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Abstract In this work, a novel lead-free relaxor-ferroelectric ceramics of (1-x)(0.65BaTiO 3 -0.35Bi 0.5 Na 0.5 TiO 3)-xSrY 0.5 Nb 0.5 O 3 ((1-x)BTBNT-xSYN x = 0.02–0.12), was designed and prepared by the conventional solid state reaction method. The results show that all of the sintered samples have a perovskite structure. The Curie Temperature (T c) moves to the low temperature side which causes the high dielectric constant at room temperature, and the ferroelectric hysteresis loop becomes slimmer and slimmer with increasing the content of SYN. Meanwhile, the optimal energy storage properties can be obtained in 0.92BTBNT-0.08SYN ceramic with an impressive discharged energy density (W rec) of 1.36 J/cm3 under 152 kV/cm, and the charge-discharge efficiency reaches 74.3%. Therefore, all these results indicate that (1-x)BTBNT-xSYN lead-free ceramics can be applied for pulsed power capacitors. Highlights • The high breakdown strength value of the ceramic can reach 152 kV/cm. • SrY 0.5 Nb 0.5 O 3 doping can decrease the grain size and thus increase the breakdown strength. • A large energy storage density of 1.36 J/cm3 can be obtained. [ABSTRACT FROM AUTHOR]

Abstract: A series of Bi(0.5−x)Lax(Na0.82K0.18)0.5Ti0.96Zr0.02Sn0.02O3 (BNKTZS‐xL) (x=0–0.18) lead‐free ceramics were designed and fabricated by using a conventional solid‐state sintering method. The effects of the La3+ content on the properties of the BNKTZS‐xL ceramics were systematically investigated. Temperature‐dependent dielectric constant curves displayed two depressed anomalies, which resulted in significantly improved dielectric temperature stability. The polarization–electric field hysteresis loops illustrated that the addition of La3+ markedly enhanced the breakdown strength, energy‐storage density, and energy‐storage efficiency. A maximum energy‐storage density of 1.95 J cm−3 was obtained for the material with x=0.10, and the energy‐storage efficiency significantly improved from 28 to 85 % upon increasing the value of x from 0 to 0.18. These properties indicate that the BNKTZS‐xL ceramics may be promising lead‐free materials for high energy‐storage capacitor applications. [ABSTRACT FROM AUTHOR]

The (1-x)SrTiO 3 -xBi 0.5 (Na 0.82 K 0.18 ) 0.5 Ti 0.96 Zr 0.02 Sn 0.02 O 3 ((1-x)ST-xBNKTZS) lead-free ceramics with x = 0–0.5 were designed and fabricated using the conventional solid-state sintering method. Their phase structure, microstructure, dielectric, ferroelectric and energy storage properties were systematically investigated. The dielectric constant of (1-x)ST-xBNKTZS ceramics increases gradually and reaches the maximum value (∼2650) with x = 0.5 at 1 kHz, which is 8.83 times as large as that of pure ST (∼300). All the samples show slim polarization-electric field ( P-E ) hysteresis loops and the maximum polarization ( P max ) can be improved to 20.65 μC/cm 2 with x = 0.5 at 100 kV/cm, which is 6.20 times as large as that of pure ST (3.33 μC/cm 2 ). The sample with x = 0.4 exhibits a high energy storage density (1.45 J/cm 3 ) and a high energy storage efficiency (86%) simultaneously. These results indicate that the (1-x)ST-xBNKTZS ceramics may be promising lead-free materials for high energy storage capacitors. [ABSTRACT FROM AUTHOR]

A series of Ba 0.85 Ca 0.15 Zr 0.1 Ti 0.9 O 3 (BCZT) ceramics with different contents of B 2 O 3 -Al 2 O 3 -SiO 2 (BAS) glass-ceramics additive were prepared via the conventional solid-state sintering method. The microstructure, dielectric properties, ferroelectric properties and energy storage properties were systematically investigated. The results show that the BCZT and BAS glass-ceramics phases can coexist in the ceramics and the average grain size reduces obviously with increasing the content of BAS glass-ceramics. The addition of BAS glass-ceramics could enhance the breakdown strength of the ceramics obviously. Due to the relatively high dielectric constant and breakdown strength, the estimated energy storage density of the (1-x)BCZT-xBAS ceramics reaches up to 1.153 J/cm 3 when x = 5%, which is improved by 5.5 times as compared with that of the pure BCZT ceramic (0.205 J/cm 3 ). [ABSTRACT FROM AUTHOR]

A series of (1-x)(0.65BaTiO 3 -0.35Bi 0.5 Na 0.5 TiO 3 )-xNa 0.73 Bi 0.09 NbO 3 ((1-x)BBNT-xNBN) (x = 0–0.14) ceramics were designed and fabricated using the conventional solid-state sintering method. The microstructure, dielectric property, relaxor behavior and energy storage property were systematically investigated. X-ray diffraction results reveal a pure perovskite structure and dielectric measurements exhibit a relaxor behavior for the (1-x)BBNT-xNBN ceramics. The slim polarization electric field ( P-E ) loops were observed in the samples with x ≥ 0.02 and the addition of Na 0.73 Bi 0.09 NbO 3 (NBN) could decrease the remnant polarization ( P r ) of the (1-x)BBNT-xNBN ceramics obviously. The sample with x = 0.08 exhibits the highest energy storage density of 1.70 J/cm 3 and the energy storage efficiency of 82% at 172 kV/cm owing to its submicron grain size and high relative density. These results show that the (1-x)BBNT-xNBN ceramics may be promising lead-free materials for high energy storage density capacitors. [ABSTRACT FROM AUTHOR]

In the present work, ternary solid solution ceramics of the (1-x)SrTiO 3 -x(0.65BaTiO 3 -0.35Bi 0.5 Na 0.5 TiO 3 ) (STB100x) were designed and fabricated using a conventional solid-state sintering method. The phase structure, microstructure, dielectric property, relaxation property, ferroelectric property and energy storage property were systematically investigated. The addition of 0.65BaTiO 3 -0.35Bi 0.5 Na 0.5 TiO 3 (BT-BNT) could enhance the saturated polarization of the ceramics obviously. All the samples show a slim P-E hysteresis loop, and the sample with x = 0.3 exhibits a high energy storage density of 1.40 J/cm 3 and an energy storage efficiency more than 90%. These results indicate that the STB100x ceramics may be a promising lead free materials for high energy storage density capacitors. [ABSTRACT FROM AUTHOR]

Magneto-dielectric laminated ceramic composites of x Ba(Fe 0.5 Nb 0.5 )O 3 -(1- x )Bi 0.2 Y 2.8 Fe 5 O 12 (BFN-BYIG) with high volume fractions of the giant dielectric constant material BFN ( x =10, 30, 50, 70 wt%) were fabricated by the solid-state sintering method. Microstructure, dielectric and magnetic properties of the composites were investigated. The composites possess stable dielectric properties in the frequency range from 100 Hz to 1 MHz with high dielectric constant and low dielectric loss. The maximum permeability of the magneto-dielectric laminated composites reaches up to about 25. And the magnetic behaviors are strongly dependent on the mass ratio of BYIG. The results indicate that such multilayer structures of BFN/BYIG can enhance the permeability and decrease the dielectric and magnetic loss efficiently. [ABSTRACT FROM AUTHOR]

Polyaniline(PANI)/CoFeO/BaSrTiO composites were prepared by an in situ polymerization method. The phase structure, morphology and electromagnetic properties of the samples were characterized by X-ray diffraction, scanning electron microscope, transmission electron microscopy, Fourier transform infrared spectrum, vibrating sample magnetometer and vector network analyzer, respectively. Measurements of the reflection loss (RL) show that the maximum RL value of the PANI/0.1CoFeO/0.9BaSrTiO composite is 30.2 dB at 5.6 GHz with the thickness of 3 mm and the bandwidth below 10 dB is 2.6 GHz (from 4.2 to 7.8 GHz). The results indicate that CoFeO and BaSrTiO particles are efficiently coated by PANI so that the PANI/CoFeO/BaSrTiO composites exhibit an enhanced impedance matching between the dielectric and magnetic loss. Therefore, this kind of composites may have the potential as high-efficient absorber for microwave absorbing applications. [ABSTRACT FROM AUTHOR]

ZnO-based linear resistance ceramics were synthesized from ZnO-MgO-AlO-LaO-SiO-FeO at 1320 °C for 3 h by the conventional ceramics method in air. The microstructure and the crystal characteristics were investigated by scanning electron microscope equipped with energy dispersive spectrometer and X-ray diffraction respectively. The influence of FeO content on the linear current-voltage ( I- V) characteristic and dielectric characteristics have been systematically investigated in detail. The results indicated that the main phase of samples doped by FeO was hexagonal wurtzite structure of ZnO with the second phase of ZnAlO. The optimum result of linear I- V characteristic was obtained with nonlinear coefficient of 1.08, when the content of FeO was 0.50 mol%. With the increasing of dopant FeO contents, the dielectric constant and resistivity of ZnO-based linear resistance ceramics were influenced significantly, moreover, the resistance-temperature characteristics presented the negative temperature coefficient effects. [ABSTRACT FROM AUTHOR]

In this letter we report the electrical and magnetoelectric properties of the 0.65BaTiO 3 -0.35Bi 0.5 Na 0.5 TiO 3 /CoFe 2 O 4 composites prepared by the solid-state sintering method targeting low-cost lead-free magnetic field sensor. Excellent electrical and magnetoelectric properties can be observed in the laminate composites compared with the particulate composites. Higher resistivity and lower leakage current can be observed in the laminate composites, which make the electric poling sufficiently and thus enhance the ME effect. The maximum ME coefficient of the laminate composites reaches up to about 113.10 mV/cm Oe, which is ten times as large as that of the particulate composites (10.08 mV/cm Oe). [ABSTRACT FROM AUTHOR]

Abstract: Hexagonal BaTiO3/Ni0.8Zn0.2Fe2O4 (BT/NZO) composites were synthesized by solid–state reaction method. Phase composition, microstructure, dielectric and magnetic properties of the composites were investigated. The BT/NZO composites had giant dielectric constants and very high permeabilities simultaneously. According to Cole–Cole plots, the composites showed a polydispersive nature of the Maxwell-Wagner relaxation. The forming mechanism of hexagonal BaTiO3 in the composites was also investigated. [Copyright &y& Elsevier]

Dense Ni0.37Cu0.20Zn0.43Fe1.92O3.88/BaFe0.5Nb0.5O3 composites were prepared by the conventional solid-state method and sintered at 950°C. The powder x-ray diffraction (XRD) patterns confirm the coexistence of the two phases. The dielectric and magnetic properties are also reported. The results show that the as-prepared composites possess high dielectric constant and permeability, which could be used in high-frequency communications for the capacitor-inductor integrating devices such as electromagnetic interference filters and antennas. [ABSTRACT FROM AUTHOR]

A low loss high-frequency magnetic composite with Y3Fe5O12 (YIG) ultrafine particles embedded in a high-density polyethylene (HDPE) matrix was fabricated by using a simple low-temperature hot-pressing technique. The magnetic and dielectric properties of the as-prepared composites were investigated in detail. The results indicate that as the volume of the ceramic fillers increases, the permittivity, permeability, dielectric and magnetic loss of the composite all increase. The cut-off frequencies of the composites are all above 700 MHz. Since the low resistivity of YIG, the dielectric losses of the composites are high and decrease with frequency in the lower frequency range. Good frequency stability of the permittivities and permeabilities, and low dielectric and magnetic losses within the measurement range have been observed. [ABSTRACT FROM AUTHOR]

Abstract: Dense Ni0.37Cu0.20Zn0.43Fe1.92O3.88/(Ba0.6Sr0.4)TiO3 composite thick films were prepared through screen printing method and sintered at 880°C. The powder XRD patterns confirm the coexistence of the two phases. The dielectric and magnetic properties are also reported. The results show that this kind of magnetic–dielectric composite thick films, possessing high permittivity and saturation magnetization, moderate dielectric tunability, and very low dielectric loss and coercivity, could be used in high-frequency communications for the capacitor–inductor integrating devices such as electromagnetic interference filters and antennas. [Copyright &y& Elsevier]

The dielectric elastomer (DE) generator (DEG), which can convert mechanical energy to electrical energy, has attracted considerable attention in the last decade. Currently, the energy-harvesting performances of the DEG still require improvement. One major reason is that the mechanical and electrical properties of DE materials are not well coordinated. To provide guidance for producing high-performance DE materials for the DEG, the relationship between the intrinsic properties of DE materials and the energy-harvesting performances of the DEG must be revealed. In this study, a simplified but validated electromechanical model based on an actual circuit is developed to study the relationship between the intrinsic properties of DE materials and the energy-harvesting performance. Experimental verification of the model is performed, and the results indicate the validity of the proposed model, which can well predict the energy-harvesting performances. The influences of six intrinsic properties of DE materials on energy-harvesting performances is systematically studied. The results indicate that a high breakdown field strength, low conductivity and high elasticity of DE materials are the prerequisites for obtaining high energy density and conversion efficiency. DE materials with high elongation at break, high permittivity and moderate modulus can further improve the energy density and conversion efficiency of the DEG. The ratio of permittivity and the modulus of the DE should be tailored to be moderate to optimize conversion efficiency (η) of the DEG because using DE with high permittivity but extremely low modulus may lead to a reduction in η due to the occurrence of premature "loss of tension". [ABSTRACT FROM AUTHOR]

Powders of K0.5Na0.5NbO3 (KNN) were prepared by the Polymerized Complex Method (PC method), based on the Pechini-type reaction route. The crystallization process of KNN during the calcination of an amorphous precursor was observed, using TG-DSC analysis and X-ray powder diffraction. After calcination the powders were ball milled, pressed into pellets, and sintered at 1100°C, which is lower than the sintered temperature of the conventional solid-state method. Using this procedure, we achieved relatively high-density and very homogeneous KNN ceramics. The electric properties of the ceramics were investigated. The results showed that these values are superior to those of sintered KNN ceramic counterparts made by the conventional solid-state method. [ABSTRACT FROM AUTHOR]

Abstract: Present work introduces a new kind of low temperature sintering microwave dielectric ceramic of Li0.5Sm0.5WO4. Li0.5Sm0.5WO4 ceramic can be prepared by the solid-state reaction method and be well densified in the temperature range from 750°C to 850°C for 0.5–6h in air. The compound crystallizes in the single-phase tetragonal system (I41/a) with unit cell parameter a =5.22211(9)Å, c =11.3220(9)Å, V =308.6(5)Å3 and Z =4. The best microwave dielectric properties can be obtained in ceramic sintered at 800°C for 2h with permittivity about 17.0, Q × f about 5792GHz and TCF about 86.7ppm/°C. The additions of Li0.5Sm0.5WO4 not only can reduce the sintering temperature, but also can adjust the TCF values of ZnWO4 to near-zero. [Copyright &y& Elsevier]

The laminated magneto-dielectric composites of Ni 0.5 Ti 0.5 NbO 4 -Bi 0.4 Y 2.6 Fe 5 O 12 with high permittivities and permeabilities were prepared by the conventional solid-state sintering method. The results show that Ni 0.5 Ti 0.5 NbO 4 (NTN) and Bi 0.4 Y 2.6 Fe 5 O 12 (BYIG) phases can coexist in the composites. Compared with the magneto-dielectric particulate composites, the laminated composites exhibit better magneto-dielectric properties in the frequency range from 10 MHz to 1 GHz (ε’ = 30.05, tan δ ε = 0.05, μ’ = 9.2, tan δ μ = 0.18, at 10 MHz). The results indicate that this kind of magneto-dielectric composites can be used in the high frequency communications for the capacitor-inductor integrating devices such as miniaturized antennas, filters and electromagnetic interference suppression devices. The permeabilities of the laminated NTN-BYIG composites are well fitted with the Looyenga formula. [ABSTRACT FROM AUTHOR]

The laminated magneto-dielectric composites of Ni 0.5 Ti 0.5 NbO 4 (NTN)-Ni 0.8 Zn 0.2 Fe 2 O 4 (NZO) were prepared by the conventional solid-state sintering method. The phase composition, microstructure, dielectric and magnetic properties of the composites were investigated. The results show that the as-prepared composites are very dense and the NTN and NZO phases can coexist in the composites without any secondary phase. The as-prepared composites also exhibit excellent dielectric and magnetic properties in the frequency range from 10 MHz to 1 GHz, which make them have potential applications for high-frequency electronic devices. [ABSTRACT FROM AUTHOR]

Bi 2 Fe 4 O 9 /NiFe 2 O 4 (abbreviated as BFO/NFO) composite powders were successfully synthesized using a simple one-step sol–gel method. The phase composition and morphology of the composite powders were characterized by an X-ray diffractometer, a Raman spectroscopy and a scanning electron microscopy, respectively. The magnetic properties of the composite powders were investigated by a vibrating sample magnetometer. All the composite powders show single-phase-like magnetic hysteresis loops. The results show that both the saturation magnetization (M s ) and the remnant magnetization (M r ) of the composite powders increase with increasing the concentration of NFO in the composite powders. The dielectric properties of the samples were measured by an impedance analyzer and the results show that the resistivity of BFO cannot be much deteriorated by the introduction of NFO. [ABSTRACT FROM AUTHOR]

Via a traditional sintering process, (1- x) [0.85BaTiO 3 -0.15Bi(Mg 2/3 Nb 1/3)O 3 - x Na 0.5 Bi 0.5 TiO 3 (x = 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1) (BT-BMN-NBT) ceramics were synthesized. The sintering temperature and density of the BT-BMN-NBT ceramics decreased with the increasing NBT content. All samples exhibited a pseudocubic phase and formed stable solid solutions with dense microstructures. The crystal structure of the BT-BMN-NBT ceramics gradually transformed from BT to NBT with increasing NBT content. The introduction of NBT with a high maximum polarization (P max) could not only enhance the relaxor ferroelectric (RFE) characteristics of the BT-based RFE, but also compensate for the reduction in P max of BT-based RFE that is due to the enhanced RFE characteristics. The temperature that corresponds to the maximum dielectric constant increases monotonously with the NBT content. P max of the BT-BMN-NBT ceramics increases significantly as the NBT content increases. The best energy storage (ES) performances (x = 0.3) of a releasable energy density (W rec) of 2.91 J/cm3 and 85.55% efficiency were realized at 200 kV/cm. Compared with the unmodified BT-BMN ceramics (1.67 J/cm3), W rec was improved by 1.48 times, which originated from the NBT modification induced increase in P max (39.5 μC/cm2) to 2.34 times the nominal BT-BMN value (16.9 μC/cm2). The results prove that the addition of NBT could improve the ES performances of BT-based relaxor ferroelectrics at low-field by increasing the polarization. [ABSTRACT FROM AUTHOR]

(1- x) Ba(Zr 0.2 Ti 0.8)O 3 - x Na 0.5 Bi 0.5 TiO 3 (x = 0, 10, 20 30, 40, 50 mol%) (BZTN) ceramics are prepared by the traditional solid phase method. All BZTN ceramics exhibit a pseudo-cubic BZT based perovskite structure. Both the average grain size and the relaxor ferroelectricity of BZTN ceramics gradually increase with increasing NBT content. The W rec of 3.22 J/cm3 and η of 91.2% is obtained for the BZTN40 ceramic at 241 kV/cm. BZTN40 ceramic also exhibits good temperature stability from room temperature to 150 °C and frequency stability from 1 Hz to 100 Hz. A P D of 0.621 J/cm3 and a t 0.9 of 82 ns is obtained for the BZTN40 ceramic at 120 kV/cm. BZTN ceramics show application potential in energy storage and pulse power capacitors. [ABSTRACT FROM AUTHOR]

In this work, Bi(Mg 2/3 Nb 1/3)O 3 (BMN) was introduced to enhance the energy storage properties of 0.65BaTiO 3 -0.35Bi 0.5 Na 0.5 TiO 3 ceramic. All of the samples were prepared by the conventional solid-state method. With increasing the dopants content, the average grain size was reduced from 0.92 μm to 0.38 μm, which consequently improves the breakdown strength (reaching 182 kV/cm). Meanwhile, the P-E loops become slimmer and slimmer and the remanent polarization is declined from 31.16 μC/cm2 to 0.62 μC/cm2. The ceramics reveal a high recoverable energy storage density of 1.6 J/cm3 and an extremely high energy efficiency of 90.3%, which are superior to those of most of lead free ceramics. The excellent energy storage performance makes the as-prepared ceramics to be candidate materials for pulsed power capacitors. • The addition of Bi(Mg 2/3 Nb 1/3)O 3 decreases the grain size of BBNT-based ceramics. • The introduction of Bi(Mg 2/3 Nb 1/3)O 3 leads to a high breakdown strength of 182 kV/cm. • A large energy storage density of 1.60 J/cm3 and an ultrahigh efficiency of 90.3% can be obtained. [ABSTRACT FROM AUTHOR]

Abstract: Screen printed Ba0.6Sr0.4TiO3 (BST6/4) thick films were fabricated by reactive sintering at a low temperature below 900°C. The dielectric properties in radio frequency range were measured on samples of sandwich structure MIM capacitors by impedance analyzer, while that in microwave frequency range were measured on samples of thick films without top and bottom electrodes by split-post dielectric resonator method. The thick films exhibited a low permittivity, while at the same time, maintained a high tunability. The permittivity and dielectric loss at 1MHz were 228.8 and 0.007, respectively. The corresponding values measured at 9.9GHz were 82.24 and 0.109, respectively. The tunability was as high as 72.4% (150kV/cm, 10kHz). This method provides a simple and effective route to obtain thick films with great potential in applications in Low Temperature Co-fired Ceramic (LTCC) and microwave tunable devices. [Copyright &y& Elsevier]

Abstract: Present work introduces a new kind of microwave dielectric ceramic, Ba4Ti3P2O15. Ba4Ti3P2O15 ceramic can be prepared by solid state reaction method and be well densified after being sintered at above 1175°C for 4h in air. All the XRD patterns can be fully indexed as single-phase structure. The best microwave dielectric properties can be obtained in ceramic sintered at 1200°C for 4h with permittivity about 20.7, Q × f about 42,210GHz and TCF about 37ppm°C−1. Measurements of the microwave dielectric properties of Ba4Ti3P2O15 ceramic revealed the existence of a maximum in the temperature dependence of the dielectric loss because of the defect dipoles relaxation. [Copyright &y& Elsevier]