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Textured relaxor-PbTiO3 ceramics have received considerable attention from both academia and industry, due to their crystal-like properties, high composition homogeneity easy-to-process, and relatively low cost compared to their crystal counterparts. In this work, the ⟨ 001 ⟩ -oriented Pb(In1/2Nb1/2)O3-Pb(Sc1/2Nb1/2)O3-PbTiO3 textured ceramics were fabricated by the template grain growth method. To explore the property variation in these textured ceramics under practical applications of piezoelectric devices, their electromechanical properties were characterized and analyzed under uniaxial stress, hydrostatic pressure, and d.c. bias electric field. The results show that the dielectric constants of all textured ceramics increase with an increase in the uniaxial prestress and hydrostatic pressure but decrease with an increase in the d.c. bias electric field. Among all textured ceramics, the textured ceramic with 3 vol. % BT templates exhibits the best stability under external fields. In particular, the electromechanical coupling factors of the textured ceramic change less than 2% with the hydrostatic pressure increase to 100 MPa. This work provides important data on textured relaxor ferroelectric ceramics, which will benefit the design and application of piezoelectric devices based on textured piezoelectric ceramics. [ABSTRACT FROM AUTHOR]

Textured relaxor-PbTiO3 (PT) ceramics possess advantages of crystal-like properties, high composition homogeneity, and low cost, and have, thus, received considerable attention from the piezoelectric community. To promote the applications of textured relaxor-PT ceramics, here we characterize the full electromechanical parameters (elastic, dielectric, and piezoelectric coefficients) and the frequency dependence of the coercive field (EC) for the recently reported textured Pb(In1/2Nb1/2)O3-Pb(Sc1/2Nb1/2)O3-PbTiO3 (PIN-PSN-PT) ceramic. Our results show that the textured PIN-PSN-PT ceramic possesses high piezoelectric coefficients (d31 = −365 pC N−1, d33 = 770 pC N−1, and g33 = 40.4 × 10−3 m2 C−1) and electromechanical coupling factors (k33 = 87% and kp = 82%), far outperforming those of the commercial ceramic PZT-5H (d31 = −274 pC N−1, d33 = 593 pC N−1, g33 = 1.97 × 10−2 m2 C−1, k33 = 75%, and kp = 65%). In addition, the textured PIN-PSN-PT ceramic exhibits lower dielectric constants (ɛ33S = 478) compared with PZT-5H and relaxor-PT crystals, which can greatly promote the sensitivity of receiving transducers. Moreover, the textured PIN-PSN-PT ceramic with a high Tr−t (172 °C) shows better thermal stability compared to commercial relaxor-PT crystals (Tr−t < 130 °C). The results presented here will benefit the development of piezoelectric devices made of textured ceramics. [ABSTRACT FROM AUTHOR]

Modified BaTiO3 ceramics that possess high dielectric permittivity and acceptable temperature stability have been widely utilized as multilayer ceramic capacitors (MLCCs) for high‐frequency bypass and power filtering in automotive applications. However, since the increasing demand for high‐capacity and small‐size, high‐permittivity materials that can serve as dielectric layers in MLCCs are urgently required. In this work, we design and fabricate a special BaTiO3‐0.03Mg‐0.02Y‐0.02CaZrO3 ceramic with a high dielectric permittivity of 3000 and the dielectric variation below ±13% in the temperature range of ‐55–150°C, fulfilling the requirements of X8R capacitors. To achieve these results, we employed grain size engineering and cation doping, using BaTiO3 precursors with a particle size of 240 nm to prepare the BaTiO3‐based ceramics with fine grains, while Mg and Y co‐doping was used for improving the temperature stability due to dielectric dispersion. Utilizing these high‐permittivity BaTiO3‐based materials, we fabricated MLCCs that satisfy the X8R criterion, possessing a high dielectric constant of 2950 and a high breakdown field (410 kV/cm). [ABSTRACT FROM AUTHOR]

The piezoelectric properties of lead zirconate titanate [Pb(Zr,Ti)O3 or PZT] ceramics could be enhanced by fabricating textured ceramics that would align the crystal grains along specific orientations. We present a seed-passivated texturing process to fabricate textured PZT ceramics by using newly developed Ba(Zr,Ti)O3 microplatelet templates. This process not only ensures the template-induced grain growth in titanium-rich PZT layers but also facilitates desired composition through interlayer diffusion of zirconium and titanium. We successfully prepared textured PZT ceramics with outstanding properties, including Curie temperatures of 360°C, piezoelectric coefficients d33 of 760 picocoulombs per newton and g33 of 100 millivolt meters per newton, and electromechanical couplings k33 of 0.85. This study addresses the challenge of fabricating textured rhombohedral PZT ceramics by suppressing the otherwise severe chemical reaction between PZT powder and titanate templates. [ABSTRACT FROM AUTHOR]

In this study, we prepared a series of Nb-doped SrTiO 3 ceramics sintered in both air and N 2 atmospheres. The X-ray diffraction (XRD) analysis indicated that all samples had a pure cubic phase perovskite structure with no secondary phase. The dielectric test showed that the Nb-doped SrTiO 3 ceramics had a high dielectric permittivity (>3 × 104) and low dielectric loss (<0.004) over a broad temperature range from −100 to 300 °C with a breakdown strength over 20 kV/cm. The dielectric performance is attributed to the designated T i T i ′ − V O · · − T i T i ′ deep-lattice-defect states localising weak-hopping electrons to generate high defect-dipole concentrations, as verified by systematic X-ray photoelectron spectroscopy (XPS) experiments. This study offers a route for designing other types of high dielectric permittivity ceramics. • Synthesized a novel Nb-doped SrTiO 3 ceramics with dense and fine-grained microstructure. • Achieved giant permittivity of 3 × 104 and low loss (<0.004) at room temperature. • The designated deep-lattice-defect states localize weak-hopping-electrons to generate high defect-dipoles concentration. [ABSTRACT FROM AUTHOR]

Textured piezoelectric ceramics, such as textured Pb(Mg1/3Nb2/3)O3‐PbTiO3 (PMN‐PT) ceramics, have attracted considerable attention from both academia and industry, as they possess crystal‐like piezoelectric properties, high composition homogeneity, and low manufacturing cost. However, the main difficulty with the textured piezoelectric ceramics is the presence of BaTiO3 (BT) templates, which greatly reduces their piezoelectricity and phase transition temperature. Thus, it is highly recommended to fabricate textured piezoelectric ceramics using as few templates as possible. Here, we successfully fabricated high‐quality <001>‐textured PMN‐28PT ceramics (texturing degree of 99%) by using an extremely small amount of BT templates (1 vol.%) with the help of CuO/B2O3 sintering aids. The textured PMN‐28PT ceramic exhibits 80% piezoelectric coefficient (d33 ∼ 1200 pC/N), 96% electromechanical coefficient (k33 ∼ 88%) and the same temperature stability (Trt ∼ 100, Tc ∼ 150°C) when compared to its single crystal counterpart. In addition, by using an alternating current electric field poling (AC‐poling), the piezoelectric coefficient d33 and dielectric permittivity ε33 of the textured PMN‐28PT ceramics were further enhanced around 5–8%. It is believed that the advantages of high electromechanical properties, low cost, and easy mass production of textured PMN‐28PT ceramic will make it a promising candidate for advanced electromechanical devices. [ABSTRACT FROM AUTHOR]

Cold sintered, Li2MoO4‐based ceramics have recently been touted as candidates for electronic packaging and low temperature co‐fired ceramic (LTCC) technology but MoO3 is an expensive and endangered raw material, not suited for large scale commercialization. Here, we present cold sintered temperature‐stable composites based on LiMgPO4 (LMP) in which the Mo (and Li) concentration has been reduced, thereby significantly decreasing raw material costs. Optimum compositions, 0.5LMP‐0.1CaTiO3‐0.4K2MoO4 (LMP‐CTO‐KMO), achieved 97% density at <300°C and 600 MPa for 60 minutes. Raman spectroscopy, X‐ray diffraction, scanning electron microscopy, and energy dispersive X‐ray mapping confirmed the coexistence of end‐members, LMP, CTO, and KMO, with no interdiffusion and parasitic phases. Composites exhibited temperature coefficient of resonant frequency ~ –6 ppm/°C, relative permittivity ~9.1, and Q × f values ~8500 GHz, properties suitable for LTCC technology and competitive with commercial incumbents. [ABSTRACT FROM AUTHOR]

Dielectric materials with high permittivity and low dielectric loss have a range of promising applications within electronic devices. Here, we report on Zr co-doped (Ga 0.5 Nb 0.5) 0.03 Ti 0.97 O 2 ceramics, fabricated using a solid-state reaction. The colossal permittivity (CP) of (Ga 0.5 Nb 0.5) 0.03 -(Zr x Ti 1-x) 0.97 O 2 ceramics was investigated (x = 0%, 1%, 4%, 6%, 10%, 20%). When the doping value of Zr was 4%, the dielectric loss was reduced to 0.098 and, at room temperature and at a frequency of 1000 Hz, the dielectric permittivity was recorded as 2420. In addition, the material's dielectric permittivity exhibited good stability at temperatures ranging from −50 °C to 200 °C. Using X-ray photoelectron spectroscopy (XPS) and Scanning electron microscopy (SEM), we have observed that Zr doping reduces grain size and increases grain boundary regions. According to our XPS and impedance analysis, Zr doping also reduces the concentration of oxygen vacancies, which are considered to be the main cause of dielectric loss. We believe that the Zr doping is an effective method for reducing the dielectric loss of CP materials. [ABSTRACT FROM AUTHOR]

Abstract The (Nb + In) co-doped rutile TiO 2 ceramics were synthesized by spark plasma sintering (SPS) and traditional solid-state sintering (TS) techniques, respectively. Highly-density co-doped rutile TiO 2 ceramics are prepared with the SPS method by 20 min, whereas it takes nearly 30 h with the TS method. It is observed that SPS ceramics showed smaller and uniform grain size, and better densification than TS counterparts. Both sets of the co-doped TiO 2 ceramics showed single rutile phase according to X-ray diffraction (XRD) results. X-ray photoelectron spectroscopy (XPS) is adopted to detect and compare the element-valence-state of both sets of the co-doped TiO 2 ceramics. The dielectric response, impedance spectroscopy (IS), and the effects of annealing treatment are systematically investigated, which could not only be helpful for optimizing their dielectric properties, but also shed the light on the colossal dielectric mechanism. Highlights • The sintering techniques is the most critical factor for CP in co-doped TiO 2 systems. • The existence of Ti3+ ions is a preliminary requirement for CP. • This paper shed light on the recognition of CP behavior in other metallic oxides. [ABSTRACT FROM AUTHOR]

Perovskite ferroelectrics (PFs) have been the dominant piezoelectric materials for various electromechanical applications, such as ultrasonic transducers, sensors, and actuators, to name a few. In this review article, the development of PF crystals is introduced, focusing on the crystal growth and piezoelectric activity. The critical factors responsible for the high piezoelectric activity of PFs (i.e., phase transition, monoclinic phase, domain size, relaxor component, dopants, and piezoelectric anisotropy) are surveyed and discussed. A general picture of the present understanding on the high piezoelectricity of PFs is described. At the end of this review, potential approaches to further improve the piezoelectricity of PFs are proposed. [ABSTRACT FROM AUTHOR]

Textured perovskite ferroelectric ceramics have attracted considerable attention from both academia and industry. In a recent study, an interesting phenomenon was observed in textured perovskite ferroelectric ceramics, i.e. the planar Poisson's ratios of these ceramics ranged from − 0.05 to 0.1, much lower than those of their non-textured counterparts (0.3–0.4). In this study, we fabricated a < 001 > -textured Pb(In 1/2 Nb 1/2)O 3 –Pb(Mg 1/3 Nb 2/3)O 3 –PbTiO 3 ceramic using 5 vol% BaTiO 3 templates. By studying the orientation dependence of Poisson's ratio, we found that the < 001 > -oriented grain exhibits a large anisotropy of planar Poisson's ratio, where some orientations even show negative Poisson's ratio, and the lowest Poisson's ratio is present as the x-axis is along < 110 > directions. Based on these results, the near-zero Poisson's ratio was attributed to the intrinsic microstructural feature of < 001 > -textured perovskite ceramic, i.e. the out-of-plane orientation of most grains is along the < 001 > crystallographic direction and the in-plane orientations of the grains are randomly distributed. [ABSTRACT FROM AUTHOR]

For lead-based ceramics used in high-power devices, it is essential that they possess both a high mechanical quality factor (Q m) and a large piezoelectric coefficient (d 33). Unfortunately, Q m is inversely proportional to d 33 for piezoelectric ceramics, which the limits their actual application. If suitable acceptor and donor dopants can be added in piezoelectric ceramics, it is rational to achieve high Q m and large d 33 simultaneously. Herein, we tried to achieve both a high mechanical quality factor and large piezoelectric activity in 0.47 pb(Mg 1/2 Nb 2/3)O 3 -0.18PbZrO 3 -0.35PbTiO 3 (PMN-PZT) ceramics via Sm 2 O 3 and MnO 2 co-doing. A range of x Mn-2Sm-PMN-PZT ceramics were fabricated by the traditional sintering method. An optimal performance was attained in 4Mn-2Sm-PMN-PZT ceramics with Q m = 1720, d 33 = 450 pC/N, ε = 2720 and k p = 0.54. The high Q m is related to the presence of defect dipoles as a result of MnO 2 doping and the large piezoelectric activity is due to the doping of Sm 2 O 3. [ABSTRACT FROM AUTHOR]

Bi 2 Mo 2 O 9 -K 2 MoO 4 (BMO-KMO) composite ceramics with >95% theoretical density were densified by cold sintering at 150 °C. XRD, Raman, back-scattered SEM and EDX spectroscopy indicated that the BMO and KMO phases coexisted in all composites without inter-diffusion and secondary phases. Temperature coefficient of resonant frequency with near-zero value ∼ -1 ppm/°C was acheived for BMO-10%KMO with pemittivity ∼ 31 and quality factor ∼ 3,000 GHz. Cold-sintered composite ceramics were directly pressed/integrated onto a printed circuit board (PCB) using the Cu metallisation as a ground plane for the design and fabrication of a circularly polarized microstrip patch antenna suitable for satellite navigation systems which achieved efficiencies 87% at 1561 MHz (BeiDou) and 88% at 1575 MHz (GPS/Galileo). The low cost, low energy integration of temperature stable, cold sintered ceramics directly onto a PCB represents a step change in substrate fabrication technology for RF devices. [ABSTRACT FROM AUTHOR]