Ultra low thermal expansion phases: Substituted 'PMN' perovskites

Among different principles which can be utilized in a structure to exhibit anomalously low thermal expansion, a 'distributed' phase transition is a candidate. Pb(Mg _{1 3}Nb _{2 3})₃ is a well known relaxor ferroelectric material in which such a transition occurs. The change in thermal expansion of PMN ceramics caused by partially substituting various ions at the B-site has been studied in order to see any new low expansion materials with good electrostriction properties exist. Partial ionic substitution of Ni²⁺, Co²⁺, Zn²⁺, Mn²⁺, Cd²⁺, Fe³⁺, Sc³⁺, Ti⁴⁺, Sn⁴⁺, Hf⁴⁺, Zr⁴⁺, and W⁶⁺ was made at B-site. The sintering temperature was kept at 1250° for 1 hour. Thermal expansion data and their interpretations are presented.