Correlation of temperature dependences of thermal expansion and heat capacity of refractory metal up to the melting point: Tungsten

In continuing the series of publications started by the article about molybdenum, a detailed study of the correlation between the volume thermal expansion coefficient, ο( T ), and the heat capacity, C ( T ), of another refractory metal, tungsten, is carried out. It is shown that a distinct correlation of ο( C ) takes place not only at low temperatures, where it is linear and is known as the Grüneisen law, but also within a much wider temperature region, up to the melting point of the metal. A significant deviation from the low-temperature behavior of the linear dependence of ο( C ) occurs when the heat capacity reaches its classical Dulong and Petit limit, 3 R . The concept of the temperature dependence of the differential Grüneisen parameter, γ′ ∼ (∂ο/∂ C ) is introduced, and its evaluation is proposed.