Zinc sulfide

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Zinc sulfide (or zinc sulphide) is a chemical compound with the formula Zn S. Zinc sulfide is a white to yellow colored powder or crystal. It is typically encountered in the more stable sphalerite (cubic) crystal structure, although the wurtzite (hexagonal) form is also known. Both of these forms are intrinsic semiconductors. The sphalerite form has a band gap of 3.54 eV at 300 K while the wurtzite form has a band gap of 3.91 eV.

A natural transition from the sphlerite form to the wurtzite form occurs at around 1293.15 K. The melting point is at 1991 K. It has a standard enthalpy of formation of -204.6 kJ/mol at 298 K. The CAS registry number is Template:CASREF.

The mineral form of zinc sulfide is sphalerite.

Zinc sulfide is a wide-bandgap semiconductor material of the II-VI group. It can be doped as both n-type semiconductor and p-type semiconductor, which is unusual for the II-VI semiconductors. ZnS is a covalently bonded solid.

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Applications

ZnS was used by Ernest Rutherford and others in the early years of nuclear physics as a scintillation detector, because it emits light on excitation by x-rays or electron beam, making it useful for x-ray screens and cathode ray tubes. It also exhibits phosphorescence due to impurities on illumination with blue or ultraviolet light.

Zinc sulfide, with addition of few ppm of suitable activator, is used as phosphor in many applications, from cathode ray tubes through x-ray screens to glow-in-the-dark products. When silver is used as activator, the resulting color is bright blue, with maximum at 450 nm. Manganese yields a yellow color. Copper provides long glow time and the familiar glow-in-the-dark greenish color. Copper doped zinc sulfide (ZnS:Cu) is used also in electroluminescent panels.

Zinc sulfide is also used as an infrared optical material, transmitting from visible wavelengths to over 12 micrometres. It can be used planar as an optical window or shaped into a lens. It is sometimes known by the trademarked name Cleartran.

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