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By Trunnano | 20 April 2022 | 0 Comments

Characteristics and Production of Zinc Sulfide ZnS

Introduction to Zinc Sulfide ZnS Powder
Zinc sulfide is a group - compound semiconductor material composed of sulfur and zinc. The molecular formula is ZnS, molecular weight is 97.45, melting point is 1020(15MPa), white crystal, the lattice constant is 0.547nm, hexagonal crystal, density is 4.08g/cm3. It is hardly soluble in water, but soluble in acid. Under prolonged exposure to humid air, it will turn into zinc sulfate. The bandgap is 3.6eV, which is the widest among group - compound semiconductor materials. Therefore, it can be used to make blue tubes. Powdered zinc sulfide is the most important field luminescent material, photofluorescence material, used in the preparation of picture tube fluorescent screens, scoreboard displays, etc. It is also infrared optical material in the window material, coating material.
Most of the zinc sulfide used for phosphor powder is prepared by the solution method, which is characterized by a large yield and low cost. The needle-like crystals of high purity zinc sulfide synthesized directly from elements in the gas phase are used to prepare high-performance coating materials and single-crystal materials. Zinc sulfide single crystal can be grown by a high-pressure single-crystal furnace and chemical vapor phase transport (CVD). ZNS sheets for optical materials can be prepared by hot-pressing and CVD methods, which are widely used in laser window materials. In recent years, the preparation of zinc sulfide film materials mostly adopts the metal-organic chemical vapor deposition method, because of the low growth temperature, the film integrity is good, fewer defects, easy to prepare heterojunction photoelectronic devices.

Physicochemical Properties of Zinc Sulfide ZnS Powder
Zinc sulfide is a white or yellowish powder. It will turn into a crystal while burning in H2S gas.  The α variant is a colorless hexagonal crystal with a density of 3.98g/cm3 and a melting point of 1700. The β variant is a colorless cubic crystal with a density of 4.102g/cm3 and transforms into α type at 1020. It's found in sphalerite. Insoluble in water, soluble in acid.
Under prolonged exposure to humid air, it converts to zinc sulfate. It is usually produced by the action of hydrogen sulfide with zinc salt solution. If adding trace Cu, Mn, and Ag as activators in crystal ZnS, different color fluorescence can be emitted after illumination.  Used as analytical reagents, coatings, paints, white and opaque glass, filling rubber, plastics, and for the preparation of phosphors. 
Zinc sulfide is corrosive and poisonous. It can irritate the skin. Operators should wear overalls and protective equipment. The workshop should be well ventilated. 
Zinc Sulfide ZnS Powder Properties
Other Names ZnS powder, zinc sulphide
CAS No. 1314-98-3
Compound Formula ZnS
Molecular Weight 97.45
Appearance white to off-white powder
Melting Point 1830°C
Boiling Point N/A
Density 4.1g/cm3
Solubility in H2O insoluble
Exact Mass N/A
Characteristics of Zinc Sulfide ZnS Powder
Zinc sulfide can be used as a white pigment. Zinc sulfide pigment has low Mohs hardness, soft texture (soft than titanium dioxide), and little wear on machine metal during processing.  This pigment has a distinct reflection in the short-wavelength region of visible light. In other words, zinc sulfide absorbs less light than titanium dioxide in the near-ultraviolet region (less than 400nm), so the color is bluer than titanium dioxide. Especially when used with fluorescent whitening agents it can produce excellent whiteness and brightness of the color. 
Refractive index of zinc sulfide:
The Refractive index is about 2.36, while the refractive index of titanium dioxide is 2.55~2.73. That is to say, the covering power of zinc sulfide is only about 60~65% of titanium dioxide. 
In fact, the index of refraction changes with temperature, and in general, the higher the temperature, the higher the index of refraction. For transparent or semi-permeable object colors, the higher the temperature, the less permeable the color. 
Flame retardant of zinc sulfide: 
ZnS can be used to replace part or all of antimony trioxide. 
As a white pigment, it shows a bright hue, about equal to 60% of the whitening power of titanium dioxide. Using ZnS as flame retardant, the amount of titanium dioxide can be saved, and it is not toxic.
Infrared transmittance of zinc sulfide: 
Zinc sulfide crystal is an important infrared transmittance material with good optical properties in mid and far-infrared regions.
The transmittance curve of ZnS crystal prepared by chemical vapor deposition is stable in the far-infrared region of 8-12 μm (8000-12000 nm), and the transmittance is above 73%. However, the transmittance begins to decrease in the far-infrared region of 3-5 μm (3000-5000 nm). Especially in the visible region (380~780nm), the transmittance decreases rapidly, and the transmittance deteriorates. After polishing, the crystal can be observed with the naked eye in a misty state, which leads to poor transmittance in the visible region. 
Zinc sulfide crystal is used as the window of infrared detector, with a general diameter of 18~30mm and a thickness of 1~3mm. Some processes produce large diameter zinc sulfide window pieces used in large and medium power infrared detectors. 
Fluorescence effect of zinc sulfide: 
When exposed to light, zinc sulfide emits a faint green fluorescence. If trace amounts of Cu, Mn, and Ag are added to the crystal zinc sulfide as activators, different colors of fluorescence can be emitted. 

Preparation Methods of Zinc Sulfide ZnS Powder
Double decomposition method: Add zinc sulfate solution to the reactor, and slowly add ammonium sulfide for double decomposition reaction under stirring. Zinc sulfide and ammonium sulfate will be generated, then remove ammonium sulfate by filtration, and then by evaporation concentration, cooling crystallization, centrifugal separation, zinc sulfide will be produced

Main Supplier of Zinc Sulfide ZnS Powder
Luoyang Tongrun Nano Technology Co. Ltd. (TRUNNANO) is a trusted global chemical material supplier & manufacturer with over 12-year-experience in providing super high-quality chemicals and Nanomaterials, including ZnS powder, nitride powder, graphite powder, zinc sulfide, calcium nitride, 3D printing powder, etc.
If you are looking for high-quality zinc sulfide powder, please feel free to contact us and send an inquiry. ([email protected])


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