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A large category of materials that are neither metals nor organic polymers is known as inorganic non-metallic materials, or simply inorganic materials. Together with metal materials and organic polymer materials, it forms the three major categories of materials. Silicate materials such as glass, cement, and ceramics are typical inorganic non-metallic materials. With the advancement of technology, many new inorganic non-metallic materials have emerged, whose range **extends beyond traditional silicate materials. These new inorganic materials have become one of the important aspects of modern technologies and high-tech fields. From a chemical composition perspective, inorganic non-metallic materials include (1) materials composed of non-metallic elements, among which there are those made up of a single non-metallic element. There are various carbon materials such as oriented graphite made from carbon, synthetic diamonds, silicon transistors and other silicon integrated circuits as well as electronic components; there are also materials with excellent properties obtained by the combination of two or more non-metallic elements, with chalcogenide compounds being excellent optoelectronic materials. (2) Compounds formed between non-metallic elements and metallic elements, such as oxides, nitrides, and carbides, are all important inorganic materials. For example, chromium-doped aluminum oxide single crystals, namely rubies, are excellent wear-resistant materials and laser materials, while aluminum oxide ceramics are widely used high-temperature and wear-resistant materials. (3) Inorganic materials composed of various salts and complex salts, such as germanates, zirconates, phosphates, titanates, and the silicates mentioned above. For example, bismuth germanate single crystals are high-performance scintillation crystals used as detection materials for high-energy rays, while lead zirconate titanate ceramics are important piezoelectric ceramic materials. Inorganic materials can be classified into single crystals, amorphous materials, and polycrystalline materials based on their internal structure. A single crystal is a solid material in which atoms or molecules are arranged in an orderly manner within it. Amorphous materials, also known as amorphous forms, have atoms or molecules that are ordered on a short scale but disordered on a long scale; ordinary glass is an example of an amorphous material. Polycrystalline refers to a structure composed of many tiny crystals, and ceramics are polycrystalline materials. For the same chemical composition, different crystal forms result in differences in properties. Generally, polycrystalline or amorphous materials are relatively easy to produce, but growing single crystals is more difficult, especially for compounds with complex compositions. Furthermore, crystals with the same chemical composition can also have different crystal structures; for example, quartz includes tridymite, cristobalite, and so on. Due to these differences in crystal structure, they exhibit different properties. The microstructure of a material affects its properties. In terms of their form, in addition to bulk materials, various other forms such as films, fibers, porous materials, and foams have been developed. The properties of these materials differ significantly from those of bulk materials. For example, a type of microporous glass has a very large specific surface area; the surface area per 1 gram of this glass can reach hundreds of square meters. This characteristic makes it useful in industries such as nuclear energy, medicine, and lighting, as well as in high-tech fields like biology and superconductivity. Like other materials, inorganic materials can also be roughly divided into two main categories based on their applications: structural materials and functional materials. Materials that are utilized solely based on properties such as strength to meet the requirements of engineering structures are known as structural materials. Modern new technologies place demands on materials that go far beyond those of structural materials; they require materials to have various special functional properties, which can often only be achieved through interactions such as those involving electricity, light, sound, magnetism, etc., within the material. Materials with such properties are known as functional materials. Some materials can be used not only as structural materials but also as functional materials. For example, composite materials made by combining carbon fibers with metals, ceramics, etc., are advanced structural materials with excellent properties that can be used to manufacture pressure-sensitive sensors. A composite material is a composite system composed of two or more materials. Below are several important categories of inorganic non-metallic materials. High-tech ceramics. Japan calls it precision ceramics. Among functional ceramics, piezoelectric ceramics can convert electrical energy into mechanical energy, or vice versa. Transducers and sensors made from them are widely used in fields such as ultrasound, sonar, electroacoustics, ignition, and detonation. Ultrasonic scanners using piezoelectric ceramics as probes have become an important medical diagnostic tool. Lightning arresters made of zinc oxide semiconductor ceramics are key components in high-voltage power transmission projects. Magnetic ceramics, represented by ferrites, have seen rapid development in applications such as permanent magnets, high-frequency soft magnets, and magnetic recording. Among structural ceramics, silicon nitride ceramics are used to manufacture mechanical seals, cutting tools, bearings, and molds for casting metals. Silicon carbide ceramics are also a good material for manufacturing wear-resistant components, and can be used to make heat exchangers as well. The most attractive prospect for structural ceramics lies in their use in heat engines; it is estimated that by the 1990s, high-temperature structural ceramics for heat engines will gradually give rise to a new industry. Optical fiber. Fiber optic communication, which uses optical fibers for transmission, marked a revolution in modern communication technology; countries such as the United States and Japan have already built thousands of kilometers of fiber optic communication networks. Optical fibers are made by drawing ultra-pure quartz glass into filaments after doping it. The low loss of optical fibers is highly dependent on the purity of the raw materials; the concentration of transition metal ions in the glass must be below one part per million, with the concentration of individual ions being below one part per hundred million. Changes in fiber performance are related not only to static fatigue and surface cracks but also to hydrogen present in the fiber; the diffusion of molecular hydrogen within the fiber increases its attenuation. Currently, scientists are also researching infrared fibers with lower loss than quartz glass fibers to meet the needs of long-distance communication. Amorphous silicon semiconductor. Amorphous silicon thin-film semiconductors are a highly active area in the field of semiconductor research today. It is deposited on a substrate by using silane as a raw material and carrying out decomposition and doping through direct current or high-frequency discharge. Amorphous silicon has an absorption coefficient for sunlight that is almost an order of magnitude higher than that of crystalline silicon. Therefore, when using amorphous silicon to manufacture solar cells, a thin film less than 1 μm thick is sufficient. Not only is less material required, but the manufacturing process is also simpler, making it an excellent material for producing large-area, inexpensive solar cells. Research shows that amorphous silicon is actually a silihydride or a silicon-fluorine-hydride alloy; recently, amorphous silicon semiconductors with multi-layer structures have also been developed, which are silicon-nitridium silicon multi-layer structures with over 300 layers. Amorphous silicon materials also possess good photoconductive properties, and their mechanical strength and wear resistance are much higher than those of other amorphous materials. Amorphous silicon can also be used to manufacture electrostatic copying drums, target surfaces for television cathode rays, information storage devices, photodetectors, and more. Fast ionic conductors. Fast ionic conductors, also known as superionic conductors or solid electrolytes, represent a highly interesting branch of materials science at present. Although these materials are solids, they exhibit electrical conductivity similar to that of ionic solutions. The charge carriers are not electrons, but cations, anions, or ion vacancies. Its ionic conductivity can reach up to 10-1 Ω-1·cm-1, with an activation energy as low as 0.1–0.2 eV. Material migration accompanies the conduction process in such conductors. Fast ion conductors hold broad application prospects in energy technology; for example, oxygen ion conductors such as stabilized zirconia in high-temperature fuel cells can efficiently convert the chemical energy of hydrogen, natural gas, and similar substances directly into electrical energy. Fast ionic conductors are also used in batteries with high energy density; sodium-sulfur batteries, for example, have many advantages and are expected to be used for energy storage in power plants and as power sources for vehicles. In addition, fast ion conductors can also be used in electrochromic display devices, ion-selective electrodes, sensing elements, and other electrochemical devices.