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In this work, the niobate-based borate glass-ceramic system K2O–Na2O–Nb2O5–B2O3 was proposed for the first time, in which the presence of alkali metal oxides not only tends to form ferroelectric crystalline phase to obtain high permittivity, but also optimizes the borate glass network structure to enhance the breakdown strength. The change of borate glass network structure and the influence on conductivity and carriers migrate is systematically discussed. The results show that the high breakdown performance is attributed to the transformation from [B∅2O−] triangle to [B∅4]- tetrahedron realizes the high extent of glass network polymerization, which effectively impedes carriers migration and reduces the conductivity. The high permittivity and low dielectric loss are obtained in the range of room temperature to 200 °C. Compared to other niobate-based glass-ceramics, the potassium sodium niobate borate glass-ceramic simultaneously achieve high discharge energy density, high power density and rapid discharge rate (∼14 ns).

Aiming at the problem that power density and energy density are difficult to obtain simultaneously under low field, a novel composition (1-x)Na0·5Bi0·5TiO3-xBaZn1/3Ta2/3O3((1-x)NBT-xBZT) was designed and fabricated via solid-state methods. With the addition of BZT, the crystal lattice, structural symmetry, grain size, and dense degree were all increased proved by XRD, Raman, and Archimedes drainage method et al. Because of the enhancement of relaxor behavior, the x=0.10 sample displayed a high permittivity er of 2871±15% and a low dielectric loss tan δ ≤ 0.025 in the wide temperature range of 60–400 oC. This ceramic also showed maximum recoverable energy density Wd (2.07 J/cm3) with high efficiency η (71.5%) under a low field of 150 kV/cm. Moreover, pulse discharge testing proved that this ceramic possessed both a significant discharge energy density WD (0.96 J/cm3) and a record high power density PD (108.54 MW/cm3). This work provided a promising material for high power and energy applications.

In this work, novel (1 [Formula: see text])(0.75Na[Formula: see text]Bi[Formula: see text]TiO3)-0.25Sr(Zr[Formula: see text]Sn[Formula: see text]Hf[Formula: see text]Ti[Formula: see text]Nb[Formula: see text])O3-[Formula: see text]NaNbO3 (NBT-SZSHTN-[Formula: see text]NN, [Formula: see text] = 0.1, 0.15, 0.2, 0.25) ceramics were fabricated. The influence of co-doping of NN and high entropy perovskite oxide (SZSHTN) on the phase structure, microstructure and dielectric properties of NBT-based lead-free ceramics was investigated. Dense microstructure with a grain size of [Formula: see text]5 [Formula: see text]m is observed. When [Formula: see text] = 0.25, a wide dielectric temperature stable range of −35.4–224.3[Formula: see text]C with a low temperature coefficient of capacitance of [Formula: see text] 10% is achieved, fulfilling the industry standard of Y9P specification. Furthermore, excellent energy storage performance with recoverable energy density of 2.4 J/cm3, discharge efficiency of 71%, power density of 25.495 MW/cm3 and discharge rate [Formula: see text] 200 ns are simultaneously obtained, which shows great potential for high temperature capacitor applications.

Bulk charge recombination is one of the main blocks to the photocatalytic efficiency. The internal electric field brought by ferroelectric polarization in ferroelectric materials and the decreasing transport distance of carriers by tailoring morphology have been proposed to overcome this problem. Herein, thin-sheet Na0.5Bi0.5TiO3 photocatalyst with strong ferroelectric polarization was prepared by topochemical molten salt synthetic (TMSS) method. Without co-catalysts, thin-sheet Na0.5Bi0.5TiO3 represented excellent photocatalytic performance that degradation efficiency towards RhB, tetracycline and ciprofloxacin were 99.8%, 76.6% and 68.3% under simulated sunlight within 100 min, respectively. P-E loops and XPS measurement demonstrated that thin-sheet shape led to a large number of atoms missing on the surface, resulting in lattice distortion, and the spontaneous polarization was greatly improved at the same time. The synergetic effect of strong ferroelectric polarization and thin-sheet shape of Na0.5Bi0.5TiO3 promoted the separation of photo-generated carriers in the bulk. This work proved that single ferroelectric materials possessed glorious ability for photocatalytic reaction via minishing the thickness and enhancing the degree of distortion to build strong internal electric field.

Dielectric ceramics with excellent discharge properties and high-temperature stability are promising and challenging for pulse power applications. In the present work, novel (1 − x)Na0.5Bi0.5TiO3–xBaMg1/3Ta2/3O3 ((1 − x)NBT–xBMT) ceramics were designed and fabricated, which showed a high permittivity er of 2102.688 ± 15% at 24–377 °C and a low dielectric loss tan δ ≤ 0.02 at 34–299 °C in x = 0.15 sample. After BMT modification, the NBT ceramics showed a nearly cubic tolerance factor of 1 and enhanced relaxor behavior. Consequently, a significant energy storage density Ws ~ 2.8 J/cm3 with high efficiency η ~ 78.67% was obtained in x = 0.15 sample at 175 kV/cm. Furthermore, pulse discharge testing demonstrated that this ceramic sample exhibited a satisfying discharge energy density WD ~ 0.88 J/cm3, a high power density PD ~ 59.07 MW/cm3 and a fast discharge speed (~ 50 ns) up to operating temperature of 170 °C, superior to most lead-free ceramics. The present work provides a novel composition with superior discharge properties.

The (1-x)BaTiO3-xCuO ceramics (x = 0, 0.5, 1.0, 1.5 and 2.0 wt%) were prepared by the traditional solid-state reaction method. The influence of the distribution of Cu-rich phase on the microscopic morphology, dielectric and complex impedance of BaTiO3 was studied. All samples show tetragonal phase structure. The images of SEM and EDS show that different amounts of CuO result in diverse distribution of Cu element at the grain boundary. The Cu element is concentrated in the grain boundary in a continuous network structure for x = 1.0 wt% and x = 2.0 wt%. And the Cu elements are mainly distributed in the punctate structure at triple junction for x = 1.5 wt%. Due to the pinning effect of Cu-rich phase at the triple junction, the grain of the BaTiO3 is refined. Not only is it beneficial to increase the permittivity and reduce the dielectric loss, but also improve the frequency stability of the dielectric performance at low frequency. In addition, the impedance analysis shows that the resistance and activation energy of conductivity of (1-x)BaTiO3-xCuO ceramics depend on the synergistic effect of the grain size and Cu-rich phase at the grain boundary. The smaller grain and the more Cu-rich phase at grain boundary, the greater resistance and activation energy of conductivity.

Lead-free antiferroelectric (AFE) materials have seen a surge of research activity in environmentally friendly energy storage technologies. Recently, considerable work has been done to improve the stability of AFE in NaNbO3 (NN) ceramics, but it remains a grand challenge to obtain typical AFE characteristic double P-E loops in NN ceramics at ambient conditions. In a preliminary estimate of tolerance factor versus average electronegativity difference, we reported the stable AFE phase in 0.95NaNbO3-0.05BiMg2/3Ta1/3O3 sample. The orthorhombic Q to P phase transition was verified by XRD and TEM. Then, the remarkable double P-E loops were obtained in 0.95NaNbO3-0.05BiMg2/3Ta1/3O3 ceramics. Furthermore, a phenomenological model was proposed to explain the P-E relationships and our results. Compared with other reported compounds, the TP-R decreased more obviously from 350 °C to 200 °C. Superior temperature stability (variations of maximum current, current density, and power density within 15% over 30–140 °C) and field induced phase transition were also confirmed by the pulse charge testing. Our work develops a new road for achieving room-temperature double P-E loops in NN ceramics by BiM1M2O3 (M1 might be Mg, Zn, etc; M2 might be Nb, Ta, etc) additives.

For the urgent demand of environmental protection and energy conservation, it is of great significance to develop environmentally-friendly dielectric ceramics with outstanding characteristic of energy storage and quick charge discharge capacity. For this study, we applied a strategy to achieve the enhancement of energy storage performance in (Ca0.5Sr0.5)1-xMgxTiO3 (abbreviate as CSMTx, x = 0.005, 0.010, 0.020, 0.040) linear ceramics based on the introduction of Mg2+ ion. Scanning electron microscopy and complex impedance measurement reveal that Mg2+ ion doping can refine grain size and increase grain boundary density, which results in grain boundary barrier strengthening owing to high-resistance grain boundaries. As a result, the marvellous energy storage properties, including an ultrahigh recoverable energy density of 2.88 J/cm3 combined with a giant energy efficiency of 90% are concurrently obtained in (Ca0.5Sr0.5)0.99Mg0.01TiO3 ceramic at an enhanced breakdown field (460 kV/cm). Meanwhile, this composition ceramic also exhibits the superior stability of frequency (1–1000 Hz) and temperature (20–100 °C) with minimal variation. In addition, the actual performance of ceramic capacitors in operation can be evaluated via the pulsed charge-discharge process. Delightedly, the superfast discharge speed (t0.9 = 20.4 ns), large current density (CD) of 421.23 A/cm2 and ultrahigh power density (PD) of 25.27 MW/cm3, as well as prominent thermal stability (20–100 °C) are synchronously produced in the CSMT2 ceramic. These merits qualify the unleaded linear ceramic as a competitive candidate for high-power capacitor applications, which offers a practicable approach for exploration on high-performance dielectric materials.

Glass-ceramics possessing high power density, energy density and fast charge-discharge rate during a wide temperature range are considered to be the ideal materials for pulse power applications. Under the premise of negligible effect on the glass network structure, the energy storage performance was improved by introducing Na+ ions, which reduced the carrier mobility and the conductivity in this study. The potassium sodium niobate silicate initial glass were synthesized by the traditional melting method, and the glass-ceramics were prepared by the crystallization treatment at 800 °C for 2 h. Introducing sodium ions promoted the formation of Na0.35K0.65NbO3 phase, and increased the permittivity to 104 simultaneously. Superior high breakdown strength (750 kV/cm) was obtained because of the competition between two physical mechanisms of electrical conductivity and micromorphology. When the sodium oxide content was 0.375, the discharge energy density of 2.44 J/cm3 and high energy storage efficiency of 93% were obtained. Compared with ceramics, polymers and other niobate-based glass-ceramics reported currently, this work had achieved high actual discharge energy density (0.156 J/cm3) and high power density (19.6 MW/cm3) under low field strength, and had an extremely fast discharge rate (~14 ns) and excellent wide temperature stability (20–120 °C).

The pulse discharge characterization of perovskite dielectric ceramics, which has confronted a barrier between research and application, has the problems of inconsistent test standards and lack of comparability. To mitigate this issue and further advance the application process, we suggest an extrinsic standard (for convenience of comparison) for energy dielectric ceramics of thickness (0.2 mm), electrode area (4 mm2) and operation voltage (2 kV). We report the pulse discharge performance parameters of three typical dielectric materials: relaxor ferroelectric (Na0.5Bi0.5)0.9Li0.1Ti0.9Ta0.1O3 (NBLTT), paraelectric Ca0.6Sr0.4TiO3 (CST) and linear dielectric K0.5Na0.5NbO3 (KNN) glass ceramics through computer simulation and fitting of pulse discharge curves based on the resistance-inductance-capacitor pulse discharge circuit. The NBLTT ceramics exhibited higher peak current (16 A under 100 kV/cm) and stability with minimal variation less than 15% from 20 to 150 °C during pulse discharge compared with linear dielectric and ferroelectric glass ceramics. In addition, the NBLTT system holds the fast discharge time (90% of the discharge energy density released in about 100 ns) and good fatigue resistance. The short discharge time, high thermal stability and low medium voltage (500–5000 V) make the NBLTT ceramics promising for pulse capacitor in large current and low electric operation voltage conditions. An operable comparison standard and the research frontiers of pulsed dielectric materials are prospected.

The excellent energy storage and pulse charge-discharge performance ceramics with high temperature stability and optical transmissivity are competitive for the development of electronic devices. In this work, comprehensive improved performances are simultaneously realized in DyxSr1-xTiO3 (DST) ceramics through defect and interface engineering. Meanwhile, increased high insulation grain boundary and reduced carrier mobility promote the increase of grain boundary resistance, and the increase of grain resistance primarily originates from the fact that D y T i ' can easily attract oxygen vacancy, forming defect dipoles and restraining the movement of oxygen vacancies. Additionally, the relative density of ceramics is increased by sintering in O2 and doping Dy ions. Hence, x = 0.008 ceramics exhibit high coverable energy storage density of 4.00 J/cm3, high energy storage efficiency of 89.49%, excellent frequency (1Hz-1 kHz) and temperature stability (20-120 °C) and transmittance of >60% are achieved at 510 kV/cm at 0.2 mm. Furthermore, x = 0.008 ceramics possess the prominent current density of 420.1 A/cm2 and the prominent power density of 19.2 MW/cm3. Meanwhile, the short discharge rate of 20 ns and excellent stability of temperature (20-120 °C) are also achieved, suggesting that it is one candidate with strong potential for the application of lead-free high power capacitors.

Colossal permittivity (CP) ceramics have a great potential in the development of miniaturization, integration and lightweight of electronic components. In this work, NdxSr1-xTiO3 (0.000 ≤ x ≤ 0.014) (NST) ceramics are successfully prepared via sintering in N2. Simultaneously microstructure and dielectric properties of NST ceramics are characterized. It can be found that 0.010 ≤ x ≤ 0.014 ceramics show CP (>20000, 20–1 × 106 Hz) and low dielectric loss ( T i T i ' , N d S r ⋅ , V O ⋅ ⋅ ) forms the defect dipoles ( Ti Ti ' − N d S r ⋅ , T i T i ' − V O ⋅ ⋅ − T i T i ' ) and the defect clusters ( V O ⋅ ⋅ − 3 T i T i ' − N d S r ⋅ ), which produces the electron pinning effect and restricts the long-range movement of the carriers. Additionally, the grain boundary with high insulation resistivity plays a major role in the resistance of ceramics, and it also acts as a high barrier layer to limit the movement of several delocalized carriers.

(1-x) (K2O–Na2O–2Nb2O5)-x (2BaO–Nb2O5–2SiO2) glass-ceramics with x = 0.10, 0.15, 0.20, 0.25 have been successfully prepared by traditional melting method. XRD and microstructure analysis demonstrate that all glass-ceramics are crystallized into uniform Na0.9K0.1NbO3 and K2(NbO)2(Si4O12) ferroelectric crystalline phase. Increasing x promotes the formation of Ba2NaNb5O15 phase with a tungsten bronze structure. Raman and complex impedance data confirmed that Ba2+ is introduced to repair the disruption of the glass network and make carrier migration difficult when x = 0.15. Thus, the x = 0.15 glass-ceramic sample possesses a maximum calculated energy storage density of 2.32 J/cm3 under 820 kV/cm because of a high degree of polymerization (DOP) glass network structure. Moreover, the pulsed discharge-charge tests are carried out to evaluate actual energy storage performance.

High performance colossal permittivity (CP) ceramic materials are indispensable for the development of electronic devices. In this work, excellent Sr1-xDyxTiO3 (0.000 ≤ x ≤ 0.018) ceramic samples were prepared through a traditional solid phase method. It can be found that the insulation resistivity of 4.7 × 107 Ω/cm3 (DC 100V), the CP of 26712 and the low dielectric loss of 0.0065 (1 kHz) are obtained in x = 0.008 ceramic samples sintered in N2. Based on the analysis of XRD, XPS and comparison of sintering in different atmospheres, the excellent dielectric property is mainly determined by defect dipoles associated with oxygen vacancy (eg. Ti Ti ' − V O ⋅ ⋅ − Ti Ti ' ). These defect dipoles limit the long-range transition of electrons and result in electronic pinning effect. Additionally, it can be perceived that the insulation resistivity of 1.12 × 109 Ω/cm3 (DC 100 V), the CP of 23134 and the low dielectric loss of 0.0098 (1 kHz) are achieved in x = 0.008 ceramic samples after reoxidation. According to the analysis of complex impedance spectroscopy, the improvement of the insulation resistivity of x = 0.008 ceramic samples is mainly attributed to the increase of the grain boundary resistance.

The high energy density and power density dielectric ceramics with wide frequency and temperature stability are competitive materials for pulse power capacitors. This research proposes an effective strategy for enhancing energy storage performance of Ca0.5Sr0.5TiO3 ceramics through the introduction of Sn4+ ion. This ion restrains grain growth, increases high insulating grain boundaries, and thus enhances the barrier height of grain boundaries, which are demonstrated in SEM micrographs and complex impedance. The Ca0.5Sr0.5Ti0.97Sn0.03O3 (SnCST3) ceramics possess high energy storage density of 2.06 J/cm3 and efficiency of 95% under breakdown strength of 330 kV/cm, which get benefit from wide band gap of 5.3 eV. While the exceptional stability with minimal fluctuation (

The present work investigates the influence of donor doping and its concentration on the flash sintering behavior of barium titanate. The characteristic of non-ohimic conductivity during flash event shows that flash sintering is associated with dielectric breakdown due to the similar physical phenomena. The polarization of dielectric particle contributes to the enhancement of local electric field strength. The magnified electric field caused by local charges accumulation gives rise to dielectric breakdown phenomenon during flash sintering. The SEM measurement indicates an obvious breakdown channel through the inside of sample, which provides a convincible evidence for dielectric breakdown. In addition, the impacts of temperature and field on carrier activation and migration are emphasized. Eventually, the non-ohmic conductivity can be explained by the physical phenomenon of dielectric breakdown described by Poole-Frenkel Emission.

A series of high entropy Ba(Zr0.2Ti0.2Sn0.2Hf0.2Me0.2)O3 (Me=Y3+,Nb5+,Ta5+,V5+,Mo6+,W6+) perovskite oxides were synthesized by using a solid state reaction method. Three multiple-cation solid solutions formed pure phase compounds, and only two compounds were sintered into ceramics. Microstructure analysis showed the influence of configurational entropy on phase stability and grain growth. Dielectric measurements showed that the high entropy ceramics possessed decent temperature stability of permittivity from 25 °C to 200 °C, low dielectric loss (

SrBi2Nb1.8−xCoxFe0.2O9 (SBCFN, x = 0, 0.1, 0.2, 0.3 and 0.4) ceramic samples were fabricated by traditional solid-state reaction. Structure was detected by XRD and SEM, which demonstrated that all samples showed pure orthorhombic Aurivillius structure and the plate-like grains were observed. The morphology gradually disappeared with Co ions doping. Relaxation peak in low-temperature region of Co-doped samples was discussed in dielectric spectra. Besides, the decrease in resistance induced by the motion of first ionized oxygen vacancies was revealed by fitted Arrhenius curves and supported by Correlated Barrier Hopping conduction model. The contribution of leakage current in P–E loops was observed. The optimum magnetic property was obtained when the molar ratio of Fe3+ and Co3+ is 1:1, which is attributed to introduction of double exchange interaction (Fe–O–Co). At the same time, the Eg was narrowed due to hybridization and lattice distortion, which was coincident with the result of resistance.

Multiferroic Bi5−xYxTi3FeO15 (BYTF-x, x = 0, 0.1, 0.3, 0.5, 0.7) ceramics were synthesized through the conventional solid-state reaction. The structure, dielectric, multiferroic and magnetodielectric properties of BYTF-x were investigated in detail. X-ray diffraction confirmed that all the samples were layered Aurivillius structure. Upon increasing Y content, the grain size of samples slightly decreases. The dielectric permittivity increased with Y doped. The Y doping has no effect on microstructural changes of plate-like grains which verified though field-emission scanning electron microscopy. The minimum remanent polarization (2Pr = 2.48 μc/cm2) was observed in BYTF-0.3 ceramic and the maximum magnetodielectric coefficient value of 1.23% was obtained in BYTF-0.3 ceramic perhaps result from the coexistence of Fe2+ and Fe3+. Additionally, weak ferromagnetic is only found in BYTF-0.3 ceramic. The ferromagnetism can be attributed to ferromagnetic double exchange interactions (Fe2+–O–Fe3+) and the spin canting of tilting FeO6 octahedra via the Dzyaloshinskii–Moriya interaction. These results indicate that Y doping Aurivillius phase may be the potential candidates for exploring superior room-temperature multiferroics.

High ambient temperature (>150 °C) of pulse power capacitors raises the strict requirements for dielectric ceramics. (1-x)Na0.5Bi0.5TiO3-xLaAlO3 ((1-x)NBT-xLA for short) dielectric ceramics with superior pulse discharge performance at high ambient temperature were designed and fabricated. With LA addition, pseudo-cubic structure and reduced tolerance factor were available, benefiting to enhance the relaxor behavior. The grain size and shape are greatly changed to submicron degree and square, respectively. The x = 0.03 sample shows typical pinched P-E loops and ultra-high Pm of 50 μC/cm2. The x = 0.07 sample exhibits ultra-high Wd of 3.18 J/cm3 and η of 60% under relative low field of 210 kV/cm mainly due to its high polarization 45 μC/cm2. This ceramic also shows a high power density of 20 MW/cm3, high pulse discharge energy density(WD) of 0.45 J/cm3, high current density of 400 A/cm2 and a high speed discharge duration of 80 ns at high ambient temperature (150 °C).

The electrostrictive effect plays an important role in the electric-field-induced strain (electrostrain) of ferroelectric ceramics. This is especially true in high-electric-field regions because of the high-order coupling effect between electric-field-induced polarization and electrostrain. In this study, the electrostrictive properties of (1-x)(Bi0.5Na0.5)TiO3-x(Ba0.85Ca0.15)(Ti0.9Zr0.1)O3 (BNT-xBCZT, x = 0.1, 0.2, 0.3, 0.4, 0.5, and 0.6) ferroelectric ceramics were investigated in the temperature range 30 °C–120 °C for obtaining high thermally stable electrostrains and for understanding the effect of composition on the longitudinal electrostrictive coefficient Q33. High electrostrains (>0.2% at 60 kV/cm) with good thermal stability (variation of less than 10%) in the tested temperature range were obtained for x = 0.1. Most importantly, Q33 of BNT-xBCZT ceramics increased almost linearly from 0.0244 m4/C2 to 0.0374 m4/C2 when x increased from 0.1 to 0.6, suggesting a composition-dependent nature. In addition, Q33 of pure BNT (0.0215 m4/C2), which has been unavailable to date, was extracted from this linear relationship. Furthermore, we revealed that the increase in Q33 is mainly due to the increase in the cell volume. Our results not only clarify the composition effect on Q33 in BNT-xBCZT ceramics but also provide a way to enhance Q33 by increasing the cell volume through appropriate doping of ions or perovskite ferroelectric compounds.

(1 − x)BiFeO3–xLaAlO3 [(1 − x)BFO–xLA] ceramics were synthesized by a conventional solid-state method. XRD and Raman results revealed a series of structural transitions R3c → R3m (x = 0.1). The grain size can be decreased to ~ 1 μm by LA addition. With increasing contents of LA, maximum magnetization was enhanced monotonically by the composition-driven lattice distortion. Furthermore, the ceramics 0.90BFO–0.1LA in this work showed improved ferroelectricity, decreased leakage current density and had a high breakdown strength of 260 kV/cm at the same time. On one hand, a maximum magnetodielectric coefficient (MC, αMD) of 3.59% was achieved in 0.80BFO–0.20LA sample. On the other hand, the x = 0.1 sample showed a high αMD of 1.4% (± 10%) at a wide frequency range of 0.7–300 kHz. These results demonstrated the BFO–LA ceramics can be a superior magnetic field sensing material.

The magnetoelectric composites of (1-x)BaTiO3-xSr2CoMoO6 (x=0.02, 0.04, 0.06, 0.08, 0.10 and 0.12) are synthesized successfully via solid state reaction. The dielectric, multiferroic and magnetodielectric properties were discussed in details. The XRD data confirm the single perovskite phase among the composites. In addition, as the content of Sr2CoMoO6 increase, the diffraction peaks shift to higher angle which indicates the gradually decreased lattice parameters. The observed dielectric relaxation phenomenon could be attributed to Maxwell-Wagner (MW) model. The weak ferromagnetism was observed for x=0.02, 0.04 with the remnant magnetization (Mr) 0.025 memu/g, 0.065 memu/g and coercivity (Hc) 4 Oe, 10 Oe, respectively despite the anti-ferromagnetic nature of Sr2CoMoO6. Furthermore, the M − H hysteresis loops of (1-x)BaTiO3-xSr2CoMoO6 change obviously with polarization state, which is related to the ordering degree of the Co and Mo sites. The reason for observed magnetodielectric effect is the influence of magnetoresistance (MR) on Maxwell-Wagner (MW) effect.

The application of numerous colossal permittivity (CP, > 103) materials was limited on account of relatively higher dielectric loss (>0.05). In this work, the xwt% B2O3 (x = 0, 0.5, 1, 2, 4) adding Ti0.99(Eu0.5Nb0.5)0.01O2 (TENO-xwt% B2O3) ceramics were prepared by a traditional solid state method. SEM analysis indicated that the average grain sizes obviously decreased by adding B2O3 and the low dielectric loss corresponding with the colossal permittivity were obtained in all samples. Especially, the higher permittivity of 4.1 × 104 and lower dielectric loss of 0.012 were achieved while x = 2 at 1 kHz and room temperature respectively, accompanying with good temperature stability ranging from −55 °C to 200 °C. Moreover, the formation mechanism of excellent dielectric properties was studied on the basis of analysis of the SEM, complex impedance and electric modulus. The results showed that the addition of B2O3 refined the grains and strengthened the interface effect. Furthermore, the B2O3 existing in the grain boundary formed barrier layer which hindered the long range motion of electrons.

(Ca0.5Sr0.5)1-1.5xLaxTiO3 (x = 0.000, 0.050, 0.075, 0.100, 0.150) ceramics were successively fabricated by conventional solid state method. Structure characterization were detected by XRD and SEM, demonstrating the influence of La2O3 doping on the microstructure. In addition, this effect on relaxor behavior corresponding to resistivity of grain boundary was discussed by dielectric and impendance spectra. The determining band gap energy (Eg) was estimated by Ultraviolet–Visible Spectrophotometry in order to investigate the effect of band gap on the breakdown strength. The dielectric breakdown strength was found to significantly enhanced on the basis of Ca0.5Sr0.5TiO3 ceramics with La2O3 doping, the (Ca0.5Sr0.5)0.8875La0.075TiO3 samples possessed widest band gap (∼5.2 eV) and exhibited maximum breakdown strength of 370 kV/cm corresponding with a large recoverable energy storage density of 2.07 J/cm3. Furthermore, the excellent stability of energy storage properties and ultrahigh energy efficiency of above 93% at wide frequency (1–1000 Hz) as well as high temperature (20–180 °C) was obtained for (Ca0.5Sr0.5)0.8875La0.075TiO3 ceramics, which reveal samples as good candidate for linear energy storage fileds.

In this work, the NBT ceramics are successfully flash sintered at a direct current 30 mA/mm2 for 30 s under different initial electric field. Subsequently, the actual temperature of samples is estimated by blackbody radiation theory under different conditions. The calculation results show that the sample temperature is close to the densification temperature of NBT ceramics used in conventional method. The rapid densification mechanism is discussed by wetting of local contact particles due to the asymmetrical Joule heating. In particular, we analyzed the particle transport mode during flash sintering in terms of particle diffusion. It is believed that the transform in the particles transport mode from solid diffusion to flow mass transfer accelerated the particles diffusion rate, which ensure the particle rearrangement and achieve the local shrinkage of particles in a short period of time.

The Sr0.8(Na0.5Bi0.5)0.2TiO3 (SNBT) ceramics were prepared by different methods as conventional sintering (CS) and microwave sintering (MS), which showed different performance. The impact of MS method on the microstructure and energy storage properties of SNBT ceramics were investigated in this study. The MS SNBT ceramics showed smaller average grain size (G), homogeneous grain size distribution and denser microstructure. Compared with CS SNBT ceramics (1.7 μm), the G of MS SNBT ceramics was smaller (0.55 μm). The MS SNBT ceramics showed much improved energy storage properties over the CS SNBT ceramics. The higher breakdown strength (Eb) and energy density (Jd) of MS SNBT ceramic were 26.12 kV/mm and 2.28 J/cm3, respectively, which were higher than that (21.01 kV/mm of Eb, 1.48 J/cm3 of Jd) of CS SNBT ceramic, while energy storage efficiency (ƞ) of MS SNBT ceramic was 74.77%, which was higher than that (73.21%) of CS SNBT ceramic.

To further manipulate the dielectric properties of (Na0.5Bi0.5)0.775Ba0.225Ti0.775Sn0.225O3 ceramics, (Na0.5Bi0.5)0.775Ba0.225Ti0.775Sn0.225O3 − x wt% Bi2O3–B2O3–ZnO (BBZ) ceramics were prepared via a conventional solid state reaction method, whilst the effect of BBZ glass content on dielectric and ferroelectric properties was investigated. In XRD patterns, the minimal secondary phase of Zn3(BO3)2 can be detected in these compounds when x > 5. With the addition of BBZ glass, diffuse phase transition behavior (DPT) and the high temperature stability of permittivity were enhanced. When x = 7, a high permittivity of 1600 ± 15%, from ~ 50 to ~ 475 °C was obtained. Additionally, a high Wd of 1.4 J/cm3 and 𝜂 of 75.5% (measured at 150 kV/cm) were achieved due to the enhanced Pm of 24 μC/cm2. This work demonstrated that the study on (Na0.5Bi0.5)0.775Ba0.225Ti0.775Sn0.225O3 ceramics with BBZ glass addition providing an adequate strategy to enhance Pm.

Single-Phase Aurivillius SrBi3Nb2FeO12 ceramics were prepared by conventional solid-state method. BiFeO3 was successfully introduced into SrBi2Nb2O9 which was confirmed by XRD and Raman results. Plate-like morphology grains which are 400–600 nm in thickness and 2–4 µm in length were observed for SrBi3Nb2FeO12 ceramics. Their permittivity and dielectric loss at 1 MHz are about 135 and 0.018, respectively. Two permittivity peaks were observed in the temperature dependent permittivity curves. Ferroelectric and weak antiferromagnetic properties were obtained simultaneously at room temperature. X-ray photoelectron spectroscopy (XPS) was carried out to investigate the chemical state of SBNF and Fe ion was found in mixed state. These results indicate that three-layered SrBi3Nb2FeO12 ceramics can be used as a kind of multiferroics in further research.

A novel technique of low temperature and fast sintering is expected to meet the productive requirements of reducing energy consumption and improving efficiency. In this work, a dense Nb-doped BaTiO3 ceramic is obtained by a sintering method applying a direct current electrical field of 140 V cm−1 for 30 s at 1055 °C. In particular, the rapid densification mechanism of flash sintering Nb-doped BaTiO3 ceramic is explained by a model about liquid film which is formed by wetting at particle contacts, due to the Joule heating runaway. It is believed that the capillary forces generated from liquid film play a dominant role during flash sintering, which ensure the compaction of local particles and achieve the densified specimen in a relatively short time.

Dense (1-x)(0.775NBT-0.225BSN)-xBZ ternary ceramics were fabricated by solid state methods and their dielectric and ferroelectric properties were systematically investigated. XRD and Raman analysis indicate that the structure complexity and phase diffusion were enhanced in 0.775NBT-0.225BSN relaxor system with BZ addition. With increasing the contents of BZ, average grain size greatly decreases. Dielectric study shows that dispersive relaxor-like behavior was beginning to convert to diffusive phase transition when x ≥ 0.2. Along with increasing the BZ contents, the slop of P-E loops and the energy-loss can gradually decrease. When x = 0.2, both a high Wd of 2.08 J/cm3 and η of 88.8% were achieved, due to the slimer P-E loops, the high Pm (∼20 μC/cm2) and Eb (245 kV/cm). As a result, the ternary ceramics system may be a good candidate for energy-storage ceramics of NBT-based materials.