Phase Diagram in Bi4-xGdxTi3O12

The temperature dependences of the dielectric constants of Bi4-x Gd x Ti3O12 (BGT-x) single crystals (x≤0.4) were measured. It was found that the paraelectric–ferroelectric phase transition temperature near 680 °C remains almost unchanged in the concentration range of 0≤x ≤0.4. Below the transition point at about 680 °C, another dielectric anomaly showing the phase transition was observed in BGT-x, where the transition temperature depends on the concentration x. We confirmed that the triggered transition from the tetragonal phase to the monoclinic phase, observed in Bi4Ti3O12, splits into two phase transitions with the addition of Gd cations, i.e., from the tetragonal phase to the orthorhombic phase and eventually to the monoclinic phase. The temperature-concentration phase diagram in BGT-x was clarified.