Structural and dielectric properties of Ga-modified BiFeO3–PbTiO3 crystalline solutions

The dielectric and structural properties of $\mathrm{Bi}({\mathrm{Ga}}_x{\mathrm{Fe}}_{\text{1−x}}){\mathrm{O}}_3–{\mathrm{PbTiO}}_3$ (BGF–PT) crystalline solutions have been investigated. Studies have focused on phase-pure perovskite materials. With increasing Ga content, we have found: (i) a coexistence of tetragonal and rhombohedral ferroelectric phases; (ii) a multicell perovskite structure for BGF–0.3PT; and (iii) a maximum tetragonal $\mathrm{c/a}$ ratio for the composition BGF–0.6PT with $\text{x=0.25.}$ Also, Ga modification increases the electrical resistivity to ${\text{⩾10}}^{12}\mathrm{\hspace{0.17em}\Omega }\mathrm{cm},$ reduces the dielectric loss or $\tan \mathrm{ \delta }$ over a wide temperature range, and increases the dielectric constant K. We have developed BGF–PT materials with values of $\text{K>400}$ and of $\tan \text{\hspace{0.05em}δ<0.03.}$