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Sintering behavior, structural evolution, dielectric, electric, and energy storage properties of BaTi1‐xLixO3‐3xF3x (x = 0–0.10) oxy fluorides have been investigated by X‐ray diffraction, Raman spectroscopy, scanning electron microscopy (SEM), impedance, and ferroelectric analyzer in this paper. The oxy‐fluoride ceramic (x =.06) could be densified at ∼1000°C/2 h in an N2 atmosphere without reduction of Ti4+. The solid solutions experienced a transformation from a tetragonal phase into a pseudo‐cubic phase at room temperature with increasing doping levels, exhibiting typical relaxor features. Pseudo‐cubic phase with a small amount of residual tetragonal phase could be observed in x =.02, while a trace amount of BaF2 secondary phase appeared, resulting in the formation of oxygen vacancies in the x ≥ 0.08 compositions. Temperature‐dependent Raman analysis of the doped compositions seems to imply the presence of local polar clusters even above the Burns temperature. Insulation of the grain could be improved by appropriate doping of BaLiF3 due to an increase in the band gap, whereas high‐level doping (x > 0.06) leads to a decrease in insulation due to the formation of oxygen vacancies (BaTi0.94‐xLi0.06+xO2.82‐2xF0.18+x). Optimized energy storage properties with recoverable energy density Wrec = 2.92J/cm3, efficiency η = 85%, and breakdown strength (BDS) = 315 kV/cm can be achieved at x =.06 composition. Sintering of BaTi1‐xLixO3‐3xF3x in the ambient atmosphere leads to the deterioration of the dielectric, electric, and energy storage properties compared with the counterpart sintered in N2 due to the formation of F− vacancies (BaTi0.94Li0.06O2.82+xF0.18‐2x). [ABSTRACT FROM AUTHOR]

Fully densified (transparent) ceramic with small grain size is highly desired to improve the field breakdown strength (BDS) and its scattering. Sintering behavior, microstructural evolution, electric, dielectric, and energy storage properties of (Ba0.6Sr0.4)1‐1.5xBixTi1‐x(Mg1/3Nb2/3)xO3 (x =.04–.10) ceramics have been studied in this paper. Phase pure cubic perovskite is observed for the x =.04 composition. Nb‐rich tungsten bronze type and Ti‐rich barium titanate secondary phases are present in the x >.05 compositions. A multiphasic transparent ferroelectric ceramic with ∼74.2% (780 nm) transmittance and a high refractive index of ∼2.3 within the visible region could be successfully obtained for the x =.10 composition by traditional ceramic process. The x =.09 composition demonstrates good energy storage performance (recoverable energy density Wrec = 3.74J/cm3, efficiency η = 77% and BDS = 390kV/cm) with extremely low scattering in BDS, suggesting potential application in large sized energy storage capacitor. [ABSTRACT FROM AUTHOR]

Structural evolution and microwave dielectric properties of LiNb0.6(Ti1‐x[Co1/3Nb2/3]x)0.5O3 (.05≤x≤.2) ceramics have been studied in this paper. Although the doped compositions maintain the M‐phase solid solutions, compositional fluctuation due to nonuniform dispersion of minor dopants could be observed as x <.05, and trace amount of Li2TiO3‐based solid solution (Li2TiO3ss) secondary phase presents in the x >.05 compositions. The microwave dielectric properties could be remarkably improved by the doping of (Co1/2Nb1/2)4+ in comparison to the undoped counterpart. Optimized microwave dielectric properties with Q × f = ∼6500 GHz, εr = ∼74 and τf = +8.2 ppm/°C could be obtained at x =.10 after sintering at 1050°C/2 h. The sintering temperature could be further reduced to 900°C/2 h by adding.2 wt% B2O3 without affecting significantly its microwave dielectric properties: εr = 73, Q × f = 6000 GHz, τf = +8.5 ppm/°C. The LiNb0.6(Ti1‐x[Co1/3Nb2/3]x)0.5O3 ceramics obtained in this case exhibit large dielectric permittivity coupled with much improved Q × f values, near zero τf, and low sintering temperature simultaneously, which makes it a promising high‐k microwave dielectric material for low temperature cofired ceramic applications. [ABSTRACT FROM AUTHOR]

A simulation method on estimation of the anode material damage caused by spark discharges is developed. These discharges are well known to cause permanent failures of microgap gas chambers (MGCs). Systematic analysis and optimization studies have been performed through finite element methods (FEND simulations using Ansys6.1. The results have evidently shown that, owing to their super high heat conductivity, introduction of diamond thin films (DTFs) as an insulating layer can enormously diminish or even avoid melting or vaporizing of the anodes via spark discharges. Furthermore, topological optimization and anode material selection studies using the FEM simulation technique have been carried out to enhance MGC operational stability. Samples based on the simulation results have been successfully fabricated and tested. Index Terms--Diamond thin films, finite element methods, microgap gas chambers, spark damage.

(3‐Aminopropyl)triethoxysilane treated La(2−x)/3Na0.06TiO3 (x = 0.06) (LNT) microparticles filled polyetheretherketone (PEEK) composites were prepared using hot pressing process. The effects of variation of LNT ceramic filling fraction on dielectric properties, water absorption, thermal stability and mechanical strength were investigated. All composites demonstrate low water absorption (less than 0.4%) when the ceramic filling fraction is lower than 0.6Vf. The obtained composites exhibited dielectric permittivities varying from ~4 to ~22 as the ceramic fillers increased from 0.1 to 0.8Vf and low losses (~10−4 @1 MHz, 3~5 × 10−3 at the frequencies of microwave (10 GHz) and millimeter wave (29‐50 GHz), respectively). The mechanical strength, dimensional and dielectric thermal stability of the composite are remarkably improved by the addition of LNT ceramic fillers. A composite with near zero temperature coefficients of dielectric permittivity or resonant frequency and flexural strength of ~140 MPa could be obtained. The out‐of‐plane coefficient of thermal expansion (CTE) could be reduced to ~20 ppm/°C as the ceramic filler loading reached 0.7Vf. [ABSTRACT FROM AUTHOR]

Ba0.3Sr0.475Ce0.03La0.12Ti0.997Mn0.003O3/Polytetrafluoroethylene (PTFE) composites were prepared using powder processing technique. The effects of the ceramic filler volume fraction and the coupling agent on the phase composition, microstructure, dielectric and thermal properties of the composites were investigated in this paper. The ceramic filler dispersion in the PTFE matrix, thus the dielectric loss, permittivity, and dimensional thermal stability of the composite was considerably improved by the modification of BST filler surface using phenyl trimethoxy silane (PTMS) coupling agent. Variation of the dielectric permittivity of the composite with composition was well fitted by the effective medium theory (EMT) model in the experimental compositional range. The obtained silane‐treated composite with 0.5 VfBST exhibits extremely low dielectric loss: εr = 16, tan δ = 5.4 × 10−4 @1 MHz and 5.16 ± 0.6 × 10−3 @ 10 GHz. The CTE of the composites was reduced to 43 ppm/°C. [ABSTRACT FROM AUTHOR]

Highlights: [•] Sintering temperature of Li2TiO3 was reduced to 900°C by doping with LiF and excessive lithium. [•] A new glass-free LTCC microwave ceramic – (1− x) Li2.08TiO3 + xLiF was obtained. [•] The obtained LTCC material exhibited excellent microwave dielectric properties. [ABSTRACT FROM AUTHOR]

Highlights: [•] Structure, sinterability and dielectric properties of LiF-doped Li2TiO3 were studied. [•] Li2TiO3 can be densitied (TD 98%) at lower sintering temperature by LiF additions. [•] Excellent microwave dielectric properties could be obtained. [ABSTRACT FROM AUTHOR]

Abstract: The phase evolution, sintering behavior and microwave dielectric properties of mixed pyrophosphates (Ca1−xZnx)2P2O7 (x=0.1–0.9) were investigated in this paper. The results show that samples with x=0.1–0.4 exhibit mixture phases of CaZnP2O7 and β-Ca2P2O7, and the samples with x=0.6–0.9 exhibit mixed phases of CaZnP2O7 and Zn2P2O7. A single-phase composition of CaZnP2O7 could be formed when x=0.5. The mixed pyrophosphates (Ca1−xZnx)2P2O7 (x=0.1–0.9) exhibit low sintering temperature (≤900 °C), low relative permittivity (<9), high Q×f value and negative temperature coefficient of resonant frequency. Maximum Q×f value of 63,130 GHz could be obtained for CaZnP2O7 sintered at 900 °C/2 h. Its dielectric constant and τf value are 7.56 and −82 ppm/°C, respectively. [Copyright &y& Elsevier]

La modified Pb(Mg1/2W1/2)O3 were prepared by solid-state reaction process, and the sintering behavior, microstructure and microwave dielectric properties were investigated by X-ray powder diffraction (XRD), Raman scattering and HP network analyzer in this paper. A series of single phase perovskite type solid solutions with A-site vacancies (Pb1-3x/2Lax(Mg1/2W1/2)O3 (0 ≤ x ≤ 2/3)) were formed. The solid solution took cubic perovskite type structure (Fm3m) with random distribution of A-site vacancies when 0 < x < 0.5, and tetragonal or orthorhombic structure with the ordering of A-site vacancies when 0.5 ≤ x ≤ 2/3. The dielectric constant and temperature coefficient of resonant frequency decrease with increasing La content. Relatively good combination microwave dielectric properties were obtained for x = 0.56: εr = 28.7; Q × f = 18098; and τf = -5.8ppm/°C. [Copyright &y& Elsevier]

Presents a letter to the editor about modern microwave communication system.

Presents a letter to the editor about modern microwave communication system.

Structural evolution and microwave dielectric properties of LiNb0.6(Ti1‐x[Co1/3Nb2/3]x)0.5O3 (.05≤x≤.2) ceramics have been studied in this paper. Although the doped compositions maintain the M‐phase solid solutions, compositional fluctuation due to nonuniform dispersion of minor dopants could be observed as x <.05, and trace amount of Li2TiO3‐based solid solution (Li2TiO3ss) secondary phase presents in the x >.05 compositions. The microwave dielectric properties could be remarkably improved by the doping of (Co1/2Nb1/2)4+ in comparison to the undoped counterpart. Optimized microwave dielectric properties with Q × f = ∼6500 GHz, εr = ∼74 and τf = +8.2 ppm/°C could be obtained at x =.10 after sintering at 1050°C/2 h. The sintering temperature could be further reduced to 900°C/2 h by adding.2 wt% B2O3 without affecting significantly its microwave dielectric properties: εr = 73, Q × f = 6000 GHz, τf = +8.5 ppm/°C. The LiNb0.6(Ti1‐x[Co1/3Nb2/3]x)0.5O3 ceramics obtained in this case exhibit large dielectric permittivity coupled with much improved Q × f values, near zero τf, and low sintering temperature simultaneously, which makes it a promising high‐k microwave dielectric material for low temperature cofired ceramic applications. [ABSTRACT FROM AUTHOR]

Abstract: 0.2PbNi1/3Nb2/3–0.8Pb(Zr,Ti)O3 (PNN–PZT) thick films were deposited on Pt wire with the diameter of 50μm by electrophoretic deposition (EPD) method. The EPD deposition times on the microstructures of PNN–PZT thick films were investigated. By optimizing the EPD process, the Pt wire can be uniformly wrapped with the PNN–PZT powders. During the sintering process, the as-deposited PNN–PZT/Pt wires were buried in the mixed powders of PbCO3 and ZrO2, and then sintered in the optimal temperature to get a dense microstructure. The piezoelectric properties of the thick films were characterized by scanning force microscopy (SFM) method. The results show that the PNN–PZT thick films prepared by EPD method have good piezoelectricity. [Copyright &y& Elsevier]