Giant pyroelectric properties in La and Ta co-doped lead-free 0.94Na 0.5 Bi 0.5 TiO 3 -0.06BaTiO 3 ceramics

Abstract

La and Ta co-doped Lead-free 0.94NBT-0.06BT ceramics were synthesized by a conventional solid-state route. The compositions remain at a morphotropic phase boundary. The depolarization temperature (Td) decreased with increasing doping contents. The room temperature (RT) pyroelectric coefficient (p) was highly enhanced compared with undoped material (3.15 x10-4 C.m-2 .°C-1) and reached 12.9 x10-4 C.m-2 .°C-1 , whereas, at Td, 58.6 x10-4 C.m-2 .°C-1 could be obtained rather than 23.9 x10-4 C.m-2 .°C-1 for undoped materials. The pyroelectric figure of merits, Fi and Fv, also showed a huge improvement from 1.12 x10-10 m.v-1 and 0.021 m 2 .C-1 of undoped material to 4.61 x10-10 m.v-1 and 0.078 m 2 .C-1 of doped materials at RT, and to 20.94 x 10-10 m.v-1 and 0.28 x10-10 m 2 .C-1 at Td. RT FC values are2 .40, 2.46, and 2.57 (x10-9 C.cm-2 .°C-1) at frequency 33, 100 and 1000 (Hz) respectively, at La = Ta = 0.2 %. The pyroelectric coefficient achieved at RT in this study is almost one order of magnitude higher than PZT materials, furthermore, the figure of merits of the new compositions are comparable with or even better in those of PZT materials and other leadfree ceramics. The improvement in the pyroelectric properties makes La and Ta co-doped NBT-0.06BT ceramics possible materials to replace lead-containing PZT ceramics for infrared detector materials at a wide temperature range.

Enhanced pyroelectric properties in (Bi0.5Na0.5)TiO3–BiAlO3–NaNbO3 ternary system lead‐free ceramics

“… Mn‐doped 0.97K 0.5 Na 0.5 NbO 3 –0.03(Bi 0.5 K 0.5 )TiO 3 , (K 0.5 Na 0.5 ) 0.96 Li 0.04 ](Nb 0.84 Ta 0.1 Sb 0.06 )O 3 , Ca 0.2 Sr 0.1 Ba 0.7 Nb 2 O 6 , 0.6(Ba 0.9 Ca 0.1 )TiO 3 –0.4Ba(Sn 0.2 Ti 0.8 )O 3 , 0.93(Bi 0.5 Na 0.5 )TiO 3 –0.07Ba(Ti 0.945 Zr 0.055 )O 3 , 0.93(Bi 0.5 Na 0.5 )TiO 3 –0.07Ba(Ti 0.945 Zr 0.055 )O 3 –0.125 mol.% Mn, 0.94(Bi 0.5 Na 0.5 )TiO 3 –0.06BaTiO 3 –0.005La, 0.005La–0.94(Bi 0.5 Na 0.5 )TiO 3 –0.06BaTiO 3 –0.002Ta, 0.71(Bi 0.5 Na 0.5 )TiO 3 –0.065BaTiO 3 –0.22SrTiO 3 …”

“…Recently, a rather high p of 7.42 × 10 −8 Ccm −2 K −1 in BNT–BT ceramics was achieved by Balakt et al through La doping . Moreover, Ta doping further improved the p of this composition to 12.9 × 10 −8 Ccm −2 K −1 , which showed one order of magnitude higher than other lead‐containing and lead‐free ceramics. However, the depolarization temperature T d was rather low (74°C for La doped BNT–BT and 54.9°C for Ta further doping, respectively), resulting in poor thermal stability, as manifested in a sharp increase of p at elevated temperature.…”

Significantly enhanced pyroelectric performance in novel sodium niobate‐based lead‐free ceramics by compositional tuning

“…Pyroelectric materials are attracting significant attention because they play an important role in infrared detectors, sensors, thermal imaging, and energy harvesting applications . Moreover, there is a close relationship between pyroelectric coefficient and electrocaloric effect based on the thermodynamic Maxwell relation .…”

“…Therefore, exploration and development of a novel high performance lead‐free pyroelectric material are highly desirable and urgently needed. In recent years, palpable progress has been made for the investigation of lead‐free pyroelectric materials, such as (Bi 0.5 Na 0.5 )TiO 3 ‐based, (K 0.5 Na 0.5 )NbO 3 ‐based, (Sr 1‐ x Ba x )Nb 2 O 6 ‐based, and BaTiO 3 ‐based materials . For example, Balakt et al observed significantly enhanced pyroelectric coefficient ( p , 12.9 × 10 −8 C cm −2 K −1 ) in La/Ta co‐doped 0.94Na 0.5 Bi 0.5 TiO 3 ‐0.06BaTiO 3 lead‐free ceramics .…”

“…In recent years, palpable progress has been made for the investigation of lead‐free pyroelectric materials, such as (Bi 0.5 Na 0.5 )TiO 3 ‐based, (K 0.5 Na 0.5 )NbO 3 ‐based, (Sr 1‐ x Ba x )Nb 2 O 6 ‐based, and BaTiO 3 ‐based materials . For example, Balakt et al observed significantly enhanced pyroelectric coefficient ( p , 12.9 × 10 −8 C cm −2 K −1 ) in La/Ta co‐doped 0.94Na 0.5 Bi 0.5 TiO 3 ‐0.06BaTiO 3 lead‐free ceramics . Chen et al investigated the effect of Ca/Sr ratio on pyroelectric properties of Ca x Sr 0.3− x Ba 0.7 Nb 2 O 6 and obtained optimum value of p (1.3 × 10 −8 C cm −2 K −1 at 303 K) for composition x = 0.3 .…”