IntroductionAs a core element of the sensor, the piezoelectric constant and dielectric constant of piezoelectric materials determine the sensitivity of the sensor. Piezoelectric materials with a high performance and a high stability are urgently needed. The electrical properties of perovskite ferroelectrics are closely related to the crystal orientation. Growing single crystals is thus an effective way to improve the electrical properties of perovskite ferroelectrics. However, the practical application of single crystals is limited due to their relatively high cost, low trigonal-rhombohedral phase transition temperature, and insufficient composition uniformity in inconsistent melting. To solve the above-mentioned single crystal application problems, the template grain growth (TGG) method for preparing textured ceramics is considered as one of the most promising methods.In this paper, a PSN-PMN-PT ternary solid solution piezoelectric material was prepared, and the [001] oriented growth of ceramics by TGG method was analyzed. In addition, the influence of template content on the phase structure, micromorphology, electrical properties and temperature stability of textured ceramics was also discussed.MethodsOxide raw materials were mixed in stoichiometric ratios and pre-sintered at 750 ℃ for 2 h to form a pure perovskite structure. The [001] oriented BaTiO₃(BT) microcrystals were added as templates into a uniform slurry with 0.29Pb(Sc_1/2Nb_1/2)O₃-0.39Pb(Mg_1/3Nb_2/3)O₃-0.32PbTiO₃ matrix powder, solvent, dispersant, plasticizer, and binder, and then ground in a ball mill. The BT templates with x of 0, 1%, 2%, 3%, and 4% were added into the slurry. Afterwards, the slurry was cast via controlling the height of the scraper and the speed of the substrate. The dried raw embryo tapes were cut, stacked, and kept at 550 ℃ for 2 h to remove organics. Finally, the samples were sintered at 1 270 ℃ for 9 h.The phase structure of the random and textured ceramics was determined by X-ray diffraction. The microstructure of the ceramics was characterized by scanning electron microscopy. To measure the electrical properties, the samples were coated with a silver paste and sintered at 550 ℃ for 40 min to form electrodes and then polarized in silicone oil at 25 kV/cm for 15 min. The piezoelectric coefficient d₃₃ was measured using a model ZJ-6A quasi-static d₃₃ tester. The temperature dependence of the dielectric constant ε_r and dielectric loss tan δ was determined by a model E4980A LCR meter. The polarization electric field (P-E) curve and the strain electric field (S-E) curve were analyzed by a model TF Analyzer 2000E ferroelectric test system. For the determination of temperature stability, the samples were annealed at high temperatures for 30 min and then tested for d₃₃ at room temperature.Results and discussionFrom the XRD analysis, BaTiO₃ as a template can effectively improve the [001] orientation of PSN-PMN-PT ceramics and achieve a high degree of [001] preferred orientation growth. The F₀₀₁ of all the textured ceramics is 97%-99%, among which the F₀₀₁ of 3%(volume fraction) BT-PSN-PMN-PT textured ceramics is 98.6%. From the scanning of the textured ceramics, the template exists stably and is well arranged in the matrix ceramics, which is a fundamental reason why the textured ceramics have a high texture degree. The piezoelectric constant of 3% BT textured PSN-PMN-PT ceramics (816 pC/N) is greater than that of random PSN-PMN-PT ceramics (402 pC/N). Based on the analysis of the dielectric loss at room temperature, the dielectric loss of the textured ceramics reduces to 0.008, which is lower than that of randomly oriented ceramics and most soft piezoelectric ceramics (i.e., >0.020). The high d₃₃, S_positive, S_total, and d₃₃^* of textured ceramics are all related to the "4R" domain engineering state. Only a transition from tetragonal to cubic phase occurs in the textured ceramics, indicating that the textured ceramics have a good temperature stability. The results of annealed piezoelectric constant test show that the d₃₃ change of 3% BT-PSN-PMN-PT ceramics at 30-160 ℃ is only 12%, further proving a good temperature stability of textured ceramics.ConclusionsThe [001] oriented texture PSN-PMN-PT ceramic with a texture degree F₀₀₁ of 98.6% was synthesized by the TGG method, obtaining the high piezoelectric properties (i.e., d₃₃ = 816 pC/N, d₃₃^* = 1 080 pm/V) and high Curie temperature (i.e., T_C = 185 ℃). This enhanced piezoelectric response was attributed to the grain orientation characteristics. Furthermore, the 3% BT-PSN-PMN-PT texture ceramic exhibited an improved temperature stability, compared with previously reported lead-based ceramics with the similar piezoelectric constants. These results showed that the textured PSN-PMN-PT ceramics had high piezoelectric properties and good temperature stability, having the application prospects of textured ceramics in electromechanical devices.