Piezoelectric materials with good stabilities and long-term durability under high temperature conditions are urgently needed for using in harsh industrial environments such as petroleum exploration and aerospace industries [, , ]. In geological mining, the working temperature of piezoelectric actuators can even reach up to 500°C [4,5]. PbNb2O6 and PbTiO3 are commonly used single compositions with TC of approximately 570°C and 490°C for these applications, and their good thermal stability makes them well-established candidates for high temperature applications [6,7]. However, the piezoelectric constant below 100pC/N and the preparation difficulty resulting from their negative thermal expansion phenomenon greatly limit the commercial application of PbNb2O6 and PbTiO3 ceramics .
Piezoelectric ceramics in the form of solid solutions, such as lead zirconate titanate (PZT), possess excellent piezoelectric properties with d33 of 374pC/N (PZT-5A) at the morphotropic phase boundary (MPB) . However, the working temperature TW range for piezoelectric devices of PZT is below 150°C because of the low Curie temperature, which is not satisfying the high temperature applications. Most recently, Bi-based solid solutions Bi(Me)O3–PbTiO3 (Me=Sc, In, Fe, Y, Yb, etc.) with ABO3 structure have attracted widespread attention due to their ability to achieve outstanding piezoelectric properties (comparable to PZT) or high Curie temperature of up to 600°C by adjusting the type and content of Me elements . Among them, BiScO3-PbTiO3 (BS-PT) possesses both large d33 ∼ 460pC/N and high TC∼450°C at MPB, and the TW of which is above 200°C . (Bi,La)(Ga,Fe)O3-(Pb,Ba)TiO3 (BLGF-PBT) solid solutions have high TC of ∼340°C, and the d33 at MPB achieves about 186pC/N . It is known that Bi(Me)O3–PbTiO3 solid solutions have mixed rhombohedral and tetragonal phases in the vicinity of MPB, exhibiting the large dielectric and piezoelectric constants, but the thermal stability of εr and d33 are poor for these mixed phase ceramics. For example, the variation of εr and d33 of BS-PT-CT ceramics with the coexistence of tetragonal and rhombohedral phases are about Δεr/ΔT ∼72 /℃ and Δd33/ΔT ∼71% /℃ in temperature range of 200–400°C .
Studies have shown that introducing the third end member into BF-PT-based solid solutions to form rhombohedral or tetragonal phased ternary ceramics could improve the dielectric and piezoelectric thermal stability of ceramics. For instance, the rhombohedral BiFeO3-0.29PbTiO3-0.05BaZrO3 ceramics and tetragonal BiFeO3-0.37PbTiO3-0.13Ba(Zr,Ti)O3 ceramics display lower variations of d33 (Δd33/ΔT) over a temperature range of 200°C–400°C, with only 1.9% /℃ and 7% /℃, respectively [13,14]. In addition, the variation of the εr for tetragonal BiFeO3-0.33PbTiO3-0.15BaTiO3 ceramics (Δεr/ΔT=2.8 /℃) at 200–400°C is less than that of the mixed phase BiFeO3-0.48PbTiO3-0.2BaZrO3 ceramics (Δεr/ΔT=9.0 /℃) [15,16]. These findings suggest that the thermal stability of single-phase ceramics is superior to that of mixed phase ceramics, likely due to their stable domain configuration and high polarization switching energy .
The BF-0.275PT-0.175BZT ceramics exhibit large piezoelectric constant d33 ∼ 220pC/N and Curie temperature TC ∼434°C, while the problem is that Ba2+ and Zr4+ ions weaken the bonding force of Bi/Pb–O and Fe/Ti–O, resulting in low Curie temperature of the ceramics [18,19]. The reduction of BZT content in BF-PT-BZT single-phase ceramics may concurrently improve the TC and thermal stability. In this paper, tetragonal BiFeO3-xPbTiO3-0.1Ba(Zr0.5Ti0.5)O3 ceramics with different PT contents were designed and prepared by the traditional solid-state reaction method to improve the d33, TC and thermal stability. The effects of PT content on the structure, dielectric, ferroelectric, and high-temperature piezoelectric properties were investigated systematically.
The ternary ceramics of (0.9-x)BiFeO3-xPbTiO3-0.1Ba(Zr0.5Ti0.5)O3 (BF-xPT-0.1BZT, x=0.29, 0.30, 0.31 and 0.32) were fabricated by the solid-state reaction method. Bi2O3 (99%), Fe2O3 (99%), PbO (99%), TiO2 (99%), BaCO3 (99%) and ZrO2 (99%) were weighed and batched based on the stoichiometric ratio, and then ball milled in polyethylene jar with zirconia balls and ethanol for 24h. The mixtures were dried and then calcined in crucibles at 750°C for 4h. The calcined powders were ball milled
Results and discussion
Fig. 1 displays the room temperature XRD patterns of BF-xPT-0.1BZT ternary ceramics. It is observed that the BF-xPT-0.1BZT ceramics show pure perovskite structure with dominant tetragonal phase without detectable second phases, indicating that BiFeO3, PbTiO3 and Ba(Zr0.5Ti0.5)O3 form the homogeneous solid solutions with various x values. The increasing concentration of PbTiO3 induces an increase in the distance between (001)T and (100)T diffraction peaks and the largest peak separation observed
In summary, BF-xPT-0.1BZT ternary ceramics with high Curie temperature and excellent piezoelectric constant were prepared by the traditional solid-state reaction method. The content of PT has a great influence on the microstructure and electrical properties of BF-xPT-0.1BZT ceramics. The increase of PT content can effectively increase the grain size and tetragonality of BF-xPT-0.1BZT, and c/a is tailored to 1.041at x=0.31. BF-0.31PT-0.1BZT possesses the largest piezoelectric constant d33 of
Declaration of competing interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
This work was supported by the Open Fund of National Key Laboratory of Science and Technology on Underwater Acoustic Antagonizing (Grant No. JCKY2020207CH02), Original exploration project of Shanghai Natural Science Foundation (Grant No. 22ZR1481100), the Young Scientists Fund and National Natural Science Foundation of China (Grant No. 12204300 and 51872180).
Electrical, luminescent properties and electronic structure of (Ho, Nb) co-doped BNT-based multifunctional ceramics
Ceramics International, Volume 49, Issue 12, 2023, pp. 20799-20807
The effects of (Ho, Nb) co-doping on the electrical, luminescent properties and electronic structure of Bi0.5(Na0.82K0.18)0.5Ti1-x(Ho0.5Nb0.5)xO3 (x=0, 0.010, 0.015, 0.020, 0.025, and 0.030, abbreviated as BNKT-xHN) ceramics were investigated. XRD analysis showed that Ho3+ and Nb5+ ions completely entered the crystal structure of BNT-based ceramics, forming a stable perovskite structure. SEM confirmed the polycrystalline nature and relatively uniform grain structure of the samples. The doping of (Ho, Nb) destroyed the long-range ferroelectricity of BNT-based ceramics, resulting in the transition from ferroelectric phase to relaxor ferroelectric phase. The maximum unipolar strain of 0.32% was obtained by introducing (Ho, Nb) with a concentration of x=0.020. Under excitation at 453nm, a strong green emission peak appears at 550nm, corresponding to the energy level transition of 5S2→5I8, while the weak red emission centered at 658nm is due to the energy level transition from 5F5→5I8. As the amount of doping increases, the luminous intensity first increases and then decreases. The first-principle method based on density functional theory was used to calculate the energy band structure and density of the system states. The calculated results show that the band gap width (Eg) decreases with the increase of doping amount, and the electron cloud density distribution of the energy level orbit is very stable. Reducing the band gap makes it easier for electrons to absorb photon energy, which may explain the micro-mechanism of changing luminous intensity.
Simultaneously achieving high transparency and applicable piezoelectricity in Sm-modified KNN-based lead-free ceramics
Journal of Alloys and Compounds, Volume 955, 2023, Article 170209
Transparent piezoelectric ceramics have drawn extensive concerns in recent years because of their electro-optical applications. However, it's challenging to achieve both high piezoelectricity and transparency simultaneously because of their intrinsic trade-off, especially for lead-free ceramics. In this work, the rare-earth element Sm is introduced into (K,Na)NbO3-based lead-free ceramics for improving transparency while keeping relatively high piezoelectricity. Ceramics with nominal compositions of [(Na0.57K0.43)0.94Li0.06][(Nb0.94Sb0.06-xSmx)0.95Ta0.05]O3 (x=0 ∼ 0.005) are fabricated via the conventional solid-state reaction method. Even with pressureless sintering, the ceramic with Sm substitution content x=0.004 possesses high transmittance of T=63% in the visible light region (without anti-reflection coatings) and good piezoelectricity (d33 = 158 pC/N). The high transparency can be attributed to the presence of a pseudocubic phase and the significant elimination of domain walls by the Sm modification, while a coexistent orthorhombic-tetragonal phase structure at room temperature is responsible for its superior piezoelectric performance which outperforms other reported KNN-based transparent ceramics. Our results demonstrate that the as-fabricated ceramics are promising lead-free ferroelectric materials for transparent electronic device applications and this work provides insights for the further development of transparent piezoelectric ceramics.
Achieving significantly enhanced piezoelectricity in aurivillius ceramics by improving initial polarization and dielectric breakdown strength
Journal of the European Ceramic Society, Volume 43, Issue 11, 2023, pp. 4757-4765
In this work, the neglected role of the dielectric breakdown strength (BDS) in piezoelectricity of bismuth layer-structured ferroelectrics (BLSFs) is revealed, enhanced initial polarization and BDS work together to improve the piezoelectricity of CaBi4Ti4O15 (CBT) ceramics via Li/Bi co-substitution. The experimental work, first-principles calculations and finite element simulation are carried out to investigate the effect of Li/Bi co-substitution in depth. The stronger spontaneous polarization (Ps) from the lattice distortion and the more favorable domain switching from the improved grain growth both contribute to an enhanced initial polarization. Besides, the changed grain-scale microstructure improves the hardness and inhibits the local discharge, the higher resistivity related to strong defect dipoles suppresses the heat generation during the poling process, all resulting in an increase of BDS by about 100%, and allowing more domains to align. This work demonstrates an effective strategy to develop BLSFs with enhanced piezoelectricity for high temperature piezoelectric applications.
Comparison of impact from typical additives for phase structure in (K, Na)NbO3-based ceramics
Ceramics International, Volume 49, Issue 11, Part B, 2023, pp. 18629-18637
Phase engineering has been widely utilized to promote piezoelectricity in potassium sodium niobate (KNN)-based ceramics via appropriate addition. However, the different impact on phase structure from various additives is still not researched deeply. Herein, the comparison of influence on phase transition temperatures (TR-O, TO-T and TC) is emphasized on from different typically additives [Bi0.5Ag0.5ZrO3 (BAZ), BaZrO3 (BZ), and Sb5+], to reveal the intrinsic essence of structure evolution. The effect on rhombohedral-orthorhombic (R–O) phase boundary can be gained as BAZ>Sb5+>BZ because of the elevating and reducing TR-O with increasing BAZ and BZ when Sb5+ is decreased, respectively. And the influence on orthorhombic-tetragonal (O-T) phase boundary can be manifested as BAZ>Sb5+≈BZ due to the decreasing and little changed TO-T with increasing BAZ and BZ as Sb5+ is reduced, respectively. Both BAZ and BZ additives are more effective on destroying long-range ordered matrix along with lower TC and stronger relaxor behavior with respect to Sb5+, which is induced by strong local structural heterogeneity from more complex composition. Furthermore, the effect of structure evolution on electrical properties is revealed systematically. This work is beneficial to understand the rules of phase boundary formation and promote structure adjustment via component design.
Structural investigation of the temperature-stable relaxor dielectric Ba0.8Ca0.2TiO3-Bi(Mg0.5Ti0.5)O3
Journal of the European Ceramic Society, Volume 43, Issue 2, 2023, pp. 362-369
Aberration corrected scanning transmission electron microscopy (STEM) and electron diffraction have been used to disclose local structure and nano-chemistry in a Ca modified BaTiO3-Bi(Mg0.5Ti0.5)O3 relaxor dielectric ceramic which exhibits high and near-invariant relative permittivity over a wide temperature range. High-resolution, synchrotron X-ray diffraction indicated a globally cubic structure (Pmm), but direct atomic-scale imaging by STEM revealed local tetragonal distortions. Nanopolar clusters were identified from B-site atomic displacement vectors measured relative to oxygen ion positions along < 100 > and < 110 > zone axes of integrated differential phase contrast (iDPC) STEM images, highlighting cluster sizes of 2–5 nm. Chemical analysis by STEM-energy dispersive X-ray spectroscopy and full pattern refinements of X-ray powder diffraction data each implied high levels of Bi vacancies within the matrix. The possibility that these A-site vacancies modulate the nanopolar structure and promote flattening of the permittivity-temperature response in this class of dielectric is discussed.
Highly thermally stable and tunable luminescence in microwave-assisted synthesized Na3Ca4(TeO3)(PO4)3:Dy3+,Eu3+ for ultra-high color rendering white light-emitting diodes
Ceramics International, Volume 49, Issue 13, 2023, pp. 22323-22331
For the commercial application of the Eu3+-activated red phosphors in NUV (∼365nm)-excited phosphor-converted white light-emitting diodes (pc-wLED), the serious obstacle is that they cannot be efficiently excited by ∼365nm. To deal with the trouble, we employed the energy transfer between Dy3+ sensitizer excited by ∼365nm and Eu3+ activator, and a color-tunable phosphor Na3Ca4(TeO3)(PO4)3 (NCTP):Dy3+,Eu3+ was prepared via a fast microwave-assisted solid-state reaction. Under the 363nm excitation, the luminous color is adjusted to red owing to the Dy3+→Eu3+ energy transfer with high efficiency, which is controlled by the dipole–dipole interaction. Moreover, the introduction of Dy3+ sensitizers in NCTP:Eu3+ enhances the structural rigidity, resulting in high luminescence thermostability. The luminescent intensity at 423K remains 90.7% of that at 298K. Notably, the 365nm chip-excited pc-wLED device assembled with NCTP:0.09Dy3+,0.4Eu3+, commercial blue BaMgAl10O17:Eu2+, and green (Ba,Sr)2SiO4:Eu2+ phosphors emits warm-white light (0.3657,0.3725) with the ultra-high Ra (94.9) and low CCT (4399K). This work offers a feasible Dy3+→Eu3+ energy transfer path for the development of efficient Eu3+-activated red phosphor towards ultra-high color rendering pc-wLED.
© 2023 Elsevier Ltd and Techna Group S.r.l. All rights reserved.
The commercial piezoelectric material PZT possesses a Curie temperature of about 350°C, but has a maximum recommended operation temperature of 150-250°C.What is the Curie point of ceramics? ›
BaTiO3 ceramic dielectric material are the most common, proved dielectric material used in mass production of ceramic capacitors today. Due to its structure, the maximum capacitance value is achieved nearby Curie temperature ~ 125°C.Which material has highest Curie temperature? ›
One of the highest Curie points is 1,121 °C (2,050 °F) for cobalt. Temperature increases above the Curie point produce roughly similar patterns of decreasing paramagnetism in all three classes of materials.What is the maximum temp for piezo? ›
Piezo Transducers: Sensing, Ultrasound
PI HVPZTs have a Curie temperature of 300°C and can be operated up to a max temperature of 150°C and some cases to 200°C (with high temperature option).
above the curie temperature, a ferromagnetic material becomes paramagnetic.What is the significance of curie constant? ›
In physics, unlike other physical constants, the curie constant is a material dependent property. It expresses the relation between the magnetic susceptibility of a material to its temperature. Measured using K.A.T-1.Why is the Curie temperature important? ›
The Curie temperature of magnets is an extremely important factor to consider when looking at industrial magnets for your industry. Each type of magnet has a maximum temperature it can withstand, and if it exceeds that temperature, it will lose magnetic properties entirely.What is the difference between Curie temperature and critical temperature? ›
Curie's temperature is the critical temperature at which certain magnetic materials undergo changes in their corresponding magnetic properties. It is denoted by T_C. It is also known as Curie Point.What is the Curie temperature of ceramic magnet? ›
They have a maximum operating temperature of approximately 250 degrees Celsius or higher and a Curie temperature of about 450 degrees Celsius. These magnets, however, are not recommended for use in cryogenic applications.
The Curie temperature of anti-ferromagnetic materials is also known as Néel temperature. It got its name in honour of the French physicist Louis Néel who explained anti-ferromagnetism in 1936. The increasing order of Curie temperature in ferromagnetic, anti-ferromagnetic and ferrimagnetic substances.
One disadvantage of piezoelectric materials is that they cannot be used for truly static measurements. In addition, the piezoelectric materials also show disadvantages in the unfavorable compatibility and poor durability with the concrete structures .How long does piezoelectric last? ›
Piezoelectric sensors are solid state sensors with no internal moving parts to wear or fatigue. Mean Time Between Failure (MTBF) analysis for typical industrial sensors predicts a life of 12 years.What is the effect of temperature on piezoelectric material? ›
It is observed that as the temperature increases, the resonant frequency decreases. The resonant frequency of the piezoelectric element is directly proportional to stiffness constant. If the temperature of the piezoelectric element increases, its stiffness decreases, and so the resonant frequency decreases.What is the Curie temperature for PZT crystal? ›
Above a certain temperature (which is called Curie point Θc) of 120°C, the prototype crystal structure is cubic, with Ba2+ ions at the cube corners, O2- ions at the face centres and Ti4+ ion at the body centre, as shown in Fig.What is the sintering temperature of PZT? ›
Pb(Zr,Ti)O3, (PZT) is known to have excellent piezoelectric properties. In general, PZT ceramics is sintered above 1200 °C.What is the temperature range of piezoelectric sensor? ›
Conventional piezoelectric sensing has been applied widely in sensing of vibration, pressure, mass, distance, chemical and bio-sensing, but its operation temperature is usually below 700 °C. Recent development on high-temperature piezoelectric sensing suggests piezoelectric sensing at temperatures close to 1,000 °C.