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A series of microwave dielectric ceramics, (1-x)Na 0.5 Y 0.5 MoO 4 -xNa 0.5 Bi 0.5 MoO 4 , with low sintering temperatures and excellent microwave dielectric properties, were prepared by solid-state reaction. The ceramics were sintered well at 820 oC, and the structure, microwave dielectric properties, and chemical compatibility were investigated. When x=0.1, the microwave dielectric constant (ε r), the quality factor (Q × f value), and the temperature coefficient of resonant frequency (TCF value) of the 0.9NYM-0.1NBM ceramic were 10.9(±0.2), 54,060(±1,000) GHz, and -48.6(±1) ppm/°C, respectively. When x=0.7, the ε r of the 0.3NYM-0.7NBM ceramic was 23.6(±0.5), the Q × f value was 19,020(±400) GHz, the TCF value was -3.1(±0.1) ppm/°C and the room temperature thermal conductivity was 1.21(±0.01) W/(m.K). After co-firing with 20 w.t. % silver powder at 820 °C, it was found that (1-x)NYM-xNBM ceramics were chemically compatible with Ag electrodes, indicating their potential as alternative materials for low-temperature co-fired ceramics (LTCC). [ABSTRACT FROM AUTHOR]

In this study, the Ba 3 P 2 O 8 and Mg 2 B 2 O 5 were fabricated by the solid-state reaction method separately, and the (1-x)Ba 3 P 2 O 8 -xMg 2 B 2 O 5 (x = 0.2–0.4) low-temperature co-fired ceramic (LTCC) materials were obtained in the sintering temperature range of 880–960 °C. The phase compositions, microstructures, elemental compositions, and microwave dielectric properties of the (1-x)Ba 3 P 2 O 8 -xMg 2 B 2 O 5 composite ceramics were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and TE 01δ mode dielectric resonator method, respectively. The results revealed that the Mg 2 B 2 O 5 phase and Ba 3 P 2 O 8 phase could coexist well in the (1-x)Ba 3 P 2 O 8 -xMg 2 B 2 O 5 composite ceramics without formation of any new phases. The abnormal grain growth of Ba 3 P 2 O 8 grains was inhibited by the addition of Mg 2 B 2 O 5. In addition, through composition of Ba 3 P 2 O 8 and Mg 2 B 2 O 5 , the temperature coefficient of resonant frequency (τ f) and quality factor (Q×f) were effectively optimized, and the sintering temperature was reduced to 880–960 °C. The optimal performance of 0.8Ba 3 P 2 O 8 -0.2Mg 2 B 2 O 5 composite ceramic was achieved at a sintering temperature of 920 °C, τ f = −1.9 ppm/°C, Q×f = 61,250 GHz, and a low permittivity ε r = 10.7. The chemical compatibility test demonstrated that the composite ceramic could coexist well with silver, which indicated that the 0.8Ba 3 P 2 O 8 -0.2Mg 2 B 2 O 5 composite ceramic is a candidate LTCC material with wide application prospects. [ABSTRACT FROM AUTHOR]

Dielectric materials with high power density, fast charge and discharge rates, and high energy-storage density are urgently required due to the rapid development of hybrid vehicles and pulse power boosting technology. In this work, the novel environment-friendly (1-x)(Ba 0.8 Sr 0.2)TiO 3 -xBi(Zn 2/3 Nb 1/3)O 3 (0.04 ≤ x ≤ 0.16) [(1-x)BST-xBZN] ceramics were designed and synthesized by traditional solid-state reaction method, exhibiting ultrahigh energy efficiency and super stability against temperature. The results show that the recoverable energy density (W rec) and the energy efficiency (η) of the (1-x)BST-xBZN ceramics are increase sharply then decrease slightly with increasing of x value. The 0.88BST-0.12BZN ceramic demonstrated a recoverable energy density of ≈ 1.62 J/cm3 and an extreme high energy efficiency of ∼ 99.8 % at 225 kV/cm at room temperature. These extreme high efficiency and high breakdown strength would make (Ba,Sr)TiO 3 -based lead-free ceramic systems might be good candidate for high power energy-storage applications pulsed power systems. [ABSTRACT FROM AUTHOR]

Abstract MoO 3 ceramics can not be well densified via conventional solid state method and a low relative density (ρ) was obtained (˜64.5% at 680 °C) with a permittivity (ε r) ˜ 7.58, a quality factor (Qf) ˜ 35,000 GHz and a temperature coefficient of resonant frequency (TCF) ˜ − 39 ppm/°C. However, cold sintering at 150 °C using 4 wt. % H 2 O at 150 MPa enhanced densification and give a relative ρ ˜76.8% and ε r ˜ 8.31 but with a Qf of only ˜ 900 GHz. The addition of (NH 4) 6 Mo 7 O 24 ·4H 2 O further improved densification to give a relative ρ ˜ 83.7% after annealing at 700 °C, resulting in a ε r ˜ 9.91 with a Qf ˜ 11,800 GHz. We conclude therefore that oxides that are difficult to be sintered via a conventional solid state route may benefit from cold sintering but despite the higher density, lower Qf cannot be avoided due to the impurities and grain boundary phases that are introduced. [ABSTRACT FROM AUTHOR]

In the present work, a novel (1-x)BiVO 4 -xLa 2/3 MoO 4 scheelite related solid solution ceramics were prepared via solid state reaction method. As revealed by X-ray diffraction data, the crystal structure changed continuously from monoclinic to tetragonal phase at x = 0.10 and then the tetragonal solid solution was kept in a wide composition range up to x = 0.70. Both the Raman and far infrared spectra supported this phenomenon. When x value reached 0.9, the ceramic sample was found to composed of both scheelite tetragonal and monoclinic La 2/3 MoO 4 phases. Large microwave permittivity value between 68 ± 0.2–73 ± 0.3 can be achieved in compositions with 0.02 ≤ x ≤ 0.10 with high Qf value about 10,000 ± 500 GHz. This series of solid solution ceramics might be candidate for both dielectric resonator and low temperature co-fired ceramic technology. [ABSTRACT FROM AUTHOR]

Bi(Sc 1/3 Mo 2/3 )O 4 ceramics were prepared via solid state reaction method. It crystallized with an ordered scheelite-related structure (a = 16.9821(9) Å, b = 11.6097(3) Å, c = 5.3099(3) Å and β = 104.649(2)°) with a space group C12/C1, in which Bi 3+ , Sc 3+ and Mo 6+ are −8, −6 and −4 coordinated, respectively. Bi(Sc 1/3 Mo 2/3 )O 4 ceramics were densifiedat 915 °C, giving a permittivity (ε r ) ∼24.4, quality factor ( Qf , Q  = 1/dielectric loss, f  = resonant frequency) ∼48, 100 GHz and temperature coefficient of resonant frequency (TCF) ∼ −68 ppm/°C. Impedance spectroscopy revealed that there was only a bulk response for conductivity with activation energy (E a ) ∼0.97 eV, suggesting the compound is electrically and chemically homogeneous. Wide band dielectric spectra were employed to study the dielectric response of Bi(Sc 1/3 Mo 2/3 )O 4 from 20 Hz to 30 THz. ε r was stable from 20 Hz to the GHz region, in which only ionic and electron displacive polarization contributed to the ε r . [ABSTRACT FROM AUTHOR]

Ultra-low temperature co-fired ceramics technology (ULTCC) requires the microwave dielectric ceramics with lower intrinsic sintering temperature than the melting point of inner electrodes. In the present work, a novel HBO 2 ceramic was found to be densified at extreme-low temperature below 200 °C, with pores, residual H 3 BO 3 , amorphous B 2 O 3 inside, with a relative permittivity ∼2.12 ± 0.02, a Qf value ∼32,700 ± 300 GHz and a temperature coefficient of resonant frequency value ∼ − 43 ± 3 ppm/°C. This material can be easily obtained by dehydration from H 3 BO 3 by sintering at low temperature below 200 °C. Its extreme-low sintering temperature and water solubility also provides the possibility to achieve some novel multi-functional inorganic-organic composite in the future. [ABSTRACT FROM AUTHOR]

(Bi 1−x Ln x ) 2 MoO 6 (Ln=Nd and La) ceramics were prepared by conventional solid state reaction method. Solid solutions crystallizing in a monoclinic structure with a space group P 21/ c were obtained in the (Bi 1−x La x ) 2 MoO 6 (x≤0.3) ceramics. For the (Bi 1−x Nd x ) 2 MoO 6 ceramics, tetragonal Nd 2 MoO 6 phase with a space group I4 1 /acd was detected when x value reached 0.2 besides the Bi 2 MoO 6 solid solution. Temperature stability and quality factor Qf value at microwave frequencies were improved by appropriate substitution for Bi 3+ by Nd 3+ and/or La 3+ in Bi 2 MoO 6 system. When x=0.2, for both (Bi 1−x Nd x ) 2 MoO 6 and (Bi 1−x La x ) 2 MoO 6 ceramics, Qf values reached maximum about 30,200 GHz and 32,900 GHz, respectively. TCF value shifted towards zero with substitution of Bi 3+ by Nd 3+ and/or La 3+ . When x=0.3, TCF values of (Bi 1−x Nd x ) 2 MoO 6 and (Bi 1−x La x ) 2 MoO 6 ceramics were −70 and −85 ppm/°C, respectively. Relation between crystal structure, microstructure and microwave dielectric properties were discussed. [ABSTRACT FROM AUTHOR]

Novel glass-free low temperature firing microwave dielectric ceramics, Bi(Ga 1/3 Mo 2/3 )O 4 , with ordered scheelite structure, were prepared through a conventional solid state reaction method. Dense ceramics were prepared at sintering temperatures from 800 to 860 °C. The Bi(Ga 1/3 Mo 2/3 )O 4 compound was crystallized with B-site ordered Scheelite-type structure with space group C2/c. The Bi(Ga 1/3 Mo 2/3 )O 4 ceramics can be well sintered at about 830 °C, exhibiting good microwave dielectric properties of ε r ~26.1, Qf~49,800 GHz, and TCF~−86 ppm/°C. Intrinsic dielectric parameters of the Bi(Ga 1/3 Mo 2/3 )O 4 ceramics were estimated by fitting far-infrared (FIR) reflectance spectra with the classical harmonic oscillator model. [ABSTRACT FROM AUTHOR]

Low firing microwave dielectric ceramics Bi 3 (Nb 1− x V x )O 7 ( x =0.0, 0.1, 0.2, 0.3, and 0.5) were prepared by the solid state reaction method. Sintering behavior, crystalline structure, microstructure, and microwave dielectric properties were studied. Temperature stable low-firing microwave dielectric ceramics with high permittivity were obtained in the Bi 3 (Nb 1− x V x )O 7 system when x =0.1 and 0.2. The Bi 3 (Nb 0.9 V 0.1 )O 7 and Bi 3 (Nb 0.8 V 0.2 )O 7 ceramics sintered at 870 °C for 2 h were found to possess high permittivity of 80 and 76, Qf (quality factor) values of 615 and 460 GHz, and TCF (temperature coefficient of frequency) values of −22 and+3.3 ppm/°C, respectively. [ABSTRACT FROM AUTHOR]

Abstract: A Bi(In1/3Mo2/3)O4 ceramic was prepared via the solid state reaction method. The pure monoclinic phase was formed at around 650°C. Ceramic samples with relative densities above 97% were obtained when sintering temperature was around 840°C. The best microwave dielectric properties were achieved in the Bi(In1/3Mo2/3)O4 ceramic sintered at 840°C for 2h with permittivity ∼25.2, Qf of 40,000GHz and temperature coefficient of resonance frequency ∼−65ppm/°C at 8.2GHz. The temperature dependence of microwave dielectric properties was also studied in a wide temperature range from −250°C to +120°C. The Qf value increased with the decrease of temperature and reached a maximum of 150,000GHz at −250°C. [Copyright &y& Elsevier]

Abstract: In the present work, novel low temperature firing microwave dielectric ceramics (K0.5Ln0.5)MoO4 (Ln=Nd and Sm) were prepared via the traditional solid state reaction method. A pure monoclinic phase can be formed at a low sintering temperature around 680°C for both (K0.5Nd0.5)MoO4 and (K0.5Sm0.5)MoO4 ceramics. The densification temperature for the (K0.5Nd0.5)MoO4 and (K0.5Sm0.5)MoO4 ceramics are 700°C and 800°C for 2h, respectively. The best microwave dielectric properties for (K0.5Nd0.5)MoO4 was obtained in ceramic sample sintered at 760°C for 2h, with a dielectric permittivity of 9.8, a Qf about 69,000GHz and a temperature coefficient of frequency about −62ppm/°C. The best microwave dielectric properties for (K0.5Sm0.5)MoO4 was obtained in ceramic sample sintered at 800°C for 2h, with a dielectric permittivity of 9.7, a Qf about 20,000GHz and a temperature coefficient of frequency about −65ppm/°C. [Copyright &y& Elsevier]

Abstract: The Bi3SbO7 ceramic was prepared by the solid state reaction method and its phase evolution at different temperatures was studied. Low temperature phase α-Bi3SbO7 was formed at about 890°C and it started to transform to high temperature phase β-Bi3SbO7 at about 960°C. Microwave dielectric constants of α-Bi3SbO7 ceramic and β-Bi3SbO7 ceramic were 43.2 and 37.6, Qf value were 2080 and 5080GHz, respectively. TCF of α-Bi3SbO7 ceramic was near zero and TCF of β-Bi3SbO7 ceramic was about −120ppm/°C. The Bi3SbO7 ceramic is a promising candidate for low temperature co-fired ceramic (LTCC) technology due to its large dielectric constant, low dielectric loss at microwave region, low sintering temperature and simple composition. [Copyright &y& Elsevier]

Abstract: The phase structure, microwave dielectric properties, and their stability with different annealing conditions have been investigated in (Li1/4Nb3/4) substituted Zr x Sn y Ti z O4 system. The sintering temperature of Zr x Sn y Ti z O4 ceramic was lowered from 1500 to 1140°C by (Li1/4Nb3/4) substitution. Both X-ray diffraction (XRD) analysis and electron diffraction (ED) analysis revealed that the (Li1/4Nb3/4) substituted Zr x Sn y Ti z O4 ceramic crystallized as the high-temperature disordered ZrTiO4 phase. As the content of Sn increased from 0.10 to 0.30, the permittivity of the (Zr1−x Sn x )(Li1/4Nb3/4)0.4Ti0.6O4 ceramic decreased gradually from 35.5 to 31.5, the Q f value increased from 37,800 to 58,300GHz, and TCF value shifted slightly from −4.5 to −33.0ppm°C−1. Both the phase structure and microwave dielectric properties of (Zr1−x Sn x )(Li1/4Nb3/4)0.4Ti0.6O4 ceramics were stable with annealing conditions. [ABSTRACT FROM AUTHOR]

Abstract: H3BO3–Si(OC2H5)4 sol–gel was prepared and added as the sintering aid for Ba6−3x Nd8+2x Ti18O54 (x =2/3, BNT) ceramic. The sintering behavior, microstructures, phase structures, and microwave dielectric properties were studied. The liquid phase was formed during the sintering process, which accelerated the process of reagent conversion and the mass-transport among the BNT powders. The sintering temperature of BNT ceramic was lowered from 1460 to 1075°C. The H3BO3-TEOS sol–gel existed in the form of glass pellets, whose sizes were tens of nanometers, uniformly distributed around the BNT grains. By this method, perfect microstructures with BNT grains uniformly distributed in the ceramic matrixes were obtained, that were beneficial to the microwave dielectric properties of BNT ceramics. A ceramic composite which could be sintered well at 1075°C and showed good microwave dielectric properties of ɛ r =73.8, Q f =8190GHz and TCF=47.2ppm/°C was obtained when 2wt.% H3BO3-TEOS sol–gel was added to the BNT ceramic. The mechanism for the low temperature sintering and the relationship between microwave dielectric properties and microstructures were discussed. [Copyright &y& Elsevier]

Abstract: A new temperature stable microwave dielectric with low-firing temperature in xBi2MoO6–(1− x)TiO2 system was prepared by conventional solid state reaction method. The crystalline phases, sintering behavior, microwave dielectric properties of xBi2MoO6–(1− x)TiO2 ceramics were studied. All the xBi2MoO6–(1− x)TiO2 ceramics could be well sintered at 850°C for 3h. X-ray diffraction analysis showed that tetragonal rutile phase and monoclinic Bi2MoO6 phase coexisted in the ceramic. The permittivity ɛ r changed from 77.5 to 33.5 and the temperature coefficient of resonant frequency τ f value shifted from +348.1 to −37.8ppm/°C as the x value increased from 0.06 to 0.65. The temperature stable microwave dielectric ceramic was obtained when x =0.57 in the xBi2MoO6–(1− x)TiO2 system, and it showed excellent dielectric properties of ɛ r =36.7, Qf=16,800GHz and τ f =0ppm/°C. [Copyright &y& Elsevier]

Abstract: In this work Bi(Sb x Nb y Ta z )O4 (x + y + z =1) samples are prepared using mixed-oxide method. A pseudo-ternary phase diagram of Bi(Sb,Nb,Ta)O4 system is given below the melting point. It is composed of a monoclinic phase region, an orthorhombic phase region and a monoclinic–orthorhombic co-existing phase region. In the orthorhombic phase region, the transformation from orthorhombic to triclinic phase is found to be sensitive to the composition and sintering temperature. Both the transformation from monoclinic to orthorhombic structure and the transformation from orthorhombic to triclinic structure have been studied by the cell parameters. [Copyright &y& Elsevier]

Abstract: Relationship between sintering process, relative density (shrinkage), grain morphological parameters and microwave dielectric properties of Bi(V0.008Nb0.992)O4 ceramics was studied. Influence of incubation time and sintering temperature on the microwave dielectric properties was discussed. The experiential logarithmic relationship and the parabola relationship were used to simulate the relationship between microwave permittivity, different incubation time and different sintering temperatures, respectively. Modification of Bosman and Havinga''s correction was used to eliminate the influence of pores on the permittivity of ceramics. The experimental, calculated and modified results corresponded well with each other. Morphological parameters of grains and pores were found to have dominant influence on microwave dielectric loss and the qualitative relationship was given. The best microwave dielectric properties were obtained in ceramics sintered at 830°C for 2h with heating ratio of 3°Cmin−1 with permittivity about 40 and Qf reaching 18,500GHz while relative density was only about 93.5%. [Copyright &y& Elsevier]

Microelectronics and electrical power systems require dielectric polymer-based dielectrics with high energy density that are simple to process. However, the currently available polymer-based dielectric materials require demanding process conditions and relatively low energy density. Herein, we propose P(VDF-HFP)-based nanocomposite by a simple and practical mechanical method based on a combination of solid phase reaction and sieving to prepare 0.88BaTiO 3 -0.12Bi(Li 0.5 Nb 0.5)O 3 nanoparticles (BT-BLN nps). The experimental and simulation result verify that the BT-BLN nps significantly improve the breakdown strength and energy storage performance of dielectric materials. Remarkably, the highest discharge energy density of the BT-BLN/P(VDF-HFP) nanocomposite film reached 14.2 J/cm3 with the addition of 3 vol% BT-BLN nanofiller at 497 MV/m, which is much higher than that of pure P(VDF- HFP) (U d ≈ 6.6 J/cm3 and E b ≈ 391.3 MV/m). Encouragingly, the Young's modulus of BLN-3vol%/P(VDF-HFP) reached 2.6 GPa, which is approximately 2.65 times higher than that of pure P(VDF-HFP) (0.98 GPa). This work established a simple and effective strategy, for solution casting processable dielectrics with performance comparable to that of fillers prepared by the liquid phase method. Significantly energy storage performance with the discharge energy density (U d) of 14.2 J/cm3 and energy storage efficiency (η) of 55.5% can be achieved by introducing an improved solid-state reaction method to prepare BT-BLN nanofillers. Image 1 • BT-BLN nanoparticles were first reported as nanocomposite filler for dielectric energy storage capacitors. • The optical image of the BT-BLN/P(VDF-HFP) nanocomposite film shows high transparency and flexibility. • The highest discharge energy density reached 14.2 J/cm3 with the addition of 3 vol% BT-BLN nanofiller at 497 MV/m. [ABSTRACT FROM AUTHOR]

Abstract: Both Li3TaO4 and Li3SbO4 ceramics were prepared via the solid state reaction method. With 1wt.% B2O3 addition, the sintering temperatures of both Li3TaO4 and Li3SbO4 ceramics can be lowered to near 930°C. The chemical compatibility of silver electrode and the low-firing ceramics has been considered, and the results showed that both the Li3TaO4 and Li3SbO4 ceramics are chemical compatible with Ag. Good microwave dielectric properties were obtained with permittivities of 14.1 and 10.3, quality factor Q f values of 29,900 (at 12.4GHz) and 14,600GHz (at 13.5GHz), and temperature coefficient of resonant frequency values of −48 and −28ppm/°C for Li3TaO4 and Li3SbO4 ceramics with 1wt.% B2O3 addition, respectively. [Copyright &y& Elsevier]

Abstract: A low firing microwave dielectric ceramic BaLa2(MoO4)4 with monoclinic structure was prepared via a solid state reaction method. The BaMoO4 and La2(MoO4)3 phases were first formed at 600°C and then the monoclinic BaLa2(MoO4)4 phase was formed gradually above 700°C. Dense and homogeneous microstructure can be obtained in ceramic sample sintered at 800–860°C for 2h with grain size lying between 3–7μm. Optimal microwave dielectric properties can be obtained in ceramic sintered at 860°C for 2h with a permittivity of ~10.3, a Qf value of ~29,800GHz and a temperature coefficient of resonant frequency of ~−76ppm/°C at about 9.9GHz. [Copyright &y& Elsevier]

Abstract In the present work, a systematic study on microwave properties of Ca 1-x Bi x Mo 1-x V x O 4 (0.2 ≤ x ≤ 0.5) solid solution ceramics synthesized by using the traditional solid-state reaction method was conducted. A scheelite structured solid solution was formed in the composition range 0.2 ≤ x ≤ 0.5. We successfully prepared a microwave dielectric ceramic Ca 0.66 Bi 0.34 Mo 0.66 V 0.34 O 4 with a temperature coefficient of resonant frequency (TCF) near to zero and a low sintering temperature by using (Bi, V) substituted (Ca, Mo) in CaMoO 4 to form a solid solution. The Ca 0.66 Bi 0.34 Mo 0.66 V 0.34 O 4 ceramic can be well sintered at only 870 °C and exhibits good microwave dielectric properties with a permittivity (ε r) ˜21.9, a Qf ˜18,150 GHz (at 7.2 GHz) (Q = quality factor = 1/dielectric loss; f = resonant frequency), a TCF ˜ + 0.1 ppm/°C. The chemical compatibility with silver indicated that the Ca 0.66 Bi 0.34 Mo 0.66 V 0.34 O 4 ceramic might be a good candidate for the LTCC applications. [ABSTRACT FROM AUTHOR]

Abstract: The phase evolution, microstructure and dielectric properties in the Ca2+ substituted Bi2O3–ZnO–Nb2O5 system were studied. The crystalline phases of the [Bi1.8(Ca x Zn1−x )0.2](Zn0.6Nb1.4)O7 pyrochlores (0.0≤x≤1.0) depend greatly on the ratio of ionic radius A/B. With the Ca2+ substitution for Zn2+ in the A site, the crystalline phase transformed from cubic to monoclinic and pure monoclinic phase was obtained for x≥0.5. As the x value increased from 0.5 to 1.0, the permittivity in the microwave range decreased from 76.4 to 75.0, the quality factor Qf value increased from 1800 to 4700GHz, and the TCF value shifted from −99 to −147ppm/°C. [Copyright &y& Elsevier]

Low sintering temperature Bi[V 1−x (Fe 1/3 W 2/3) x ]O 4 (BVFWx) (0.02 ≤ x ≤ 0.08) ceramics have been prepared by solid-state reaction. Compositions with 0.02 ≤ x ≤ 0.08 were scheelite-structure, but distortion of [BO 4 ] tetrahedra decreased with increase in x. Although the crystal class remained monoclinic, the phase transition temperature (T C) decreased from 255 ℃ (BV) to 51 ℃ (BVFW0.08), suggesting that higher concentrations of (Fe 1/3 W 2/3) would result in the stabilization of tetragonal scheelite at room temperature. The decrease in the [BO 4 ] distortion additionally resulted in a large reduction in the magnitude of the temperature coefficient of resonant frequency (TCF) with near-zero values obtained by sintering BVFW0.08:2BVFW0.06 at 780 °C to give TCF ≈ −5.9 ppm / °C, relative permittivity ε r ≈ 77.4, and microwave quality factor, Q × f ≈ 8100 GHz (@ ~ 4.3 GHz). These promising microwave dielectric properties coupled with the low sintering temperature suggest that BVFWx ceramics are of interest in low-temperature cofired ceramic (LTCC) technology, and for monolithic resonator and filter applications. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: A series of (ABi)1/2MoO4 (A=Li, Na, K, Rb, Ag) compositions were studied in regard to the sintering behavior, phase composition, microwave dielectric properties and chemical compatibility with silver and/or aluminum for electrodes. All the (ABi)1/2MoO4 (A=Li, Na, K, Rb, Ag) ceramics could be sintered below 700°C with relative densities above 93%. Whereas the (KBi)1/2MoO4 ceramic can be sintered to a high density at around 630°C/2hrs with a relative permittivity ∼37, a Qf value of 4000GHz and a temperature coefficient of resonant frequency (TCF)∼ +117ppm/°C. Furthermore, from the XRD analysis of co-fired ceramics, the (KBi)1/2MoO4 ceramic reacts with silver but not with aluminum at its densification temperature. The (ABi)1/2MoO4 (A=Li, Na, K, Rb, Ag) type ceramics can all be considered into the new field of ultra-low temperature co-firing dielectrics for multilayer applications. [Copyright &y& Elsevier]

Abstract: Effects of 1.0wt.% V2O5–CuO mixture addition on the sintering behavior, phase composition and microwave dielectric properties of BiSbO4 ceramics have been investigated. BiSbO4 ceramics can be well densified below temperature about 930°C with 1.0wt.% V2O5–CuO mixtures addition with different ratios of CuO to V2O5. The formation of BiVO4 phase and substitution of Cu2+ can explain the decrease of sintering temperature. Dense BiSbO4 ceramics sintered at 930°C for 2h exhibited good microwave dielectric properties with permittivity between 19 and 20.5, Qf values between 19,000 and 40,000GHz and temperature coefficient of resonant frequency shifting between −71.5ppm°C−1 and −77.8ppm°C−1. BiSbO4 ceramics could be a candidate for microwave application and low temperature co-fired ceramics technology. [Copyright &y& Elsevier]

Abstract: The influence of B2O3–CuO addition on the sintering behavior, phase composition, microstructure and microwave dielectric properties of BiSbO4 ceramic have been investigated. The BiSbO4 ceramics can be well densified to approach above 95% theoretical density in the sintering temperature range from 840 to 960°C as the addition amount of B2O3–CuO increases from 0.6 to 1.2wt.%. Sintered ceramic samples were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The microwave permittivity ɛ r saturated at 19–20 and Qf values varied between 33,000 and 46,000GHz while temperature coefficient of resonant frequency shifting between −70 and −60ppm/°C at sintering temperature around 930°C. Lowering sintering temperature of BiSbO4 ceramics makes it possible for application in low temperature co-fired ceramic technology. [Copyright &y& Elsevier]

In the present work, HP-BiNbO4 was found, by in situ X-ray diffraction, thermal expansion and differential thermal analysis, to transform to orthorhombic BiNbO4 at around 680°C along with an abrupt increase of volume, and to then transform to the triclinic BiNbO4 at around 1000°C with an endothermic phenomenon. The results indicate that the dielectric permittivity of HP-BiNbO4 ceramic prepared via the high-temperature/high-pressure method was increased remarkably and this might work in other dielectric systems. [ABSTRACT FROM AUTHOR]