Some Solid State Chemistry Aspects of Lead-Free Relaxor Ferroelectrics

Some solid state chemistry aspects are investigated in relaxor ferroelectrics of both perovskite and tetragonal tungsten bronze (TTB) structure. Various issues regarding composition, cationic charge, electronic configuration, and structure are discussed. The relaxor behavior appears when two different cations occupy the same crystallographic site. One of the cations in the octahedral site has to be ferroelectrically active. The relaxor effect is correlated to cationic distribution disorder in the same site, depending on composition and structure (perovskite or TTB).