As inorganic materials are put to more and more practical uses--mainly in electric, magnetic, and optical devices--materials scientists must have an increasingly sophisticated understanding of the chemical and physical properties of inorganic compounds. This volume--the first of its kind in twenty years--provides a unified presentation of the chemistry of non-stoichiometric compounds based on statistical thermodynamics and structural inorganic chemistry. Four modern examples of non-stoichiometric compounds--ionic conducting compounds, hydrogen absorbing alloys, magnetic materials, and electrical materials--are discussed in detail. Students and researchers in structural inorganic chemistry, crystallography, materials science, and solid state physics will find this much-needed book both practical and informative.