Photoluminescence and electrical properties of Eu~(3+)-doped Na_(0.5)Bi_(4.5)Ti_4O_(15)-based ferroelectrics under blue light excitation

摘要

Na_(0.5)Bi_(4.5-x)Eu_xTi_4O_(15) (NBT-xEu~(3+)) ceramics with x = 0,0.05,0.10,0.15,0.20, 0.25, 0.30 and 0.40 were prepared by conventional ceramics processing. NBT-0.25Eu~(3+) ceramics show the strongest red and orange emissions corresponding to the ~5D_0 → ~7F_2 (617 nm) and ~5D_0 → ~7F_1 (596 nm) transitions, respectively. The strongest excitation band around 465 nm matches well with the emission wavelength of commercial InGaN-based blue LED chip, indicating that Eu~(3+)-doped NBT ceramics may be used as potential environmental friendly red-orange phosphor for W-LEDs application. As an inherent ferroelectric and piezoelectric material, the electrical properties of this potentially multifunctional electro-optical material have been also studied. The introduction of Eu~(3+) distinctly increased the Curie temperature (T_C) of NBT-xEu~(3+) ceramics from 640℃ to 711 ℃ as x ranges from 0 to 0.40. For higher temperature applications, the electrical conductivity was also investigated. The conduction of charge carriers in high-temperature range originates from the conducting electrons from the ionization of oxygen vacancies. High T_C and low tariff makes Eu~(3+)-doped NBT ceramic also suitable for high temperature piezoelectric sensor applications and electro-optical integration.