What are the physical properties of High Purity Zinc Sulfide?

High purity zinc sulfide (ZnS) is a versatile compound with a wide range of applications, thanks to its unique physical properties. As a leading supplier of high purity zinc sulfide, I am excited to delve into the fascinating world of this compound and explore its key physical characteristics.

Crystal Structure

Zinc sulfide exists in two main crystal structures: sphalerite (also known as cubic zinc blende) and wurtzite (hexagonal). The sphalerite structure is the more common form at room temperature and pressure. In the sphalerite structure, each zinc ion is surrounded by four sulfur ions in a tetrahedral arrangement, and vice versa. This structure gives zinc sulfide its characteristic cubic symmetry.

The wurtzite structure, on the other hand, has a hexagonal symmetry. It is less stable than the sphalerite structure under normal conditions but can be formed under certain growth conditions or at high pressures. The difference in crystal structure can have a significant impact on the physical properties of zinc sulfide, such as its optical and electrical properties.

Density

The density of high purity zinc sulfide depends on its crystal structure and purity. For sphalerite, the density is approximately 4.09 g/cm³, while for wurtzite, it is around 4.10 g/cm³. These values are relatively high compared to many other common materials, which is due to the high atomic mass of zinc and sulfur and the close packing of atoms in the crystal lattice.

The high density of zinc sulfide makes it useful in applications where weight is not a major concern but a high mass per unit volume is desired. For example, it can be used as a filler in polymers to increase their density and improve their mechanical properties.

Melting and Boiling Points

Zinc sulfide has a relatively high melting point of around 1830 °C (3326 °F) and a boiling point of approximately 1185 °C (2165 °F) at normal atmospheric pressure. These high temperatures are a result of the strong ionic bonds between the zinc and sulfur atoms in the crystal lattice.

The high melting and boiling points make zinc sulfide suitable for applications that require materials to withstand high temperatures. For instance, it can be used in high-temperature furnaces and as a refractory material in the metallurgical industry.

Hardness

In terms of hardness, zinc sulfide is relatively hard, with a Mohs hardness of around 3.5 - 4. This means that it is harder than materials like gypsum (Mohs hardness of 2) but softer than materials like fluorite (Mohs hardness of 4).

The hardness of zinc sulfide makes it suitable for use in abrasive applications, such as in the production of grinding wheels and sandpaper. It can also be used as a protective coating to prevent wear and tear on surfaces.

Optical Properties

One of the most remarkable physical properties of high purity zinc sulfide is its excellent optical properties. Zinc sulfide is a wide-bandgap semiconductor with a bandgap energy of approximately 3.6 - 3.8 eV at room temperature. This wide bandgap makes it transparent to a wide range of wavelengths, from the ultraviolet (UV) to the infrared (IR) region.

In the visible light range, zinc sulfide is often used as a phosphor material. When excited by an external energy source, such as electrons or photons, it emits light in the visible spectrum. This property makes it useful in applications such as cathode ray tubes (CRTs), fluorescent lamps, and scintillation detectors.

In the infrared region, zinc sulfide has a high transmittance, making it an ideal material for optical windows, lenses, and prisms in infrared optical systems. It is commonly used in thermal imaging cameras, night vision devices, and infrared spectrometers. For more information on optical applications of zinc sulfide, you can visit Optical Coating Zinc Sulfide.

Electrical Properties

Zinc sulfide is a semiconductor, which means that it has electrical conductivity between that of a conductor and an insulator. The electrical conductivity of zinc sulfide can be controlled by doping it with impurities. For example, doping with elements such as copper or silver can increase its conductivity, making it a p-type semiconductor, while doping with elements like chlorine or bromine can create an n-type semiconductor.

The semiconductor properties of zinc sulfide make it useful in electronic devices such as light-emitting diodes (LEDs), photovoltaic cells, and field-effect transistors (FETs). In LEDs, zinc sulfide can be used as an active layer to emit light when an electric current is passed through it. In photovoltaic cells, it can be used to convert sunlight into electricity.

Chemical Stability

High purity zinc sulfide is relatively stable under normal conditions. It is insoluble in water and most common organic solvents. However, it can react with strong acids and oxidizing agents. For example, it reacts with hydrochloric acid to produce hydrogen sulfide gas and zinc chloride.

The chemical stability of zinc sulfide makes it suitable for use in harsh chemical environments. It can be used as a corrosion-resistant coating on metals to protect them from chemical attack.

Applications in High-Performance Plastics

In addition to its optical and electrical applications, high purity zinc sulfide is also widely used in high-performance plastics. When added to plastics, it can improve their mechanical properties, such as strength, stiffness, and impact resistance. It can also enhance their thermal stability and flame retardancy.

The use of zinc sulfide in high-performance plastics is growing rapidly, especially in the automotive, aerospace, and electronics industries. For more information on the use of zinc sulfide in high-performance plastics, you can visit High Performance Plastic Zinc Sulfide.

Conclusion

In conclusion, high purity zinc sulfide is a remarkable compound with a wide range of physical properties that make it suitable for a diverse array of applications. Its unique crystal structure, high density, high melting and boiling points, hardness, excellent optical and electrical properties, and chemical stability make it a valuable material in many industries.

As a supplier of high purity zinc sulfide, I am committed to providing our customers with the highest quality products that meet their specific requirements. Whether you are looking for zinc sulfide for optical applications, electronic devices, or high-performance plastics, we have the expertise and resources to deliver the right solution for you.

If you are interested in learning more about our high purity zinc sulfide products or would like to discuss your specific needs, please feel free to contact us. We look forward to the opportunity to work with you and help you achieve your goals.

References

• "Handbook of Inorganic Chemicals" by Pradyot Patnaik
• "Semiconductor Physics and Devices" by Donald A. Neamen
• "Materials Science and Engineering: An Introduction" by William D. Callister Jr. and David G. Rethwisch