Quantum ferroelectric and ferroelectric relaxor behavior has been found in $\left({\mathrm{Sr}}_{1-1.5x}{\mathrm{Bi}}_x\right){\mathrm{TiO}}_3.$ For $x<~0.0267,$ the quantum ferroelectric relationship $T_{{\varepsilon }_m}\propto (x-x_c{)}^{1/2}$ holds with $x_c\approx 0.0005,$ and obvious hysteresis loops were observed. The polarization relaxation shows critical slowing down. At high Bi concentration, a crossover from quantum ferroelectric to relaxor behavior occurred. The coexistence of ferroelectric and relaxor behavior in ${\mathrm{B}\mathrm{i}:\mathrm{S}\mathrm{r}\mathrm{T}\mathrm{i}\mathrm{O}}_3$ was attributed to a ferroelectric domain state induced by random fields.

• Received 29 December 1997

DOI:https://doi.org/10.1103/PhysRevB.57.7403