Substitution of Bi and Nb Ions in Lead Zirconate‐Titanate

Abstract

Solid‐state substitution of Bi and Nb ions in the perovskite crystal structure of Pb(Ti 0.47 Zr 0.53 )O 3 was investigated by sample weight changes at 1150°C in an “equilibrium” PbO atmosphere. A model is discussed that includes the effect of charge neutralization, requiring weight losses for A‐site substitutions and weight gains for B‐site substitutions. Experiments support the substitution of Bi as Bi 3+ on the Pb 2+ A site and Nb as Nb 5+ on the (Ti,Zr) 4+ B site of lead zirconate‐titanate. For each mole of BiO 1.5 added to a specimen, 1.5 moles of PbO are lost; for each mole of NbO 2.5 added, 0.5 moles of PbO are gained. These results agree with the proposed model and with ionic size arguments. The weight changes were time‐dependent during the first 30 to 40 h at 1150°C. This behavior is accounted for by the presence of transient second phases.