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|Section2= |Section3= |Section4= |Section7= |Section8= }} Thorium dioxide (ThO2), also called thorium (IV) oxide, is a crystalline solid, often white or yellow in color. It was formerly known as thoria. It is produced mainly as a by-product of lanthanide and uranium production.〔 Thorianite is the name of the mineralogical form of thorium dioxide. It is moderately rare and crystallizes in isometric system. The melting point of thorium oxide is 3300 °C – the highest of all known oxides. Only a few elements (including tungsten and carbon) and a few compounds (including tantalum carbide) have higher melting points. ==Chemistry== The compound is radioactive due to the radioactivity of thorium. Thorium dioxide can be turned into a nuclear fuel by breeding it into uranium-233 (see below and refer to the article on thorium for more information on this). The high thermal stability of thorium dioxide allows applications in flame spraying and high-temperature ceramics. Thoria has the fluorite crystal structure. This is uncommon among binary dioxides (other examples include cerium dioxide, hafnium dioxide, uranium dioxide and plutonium dioxide). The band gap of thoria is about 6 eV. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Thorium dioxide」の詳細全文を読む スポンサード リンク
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