Thermally stable high strain and piezoelectric characteristics of (Li, Na, K)(Nb, Sb)O₃‐CaZrO₃ ceramics for piezo actuators

Abstract

The 0.97(Na0.5K0.5)(Nb1−xSbx)O3‐0.03CaZrO3 ceramic with x = 0.09 exhibits a high d33 of 518 pC/N and a strain of 0.13% at 4.0 kV/mm owing to its orthorhombic‐pseudocubic polymorphic phase boundary (PPB) structure. However, these values decreased considerably above 90°C owing to its low Curie temperature (TC), indicating that its thermal stability is not sufficient for practical applications. Li2O was added to the specimen with x = 0.11 to improve its thermal stability of the strain and d33 by increasing the TC without degrading the actual d33 and strain values. The 0.97(Li0.04Na0.46K0.5)(Nb0.89Sb0.11)O3‐0.03CaZrO3 ceramic, having an orthorhombic‐tetragonal PPB structure, exhibits a d33 of 502 pC/N and a strain of 0.16%. This large strain was maintained up to 150°C and the d33 slightly decreased to 475 pC/N at 130°C. Therefore, this lead‐free ceramic displays excellent piezoelectric characteristics with improved thermal stability, indicating that it can be applied to piezoelectric actuators.

Investigation the effect of Sb on phase boundary variation of 0.965(Na0.5K0.5)(Nb1-xSbx)-0.035BaZrO3 ceramics and the corresponding piezoelectric properties

“…And for x = 0.10, the crystal structure turned into 100% rhombohedral structure with R wp = 6.12 and GOF = 4 (Figure 2(e)). As reported by Lee et al [29], this result could be further verified by the remained piezoelectric (ferroelectric) properties of the specimen with x = 0.10.…”

“…A homogeneous perovskite phase without secondary phases was obtained in 0.965CNKN 1-x S x -0.035BZ ceramics (0.00 ≤ x ≤ 0.10) sintered at 1070°C for 8 hours, as shown in Figure S1 of Supplementary Material. To have a detail analysis on the variation (2-20) R could be found, demonstrating the rhombohedral phase became the single phase [29]. To further confirm the above analysis, slow scan analysis at 45.5° was performed, and similar conclusion could be drawn which is shown in Figure S2 of Supplementary Material.…”

“…For x = 0.04, the T C and T O-T declined to 208°C and 120°C, respectively, which is shown in Figure 3(b). The T C of x = 0.06 was around 146°C, leading to the tetragonal phase zone was quickly squeezed [29] and a T O-R emerged at approximately 92°C, indicating orthorhombic dominant-rhombohedral PPB structure was formed (Figure 3(c)). For the specimen with x = 0.08 (Figure 3(d)), the T C declined to ~ 77°C, which induced the formation of rhombohedral dominantorthorhombic PPB structure.…”

“…Moreover, if PPB structure is developed upon pesudocubic structure, a high P r value could be also expected because of more possible spontaneous polarization directions during the poling process. Therefore, in recent years, there have been several studies reported to create orthorhombic-pseudocubic PPB structure or tetragonal-pseudocubic PPB structure near room temperature and promising piezoelectricity was also obtained [25][26][27][28][29]. As the research further developed, the pseudocubic structure was identified as tetragonal-cubic PPB structure in NK(Nb 1-x Sb x )-MTiO 3 (M = Ca, Ba) ceramics [25,28] and rhombohedral structure in NK(Nb 1-x Sb x )-CaZrO 3 ceramics [29].…”

Outstanding Piezoelectricity of (K, Na)(Nb, Sb)O3-SrZrO3-(Bi, Ag)ZrO3 Piezoceramics and Their Application to a Planar-Type Actuator

“…Various ABO 3 -type additives (A = Ca/Sr/Ba, B = Ti/Zr) have been employed to develop such a structure [16,27,29,[37][38][39][40][41][42]. (Bi 0.5 M 0.5 )NO 3 (M = K/Na/Ag, N = Hf/Zr) additives have also been utilized to form various multi-structures with nanodomains [34,36,[43][44][45][46][47].…”