Zinc sulfide is also an infrared optical material, transmitting from visible wavelengths to just over 12 micrometers. It can be used planar as a visual window or shaped into a lens. It is made as microcrystalline sheets by the synthesis from hydrogen sulfide gas and zinc vapor, and this is sold as FLIR-grade (Forward Looking Infrared), where the zinc sulfide is in a milky-yellow, opaque form. This material, when hot, isostatically pressed (HIPed) and can be converted to a water-clear format known as Cleartran (trademark). Early commercial forms were marketed as Irtran-2, but this designation is now obsolete. Zinc sulfide is a standard pigment, sometimes called statolith. When combined with barium sulfate, zinc sulfide forms lithopone. Fine ZnS powder is an efficient photocatalyst, which produces hydrogen gas from water upon illumination. Sulfur vacancies can be introduced in ZnS during its synthesis; this gradually turns the white-yellowish ZnS into a brown powder and boosts the photocatalytic activity through enhanced light absorption. Both sphalerite and Wurtzite are intrinsic, wide-bandgap semiconductors. These are prototypical II-VI semiconductors and adopt structures related to many other semiconductors, such as gallium arsenide. The cubic form of ZnS has a band gap of about 3.54 electron volts at 300 kelvins, but the hexagonal shape has a band gap of about 3.91 electron volts. ZnS can be doped as either an n-type semiconductor or a p-type semiconductor. The French chemist Théodore Sidot first reported the luminescence of ZnS in 1866. His findings were presented by A. E. Becquerel, renowned for his luminescence research. ZnS was used by Ernest Rutherford and others in the early years of nuclear physics as a scintillation detector because it emits light upon excitation by X-rays or electron beams, making it useful for X-ray screens and cathode ray tubes. This property made zinc sulfide useful in the dials of radium watches. If you are looking for high quality, high purity, and cost-effective zinc sulfide, or if you require the latest price of zinc sulfide, please feel free to email contact mis-asia.