Influence of attrition milling on the electrical properties of undoped-BaTiO3

Undoped-BaTiO3 powder prepared from the mixed oxide route (0 h sample) has been attrition milled using yttria-stabilized ZrO2 milling media for 0.5–3 h prior to formation of dense ceramics. Both isovalent (Zr4+ → Ti4+) and aliovalent (Y3+ → Ba2+) dopant contamination effects have been observed. Systematic changes occur in the lattice parameters, polymorphic phase transition temperatures and dielectric properties below the Curie temperature for 0–2 h attrition milled powders and these are attributed primarily to an ion-size effect associated with Zr-doping on the Ti-site due to milling media contamination. The bulk conductivity of attrition milled samples at high temperature decreases by ∼2–3 orders of magnitude compared to 0 h samples and the activation energy associated with bulk conduction increases from ∼1 eV for 0 and 0.5 h samples to 1.4 eV for 3 h samples. The change in bulk conductivity and conduction mechanism for the attrition milled samples is attributed to aliovalent Y3+ dopant contamination from the milling media.