Jinko Solar offers both polycrystalline and monocrystalline photovoltaic modules. It uses 776,000 polycrystalline silicon photovoltaic modules. Most of these films are fabricated with polycrystalline or amorphous microstructures. Q Cells develops and produces mono- and polycrystalline silicon photovoltaic cells and solar panels. Ionic compound materials are usually crystalline or polycrystalline. However most magnetic materials are polycrystalline, composed of microscopic crystalline grains. PTCs are constructed from thermally sensitive silicons or polycrystalline ceramic materials. Invisible braces are a type of transparent ceramics called translucent polycrystalline alumina (TPA). Diffusion in polycrystalline materials can involve short circuit diffusion mechanisms. Misorientation is the difference in crystallographic orientation between two crystallites in a polycrystalline material. Carbides are also used in polycrystalline superalloys to inhibit grain boundary sliding. SVE models have been developed to study polycrystalline microstructures. Since around 1970, however, most MOS circuits have used self-aligned gates made of polycrystalline silicon. This is above the standard rating of 37.0% for polycrystalline photovoltaic or thin-film solar cells. As anticipated, single-crystal copper did prove to have better conductivity than polycrystalline copper.