Incorporation of Yttrium in Barium Titanate Ceramics

In this work, X-ray diffractometry and scanning electron microscopy techniques were used to study the incorporation of yttrium in BaTiO₃, with the following nominal compositions: (Ba_{1- x} Y _x )TiO₃(0.015 ≤ to x ≤ to 0.08), (Ba_{1- x} Y _x )Ti_{1- x /4}-(□_Ti) _{x /4}O₃(0.005 ≤ to x ≤ to 0.1), and Ba(Ti_{1- y} Y _y )O_3-delta(0.028 ≤ to y ≤ to 0.258). The phase assemblage and the lattice parameters indicated a slight solubility (∼1.5 at.%) of yttrium at the Ba sites at 1440°C but a high solubility (∼12.2 at.%) of yttrium at the Ti sites at 1515°C. When BaTiO₃was heavily doped with yttrium at the Ti sites (a yttrium concentration ( y ) of <0.059), the crystallographic structure was tetragonal, whereas for y greater than equal to 0.059, the crystallographic structure was cubic.