Elimination of pyrochlore phase in high-concentration Sm3+-doped PMN-PT piezoelectric ceramics by excessive MgO

Undesirable pyrochlore phase often appears in Pb(Mg_1/3Nb_2/3)O₃-PbTiO₃ (PMN-PT)-based ceramics with high rare-earth ion (RE³⁺) doping concentration, which greatly limits their development. In this study, 0–5 mol% Sm³⁺-doped Pb(Mg_1/3Nb_2/3)O₃-29PbTiO₃ (PMN-29PT:0-5Sm) ceramics were first synthesized using traditional precursor method. In the X-ray diffraction spectra and scanning electron microscope images of PMN-29PT:3-5Sm ceramics, the diffraction peaks of pyrochlore phase and pyrochlore grains with octahedral morphology were observed, respectively. The reason for the appearance of the pyrochlore phase is that Sm³⁺ doping causes the Nb-rich regions. To eliminate the pyrochlore phase, PMN-29PT:3-5Sm ceramics were resynthesized by an improved precursor method in which an excess of 4 mol% MgO was added to the reactants before pre-sintering. After adding an excess of 4 mol% MgO, the concentration ratio of Nb⁵⁺ and Mg²⁺ in the pyrochlore grains returned to the value in the perovskite grains, and the pyrochlore phase was transformed into the perovskite phase PMN. The dielectric, ferroelectric, and electromechanical properties were compared before and after eliminating the pyrochlore phase. The results show that the comprehensive performance of the ceramics is improved after eliminating the pyrochlore phase.     

Dielectric and piezoelectric properties of PMN-PT ceramics doped with strontium

Motivated by the need of piezoelectric ceramics with enhanced piezoelectric properties, we investigated the effects of Sr addition on the structural, dielectric and piezoelectric properties of PMN-PT ceramics. The synthesis of (1-x)[(Pb_1?ySr_y)(Mg_1/3Nb_2/3)O₃]-x(Pb_1?ySr_yTiO₃) (PsMN–PsT) (y: 0 ? 0.10, x: 0.35 – 0.40) ceramics was carried out by the colloidal coating method to distribute Sr uniformly in PMN and PT respectively. When x=0.35, it was found that y=0.02 gave the optimal piezoelectric properties. Furthermore, by keeping y=0.02 and varying x, it was found that x=0.37 gave even better piezoelectric properties with the optimal piezoelectric strain coefficient d₃₃ (630 pC/N), piezoelectric coupling factor k_p (0.52), dielectric constant ε_r (4000), and Curie temperature T_c (210 °C), exhibiting great potential for actuator and sensor applications.     

BiScO3-PbTiO3 piezoelectric ceramics with Bi excess for energy harvesting applications under high temperature

0.36BiScO₃-0.64PbTiO₃ ceramic is a competitive piezoelectric material even though it contains lead and volatile Bi contents. It contains a relatively decreased lead content compared to that of the Pb(Zr,Ti)O₃ system but it has similar piezoelectric properties with high Curie temperature. However, due to the very volatile component of Bi the 0.36BiScO₃-0.64PbTiO₃ system has Bi-deficient composition. Therefore, in order to compensate for deficient Bi contents in the 0.36BiScO₃-0.64Pb,TiO₃ system, excess 0.005, 0.01, 0.015 and 0.02 mol of Bi were added to the ceramics to enhance the piezoelectric properties for the first time. By employing excess Bi addition, the piezoelectric charge coefficient, electromechanical coupling factor, output open circuit voltage, and generated output power density were improved from 417 pC/N, 51.48%, 19.69 V and 0.28 mJ/cm³ to 452 pC/N, 52.25%, 26.93 V and 0.48 mJ/cm³. We expect that piezoelectric properties of 0.36BiScO₃-0.64PbTiO₃ ceramics were improved by adding Bi excess.     

Evaluation of the pore morphologies for piezoelectric energy harvesting application

Piezoelectric energy harvesting has attracted significant attention in recent years due to their high-power density and potential applications for self-powered sensor networks. In comparison to dense piezoelectric ceramics, porous piezoelectric ceramics exhibit superiority due to an enhancement of piezoelectric energy harvesting figure of merit. This paper provides a detailed examination of the effect of pore morphology on the piezoelectric energy harvesting performance of porous barium calcium zirconate titanate 0.5Ba(Zr_0.2 Ti_0.8)O₃-0.5(Ba_0.7Ca_0.3)TiO₃ (BCZT) ceramics. Three different pore morphologies of spherical, elliptical, and aligned lamellar pores were created via the burnt-out polymer spheres method and freeze casting. The relative permittivity decreased with increasing porosity volume fraction for all porous BCZT ceramics. Both experimental and simulation results demonstrate that porous BCZT ceramics with aligned lamellar pores exhibit a higher remanent polarization. The longitudinal d₃₃ piezoelectric charge coefficient decreased with increasing porosity volume fraction for the porous ceramics with three different pore morphologies; however, the rate of decrease in d₃₃ with porosity is slower for aligned lamellar pores, leading to the highest piezoelectric energy harvesting figure of merit. Moreover, the peak power density of porous BCZT ceramics with aligned lamellar pores is shown to reach up to 38 μW cm^-2 when used as an energy harvester, which is significantly higher than that of porous BCZT ceramics with spherical or elliptical pores. This work is beneficial for the design and manufacture of porous ferroelectric materials in devices for piezoelectric energy harvesting applications.     

Improved Li and Sb doped lead-free (Na,K)NbO3 piezoelectric ceramics for energy harvesting applications

Piezoelectric energy harvesting is the most widely investigated technology for renewable energy applications. In this work, (1-x)(Na_0.5K_0.5)NbO₃-xLiSbO₃ piezoelectric ceramics were prepared through conventional mixed oxide fabrication methods with different sintering temperatures. Although the (Na_0.5K_0.5)NbO₃ piezoelectric material is representative among the lead-free ceramics, it is difficult to densify by typical sintering techniques owing to its easy evaporation properties of potassium (K⁺) and sodium ion (Na⁺). Hence, lithium (Li⁺) and antimony ion (Sb⁵⁺) were used for the partial substitution of (Na_0.5K_0.5)NbO₃. With the optimized sintering temperature, Li⁺ and Sb⁵⁺ are expected to be crucial in increasing the density and enhance the piezoelectric and ferroelectric properties. In this study, the phase, microstructure, and dielectric and electrical properties of (1-x)(Na_0.5K_0.5)NbO₃-xLiSbO₃ ceramics depending on the sintering temperature is examined by employing X-ray diffraction, field emission scanning electron microscopy, impedance analyzer, and mechanical force system for energy harvesting.     

Fabrication and ferroelectric/dielectric properties of La-doped PMN-PT ceramics with high optical transmittance

Relaxor ferroelectric 0.75(Pb_1–3x/2La_x)(Mg_1/3Nb_2/3)O₃-0.25(Pb_1–3x/2La_x)TiO₃ (La³⁺:PMN-PT x/75/25, where x=2.8, 3.0, 3.5, and 4.0 mol% of La³⁺) transparent ceramics were fabricated by the combination of oxygen atmosphere pressureless sintering and hot-pressing sintering process. The optical transmittances of above four ceramics are higher than 60% at the wavelength of 500–900 nm. La³⁺:PMN-PT 3.0/75/25 exhibits the highest transparency around 70% at 900 nm which is very close to the theoretical transmittance 71%. Each of the four ceramics exhibits the pure perovskite phases. They show fully dense microstructures and their relative densities are higher than 99.8%. The ferroelectric and dielectric measurements indicate that these four ceramics exhibit relaxation characteristics. With increasing La³⁺ content, (200) peak in XRD patterns shifts to higher angles and the average grain size increases, while the temperature Tε_max corresponding to the maximum ε_r, the remanent polarizations P_r and coercive fields E_c decrease gradually.     

Enhanced pyroelectric properties of lead-free BNT-BA-KNN ceramics for thermal energy harvesting

In this work, (1−x)(0.98Bi_0.5Na_0.5TiO₃-0.02BiAlO₃)-x(Na_0.5K_0.5)NbO₃ (BNT-BA-xKNN) lead-free pyroelectric ceramics were prepared by a solid-state reaction method. The effect of Na_0.5K_0.5NbO₃ (KNN) content on microstructure, phase transition, and electrical properties of the BNT-BA-xKNN ceramics were systematically investigated. The results show that the appropriate content of KNN can induce the formation of the tetragonal structure, which results in the decreased ferroelectric-antiferroelectric phase transition temperature as a result of the break of long-range translational symmetry of BNT lattices. Therefore, the ferroelectric and pyroelectric properties of the BNT-BA-xKNN near room temperature are improved. The room-temperature pyroelectric coefficient significantly increases from 3.66 × 10⁻⁴ C/m²/K at x = 0 to 8.04 × 10⁻⁴ C/m²/K at x = 0.02, making a great contribution to the superior pyroelectric energy harvesting. The output energy density in one cycle of the BNT-BA-0.02KNN is 23.32 μJ/cm³, which is twice as high as that of the pristine samples. The enhancement of material properties suggests that the pyroelectric energy harvesting can be efficiently optimized by the adequate control of the phase structure.     

The structural origin of enhanced energy harvesting performance in piezoelectric perovskite

Energy harvesting, which can translate the wasted vibration energy into electric energy, is now a hot topic in the field of new energy, and the key point is to design high power piezoelectric ceramic according with the requirements of low-frequency vibration energy harvesting. In this study, high quality Co-modified 0.2Pb(Zn_1/3Nb_2/3)O₃–0·8Pb(Zr_0·50Ti_0·50)O₃ (PZN–PZT+Co) ceramics have been prepared by the two-stage method, and the energy harvesting characteristics were investigated. The results showed that the hierarchical nanodomain structure boosts the strong piezoelectric activity, leading to the high energy harvesting performance. The PZN–PZT+Co ceramic sintered at 1000 °C exhibits an excellent d₃₃ × g₃₃ value of 14080 × 10^?15 m²/N, which are much larger than that of commercial PZT-based ceramics. In the mode of the cantilever-type energy harvester, the output voltage and energy density of 33 V, 4.4 μW/mm³ were obtained at a low resonance frequency of 85 Hz and acceleration of 10 m/s², showing potential application in piezoelectric energy harvester.     

A flexible piezoelectric pressure sensor based on PVDF nanocomposite fibers doped with PZT particles for energy harvesting applications

Flexible piezoelectric energy harvesters are a suitable choice for scavenging wasted mechanical energy because of the high demand for sustainable power sources. Flexible pressure sensors based on PVDF-PZT nanocomposite with different PZT volume fractions (0.011, 0.041, 0.096, 0.17, 0.3, and 0.37) were prepared in the form of fibers through an electrospinning method for piezoelectric energy harvesting application. According to the results, dielectric constant and piezoelectric coefficients (e.g. piezoelectric coefficient, and figure of merit) gradually increased with the doping of PZT particles into PVDF fibers. Dielectric constant (ϵ), piezoelectric coefficient (d), and figure of merit (d × g) for PVDF-PZT nanocomposite with 0.011 PZT volume fraction were 37.29, 10.51 pCN⁻¹, and 33.46 × 10⁻¹⁶ m²/N, respectively, and increased to 104.81, 22.93 pCN⁻¹, and 56.68 × 10⁻¹⁶ m²/N for PVDF-PZT nanocomposite fibers with a volume fraction of 0.37. As piezoelectric energy harvesters, piezoelectric sensitivity of PVDF-PZT nanocomposite fibers rose with increasing the PZT volume fraction. The generated output voltage was 184 mV under an applied force of 2.125 N with the piezoelectric sensitivity calculated as 173.507mV/Nμm for PVDF-PZT nanocomposite fibers with 0.37 PZT volume fractions which increased compared to pristine PVDF fibers (generated output voltage = 22 mV under applied force 2.4 N, piezoelectric sensitivity = 29.49 mV/Nμm). The achieved output power density of PVDF-PZT nanocomposite fibers with 0.37 PZT volume fractions was obtained 30.69μW cm⁻² higher than PVDF-PZT nanocomposite fibers with 0.011 PZT volume fractions (18.44μW cm⁻²).     

Enhanced electromechanical properties of CaZrO3-modified (K0.5Na0.5)NbO3-based lead-free ceramics

Pairing of large strain response and high d₃₃ with high T_c in (K_0.5Na_0.5)NbO₃-based materials is of high significance in practical applications for piezoelectric actuators. Here, we report remarkable enhancement in the electromechanical properties for (1-x)(K_0.52Na_0.48) (Nb_0.95Sb_0.05)O₃-xCaZrO₃ (KNNS-xCZ) lead-free ceramics through the construction of a rhombohedral (R)-tetragonal (T) phase boundary. We investigated the correlation between the composition-driven phase boundary and resulting ferroelectric, piezoelectric, and strain properties in KNNS-xCZ ceramics. The KNNS-xCZ ceramics with x=0.02 exhibited a large strain response of 0.23% while keeping a relatively large d₃₃ of 237pC/N, which was mainly ascribed to the coexistence of R and T phases confirmed by the XRD and dielectric results. It was found that pairing of large strain response and high d₃₃ in KNN-based materials was achieved. As a consequence, we believe that this study opens the possibility to achieve high-performance lead-free electromechanical compounds for piezoelectric actuators applications.     

Enhancing piezoelectric properties of Ba0.88Ca0.12Zr0.12Ti0.88O3 lead-free ceramics by doping Co ions

The piezoelectric properties of lead-free Ba_0.88Ca_0.12Zr_0.12Ti_0.88O₃ (BCZT) ceramics were greatly optimized by doping Co ions using a CoO powder. The role of Co²⁺ and Co³⁺ in enhancing the piezoelectric properties and the relationship between the content ratio Co³⁺/Co²⁺ and piezoelectric performance were studied. The X-ray diffraction patterns of all samples indicated that crystalline phases were a BCZT-based single perovskite structure regardless of the Co ion content. The phase transition temperature and lattice distortion degree were related to the Co ion content and the content ratio Co³⁺/Co²⁺ because Co²⁺ resulted in higher oxygen vacancy generation, whereas Co³⁺ induced larger lattice shrinkage. The ceramic containing 0.10 wt% of Co ion showed the best piezoelectric and dielectric performance with the highest piezoelectric constant d₃₃ ~ 490 p.m./V at room temperature and the highest Curie temperature T_c of 110 °C, which increased by 29% and 16%, respectively. In this case, the content ratio Co³⁺/Co²⁺ reached the maximum value of 0.86. The high piezoelectric properties and phase stability of BCZT ceramics by doping Co ions make these ceramics promising piezoelectric materials for practical applications.     

Enhanced transduction coefficient in piezoelectric PZT ceramics by mixing powders calcined at different temperatures

Large transduction coefficient ($d_{33}\times g_{33}$) is difficult to obtain in piezoelectric ceramics because these two parameters show opposite trends with compositional modifications. Herein, the Pb(Zr_0.53Ti_0.47)O₃ ceramic powders were calcinated under different temperatures (A:830 °C, B:860 °C, and C:890 °C), and then mixed together according to different weight ratios (1A:1B:1C, 1A:2B:1C, 1A:2B:3C and 3A:2B:1C) for ceramics preparation. Both d₃₃ and g₃₃ are improved successfully, and the transduction coefficient with the weight ratio of 1A:2B:3C reaches up to 17,500 × 10⁻¹⁵ m²/N, which is 60 % higher than that with the powders calcinated under 830 °C, and at least twice those of commercial PZT-4, PZT-5A and PZT-8 ceramics. The improved transduction coefficient is owing to the enhanced piezoelectric constant and spontaneous polarization resulted from the increased grain size, relative density and the fraction of tetragonal phase. These results indicate that this is a simple but effective way to tailor the transduction coefficient in piezoelectric ceramics.     

A critical review on lead-free hybrid materials for next generation piezoelectric energy harvesting and conversion

This article aims to provide a comprehensive review of lead-free hybrid nano materials based piezoelectric fillers. It narrates the basic concept of piezoelectricity and discusses the salient properties of piezoelectric materials. Piezoelectric materials divided into classes of ceramics (lead based and lead free), polymers and composites, have been discussed in detail. The potential environmental threat posed by lead (Pb) in the lead based piezoelectric materials have gradually shifted the focus to lead free piezoelectric materials. Hence, lead free piezoelectric materials have been the main focus of this review. Lead free hybrid fillers, to enhance the piezoelectric properties of composites, have been covered as an integral part of this review. This topic has been covered principally under headings of KNN based fillers, Bi based fillers, Ba based fillers and MoS₂ based fillers. The effect of doping into piezoelectric fillers have also been discussed in detail. With piezoelectricity being used in different fields of applications, a part of this review elucidates the use of piezoelectric materials to cater to the needs of technology. A brief overview has been provided regarding the use of piezoelectric materials in energy harvesting, as sensor, actuators, transducers, in structural health monitoring and repair, and in biomedical applications. The future scope of piezoelectricity and piezoelectric materials in fulfilling the demands of technology has been discussed in the concluding part of the review.     

Sm2O3 and MnO2 codoped PMN-PZT ceramics with both high mechanical quality factor and piezoelectric properties

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 (d₃₃). Unfortunately, Q_m is inversely proportional to d₃₃ 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 d₃₃ simultaneously. Herein, we tried to achieve both a high mechanical quality factor and large piezoelectric activity in 0.47 pb(Mg_1/2Nb_2/3)O₃-0.18PbZrO₃-0.35PbTiO₃ (PMN-PZT) ceramics via Sm₂O₃ and MnO₂ co-doing. A range of xMn-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, d₃₃ = 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 MnO₂ doping and the large piezoelectric activity is due to the doping of Sm₂O₃.     

Enhanced piezoelectric properties and temperature-insensitive strain behavior of <001>-textured KNN-based ceramics

In this study, <001>-textured 0.99(K_0.5Na_0.5)_0.95Li_0.05Nb_0.93Sb_0.07O₃−0.01CaZrO₃ [abbreviated as 0.99KNLNS-0.01CZ] lead-free ceramics were prepared by templated grain growth (TGG) using plate-like NaNbO₃ templates and sintered by a two-step sintering process with different soaking time. All textured samples with high Lotgering factor (f >85%) presented orthorhombic and tetragonal coexisting phase, and the proportion of orthorhombic phase was varied with prolonged soaking time. A large piezoelectric constant d₃₃ (~ 310 pC/N) was obtained in the textured samples with a 12 h soaking time, which was almost twice larger compared to the randomly oriented one. Furthermore, the field-induced piezoelectric strain coefficient d₃₃^*(~ 440 pm/V) of the textured ceramics with 6 h soaking time was larger than the value of randomly oriented one (~ 298 pm/V) at room-temperature. Enhanced piezoelectric response and good temperature stability prove that <001>-textured 0.99KNLNS-0.01CZ ceramics are promising candidates in the field of lead-free piezoelectric materials.     

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.     

Piezoelectric properties of (1-x)BZT-xBCT system for energy harvesting applications

In this study, we investigated (1-x)Ba(Zr_0.2Ti_0.8)O₃–x(Ba_0.7Ca_0.3)TiO₃ lead-free piezoelectric ceramics for energy harvester applications. The (1-x)BZT-xBCT ceramic is a promising lead-free piezoelectric material in the field of piezoelectric energy harvesting. Piezoelectric and energy properties of (1-x)BZT-xBCT ceramics were analyzed to confirm the possibility of using them as energy-harvesting materials. Especially, the vicinity of the phase convergence region was investigated to improve their piezoelectric properties. In the phase convergence region, cubic, rhombohedral, orthorhombic, and tetragonal regions co-exist within the narrow region. Near the phase transition region between the orthorhombic and tetragonal phase, the highest piezoelectric property d₃₃?=?464 pC/N and the highest energy density of 158.5 μJ/cm³ were observed. This output energy density of 158.5 μJ/cm³ is the recorded highest value among lead-free ceramics. We found that the optimal sintering temperature was 1475?°C and the optimal composition was BZT-0.5BCT.     

Effect of grain size on piezoelectric,ferroelectric and dielectric properties of PMN-PT ceramics

Grain size has significant effects on the electromechanical response of piezoceramics. Since the sintering temperature and holding duration affect the grain size and correspondingly their effective piezoelectric response, these issues should be appropriately addressed in order to properly design smart and intelligent systems. In this paper, PMN-PT piezoceramics with different grain sizes are synthesized by using conventional solid state processing and two-stage sintering method. Grain size effects on the hysteresis, fatigue and creep response are analyzed. Dielectric, ferroelectric and piezoelectric material properties of PMN-PT ceramics are investigated. The piezoelectric coefficient and remnant polarization exhibit diverse grain size effects depending on the sintering temperature and holding duration. The relative dielectric permittivity, piezoelectric coupling constant and dielectric constant show maximum values of 4104.2, 559 pC/N 562.291 pC/N and 0.705 for the microstructure with average grain size of 3.8?μm. The myriad effects of grain size on piezoelectric response are reported in details.     

High room-temperature pyroelectric property in lead-free BNT-BZT ferroelectric ceramics for thermal energy harvesting

Pyroelectrics are attracting increasing attention because they enable pyroelectric generators to extract energy from low-gradient-temperature heat for portable electronic devices. High pyroelectric coefficient around room temperature is essential for high-performance energy harvesters, which, unfortunately, is only commonly achieved in lead-based ferroelectrics. Herein we report a high room temperature pyroelectric response of 27.2 × 10^?4 C m^-2 K^-1 in 0.94(Bi_0.5Na_0.5)TiO₃-0.06Ba(Ti_0.75Zr_0.25)O₃ lead-free ceramics by modulating the Zr⁴⁺/Ti⁴⁺ ratio to tune the ferroelectric-relaxor antiferroelectric-like phase transition point to around ambient temperature, whose pyroelectric response is one order of magnitude higher than that of the sample without Zr and even comparable to those of lead-containing pyroelectrics. The theoretical analysis revealed that introduced Zr⁴⁺ could incorporate into the TiO₆ octahedral lattices and break the long-range translational symmetry of BaTiO₃ lattices, resulting in the reduction of B-site ion displacement activation energy and transition point of ferroelectric-relaxor antiferroelectric-like phase, giving rise to a pronounced room-temperature pyroelectric effect in BNT-BZT.     

Fluorescence intensity ratio (FIR) analysis of the temperature sensing properties in transparent ferroelectric PMN-PT:Pr3+ ceramic

A transparent ferroelectric 0.75Pb(Mg_1/3Nb_2/3)O₃-0.25PbTiO₃:0.015Pr³⁺ ceramic was synthesized and its temperature-sensing ability was investigated based on the fluorescence intensity ratio (FIR) method. The transparency was found to be of the order of 68% at 900 nm for a sample thickness of 0.7 mm, comparable to the theoretical value of ~71%, benefiting the photoluminescence of the Pr³⁺ ions inside the ceramic. Instead of the traditional Boltzmann exponential style and varying sensitivity, a highly linear temperature response was obtained for the studied ceramic. Further, a constant FIR sensitivity of 0.70 %K^-1 was achieved over the temperature range of -50–40 °C, making the ceramic suitable for thermometry at room temperature and below.