Se 1− x ), has also been carried out using mixed powders of ZnS and ZnSe as source materials. Cubic zinc-blende-type single crystals have been obtained over the entire composition range. The compositions of these crystals were in good agreement with those of the mixing ratio of the source powder. These crystals showed self-activated luminescence under ultraviolet excitation, and the color of the luminescence varied from blue (ZnS) to red (ZnSe), depending on the composition.

Dendritic growth of ZnS crystals

The dendritic growth of ZnS crystals in the form of long ribbons, plates and needles was observed when ZnS crystallized from liquid Ga. The cubic ribbons and plates propagated in the directions, the needles were hexagonal and their main propagation was parallel to the c-axis. It has been found that for a cubic lattice (ribbons and plates) the growth mechanism of ZnS show the same features as the growth of Ge, Si, In, Sb, etc. dendrites.

Dendritic growth of ZnS crystals

The dendritic growth of ZnS crystals in the form of long ribbons, plates and needles was observed when ZnS crystallized from liquid Ga. The cubic ribbons and plates propagated in the directions, the needles were hexagonal and their main propagation was parallel to the c-axis. It has been found that for a cubic lattice (ribbons and plates) the growth mechanism of ZnS show the same features as the growth of Ge, Si, In, Sb, etc. dendrites.