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As quoted in an online version of: David R. Lide (ed), CRC Handbook of Chemistry and Physics, 84th Edition.CRC Press. Boca Raton, Florida, 2003; Section 4, Properties of the Elements and Inorganic Compounds; Physical Properties of the Rare Earth Metals
Tantalum hafnium carbide is a refractory chemical compound with a general formula Ta x Hf y C x+y, which can be considered as a solid solution of tantalum carbide and hafnium carbide. It was originally thought to have the highest melting of any known substance but new research has proven that hafnium carbonitride has a higher melting point.
Hafnium carbide (Hf C) is a chemical compound of hafnium and carbon.Previously the material was estimated to have a melting point of about 3,900 °C. [2] More recent tests have been able to conclusively prove that the substance has an even higher melting point of 3,958 °C exceeding those of tantalum carbide and tantalum hafnium carbide which were both previously estimated to be higher. [3]
The melting points of tantalum carbides was previously estimated to be about 3,880 °C (4,150 K; 7,020 °F) depending on the purity and measurement conditions; this value is among the highest for binary compounds. [6] [7] And only tantalum hafnium carbide was estimated to have a higher melting point of 3,942 °C (4,215 K; 7,128 °F). [8]
Hafnium-based compounds are employed in gates of transistors as insulators in the 45 nm (and below) generation of integrated circuits from Intel, IBM and others. [69] [70] Hafnium oxide-based compounds are practical high-k dielectrics, allowing reduction of the gate leakage current which improves performance at such scales. [71] [72] [73]
Tantalum is a chemical element; it has symbol Ta and atomic number 73. It is named after Tantalus, a figure in Greek mythology. [11] Tantalum is a very hard, ductile, lustrous, blue-gray transition metal that is highly corrosion-resistant.
The mixed carbide tantalum hafnium carbide (Ta 4 HfC 5) possesses the highest melting point of any currently known compound, 4,263 K (3,990 °C; 7,214 °F). [21] Recent supercomputer simulations suggest a hafnium alloy with a melting point of 4,400 K. [22] Hafnium forms both a hafnium(III) and a hafnium(IV) nitride.
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