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Dielectric capacitors with rapid discharge rates and high power density are the basis for advanced pulsed power systems. Sr 0.7 Bi 0.2 TiO 3 (SBT) is expected to be used in energy storage capacitors owing to the small hysteresis and high energy storage efficiency (η). Nevertheless, the low breakdown strength (BDS) limits the enhancement of energy storage density. This study explores the potential of Ho 2 O 3 -modified SBT to address this limitation. Introducing Ho reduces oxygen vacancies, decreases electrical conductivity, and increases thermal conductivity, thus enhancing BDS. The enhancement mechanism of electrical performance is studied through microscopic morphology analysis, structural refinement and numerical simulation. The Sr 0.7 Bi 0.15 Ho 0.05 TiO 3 exhibits remarkable properties, including ultra-low loss tanδ (0.1 %), ultra-high η (95.8 %), and outstanding thermal, frequency, and cycling stability in energy storage properties. Additionally, Sr 0.7 Bi 0.15 Ho 0.05 TiO 3 possesses a high power density (67.9 MW/cm3) and a rapid discharge rate (0.03 μs). The findings indicate that Sr 0.7 Bi 0.15 Ho 0.05 TiO 3 is a prospective material for energy storage capacitors. [ABSTRACT FROM AUTHOR]

In this study, novel lead-free (1- x)Sr 0·7 Bi 0·2 TiO 3 - x La(Mg 0·5 Zr 0.5)O 3 ((1- x)SBT- x LMZ) ceramics were designed and fabricated by the conventional solid-state reaction method. The dielectric performance, energy storage characteristics and charge-discharge behavior of the ceramics were systematically investigated. Specifically, the temperature stability of dielectric constant is improved by doping SBT with LMZ. On a separate note, BDS is also enhanced ascribed to the reduction of the grain size. Consequently, the 0.87SBT-0.13LMZ exhibits high critical electric field of 340 kV/cm with ultrahigh efficiency (η) of 98.2% and recoverable energy storage density (W rec) of 1.22 J/cm3. Moreover, pulsed charge-discharge test elucidates that 0.87SBT-0.13LMZ possesses great thermal stability (30 °C–150 °C) along with a fast discharge period of 0.125 μs, high power density (P D) of 72.38 MW/cm3 as well as a high pulsed discharge energy density (1.2 J/cm3) at 380 kV/cm. Based on these outstanding characteristics, the 0.87SBT-0.13LMZ is considered as a potential candidate for pulse systems. [ABSTRACT FROM AUTHOR]

Abstract The CaO-ZnO-B 2 O 3 -P 2 O 5 glass-ceramics with various amounts of TiO 2 as crystallized agent were prepared by solid-state method. The effects of TiO 2 addition on the crystallization kinetics, microstructure and dielectric properties were systematically evaluated. Adding moderate content of TiO 2 can obviously promote crystallization and improve the microstructure of the glass-ceramics, due to the reduction of crystallization activation energy. It is also found that with the content of TiO 2 increasing, the dielectric constant (ε r) and quality factor (Q×f) of the glass-ceramics firstly increase and then decrease, however, temperature coefficient of resonance frequency (τ f) moves to positive value. Meanwhile, the sintering temperature also has a direct influence on the dielectric properties of the glass-ceramics. The glass-ceramic with 0.5 wt% TiO 2 sintered at 760 °C for 2 h possesses good dielectric properties of ε r = 4.75, Q×f= 23500 GHz, τ f = −17 ppm/°C, which indicates that the as-prepared glass-ceramic is a promising candidate for low temperature co-firing ceramics. [ABSTRACT FROM AUTHOR]

This study introduced a novel low-loss tungstate ceramic, La 7 Nb 3 W 4 O 30 (LNWO), synthesized using the solid-state techniques. The structural analysis of the La 7 Nb 3 W 4 O 30 ceramic material, utilizing X-ray diffraction (XRD) patterns and followed by detailed structural refinement, validated its rhombohedral structure. Transmission electron microscopy (TEM) was utilized to confirm the ordered layer arrangement characteristic of the rhombohedral structure. The internal structure was characterized by scanning electron microscopy (SEM), with the sample's relative density reaching 97.5 %. The correlation between the full width at half maximum (FWHM) of the Raman matrix at 901 cm−1 corresponding to the symmetric bending mode vibrations of WO 5 and the Q × f value was discussed. Furthermore, the main factors affecting the dielectric constant, including density, bond valence, secondary phases, and variations in porosity, were analyzed. Encouragingly, the ceramic showed significant microwave dielectric properties when it was sintered at 1425 °C (ε r = 23.68, Q × f = 26,687 GHz (f = 7.2 GHz), τ f = −35.2 ppm/°C). [ABSTRACT FROM AUTHOR]

A novel Li 4 AlSbO 6 (LASO) microwave dielectric ceramic with a monoclinic structure and space group C12/c1 was successfully prepared using traditional solid-state methods. When the sintering temperature was 1200 °C, it had excellent microwave dielectric properties, with ε r = 8.2, Q × f = 22,098 GHz, and τ f = −15.53 ppm/°C. Raman spectroscopy analysis showed that the FWHM of the strong peak at 691 cm−1 reflected the variation trend of Q × f value and was opposite to the variation trend of Q × f value. Additionally, the augmentation in the Q × f value can be attributed to a higher relative density. As per the bond valence analysis, ε r is closely connected to the rattling and compressing effects of A-site cations, and the higher ε theo than ε r in Li 4 AlSbO 6 can be attributed to the strong compression effect induced by Li+. Additionally, τ f may be influenced by both the Sb–O bond and relative density. [ABSTRACT FROM AUTHOR]

This study investigates NaY9Si6O26 ceramics prepared through the solid‐phase method, focusing on their microwave dielectric properties and crystallographic characteristics. X‐ray diffraction analysis reveals a hexagonal crystal structure for NaY9Si6O26 ceramics within the P63/m (176) space group. Rietveld refinement analysis precisely determines the lattice constants as a = b = 9.3423 Å, c = 6.7524 Å, and a unit cell volume of V = 510.3877 Å3. Additionally, Raman spectroscopy unveils a noteworthy correlation between the quality factor and the full width at half maximum of the A1g(O) mode at 878 cm−1. The structural attributes, including lattice fringes and diffraction patterns of hexagonal NaY9Si6O26 ceramics, are elucidated through transmission electron microscopy. Of significance are the microwave dielectric properties of NaY9Si6O26 ceramics sintered at 1465°C, revealing a relative permittivity (εr) of 10.42, an impressive Q × f product of 33 766 GHz (at f = 11.14 GHz), and a temperature coefficient of resonant frequency (τf) of −28.7 ppm/°C. This comprehensive investigation contributes to the understanding of both the structural and microwave dielectric characteristics of NaY9Si6O26 ceramics, with potential applications in advanced electronic devices. [ABSTRACT FROM AUTHOR]

This study delves into the synthesis and characterization of rare earth germanate La 4 GeO 8 ceramics, employing the solid-phase reaction method, with a focus on their microwave dielectric properties and crystallographic characteristics. The research employs X-ray diffraction (XRD) and transmission electron microscopy (TEM) to ascertain the orthorhombic crystal structure within the Pnma space group. Rietveld refinement analysis precisely determines the lattice constants (a = 18.3006 Å, b = 7.6697 Å, c = 5.8513 Å) and unit cell volume (V = 821.28429 Å3). Raman spectroscopy provides insights into the correlation between the quality factor (Q × f) and the Full Width at Half Maximum (FWHM) of the A g (O) mode at 733 cm⁻1. A notable highlight of the study is the exceptional microwave dielectric performance of La 4 GeO 8 ceramic sintered at 1540 °C, characterized by a relative dielectric constant (ε r) of 13.24, a Q × f product of 47,826 GHz at 10.16 GHz, and a temperature coefficient of frequency (τ f) of −82.3 ppm/°C. This comprehensive investigation offers valuable insights into the structural and microwave dielectric properties of AB-type rare earth germanate La 4 GeO 8 ceramics, underscoring their potential in advanced dielectric material applications. [ABSTRACT FROM AUTHOR]

This study presents a comprehensive investigation into the dielectric properties of LiY 9 Si 6 O 26 ceramics, which were prepared for the first time using the solid-state method. XRD patterns and Rietveld refinement analysis conclusively demonstrate that LiY 9 Si 6 O 26 adopts a hexagonal crystal structure with space group P63/m (176). Furthermore, Raman spectroscopy reveals a significant correlation between the quality factor and the FWHM of the A 1g (O) mode at 879 cm−1. Transmission electron microscopy (TEM) was employed to verify the ordered layered structure inherent in the hexagonal LiY 9 Si 6 O 26 ceramics. The microstructure of the ceramic grains was analysed using scanning electron microscopy (SEM), which revealed a remarkably high relative density of 96.4% for the LiY 9 Si 6 O 26 ceramic. The Si–O bond valences (V Si – O) were found to be closely associated with the τ f in LiY 9 Si 6 O 26 ceramics. Remarkably, the microwave dielectric properties of LiY 9 Si 6 O 26 ceramics sintered at 1425 °C were ascertained to be ε r = 10.54, Q × f = 25,579 GHz (f = 10.3 GHz), and τ f = 2.64 ppm/°C. These outstanding properties position LiY 9 Si 6 O 26 ceramics as promising candidates for high-performance dielectric materials. [ABSTRACT FROM AUTHOR]

• ① A novel Nd 2 CaSnO 6 microwave dielectric ceramic was first discovered: ε r = 20.65, Q × f = 27,523 GHz, and τ f = –36.0 ppm/°C. • ② We analyzed the relationship between Raman spectroscopy and microwave dielectric properties. • ③ TEM analysis confirmed the double perovskite structure of Nd 2 CaSnO 6 ceramics. • ④ SEM images revealed the microstructure of the ceramic grains, with the maximum relative density reaching 97.5 %. This study elucidates the synthesis of a new class of Nd 2 CaSnO 6 microwave dielectric ceramics employing the conventional solid-phase method. X-ray diffraction (XRD) patterns and Rietveld refinement analysis revealed that the Nd 2 CaSnO 6 material crystallized into a single phase with an P21/n (14) space group. The double perovskite structure Nd 2 CaSnO 6 ceramics was confirmed through transmission electron microscopy (TEM), the structure exhibits a layered arrangement that is orderly. The internal microstructure was characterized using SEM, which showed that the sample's relative density reached 97.5 %. We discuss the correlation between FWHM and Q × f value of the Raman matrix at the Raman shift of 650.1 cm–1. Additionally, the main factors affecting the dielectric constant were analyzed, including density, secondary phase and porosity changes, etc. The ceramics exhibited remarkable microwave dielectric properties (ε r = 20.65, Q × f = 27523 GHz, and τ f = –36.0 ppm/ °C) when sintered at 1390 °C, indicating their potential as a microwave dielectric material. [Display omitted] [ABSTRACT FROM AUTHOR]

Ceramics of Y 2 GaSbO 7 (YGSO) were prepared by the solid-state reaction method. The ceramics were confirmed by XRD and TEM to exhibit the Fd-3 m (227) space group and a cubic pyrochlore structure within the temperature range of 1420–1500 °C. XPS verified that the valence states of Y, Ga, and Sb in the ceramics were + 3, + 3, and + 5, respectively. Additionally, the relationship between the FWHM of the notable peak at 775 cm−1 and the Q × f value was elucidated through Raman spectroscopic analysis. The analysis of the P-V-L theory revealed that the Sb-O bond is crucial in determining ε r , while the values of τ f and Q × f are affected by the Y-O bond. At 1460 °C, YGSO ceramics obtained the maximum relative density (97.5%) and the best microwave dielectric properties (ε r = 14.78, Q × f = 50,153 GHz, and τ f = –22.3 ppm/°C). • For the first time, a Y 2 GaSbO 7 microwave dielectric ceramic with a pyrochlore structure was discovered. • The Raman spectra of the ceramics were analyzed, and the valence state was studied using XPS. • TEM analysis confirmed the cubic structure of Y 2 GaSbO 7 ceramics. • SEM images revealed the microstructure of the ceramic grains, with the maximum relative density reaching 97.5%. • The relationship between α , f i , E b , U b , and the dielectric properties of Y 2 GaSbO 7 ceramics was examined using P-V-L theory. [ABSTRACT FROM AUTHOR]

A novel CuO-ZnO-B 2 O 3 -Li 2 O glass-ceramic was prepared by solid phase method, and. Its phase transition, sintering and dielectric performance was studied. No crystalline phase is observed for the specimen sintered at 560 °C. However, the samples sintered at 580 °C and 600 °C, consist of ZnB 4 O 7 and Cu 2 B 4 O 7. And the Li 2 CuB 4 O 8 appears with further increasing temperature. The ε r and τ f change slightly but the Q × f value alter greatly with firing temperature. The glass-ceramic fired at 620 °C possesses optimum properties with ε r = 3.33, Q × f = 17,724 GHz and τ f ≈ 0 ppm/°C. Furthermore, the as-prepared glass-ceramic exhibits good co-firing compatibility with Ag and Al electrode. These properties qualify the dielectric material as promising alternatives for wireless communication applications. [ABSTRACT FROM AUTHOR]