Improved piezoelectric and bright up-conversion photoluminescent properties in Ho-doped Bi0.5Na0.5TiO3–BaTiO3 lead-free ceramics

Abstract

Lead-free ceramics of 0.94(Bi 1-x Ho x Na) 0.5 TiO 3 -0.06BaTiO 3 have been prepared by a conventional solid reaction method and their piezoelectric, ferroelectric and photoluminescent properties have been studied. After the partial substitution of Ho 3? for Bi 3? , a new Bi 0.5 Na 0.5 TiO 3 -based solid solution with a pure perovskite structure is formed. The doping of Ho 3? has no obvious influence on the crystal structure of the ceramics. After the addition of a small amount of Ho 3? (x = 0.015), the piezoelectricity (d 33 = 187 pC/N, k p = 41.1 %, respectively) and ferroelectricity (P r = 25.2 lC/cm 2 ) of ceramics are enhanced. The down-conversion and up-conversion photoluminescence of the ceramics are observed. A green down-conversion emission band at 548 nm is observed which is from the 5 S 2 ? 5 I 8 transition of Ho 3? ; the main down-conversion excitation bands located at 410-500 nm is due to the 5 I 8 ? 5 G 5, 6 transitions, and the maximum brightness of down-conversion photoluminescence are obtained at x = 0.015. The ceramic with x = 0.01 exhibits the maximum value of the up-conversion emission at 475 nm, which is attributed to the 5 F 3 ? 5 I 8 transition. Our study shows that the ceramics with x = 0.01-0.02 exhibit simultaneously good piezoelectricity, strong ferroelectricity and excellent photoluminescence, suggesting a potential application in the electro-optic devices.

Multiple improvement in piezoelectricity, ferroelectricity, and fluorescence of 0.94(Bi0.984Er0.016Na)0.5TiO3–0.06BaTiO3 by optimizing sintering temperature/dwell time

“…b, the rhombohedral symmetry is characterized by the splitting of (003)/(021) peaks at ∼40° in the 0.94(Bi 0.984 Er 0.016 Na) 0.5 TiO 3 –0.06BaTiO 3 ceramics sintered at 1080–1240 °C for 2 h; and the splitting of (002)/(200) peaks between 46° and 48° are simultaneously observed, corresponding to a tetragonal symmetry. To our knowledge, the simultaneous existence of (003)/(021) peaks at ∼40° and (002)/(200) peaks at ∼46.5° has been frequently considered as a main characteristic of the formation of rhombohedral and tetragonal MPB in BNT‐based materials . However, some researchers reported that the splitting of peaks can be suspected resulting from Kα1 (1.54056 Å) and Kα2 (1.54439 Å) radiations .…”

Structural Evolution and Enhanced Energy Density, Ferroelectric Property Investigation in Gd Substituted NBT – BT Lead Free Ferroelectric Ceramics

“…To improve the electric properties and to enhance the energystorage density of NBT -BT ceramics, the effects of A -Site, B -Site or simultaneous A and B sites substitution with rare earth (RE) elements were extensively studied. It has been reported that the partial substitution of some rare-earth ions such as Ho 3+ /Dy 3+ /Nd 3+ and Er 3+ for Bi 3+ in NBT based lead free ceramics can develop new multifunctional materials with excellent structural, dielectric, ferroelectric, piezoelectric, photoluminescent and other optical properties [19][20][21][22]. As the Gadolinium (Gd 3+ ), is a rare earth ion, wellknown for its improving character of pyroelectric properties [23].…”

Enhanced Electrocaloric Effect and Energy Storage Density of Nd‐Substituted 0.92NBT‐0.08BT Lead Free Ceramic

“…[8] These issues were addressed by several research groups by approaching different methods with the help of specific site substitution and fabricating solid solutions (like rare earth-doped NBT-BT) with higher symmetry matrix to minimization of E c and conductivity which is useful for the storage device applications. [9,10] Over past few decades, sporadic progress was made on dielectric systems due to their relatively low response of electrocaloric effect (ECE) as compared to other candidates. [11,12] The indirect method gives the justification for finding the ECE from polarization curves over the functional temperature with the help of Maxwell relations .…”