Bright reddish-orange emission and enhanced electrical properties of Sm-doped unfilled tetragonal tungsten bronze Ba4LaTiNb9O30

Ba4La1−xSmxTiNb9O30 (BLTN: Sm3+x) ceramics with different x have been synthesized. Their structural, photoluminescence, dielectric, and ferroelectric properties are investigated. By Rietveld structural refinement, BLTN: Eu3+x samples belong to the single unfilled tetragonal tungsten bronze (TTB) phase with space group P4bm. With deliberate introduction of Sm3+ ions in the unfilled TTB-type structure, BLTN: Sm3+x samples simultaneously present bright reddish-orange emission and enhanced electrical properties. The reddish-orange emission, originating from 4G5/2→6HJ (J=5/2, 7/2, and 9/2) transitions, has been observed by naked eyes under near ultraviolet radiation at room temperature. Furthermore, dielectric permittivity sharply changes with x and finally ferroelectric phase transitions above room temperature are realized in BLTN: Sm3+x under the stimulation of Sm3+ ions. It is believed that BLTN: Sm3+x involving bright reddish-orange emission and enhanced electrical properties may act as a potentially multifunctional optical-electro material.