Binary molybdates and tungstates of monoand trivalent elements as possible ferroelastics and ferroelectrics

Phase transitions in binary molybdates and tungstates of mono- and trivalent elements, as well as some of their physical properties are reviewed with a special attention to ferroelastic and ferroelectric behavior. There are many compounds with phase transitions of the displacement type and reconstructive ones. The author tried to pick out only compounds with the displacement-type transitions. This allowed the identification of many compounds interesting for physics of ferroelasticity and ferroelectricity among the structure families of scheelite, glaserite, palmierite, wolframite etc. So far, they have been studied in the main (better or worse) by chemists. Now physisists have to study them.