Silver solid solution piezoelectrics

Using density functional theory calculations, we investigate the feasibility of using silver on the perovskite A-site in high-performance lead-free piezoelectrics. The calculations show that silver atoms are ferroelectrically active and can off-center by 0.5 Å. To induce Ag ferroelctric behavior absent in pure AgNbO3 we explore solid solutions of AgNbO3 with well-known simple perovskites PbTiO3, BaZrO3, and BaTiO3. For the AgNbO3–PbTiO3 solid solution, we predict a morphotropic phase boundary near sAgNbO3d3/8sPbTiO3d5/8. We find an unusual sequence of compositional phase transitions in AgNbO3–BaZrO3 and AgNbO3–BaTiO3 which are due to the effects of volume expansion in perovskites. For the AgNbO3–BaTiO3 solid solution we find two morphotropic phase boundaries at 12.5% and 37.5% AgNbO3 compositions with favorable piezoeletric properties and indications of high TC. © 2004 American Institute of Physics. [DOI: 10.1063/1.1787946]