Abstract:A good book not only introduces and explains a subject clearly to the uninitiated but also makes those who know, or think that they know, the field look at it in a new way.Here is such a book as it in...A good book not only introduces and explains a subject clearly to the uninitiated but also makes those who know, or think that they know, the field look at it in a new way.Here is such a book as it introduces ionic solids based on multiple anions.Ions are usually first encountered in the simple salt sodium chloride, but more complex ionic materials with useful properties have almost invariably been developed by fixing the anion and mixing different cations.The high-temperature YBCO superconductor YBa 2 Cu 3 O 7 has three different metal cations but only oxide anions, and methylammonium lead iodide, (CH 3 NH 3 )PbI 3 , one of the most studied materials in recent years due to its exceptional photovoltaic properties, comprises two cations made up of four elements in total, but with only iodide as the anion.Entire books and conferences are devoted to 'halide', 'oxide', or 'nitride' materials, and even subsets such as 'transition metal oxides' have expanded into major research fields.'Mixed-anion Compounds' authored by Hiroshi Kageyama, Hiraku Ogino, Tong Zhu and Tetsuya Hasegawa starts from the alternative viewpoint of exploring ionic materials by mixing anions.It introduces (or reintroduces) the reader to synthesis, structural characterization, property optimization, and band structure calculations for solids while always asking 'how do we do this for multiple anions'?There are plenty of surprises such as the stability of many solid oxide hydrides that might have been expected to decompose into a wet mess.This book will be invaluable to new materials students as well as experienced researchers.In particular it gives a fresh perspective to those who fixed the anion in their research many years agoit is time to start mixing!Read More