Pyroelectric properties of 91.5Na0.5Bi0.5TiO3–8.5K0.5Bi0.5TiO3 lead-free single crystal

The dielectric and pyroelectric performances of 91.5Na[Formula: see text]Bi[Formula: see text]TiO3–8.5K[Formula: see text]Bi[Formula: see text]TiO3 lead-free single crystal were investigated. The depolarization temperature of the crystal is about 153[Formula: see text]C. Among the [Formula: see text]001[Formula: see text], [Formula: see text]110[Formula: see text], and [Formula: see text]111[Formula: see text] crystallographic orientations, the [Formula: see text]111[Formula: see text]-oriented crystal possesses the highest pyroelectric coefficient and the largest figures of merit, and the values of [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text]are 5.63× 10[Formula: see text] C/m2 ⋅ K, 0.06 m2/C, and 21.5 [Formula: see text]Pa[Formula: see text] for the [Formula: see text]111[Formula: see text]-oriented crystal at room temperature. The [Formula: see text]and [Formula: see text]exhibit weak frequency dependence in the range of 100–300 Hz. With the increase of the temperature, the value of [Formula: see text]increases, while the [Formula: see text] value of [Formula: see text] decreases from 18[Formula: see text]C to 103 [Formula: see text]C.

The (1-x)BiFeO3-xBaTiO3-Bi(Zn0.5Ti0.5)O3 high temperature lead-free piezoelectric ceramics with strong piezoelectric properties

The structure, microstructure, piezoelectric properties, ferroelectric properties and Curie temperature of (1- x )BiFeO 3 - x BaTiO 3 -Bi(Zn 0.5 Ti 0.5 )O 3 +MnO 2 +Li 2 CO 3 ceramics were investigated experimentally by improved solid-state reaction approach. The crystalline structures were examined by X-ray diffractometry. When x = 0.3, the rhombohedral and pseudocubic phases coexist in the ceramic structure. It is considered that the morphotropic phase boundary was formed here. At the same time, the piezoelectric performance d 33 , Curie temperature T C , and depolarization temperature are as high as 184 pC/N, 550°C, 530°C at x = 0.3, respectively. It is worth noting that when x = 0.24, the ceramics have a high T C = 580°C and low dielectric loss tan δ = 1.9%. These results show that the BFBT-BZT system ceramics are applicable ceramics with high piezoelectric properties in high temperature fields.

Effect of processing on the structures and properties of bismuth sodium titanate compounds

The processing of sodium (Na) and bismuth (Bi)-based piezoelectric compounds are always a concern due to their volatilization at high temperatures (> 1000 °C) and the hygroscopic nature of the precursors. The effect of drying and impurities in the precursors on 0.94(Bi0.5Na0.5TiO3)–0.06BaTiO3 (BNTBT) ceramics was investigated. A substantial difference in the weight fraction of polar (R3c) and weak-polar (P4bm) phase at room temperature was observed for BNTBT obtained from dried, undried and low purity precursors, evaluated by XRD and Raman. The local crystal structure was evaluated by transmission electron microscope, which showed the presence of both ferroelectric domains and polar nano regions. The electrical measurements corroborated well with the structure results, and showed a variation in the depolarization temperature (Td). The results highlight the importance of the pre-processing steps on the functional compounds obtained from sensitive elements, which has broader implementations for similar systems.