Crystallographic texture and phase structure induced excellent piezoelectric performance in KNN-based ceramics

It is difficult to maintain strong piezoelectric properties over a wide temperature range in (K,Na)NbO₃ (KNN)-based ceramics owing to the polymorphic phase boundary (PPB). Here, we propose advantageously utilizing the synergistic effect of crystal orientation and phase structure to address this issue. The 〈0 0 1〉_pc textured (1 − x)(K_0.48Na_0.52)(Nb_0.96Sb_0.04)O₃–x(Bi_0.5Ag_0.5)ZrO₃ (KNNS–xBAZ) ceramics with different phase structures were synthesized via the templated grain growth method. A high piezoelectric coefficient (d₃₃) of 505 ± 25 pC/N, an electric field-induced strain of 0.21%, and a superior temperature stability (d₃₃ exhibited a high retention of ≥78% at the temperature up to 200°C; strain maintained within 5.7% change over a temperature range of 30–150°C) were simultaneously achieved in textured KNNS–0.03BAZ ceramics. The flattened Gibbs free energy induced by the R–O–T multiphase coexistence, the strong anisotropy of crystals, and the abundant nanodomains contributed to the enhanced piezoelectric properties. The contribution of the strong anisotropy of crystals in 〈0 0 1〉_pc textured ceramics compensates for the deterioration of the piezoelectric properties caused by the phase structure deviation from the PPB with increasing temperature, which benefits the superior temperature stability of the textured KNNS–0.03BAZ ceramics. The previous merits prove that utilizing the synergistic effect of crystal orientation and phase structure is an effective strategy to boost the piezoelectricity and their temperature stability of KNN-based ceramics.     

Sintering temperature effect on microstructure,electrical properties and temperature stability of MnO-modified KNN-based ceramics

Lead-free 0.955K_0.5Na_0.5NbO₃-0.045Bi_0.5Na_0.5ZrO₃?+?0.6%MnO (KNN-0.045BNZ?+?Mn0.6) ceramics have been prepared by a conventional solid-state sintering method in air. All the samples sintered at different temperatures possess a coexisting phase boundary (CPB) between rhombohedral (R) phase and tetragonal (T) phase. The increase of sintering temperature (T_s) increases the phase fraction of T phase in CPB region. Mn²⁺, Mn³⁺ and Mn⁴⁺ ions coexist in all the KNN-0.045BNZ?+?Mn0.6 ceramics sintered at 1110?°C to 1190?°C. High sintering temperature can induce a transformation from ${\mathrm{M}\mathrm{n}}_{\mathrm{N}\mathrm{b}}^{\text{'}\text{'}}$ defects to ${\mathrm{M}\mathrm{n}}_{\mathrm{N}\mathrm{b}}^{\text{'}}$ defects. The samples with fine grain show stable octahedral structure. The KNN-0.045BNZ?+?Mn0.6 ceramics with fine grain possess excellent temperature stability of $d_{33}^{*}$ due to the wide phase transition region. The increase of sintering temperature induces the (R-T) phase transition temperature to move to room temperature.     

(Bi0.5Na0.5)TiO3 ferroelectric ceramics: Achieving high depolarization temperature and improved piezoelectric properties

(Bi_1/2Na_1/2)TiO₃-based materials have received much attention due to large electro-strain and high piezoelectric constant (d₃₃), but the tough issue is that the existence of inherent depolarization temperature (T_d) limits the temperature stability and application temperature range. Previously, reports about the formation of BNT/oxide (i.e., ZnO, Al₂O₃) composites thought that T_d can be deferred to a higher temperature and then thermal depolarization improves. However, the deferred T_d of BNT/oxide composites is limited, accompanied by a low d₃₃. Here, we design the {[Bi_0.5(Na_0.8K_0.2)_0.5]_1-xPb_x}TiO₃ ceramics, leading to a big shift of T_d from 77 ℃ to 390 ℃. Large d₃₃ (140 pC/N) and high T_d (∼263 ℃) can be simultaneously achieved for the sample with Pb=0.05, and T_d could be further deferred higher (390 ℃) for Pb=0.20. The off-centre displacement of Pb induced by Pb-O hybridization in the PbO₁₂ polyhedron and ferroelectric order stabilized by the addition of Pb can provide the driving force to strengthen the ferroelectric order, and then promote the thermal stability.     

Enhanced piezoelectric properties and low electrical conductivity of Ce-doped Bi7Ti4.5W0.5O21 intergrowth piezoelectric ceramics

New types of Ce-doped Ce_xBi_7-xTi_4.5W_0.5O₂₁ (BTW-BIT-xCe) Aurivillius intergrowth ceramics with high Curie temperatures were synthesized to improve the piezoelectric performances as well as the conduction behaviour, and these ceramics exhibit great potential for high-temperature lead-free piezoelectric applications. The crystal structure, electrical properties and conduction behaviour of BTW-BIT-xCe samples were analysed thoroughly. The XRD patterns combined with Rietveld refinements of the patterns showed that the crystal structure transformed from orthorhombic structure towards pseudo-tetragonal structure with increasing CeO₂ dopant, indicating that a higher symmetry was obtained. The dielectric properties of Ce-doped samples were improved, accompanied by a significant drop in the dielectric loss and a slight decreased Curie temperature (705 °C–683 °C). An enhanced piezoelectric constant d₃₃ of 25.3 pC/N was obtained in BTW-BIT-0.12Ce, which may be attributed to a common decrease in the electrical conductivity and coercive field. Besides, a low electrical conductivity of 2 × 10^-6 S/cm at 540 °C was achieved in the same component owing to a decreased concentration of the oxygen vacancies, which was verified by analyses on XPS spectra. The above results indicate that Ce-doped BTW-BIT samples have great development potential for high temperature piezoelectric applications.     

Improving fatigue properties,temperature stability and piezoelectric properties of KNN-based ceramics via sintering in reducing atmosphere

It has great research value and application potential to develop K_0.5Na_0.5NbO₃(KNN)-based ceramics with low sintering temperature (T_sinter) and excellent piezoelectric properties. However, it is difficult to achieve the two goals of reducing T_sinter and improving piezoelectric properties together. We provide a new process (NP) to solve this problem. Compared with traditional process (TP), T_sinter of 0.945K_0.48Na_0.52Nb_0.96Ta_0.04O₃-0.055BaZrO₃+6 mol%MnO (KNNT-0.055BZ+6 Mn) sintered by NP is reduced greatly and its piezoelectric strains are improved obviously. Reducing atmosphere is an important part for NP. The reducing atmosphere condition can improve piezoelectric strain by increasing extrinsic contribution of reversible non-180° domains and intrinsic contribution of reversible R(rhombohedral)-M(monoclinic) phase transition. NP ceramics sintered at low T_sinter = 1045 °C (NP1045) possess excellent d*₃₃ (575 pm/V) at the electric field (20 kV/cm). The NP1045 ceramics fatigued after 10⁶ unipolar cycles show excellent fatigue resistance. Its d*₃₃ (575 pm/V) varies less than 10 % from room temperature to 185 °C.     

SnO2 modified PNN-PZT ceramics with ultra-high piezoelectric and dielectric properties

In this work, a two-step solid-state reaction method is used to prepare the 0.55 Pb(Ni_1/3Nb_2/3)O₃-0.135PbZrO₃-0.315PbTiO₃/xSnO₂ (PNN-PZT/xSnO₂) ceramics. The influences of SnO₂ on the crystalline structure, electromechanical properties, and temperature stability of PNN-PZT ceramics were studied in detail. The results demonstrate that the Sn⁴⁺ ions are successfully introduced into the PNN-PZT crystalline lattice and substitute B-site Ni²⁺ and Zr⁴⁺. The x = 0.0025 ceramic with the coexistence of rhombohedral, tetragonal, and pseudocubic phases exhibits the optimized comprehensive properties: the quasi-static piezoelectric constant d₃₃, large-signal d₃₃*, electromechanical coupling coefficients k_p and k_t, free dielectric constant ε_r, and mechanical quality factor Q_m are 1123 pC/N, 1250 p.m./V, 0.63, 0.54, 9529, and 57, respectively. Meanwhile, the Curie temperature for this composition is 103 °C, almost maintaining the same level as the PNN-PZT matrix. After annealing at 75 °C, the retained d₃₃ of x = 0.0025 ceramic is as high as 975 pC/N, superior to the PNN-PZT matrix (retained d₃₃ ≈ 873 pC/N). Our results provide a promising piezoelectric material for board bandwidth, high sensitivity, and miniaturized medical ultrasonic transducers applications.     

Room temperature constructing rhombohedral-tetragonal phase boundary in novel (Bi,Na)(Zr,Ti)O3 modified (K,Na)(Nb,Sb)O3 ceramics: Phase structure,defect and piezoelectric performance

Lead-free (1-x)(K_0.5Na_0.5)(Nb_0.96Sb_0.04)O₃-x(Bi_0.5Na_0.5)(Zr_0.8Ti_0.2)O₃ ceramics (abbreviated as (1-x)KNNS-xBNZT, x = 0, 0.01, 0.02, 0.03, 0.035 and 0.04) were synthesized by the solid-state method, and the dependence of phase evolution, microstructure, oxygen vacancy defect and electrical properties on compositions were carefully investigated. All ceramics had a pure perovskite structure and a dense microstructure. The phase transition temperatures (T_R-O and T_O-T) of the ceramics were adjusted by adding BNZT, and the rhombohedral-tetragonal (R-T) phase coexistence boundary was successfully constructed at room temperature when x = 0.03, the excellent piezoelectric performance (d₃₃ ～ 323 pC/N, k_p ～ 0.372) and high Curie temperature (T_C ～ 276 °C) have been achieved at this time. The grain size of the ceramics showed a strong difference on x content, and the maximum relative density value of 95.42% was obtained. The domain structure characterized by PFM confirmed that the ceramics possess small-sized nano-domains and complex domains at x = 0.03, which are the origin of enhanced piezoelectric properties. Moreover, the oxygen vacancy defect that can pin the domain walls was increased with the addition of (Bi_0.5Na_0.5)(Zr_0.8Ti_0.2)O₃. As a result, the doping with BNZT can significantly affect the phase structure and electrical properties of the ceramics, indicating that the (1-x)KNNS-xBNZT ceramics system with a R-T phase boundary is a promising lead-free piezoelectric material.     

Poling and depoling influence on the micro-stress states and phase coexistence in KNN-based piezoelectric ceramics

In this work a microstructural qualitative and quantitative study of spatial stress distributions in modified KNN ceramics (K_0.44Na_0.52Li_0.04)_1-xCo_x/2 (Nb_0.86Ta_0.10Sb_0.04)O₃, according to the polarization state is shown. X-ray diffraction reflects a perovskite crystalline structure with coexistence of Tetragonal and Orthorhombic phases (T/O). Confocal Raman microscopy shows that these crystalline phases are distributed in randomly micrometric regions through the ceramic volume. Tetragonal regions show higher piezoelectric coefficient and exhibit a higher micro-stress that hardens the ferroelectric response. By the contrary, the occurrence of orthorhombic micro-regions softened the ferroelectric behavior and reduced their piezoelectric coefficients. The ferroelectric response of ceramics is studied, where poling is also shown as a factor that affects the spatial micro-stress distributions. Finally, a model that relates the results obtained by Raman characterization with the ferroelectric properties and stress states is proposed.     

Design on improving piezoelectric strain and temperature stability of KNN-based ceramics

Lead-free 0.99(0.96K_0.46Na_0.54Nb_1-xTa_xO₃-0.04Bi_0.5(Na_0.82K_0.18)_0.5ZrO₃)-0.01CaZrO₃ (0.99(0.96KNNTax-0.04BNZ)-0.01CZ) ceramics were prepared by a solid-state sintering method. Ta₂O₅ doped in the 0.99(0.96KNNTax-0.04BNZ)-0.01CZ ceramics results in a phase structure transition from the orthorhombic (O)/tetragonal (T) phase to the rhombohedral (R)/T phase. The Ta₂O₅ dopant induces a decrease in the average grain size from ~1.70 to ~0.69 μm. At x = 0.02 and 0.04, the ceramics have a high reverse piezoelectric coefficient (~500 pm/V under 25 kV/cm). The ceramics with x = 0.04 show an optimal level of unipolar strain, reaching 0.17% under 35 kV/cm at room temperature, and their field-induced strain varies <10% in the temperature range from 25 to 135°C. The presence of the O phase in the polymorphic phase boundary (PPB) improves the temperature stability the reverse piezoelectric coefficient (). Obtaining KNN-based ceramics with good piezoelectric properties and weak temperature sensitivity by designing a R/O/T phase boundary and controlling the average grain size to the submicrometer level is highly feasible.     

Effect of MnO2 addition on the structure and electric properties of (Ba0.94Ca0.06)(Ti0.9Sn0.1)O3 ceramics

The (Ba_0.94Ca_0.06)(Ti_0.9Sn_0.1)O₃ (BCTS) ceramics with pure perovskite structure were prepared by conventional solid-state reaction route with the addition of 0–0.8?mol% MnO₂. The crystal structure, microstructure, and electric properties were investigated systematically. X-ray diffraction patterns showed that the addition of MnO₂ changed the ratio of the coexistence of orthorhombic and tetragonal phases, which had apparent influences on the piezoelectric properties of ceramics. When the addition amount is 0.2?mol%, the average grain size increases from ~41.88–52.24?µm, and, however, the average grain size decreases with further addition > 0.2?mol%. A good combination of properties and performance could be achieved with the addition of 0.4?mol% MnO₂. The mechanical quality factor Q_m, dielectric loss tanδ, piezoelectric constant d₃₃, and planar electromechanical coefficient k_p measured are 216, 0.011, 578?pC/N, and 0.39, respectively. Therefore, results of this study suggest that the BCTS-Mn ceramics synthesized could exhibit a great potential for piezoelectric component applications.     

Simultaneously enhanced piezoelectric response and piezoelectric voltage coefficient in textured KNN‐based ceramics

<001> ‐textured 0.99(K_0.49Na_0.49Li_0.02)(Nb_0.97‐xSb_0.03Ta_x)O₃‐0.01CaZrO₃ [abbreviated as 0.99KNLN_0.97‐xST_x‐0.01CZ, x = 0.03, 0.07, 0.10, 0.15, 0.20, 0.25] ceramics were prepared by templated grain growth (TGG) method and a two‐step sintering process. Giant longitudinal piezoelectric coefficient d₃₃ (391 pC/N) and piezoelectric strain coefficient d₃₃* (630 pm/V under an AC E‐field of 20 kV/cm) can be obtained in the textured ceramics with x = 0.25. All textured ceramics display superior k_p (>54%) and g₃₃ (>23 × 10^?3 Vm/N) which are in an order of magnitude with PZT ceramics. The maximum value of k_p (~63.3%) obtained in textured ceramics with x = 0.15 is higher than that of famous textured LF4 ceramics. Excellent comprehensive properties suggest that <001> ‐textured 0.99KNLN_0.97‐xST_x‐0.01CZ ceramics are promising candidates in the field of lead‐free piezoelectric materials.     

Achieving large piezoelectric response and ultrahigh electrostriction in [001] textured BiScO3-PbTiO3 high-temperature piezoelectric ceramics

[001] textured 0.40BiScO₃-0.60PbTiO₃-0.125 mol%Nb⁵⁺ (BS-60PT-0.125Nb) high-temperature piezoelectric ceramics were synthesized using templated grain growth process. A high texture degree F₀₀₁ of 99% was obtained using 2 vol% BaTiO₃ (BT) templates. The piezoelectric charge constant d₃₃ and the unipolar strain under 40 kV cm⁻¹ at room temperature for the textured ceramics are 646 pC N⁻¹ and 0.36%, respectively, which is over two times as those for untextured ceramics (∼243 pC N⁻¹ and 0.17%). The electrostriction Q₃₃ value of the textured sample remarkably increased from 0.034 m⁴ C⁻² to 0.068 m⁴ C⁻² under 30 kV cm⁻¹, showing a twice higher than untextured. Compared with random ceramics, the improvement piezoelectric response of the textured ceramics is primarily attributed to the increase of the dielectric constant ε_r and electrostriction coefficient Q₃₃ along [001] orientation, which is originating from the anisotropy of piezoelectricity. The BS-60PT-0.125Nb textured ceramics have large piezoelectric response and ultrahigh electrostriction with high temperature stability (high depolarization temperature T_d of ∼360°C and high Curie temperature T_c of 421°C), showing great potential for the piezoelectric applications at high temperatures.     

Microstructure and piezoelectric properties of thermal sprayed Bi0.5(Na0.70K0.20Li0.10)0.5TiO3 ceramic coatings

The microstructure of Bi_0.5(Na_0.70K_0.20Li_0.10)_0.5TiO₃ (BNKLT) coatings fabricated by thermal spray method was closely examined by TEM, revealing the coexistence of rhombohedral and tetragonal perovskite main phases, and very minor secondary phases, while all amorphous phase was crystallized after heat treatment. Obtaining coexisting rhombohedral and tetragonal perovskite phases after the thermal spray process involving the melting-recrystallization and heat treatment process resulted in piezoelectric ceramic coating with excellent electrical and electromechanical properties. The effective piezoelectric coefficient d₃₃ of the heat-treated BNKLT coating reached 86?pm/V with substrate clamping, measured over macroscale by laser scanning vibrometer.     

Meticulously tailoring phase boundary in KNN-based ceramics to enhance piezoelectricity and temperature stability

Although KNN-based ceramics with high electrical properties are obtained through a variety of strategies, the temperature sensitivity is still one of the key technical bottlenecks hindering practical applications. Here, we use a new strategy, meticulously tailoring phase boundary, to refine the ferroelectric boundary of KNN-based ceramics, leading to high piezoelectricity companied with improving temperature stability. The highest d₃₃ value in this system reaches 501 pC/N with a T_C ∼ 240°C, whereas a large strain of ∼0.134% can be kept with 10% lower deterioration until 100°C. The origin of high piezoelectricity is mainly attributed to the well-preserved multiphase coexistence and the appearance of nanodomains, which greatly facilitate the polarization rotation. Instead of the changed intrinsic thermal insensitivity, the precision phase boundary engineering plays an important role in strengthening the temperature stability of electric-induced strain. This work provides a simple and effective method to obtain both high electrical properties and excellent thermal stability in KNN-based ceramics, which is expected to promote the practical applications in the future.     

(Bi0.5Na0.5)ZrO3 modified KNN-based ceramics: Enhanced electrical properties and temperature insensitivity

To further improve the properties of KNN-based lead-free ceramics, a new ceramic system, (0.98-x)K_0.525Na_0.475Nb_0.965Sb_0.035O₃-0.02 BaZr_0.5Hf_0.5O₃-x(Bi_0.5Na_0.5)ZrO₃(KNNS-BZH-xBNZ) was designed, the relevant properties such as piezoelectricity, strain, and temperature stability were analysed in detail. It was found that the R-T phase boundary can be successfully constructed when x=0.030, and this two-phase coexistence shows relatively good comprehensive properties (d₃₃~410 pC/N, T_C~255 °C, S_uni~0.132%, and d₃₃*~441 pm/V). Meanwhile, its strain property also shows good temperature stability from room temperature to 180 °C (S_uni100°C/S_uniRT~97.5% and S_uni180°C/S_uniRT~83.9%), which is comparatively superior to many KNN-based ceramics and some lead-based ceramics. Therefore, KNNS-BZH-xBNZ ceramics may broaden the practical application of lead-free ceramics.     

Coexistence of excellent piezoelectric performance and thermal stability in KNN-based lead-free piezoelectric ceramics

With close attention being paid to environmental issues and more legislation coming into force to limit the application of Pb-based materials, accelerating research on lead-free piezoelectric ceramics has become increasingly requisite and urgent. Herein, we have devised and synthesized (1-x)(K_0.5Na_0.5)_0.98Ag_0.02(Nb_0.96Sb_0.04)O₃-x(Bi_0.5Na_0.5)ZrO₃ [abbreviated as (1-x)KNANS-xBNZ, x = 0.01, 0.02, 0.03, 0.035, 0.04, 0.045, 0.05, 0.06] Pb-free ceramics. Phase transition, microstructure, electrical properties, and temperature stability of the ceramics have been comprehensively investigated. The findings illustrate that optimizing BNZ content can give rise to a rhombohedral-tetragonal (R-T) phase boundary when x = 0.04, 0.045, 0.05. The specimens with x = 0.04 show improved piezoelectric properties (d₃₃ ~ 440 pC/N, k_p ~ 53%, T_C ~ 250 °C, d₃₃* ~ 553 pm/V) and good temperature stability. The overall performance is excellent and indicates that (1-x)KNANS-xBNZ ceramics have great potential for replacing their lead-based counterparts.     

Enhanced piezoelectric properties and electrical resistivity in W/Cr co-doped CaBi2Nb2O9 high-temperature piezoelectric ceramics

W/Cr co-doped Aurivillius-type CaBi₂Nb_2-x(W_2/3Cr_1/3)_xO₉ (CBN) (x?=?0.025, 0.050, 0.075, 0.100, and 0.150) piezoelectric ceramics were prepared by the conventional solid-state reaction method. The crystal structure, microstructure, dielectric properties, piezoelectric properties, and electrical conductivity of these ceramics were systematically investigated. After optimum W/Cr modification, the CBN ceramics showed both high d₃₃ and T_C. The ceramic with x?=?0.1 showed a remarkably high d₃₃ value of ~15 pC/N along with a high T_C of ~931?°C. Moreover, the ceramic also showed excellent thermal stability evident from the increase in its planar electromechanical coupling factor k_p from 8.14% at room temperature to 11.04% at 600?°C. After annealing at 900?°C for 2?h, the ceramic showed a d₃₃ value of 14?pC/N. Furthermore, at 600?°C, the ceramic also showed a relatively high resistivity of 4.9?×?10⁵ Ω?cm and a low tanδ of 9%. The results demonstrated the potential of the W/Cr co-doped CBN ceramics for high-temperature applications. We also elucidated the mechanism for the enhanced electrical properties of the ceramics.     

Enhanced dielectric and piezoelectric properties in Na0.5Bi4.5Ti4O15 ceramics with Pr-doping

The bismuth layer-structured Na_0.5Bi_4.5-xPr_xTi₄O₁₅ (x?=?0, 0.1, 0.2, 0.3, 0.4, and 0.5) (NBT-xPr³⁺) ceramics were fabricated using the traditional solid reaction process. The effect of different Pr³⁺ contents on dielectric, ferroelectric and piezoelectric properties of Na_0.5Bi_4.5Ti₄O₁₅ ceramics were investigated. The grain size of Pr³⁺-doping ceramics was found to be smaller than that of pure one, the maximum dielectric constant and Curie temperature T_c gradually decreased with increasing Pr³⁺ contents, and the dielectric loss decreased at high temperature by Pr³⁺-doping. Moreover, the activation energy (E_a), resistivity (Z’), remanent polarization (2P_r) and piezoelectric constant (d₃₃) increased by Pr³⁺-doping. The NBT-xPr³⁺ ceramics with x?=?0.3 achieved the optimal properties with the maximum dielectric constant of 1109.18, minimum loss of 0.00822 (250?kHz), E_a of 1.122?eV, Z’ of 7.9?kΩ?cm (725 ºC), d₃₃ of 18 pC/N, 2P_r of 12.04 μC/cm². The enhancement was due to the addition of Pr³⁺ which suppressed the decreasing of resistivity at high temperature and made it possible for NBT-xPr³⁺ ceramics to be poled in perpendicular direction, implying that it is a great improvement for Na_0.5Bi_4.5Ti₄O₁₅ ceramics in electrical properties.     

Composition and poling condition-induced electrical behavior of (Ba0.85Ca0.15)(Ti1−xZrx)O3 lead-free piezoelectric ceramics

Lead-free (Ba_0.85Ca_0.15)(Ti_1−xZr_x)O₃ (BCTZ) piezoelectric ceramics were fabricated by normal sintering in air atmosphere. BCTZ ceramics with x = 0.10 possess a coexistence of tetragonal and rhombohedral phases at ∼40 °C. The Curie temperature of BCTZ ceramics decreases with increasing the Zr content. Piezoelectric properties of BCTZ ceramics are dependent on the poling conditions (i.e., the poling temperature and the poling electric field), and the underlying physical mechanism is illuminated by the phase angle. The BCTZ (x = 0.10) ceramic, which locates at the existence of two phases and is poled at E ∼ 4.0 kV/mm and T_p ∼ 40 °C, exhibits an optimum electrical behavior at a room temperature of ∼20 °C: d₃₃ ∼ 423 pC/N, k_p ∼ 51.2%, 2P_r ∼ 18.86 μC/cm², 2E_c ∼ 0.47 kV/mm, ?_r ∼ 2892, and tan δ ∼ 1.53%.     

Enhancement of piezoelectric and ferroelectric properties of BaTiO3 ceramics by aluminum doping

Ferroelectric and piezoelectric properties of BaTiO₃ and Al-doped BaTiO₃ ceramics were investigated. The ferroelectric study demonstrated that, by doping Al³⁺ ions in the A-site of BaTiO₃, the polarization–electric field loop exhibited enhanced remnant polarization (from 12 to 17.5  μC/cm²), saturation and switching. In addition, the piezoelectric constant (d₃₃) increased with Al-doping for both static and dynamic strain values (from 75 to 135 and from 29.2 to 57.9 pC/N, respectively, at a maximum applied electric field of 16 kV/cm). Furthermore, the dielectric constant values increased and both the dielectric loss factor and leakage current decreased, even though the transition temperature shifted to lower temperature (from 121 to 113 °C) for the Al-doped sample. Therefore, the Al-doped BaTiO₃ has adjustable piezoelectric and ferroelectric properties.