Ordering of the lowest tungsten carbide W2C

Atomic-vacancy ordering of the lowest tungsten carbide W2C with the basis hexagonal structure of the L’3 type is analyzed by neutron and x-ray diffraction studies. It is found that the trigonal phase ɛ-W2C (space group \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document} $$P\bar 3$$ \end{document} 1m) is the only ordered phase in the temperature range from ∼2700 to 1370 K. The disorder-order phase transition channel associated with the formation of the trigonal ɛ-W2C phase is found to include three superstructure vectors k15(1), k15(2), and k17(1) of two stars {k15} and {k17}. The distribution function of the carbon atoms in the trigonal ɛ-W2C superstructure is calculated.