Phase Perovskite Structure Research Articles

Ultrahigh Energy-Storage in Dual-Phase Relaxor Ferroelectric Ceramics.

High-performance dielectric energy-storage ceramics are beneficial for electrostatic capacitors used in various electronic systems. However, the trade-off between reversible polarizability and breakdown strength poses a significant challenge in simultaneously achieving high energy density and efficiency. Here a strategy is presented to address this issue by constructing a dual-phase structure through in situ phase separation. (Bi0.5Na0.5)TiO3-BaTiO3-based relaxor ferroelectric ceramics are developed, creating a grain-separated dual perovskite phase structure using a facile solid-state reaction method. These ceramics feature two interactive relaxor phases with diversified nanoscale polar structures and heterogeneous grain boundaries, synergistically contributing to high polarization with low hysteresis, substantially increased resistivity, and suppressed electrostrain. Remarkably, a record-high energy density of 23.6Jcm-3 with a high efficiency of 92% under 99kVmm-1 is achieved in the bulk ceramic capacitor. This strategy holds promise for enhancing overall energy-storage performance and related functionalities in ferroelectrics.

Crystallization management of CsPbI2Br perovskites by PbAc2-incorporated twice spin-coating process for efficient and stable CsPbI2Br perovskite solar cells

CsPbI2Br perovskite solar cell has been extensively studied due to its exceptional thermal stability and relatively stable perovskite phase structure. However, the presence of bromine leads to a rapid crystallization rate of CsPbI2Br films, resulting in small grain size and high defect density. Additionally, CsPbI2Br demonstrates poor light absorption due to its wide bandgap. Therefore, it is crucial to control the crystallization rate and increase the film thickness to reduce defect density, enhance light absorption, and improve photovoltaic performance. In this study, we utilized a PbAc2-incorporated twice spin-coating (PTS) process to address these issues. Initially, PbAc2 was added to the CsPbI2Br precursor solution to form a CsPbI2Br film, which was then coated with the CsPbI2Br precursor solution to produce the PTS film. Ac− can delay the perovskite crystallization, leading to the formation of thicker and denser CsPbI2Br films. Moreover, lone-pair electrons of the oxygen atom provided by Ac− formed coordination bonds with under-coordinated Pb2+ ions to fill halogen ion vacancies, thereby reducing the defect density. Ultimately, the PTS CsPbI2Br device achieved a peak power conversion efficiency (PCE) of 16.19% and maintained 96.7% of its initial PCE over 1500 h at room temperature under 25% relative humidity without any encapsulation.

Significant impact of TiO2 purity on the phase structure and electrical properties of BiFeO3–BaTiO3 lead‐free piezoelectric ceramics

AbstractIn many studies, the properties of BiFeO3–BaTiO3 (BF–BT) ceramics vary greatly using different raw reagents, which makes it challenging to obtain reliable and repeatable properties of BF–BT‐based devices. In this work, 0.7BiFeO3–0.3BaTiO3 (0.7BF–0.3BT) ceramics were fabricated by a conventional solid‐phase synthesis using TiO2 reagents with varied purities of 98%, 99%, 99.9%, and 99.99%, respectively. The phase structure, microstructure, ferroelectric, and piezoelectric properties were comprehensively studied. All compositions of the ceramics exhibit a pseudo‐cubic phase perovskite structure, and the fraction of the rhombohedral phase increases with increasing the TiO2 purity. Additionally, backscattered electron images and energy‐dispersive spectroscopy revealed an obvious core–shell structure within grains. In particular, the 0.7BF–0.3BT ceramics prepared with 98% purity TiO2 exhibited superior ferroelectric and piezoelectric properties, d33 ∼ 220 pC/N and ∼ 230 pm/V. The ceramics prepared with higher purity TiO2 suffered from severe leakage conduction, which can be well addressed by adding excess TiO2. Our work reveals the importance of different grades of purity TiO2 on the electrical properties of BF–BT ceramics.

Lanthanide element variation in rare earth doped ceria – FeCo2O4 dual phase oxygen transport membranes

The increased interest in dual-phase membrane materials for oxygen separation leads to the continuous optimization of their composition. Rare-earth doped ceria is a promising candidate as the ion-conducting phase in the membrane. Spinel-structured FeCo2O4 was investigated as an electronic conducting phase forming an additional electronic conducting perovskite-structured phase during sintering when combined with Ce1−xLnxO2−δ. The influence of rare-earth lanthanide elements, i.e., Gd and Sm, as well as their concentration, i.e. x = 0.1 and 0.2, on the final phase composition and microstructure as well as its related functional properties in particular oxygen permeation is analyzed. 20 mol.% doping of either Gd or Sm reveals a multi-phase microstructure after sintering. Moreover, segregation of Gd/Sm, iron, and cobalt is found at the ceria-ceria grain boundaries in Ce0.8Sm0.2O2−δ- and Ce0.9Gd0.1O2−δ-based composites. In contrast, 10 mol.% Gd–doping leads to a dual-phase membrane material without the formation of any other phase. In all cases, the percolation threshold is reached at approx. 20 vol% of the electron-conducting phase in the system leading to similar maximum permeation rates determined by the ionic conductivity of the ceria phase.

Firing Temperatures Effect on Phase Formation, Microstructure and Electrical Properties of BNBKL Ceramics Fabricated via the Solid-State Combustion Technique

Lead-free 0.85Bi0.5Na0.475Li0.025TiO3-0.11Bi0.5K0.5TiO3-0.04BaTiO3 (BNBKL) ceramics were prepared by the solid-state combustion technique. The BNBKL powders and ceramics were calcined and sintered between 650 to 850 °C for 1–5 h and 1100 to 1140 °C for 2 h, respectively. The effect of firing temperatures on the phase structure, microstructure, and electrical properties of BNBKL ceramics was investigated. X-ray diffraction patterns of BNBKL powders showed a pure perovskite phase structure at a calcination temperature of 800 °C for 3 h. The BNBKL ceramics sintered at different temperatures possessed coexisting rhombohedral (R) and tetragonal (T) phases. The ceramic grains showed a polyhedral shape with directionless growth. The average grain size of the BNBKL ceramics increased from 0.80 to 1.26 µm when the sintering temperature increased from 1100 to 1140 °C. The density of the BNBKL ceramics increased as the sintering temperature increased up to 1120 °C, after that it decreased. The highest density (6.05 g/cm3) and dielectric constant (5855), were obtained at the sintering temperature of 1120 °C. As the sintering temperature increased, the polarization hysteresis loops (P-E loops) of the BNBKL ceramics exhibited less saturation and were more pinched, indicating more relaxor behavior.

Comparative Study of the Synthesis of a Red Ceramic Pigment Using Microwave Heat Treatment

In this study, a new red ceramic pigment has been developed within a perovskite structure, and microwave heat treatments have been applied. Those red ceramic pigments within the YAlO3 system doped with chromium with the nominal composition Y0.98Al0.98Cr0.04O3 were synthesized by traditional routes and alternative methods like coprecipitation. Also, heat treatment has been studied comparing a traditional electric and microwave kiln. Different flux agents have been incorporated to improve the synthesis reaction. Prepared pigments have been characterized by X-ray diffraction (XRD) as having a predominant phase of perovskite structure, which is responsible for the red shade, and a minority garnet phase that causes more brown colorations. Studies by Ultraviolet-Visible spectroscopy gave rise to a series of absorption bands that indicate the presence of Cr(III) in the octahedral position corresponding to perovskite and Cr(IV) corresponding to garnet in both the octahedral and tetrahedral positions. The perovskite phase is favored with the use of flux mix, corroborating the UV-visible results and being more pronounced in traditional high temperature thermal treatments. The coprecipitation route has been studied to increase the reactivity of the particles given their nanometric size; however, this reactivity favors a greater appearance of undesirable garnet phases with both types of flux. Scanning Electron Microscopy (SEM) micrographs offer information obtained from the secondary electrons of predominantly cubic crystalline phases with sizes between 1 µm and 2 µm in pigments synthesized via the traditional method and sizes less than 1µm together with the glassy phase in pigments synthesized via coprecipitation. Microwave thermal treatments have been studied, obtaining pigments with a majority structure of perovskite and garnet at lower temperatures and relatively short synthesis times. The feasibility of use in porous single-fired ceramic glazes has been studied, whose chromatic coordinates have been collected using an Ultraviolet-Visible Spectrophotometer based on the CIEL*a*b* system.

Bifunctional Lewis Base‐Assisted Fabrication of High‐Quality CsPbIBr2 Perovskite for Efficient and Stable Solar Cells

The inferior phase stability and unsatisfactory crystal quality of inorganic lead halide perovskites have severely impeded the development of inorganic perovskite solar cells. Herein, a bifunctional Lewis base additive, phenylthiourea (PTU), is incorporated into the CsPbIBr2 precursor to simultaneously enhance the quality and ameliorate the stability of the CsPbIBr2 perovskite film. The CS group of PTU strongly coordinates with PbBr2 to form the intermediate phase in the perovskite precursor, which effectively tunes the crystallization process of CsPbIBr2 and enables the formation of high‐quality CsPbIBr2 perovskite film with high crystallinity, large crystal grains, and indistinct grain boundaries. Meanwhile, the introduction of PTU additive leads to the sulfur insertion into the interstices of CsPbIBr2 perovskite lattice, which can stabilize the perovskite phase structure and passivate the undercoordinated Pb2+ defects. With these benefits, the assembled carbon‐based perovskite solar cell based on PTU‐CsPbIBr2 perovskite film delivers a high power conversion efficiency of 10.09%. In addition, the unencapsulated device maintains over 80% of its initial efficiency after 800 h of storage under ambient air. These results demonstrate an effective strategy to improve the performance and stability of inorganic perovskite solar cells.

Enhanced Ferroelectric and Dielectric Properties of Niobium-Doped Lead-Free Piezoceramics.

Lead-free ceramics are promising candidates for replacing lead-based piezoelectric materials such as lead-zirconate-titanate (PZT) if they can compete in dielectric and ferroelectric characteristics. In this work, for lead-free piezoelectric ceramic, 0.74(Bi0.5Na0.5TiO3)-0.26(SrTiO3) (BNT-ST26) and niobium-substituted (Nb-BNT-ST26) ceramics were synthesized by solid-state reactions. The evolution of niobium substitution to the perovskite phase structure of BNT-ST26 ceramics was confirmed by X-ray diffraction (XRD) analysis and Raman spectra. Electromechanical properties of Nb-BNT-ST26 ceramics initially increased with the addition of niobium up to 0.5% and decreased with a further increase in Nb content. Temperature-dependent dielectric curves showed that the depolarization temperature (Td) decreased below room temperature because of Nb substitution. The composition with 0.5% Nb yielded a maximum bipolar strain (Smax) of 0.265% and normalized strain of d33* ~ 576 pm/V under an electric field of 4.6 kV/mm at room temperature. At this critical concentration of 0.5% Nb, maximum saturation polarization of 26 μC/cm2 was achieved. The dielectric constant with temperature peaks became more diffused and the depolarization temperature decreased with the increasing Nb content. The study concludes that Nb-doped BNT-ST26 is an excellent material for high-temperature, stable, frequency-dependent, lead-free piezoelectric devices.

From tetragonal to cubic: perovskite phase structure evolution for high-performance solar cells

From tetragonal to cubic: perovskite phase structure evolution for high-performance solar cells

Effects of Ca3Co4O9 addition on physical and electrical properties of lead-free Bi0.5(Na0.80K0.20)0.5TiO3-0.005LiNbO3 ceramic

In the present work, highly dense complex perovskite oxide ceramics with the formula of (1-x)[Bi0.5(Na0.80K0.20)0.5TiO3-0.005LiNbO3]-x(Ca3Co4O9) or (1-x)[BNKT-0.005LN]-xCCO, where x = 0, 0.010, 0.015, 0.020 and 0.025 mol fraction were fabricated by a solid-state mixed oxide method. After sintering at 1125 °C for 2 h, all ceramics were characterized in terms of physical, phase evolution, microstructure, dielectric, ferroelectric, and piezoelectric properties. XRD patterns of all samples indicated single phase of perovskite structure with good relative density value of ∼ 97 − 98%. The SEM image indicated that cubic-like shaped grains were observed in all samples. The average grain size was found to increase with increasing the modifier content. Optimum electrical properties (i.e. εr = 1485, tanδ = 0.0460, Pr = 13.13 µC/cm2, Ec =14.92 kV/cm and d33 = 145 pC/N) were found in the sample with x = 0.010 mol fraction.

Lattice Expansion and Crystallite Size Analyses of NiO-BaCe0.54Zr0.36Y0.1O3-δ Anode Composite for Proton Ceramic Fuel Cells Application

This study reports on the structure analyses of NiO-BCZY (BCZY = BaCe0.54Zr0.36Y0.1O3-δ) anode composite materials with the ratio of 50:50 for proton ceramic fuel cells (PCFCs) application. A product of sintered NiO-BCZY was developed to understand the structural properties of the anode materials. The objectives of this work were (a) to investigate the lattice expansion of the anode by using a high-temperature XRD (HT-XRD) from 400–700 °C; and (b) to calculate the crystallite size of the sample by using Scherrer’s and Williamson Hall’s methods. The results obtained from the HT-XRD revealed that the diffraction peaks of NiO and BCZY are matched with the cubic phase perovskite structure. For example at T = 400 °C, the lattice parameter of NiO is a = 4.2004 Å and BCZY is a = 4.3331 Å. The observation also showed that the lattice expansion increased with the temperature. Furthermore, analyses of the Scherrer and Williamson Hall methods, respectively, showed that the crystallite size is strongly correlated with the lattice expansion, which proved that the crystallite size increased as the operating temperature increased. The increment of crystallite size over the operating temperature contributed to the increment of conductivity values of the single cell.

Photoluminescence effects and probing phase transition of Sm3+-doped Ba(Ti0.8Hf0.2)O3-(Ba0.7Ca0.3)TiO3 phosphor prepared by hydrothermal method

A series of [(Ba(1-0.3y)Ca0.3y)1-xSmx][Ti(0.8+0.2y)Hf(0.2-0.2y)]O3 (Sm3+-doped (1-y)Ba(Ti0.8Hf0.2)O3-y(Ba0.7Ca0.3)TiO3, abbreviated as Sm3+-doped BCTH, or (1-y)BHT-yBCT:xSm3+, x = 0.0005–0.03, y = 0.2–0.7, y representing the mole fraction of (Ba0.7Ca0.3)TiO3) nano phosphors were prepared by a hydrothermal method. The Sm3+ ions doping amount and triple-point morphotropic phase boundary (TMPB) composition dependent photoluminescence properties were systematically investigated. The hydrothermal synthesized powders present rather pure pseudo-cubic perovskite phase structure at room temperature and locate on the rhombohedral side of MPB. Under the excitation of 409 nm light, the powders exhibit dominant orange-red emission peaks with characteristic emission of the Sm3+ ions at around 564 nm, 596 nm, 644 nm, and 703 nm, relating to the transitions of 4G5/2 → 6H5/2, 6H7/2, 6H9/2 and 6H11/2, respectively. The BHT-0.5BCT:0.005Sm3+ powder exhibits optimal emission in these Sm3+-doped BCTH powders. Furthermore, the phase transition temperature can be characterized by the multi-feature changes of the temperature dependent fluorescence intensity.

Effect of Different Ca2+ and Zr4+ Contents on Microstructure and Electrical Properties of (Ba,Ca)(Zr,Ti)O3 Lead-Free Piezoelectric Ceramics

In the preparation of (Ba,Ca)(Zr,Ti)O3 lead-free piezoelectric ceramics, different Ca2+ and Zr4+ contents will greatly affect the phase structure, microstructure, and electrical properties of the ceramics. XRD shows that all samples have pure perovskite phase structure, and the (Ba0.85Ca0.15)(ZryTi1−y)O3 ceramics morphotropic phase boundary region from tetragonal phase to rhombohedral phase near 0.08 ≤ y ≤ 0.1. From the dielectric temperature curve, the phase transition temperature (TO-T) was found near room temperature at 0.12 ≤ x ≤ 0.18 for the (Ba1−xCax)(Zr0.1Ti0.9)O3 ceramics. Both Ca2+ and Zr4+ increase have a significant decrease on the Curie temperature Tc. All samples were revealed as relaxers with diffusivities in the range 1.29 ≤ γ ≤ 1.82. Different from the undoped ceramics, ceramics doped with Ca and Zr ions exhibit saturated P–E hysteresis loops, and their ferroelectric properties are significantly optimized. In particular, the (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 ceramic demonstrated optimal properties, namely d33 = 330 pC/N, kp = 0.41, εr = 4069, Pr = 4.8 μC/cm2, and Ec = 3.1 kV/cm, indicating that it is a viable lead-free piezoelectric contender. Variations in Ca and Zr content have a significant effect on the crystal grain sizes and densities of ceramics, which is strongly associated with their piezoelectricity.

High dielectric permittivity and ultralow dielectric loss in Nb-doped SrTiO3 ceramics

In this study, we prepared a series of Nb-doped SrTiO3 ceramics sintered in both air and N2 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 SrTiO3 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 TiTi′−VO··−TiTi′ 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.

Research on the Electrochemical Properties of Al2−x Zn x O3−α

To understand the electrochemical properties of the Al2O3 based proton conductor in more detail, a solid-state electrolyte Zn-doped Al2O3 was successfully prepared using the solid-state reaction method at the temperatures of 1873 K for 10 h. The phase structure and microscopic morphology of these materials are thoroughly investigated. The structural analysis results revealed that the electrolyte has a pure perovskite phase structure. The crystal grains are relatively uniform, the ceramic material is dense, and the relative density is greater than 97 percent, according to microscopic morphology analysis. The electrical conductivity of the specimen was measured using the two-terminal AC method to clarify the electrochemical properties of Zn-doped Al2O3. The H/D isotope effect of electrical conductivity was studied, and it was discovered that protons are the dominant charge carrier at temperatures ranging from 1073 to 1473 K in hydrogen-rich atmospheres. The electrochemical impedance spectroscopy test showed that in the temperature range of 1073K–1473 K, the conductivity of the sample increases with the increase of temperature, and the electrochemical performance of the sample is the best when the doping amount is x = 0.012. The conductance activation energy () is in the range of 1.01–1.62 eV in hydrogen-rich atmospheres. From the point of view of electromotive force measurement, the theoretical (computational) electrical potential matches the measured potential very well. In a hydrogen-rich atmosphere of 1073–1473 K, the proton mobility of Al2−x Zn x O3−α exceeds 0.90. In this work, we proved that Al2−x Zn x O3−α sample is a proton conductor.

Bandgap engineering and enhancing photovoltaic effect in Bi0.5Na0.5TiO3-based ferroelectric ceramics

Defect-induced semiconducting ferroelectric oxides allow the classically ferroelectric Bi0.5Na0.5TiO3 (BNT) to adopt a low bandgap while maintaining ferroelectricity and enhancing its photovoltaic output. A series of ferroelectric semiconductors of (1–x)Bi0.5Na0.5TiO3-xBaNb0.5Zn0.5O3-δ(BNT-BZN) (x = 0.05, 0.10, 0.15, and 0.20) with photovoltaic effects was successfully synthesised. The BNT-BZN ferroelectric semiconductor exhibits a single perovskite structure phase, with the phase structure shifting from orthogonal to tetragonal with increasing x content. Non-equilibrium stoichiometric defects and interstitial ions in the BZN-modified BNT ceramic were found to slightly reduce the optical bandgap of BNT to 2.51 eV. Under standard simulated sunlight irradiation, the short-circuit current density (Jsc) of the device with x = 0.10 was ∼1.34 μA/cm2, and the Jsc was modestly enhanced to 3.18 μA/cm2 after 60 kV/cm high-field polarizing. The impedance tests showed that the 0.90BNT-0.10BZN ceramic behaves as a p-type semiconductor, suggesting that semiconducting BNT-BZN ceramics have potential applications in photovoltaic devices and photoelectric conversion.

Enhanced dielectric energy storage performance of A-site Ca2+-doped Na0.5Bi0.5TiO3–BaTiO3–BiFeO3 Pb-free ceramics

(1-x) (0.98Na0.5Bi0.5TiO3–0.01BaTiO3–0.01BiFeO3)–xCaTiO3 (NBB-xCT) ceramics were produced using traditional solid-state synthesis methods. The surface morphology, domain structure, and electrical properties of the ceramic samples were systematically studied. In addition, the temperature and frequency stabilities of the NBB-15CT sample at 200 kV/cm were tested. Generally, NBB-xCT ceramics exhibit a typical single perovskite phase structure. The results indicate that the NBB-15CT ceramics showed a high energy density of 3.14 J/cm3 at 250 kV/cm. The piezoresponse force microscopy (PFM) results showed that the addition of CT broke the macrodomains of the 0.98Na0.5Bi0.5TiO3-0.01BaTiO3-0.01BiFeO3 ceramic and helped to form nanodomains, leading to an improved energy storage performance. The above performance indicates that the specimens possess very good temperature-and frequency-dependent energy storage performances at 30–150 °C and 1–100 Hz. Moreover, the electric energy storage and release in the NBB-15CT ceramic indicated that the power density could reach 55.30 MV/cm3 at 180 kV/cm. Therefore, the NBB-15CT ceramic is a promising material for electrical capacitors.

Lowering Synthesis Temperature of BaTiO3-Bi(Zn0.5Zr0.5)O3 Ceramics by Salt Flux Assistance and Dielectric Properties Investigations

Phase formations and dielectric properties of lead free barium titanate bismuth zinc zirconate, BaTiO3-Bi(Zn0.5Zr0.5)O3 (BT-BZZ), were comparatively investigated between two different synthesis routes, solid state reaction and salt flux assistance methods. The perovskite (1-x)BT-(x)BZZ ceramics, where x = 0.02, 0.05 and 0.10, were synthesized by using reagent grade oxides and the NaCl salt was used as a surface active agent to lower the calcination temperature. Phase formations were examined by X-ray diffraction technique (XRD). It was found that the solid solutions of (1-x)BT-(x)BZZ can be obtained with lower temperature at least 200 °C via salt flux assistance method. The NaCl salt addition could result in single phase of perovskite structure at every compositions with the calcination temperature as low as 800 °C. Dielectric measurements revealed that the Curie temperature (Tc) shifted to lower temperature with increase of BZZ concentration. Moreover, the dielectric behavior transformed to diffuse phase transition when x = 0.1. The samples prepared via salt flux assistance method exhibited smaller grain size which were revealed by scanning electron microscope. In addition, P-E hysteresis measurements illustrated the higher high E-field dielectric constant with the narrower P-E loop when the salt flux was applied.

Characterization of structural and electrical properties of Ca0.61Nd0.26TiO3 ceramic tailored by complex ions (Al0.5Nb0.5)4+

Miniaturization and low power dissipation are a trend for the development of ceramic-based microwave devices. Therefore, the decrease of the dielectric loss properties of microwave dielectric ceramic material compounds with a high dielectric constant is considered a quite important subject. In this work, the Ca0.61Nd0.26TiO3 material configuration with orthorhombic perovskite structure was thoroughly investigated by applying the strategy of (Al0.5Nb0.5)4+ substitution at the B-site. More specifically, the Ca0.61Nd0.26Ti1-x(Al0.5Nb0.5)xO3 sample with a nearly 60% increase in the quality factor (Q×f) was obtained. Also, the relationship between the structural and the electrical properties of Ca0.61Nd0.26Ti1-x(Al0.5Nb0.5)xO3 (0 ≤ x ≤ 0.15) samples were explored via performing X‐ray diffraction (XRD) measurements, Raman spectra, transmission electron microscopy (TEM) and calculation of the insulation resistance, etc. The extracted outcomes divulged that samples at x = 0–0.12 formed a single perovskite-structured phase, while the grain size of samples decreased by increasing the x value, leading to a drop decline of both the dielectric constant (εr) and electrical conductivity. Additionally, insights from the acquired Raman spectra confirmed that the stressed-rigid oxygen octahedral networks could lower the positive τf value of Ca0.61Nd0.26TiO3-based ceramic compounds. Interestingly, as the doping content of (Al0.5Nb0.5)4+ increased, the Ti3+ in samples was restrained at x = 0.04, whereas the insulation properties of the samples increased. Hence, the conductivity loss was declined. Furthermore, the TEM images illustrated the appearance of a 1: 1 ordered structure at the B-site of the (Al0.5Nb0.5)4+-doped samples. As a result, the Q×f value of the samples raised from 11,095GHz at x = 0–17,802 GHz at x = 0.12, enhanced by 60%. On top of that, for the sample with x = 0.15, the existence of the Ca2Nb2O7 phase deteriorated the microwave dielectric properties of the Ca0.61Nd0.26Ti1-x(Al0.5Nb0.5)xO3 samples, and especially Q×f value.

Sintering characteristics and microwave dielectric properties of 0.5(Ca0.7Nd0.2)TiO3–0.5(Li0.5Nd0.5)TiO3 ceramics with La2O3–B2O3–CaO–P2O5 additive

In this paper, the effects of glass-ceramics sintering aid, La2O3–B2O3–CaO–P2O5 (LBCP), on the sinterability, microstructure, and microwave dielectric properties of 0.5(Ca[Formula: see text]Nd[Formula: see text]TiO3–0.5(Li[Formula: see text]Nd[Formula: see text]TiO3 (CNT–LNT) ceramic have been investigated. The results indicated that LBCP glass-ceramics has good wettability to CNT–LNT (contact angle at 980[Formula: see text]C is 31.9[Formula: see text]), and it can be used as an effective sintering aid to reduce the sintering temperature of CNT–LNT ceramic from 1300[Formula: see text]C to 980[Formula: see text]C. LBCP glass-ceramics did not change the main crystal phase (perovskite structure) of the sample, but a small amount of LaBO3 and LaPO4 phases was precipitated. Since the LaBO3 and LaPO4 phases are low-loss phases, it is believed that the crystal phases can improve the dielectric properties of the sample, especially the dielectric loss. The samples with 10 wt.% of glass additive sintered for 4 h at 980[Formula: see text]C exhibit the optimized properties: a high dielectric constant of 80.8 and a [Formula: see text] value of 2031 GHz. The high [Formula: see text] and [Formula: see text] value, coupled with a relatively low sintering temperature, suggest that the optimized compositions have the potential to be used in microwave low-temperature co-fired ceramics applications.