Improved ferroelectric and dielectric properties of Sm, La co-doped Bi4Ti3O12 multifunctional thin films with orange-red emission

Structure, dielectric, ferroelectric, fatigue, and photoluminescent properties of Bi3.86-kSm0.14LakTi3O12 (BSLT) thin films synthesized by sol-gel method were investigated. The XRD analysis indicated that the BSLT thin films formed single phase orthorhombic structure, and orthorhombic distortion was found to increase with increasing lanthanum doping content. Raman spectra revealed that BSLT thin films have significantly structure distorted because of La3+ doping, which is consistent with XRD results. Increasing La substitution results in improvement in dielectric and ferroelectric properties of BSLT thin films due to distorted structure and defects reduction. The films show almost fatigue-free ferroelectric polarization behavior at room temperature. Besides, the BSLT thin films show orange-red color emission at 604 nm and long florescence lifetime (about 0.75 ms). This study indicates that the thin films with an appropriate doping concentration of Sm3+, La3+ ions may have potential applications in multifunctional optoelectronic devices.