Microwave dielectric properties of glass–ceramic composites for low temperature co-firable ceramics (original) (raw)
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Sinterability and microwave dielectric properties of 0.95MgTiO3–0.05CaTiO3–glass ceramic composites
Journal of Alloys and Compounds, 2009
Phase pure dielectric ceramic material of composition 0.95MgTiO 3 -0.05CaTiO 3 (MCT) was prepared using conventional solid state ceramic route. Glasses of different compositions viz. 60ZnO-30B 2 O 3 -10SiO 2 (ZBS), 30BaO-60B 2 O 3 -10SiO 2 (BBS), 50ZnO-50B 2 O 3 (ZB) and B 2 O 3 were added to the MCT. Effects of the addition of these glasses on the sinterability, microstructure and microwave dielectric properties in the frequency range of 4-6 GHz of MCT were investigated. The structure and microstructure of the glass ceramic composites were studied using XRD, SEM and EDS techniques respectively. The microwave dielectric properties of these composite materials were also investigated. Addition of 15 wt% ZBS glass lowers the sintering temperature of MCT from 1275 to 1050 • C, with relatively high Q × f = 29,000 GHz, ε r of 17.7 and of low f = −10.2. Addition of 5 wt% B 2 O 3 glass also reduced the sintering temperature to 1050 • C, ε r of 17.5, Q × f = 22,000 GHz and f = −1.6 ppm/ • C.
Microwave dielectric properties of glass-MCT low temperature co-firable ceramics
Journal of the European Ceramic Society, 2004
Interaction between the (Mg 0.95 Ca 0.05 )TiO 3 (MCT) microwave dielectric materials and BaBSiO glass materials was examined. Rigorous interaction occurs when the MCT-glass composite materials were densified at 800-900 C, which, fortunately, does not seriously degrade the microwave dielectric properties of the materials such that dielectric constant (K)=8-10 was achieved for MCT-glass composite materials, no matter whether they were in pellet or tape form. The MCT-glass composites with MCT-BaB-SiO=50:50 (vol.%) possess low shrinkage characteristics, when densified at 800-900 C for 10 min, and were used as constrain layer for an LTCC sandwich. LTCC tapes possessing very small x-y shrinkage ( < ¼ 0.05%) and good microwave properties (k=8.0 ) are thus synthesized. #
The effect of glass additives on the microwave dielectric properties of Ba(Mg1/3Ta2/3)O3 ceramics
The effect of glass additives on the densification, phase evolution, microstructure and microwave dielectric properties of Ba(Mg1/3 Ta2/3)O3 (BMT) was investigated. Different weight percentages of quenched glass such as B2O3, SiO2, B2O3–SiO2, ZnO–B2O3, 5ZnO–2B2O3, Al2 O3–SiO2, Na2 O–2B2O3 10H2O, BaO–B2O3–SiO2, MgO–B2O3–SiO2, PbO–B2O3–SiO2, ZnO–B2O3–SiO2 and 2MgO–Al2O3–5SiO2 were added to calcined BMT precursor. The sintering temperature of the glass-added BMT samples were lowered down to 1300 1C compared to solid-state sintering where the temperature was 1650 1C. The formation of high temperature satellite phases such as Ba5Ta4O15 and Ba7Ta6O22 were found to be suppressed by the glass addition. Addition of glass systems such as B2O3, ZnO–B2O3, 5ZnO–2B2O3 and ZnO–B2O3–SiO2 improved the densification and microwave dielectric properties. Other glasses were found to react with BMT to form low-Q phases which prevented densification. The microwave dielectric properties of undoped BMT with a densification of 93.1% of the theoretical density were r ¼ 24:8; tf ¼ 8 ppm=1C and Quf=80,000GHz: The BMT doped with 1.0wt% of B2O3 has Quf=124,700GHz; r ¼ 24:2; and tf ¼ 1:3 ppm=1C: The unloaded Q factor of 0.2wt% ZnO–B2O3-doped BMT was 136,500GHz while that of 1.0wt% of 5ZnO–2B2O3 added ceramic was Quf=141,800 GHz. The best microwave quality factor was observed for ZnO–B2O3–SiO2 (ZBS) glass-added ceramics which can act as a perfect liquid-phase medium for the sintering of BMT. The microwave dielectric properties of 0.2 wt% ZBS-added BMT dielectric was Quf=152,800 GHz, r ¼ 25:5; and tf ¼ 1:5ppm=1C: r 2004 Elsevier Inc. All rights reserved.
Journal of Advanced Ceramics, 2019
The effects of the Ca 0.7 Nd 0.2 TiO 3 ceramic addition on the crystallization, densification, and dielectric properties of CaO-B 2 O 3-SiO 2-(Al 2 O 3) glass (C1: CaO-B 2 O 3-SiO 2 glass and C1A03: CaO-B 2 O 3-SiO 2-Al 2 O 3 glass) for low-temperature co-fired ceramic (LTCC) applications are investigated. The cristobalite phase crystallized from C1 glass was inhibited by adding Al 2 O 3. During sintering, Ca 0.7 Nd 0.2 TiO 3 ceramic reacted with CaO-B 2 O 3-SiO 2-(Al 2 O 3) glass to form the sphene (CaTiSiO 5) phase. The amount of sphene phase increases with increasing sintering temperature. By adding 50-60 wt% C1 or C1A03 glass, Ca 0.7 Nd 0.2 TiO 3 can be densified at 850-900 ℃. The relative dielectric constants for Ca 0.7 Nd 0.2 TiO 3 added with C1 and C1A03 glasses were all 20-23. Ca 0.7 Nd 0.2 TiO 3 added with C1 glass exhibited a lower dielectric constant than C1A03 glass due to cristobalite phase formation. For Ca 0.7 Nd 0.2 TiO 3 ceramics added with 50 wt% glass, the variation in Q × f value presented the same trend as the sphene formation amount variation. The best Q × f value of 2380 GHz was achieved for Ca 0.7 Nd 0.2 TiO 3 ceramics added with 50 wt% C1A03 glass sintered at 900 ℃ due to the dense structure and greater amount of sphene. Ca 0.7 Nd 0.2 TiO 3 ceramics added with 50 wt% C1A03 glass sintered at 900 ℃ exhibited a dielectric constant of 22.8 and Q × f value of 2380 GHz, which are suitable for microwave LTCC applications.
Phase evolution and microwave dielectric properties of MgO–B2O3–SiO2–based glass–ceramics
Ceramics International, 2012
In the present work, a full range of compositions of xBi 2/3 MoO 4 -(1 − x)BiVO 4 (0.0 ≤ x ≤ 1.0) was prepared by the solid state reaction method. All the ceramic compositions could be readily densified to below 850°C. As the x value increased, the monoclinic scheelite structure continuously changed to a tetragonal structure at x = 0.10, which means the ferroelastic phase transition temperature was lowered to near room temperature. In the compositional range 0.50 ≤ x < 0.70, a novel ordered scheelite phase was formed, most likely through A-site vacancy ordering. For compositions x ≥ 0.70, a composite two-phase region consisting of the ordered scheelite and Bi 2/3 MoO 4 phases was formed. High microwave permittivity around 75 and Qf values around 8000 GHz could be obtained in the compositions near the phase boundaries between monoclinic and tetragonal scheelite phases. The intrinsic microwave dielectric properties were extrapolated from the far infrared reflectivity spectra, and it was found that the polarization was dominated by the Bi-O stretches when x ≤ 0.10.
Influence of glass additives on the microwave dielectric properties of Ca5Nb2TiO12 ceramics
Investigation was made to correlate the effect of composition and concentration of glass content on the sintering temperature and microwave dielectric properties of polycrystalline Ca5Nb2TiO12 ceramics. Glass systems, such as B2O3, SiO2, B2O3–SiO2, ZnO–B2O3, Al2O3–SiO2, Al2O3–B2O3–SiO2, BaO–B2O3–SiO2, MgO–B2O3–SiO2, ZnO–B2O3–SiO2, PbO–B2O3–SiO2, and 2MgO–Al2O3–5SiO2 were added to calcined Ca5Nb2TiO12 powder in different weight percentages. The structure and microstructure of the sintered ceramics were studied using powder X-ray diffraction and scanning electron microscopic methods. The specimens were characterized in the microwave frequency range (3–6 GHz). The study revealed that alumina and silica based glasses were more effective in improving the dielectric properties of Ca5Nb2TiO12 ceramics, whereas borate glasses are more suited for lowering the sintering temperature
Effect of Glass Addition on the Microwave Dielectric Properties of CaMgSi2O6 Ceramics
CaMgSi2O6 (CMS) ceramics prepared by the solid-state ceramic route have a sintering temperature of 13001C/2 h. The sintering temperature of CMS was reduced below the melting point of Ag using low-melting LBS and LMZBS glasses. In the case of CMS115 wt% LMZBS sintered at 9001C/2 h, the dielectric properties obtained were er58.2, Quf532,000 GHz (10.15 GHz), and tf5–48 ppm/1C. The CMS115 wt% LBS composite, sintered at 9251C/2 h, showed er58, Quf515,000 GHz (10.17 GHz), and tf5–49 ppm/1C. The chemical compatibility of Ag with the ceramic–glass composites was also investigated for low-temperature co-fired ceramic applications.
Tailoring the microwave dielectric properties of Ba(Mg1/3Ta2/3)O3 ceramics
Journal of The European Ceramic Society, 2006
The effect of glass fluxing and isovalent substitution on the microwave dielectric properties of low permittivity Sr 2 Al 2 SiO 7 (SAS) ceramic has been investigated. X-ray diffraction pattern of all the compositions indicate the formation of tetragonal Gehlenite type ceramics with space group P4 2 1 m (no. 113). The addition of small amounts of lithium magnesium zinc borosilicate (LMZBS) glass to Sr 2 Al 2 SiO 7 ceramic enhanced the densification. Glass fluxing also improved the quality factor and relative permittivity. A small partial substitution of Al 3+ and Si 4+ by Ga 3+ and Ge 4+ was found to degrade the dielectric properties of SAS ceramic. The composition Sr 2 Al 2 SiO 7 + 1 wt. % LMZBS glass showed the best dielectric properties with ε r = 7.3, Qu×f = 36000 GHz and τ f =-23.0 ppm/ o C.
International Journal of Applied Ceramic Technology, 2009
CaMgSi2O6 (CMS) ceramics prepared by the solid-state ceramic route have a sintering temperature of 1300°C/2 h. The sintering temperature of CMS was reduced below the melting point of Ag using low-melting LBS and LMZBS glasses. In the case of CMS+15 wt% LMZBS sintered at 900°C/2 h, the dielectric properties obtained were ɛr=8.2, Qu×f=32,000 GHz (10.15 GHz), and τf=–48 ppm/°C. The CMS+15 wt% LBS composite, sintered at 925°C/2 h, showed ɛr=8, Qu×f=15,000 GHz (10.17 GHz), and τf=–49 ppm/°C. The chemical compatibility of Ag with the ceramic–glass composites was also investigated for low-temperature co-fired ceramic applications.
Microwave dielectric properties of Ca[(Li1/3Nb2/3)1−x Tix]O3−δ ceramics with glass
Journal of Electroceramics, 2006
The effect of the addition of glass on the densification, low temperature sintering, and microwave dielectric properties of the Ca[(Li 1/3 Nb 2/3) 1−x Ti x ]O 3−δ (CLNT) was investigated. Addition of glass (B 2 O 3-ZnO-SiO 2-PbO system) improved the densification and reduced the sintering temperature from 1150 • C to 900 • C of Ca[(Li 1/3 Nb 2/3) 1−x-Ti x ]O 3−δ microwave dielectric ceramics. As increasing glass contents from 10 wt% to 15 wt%, the dielectric constants (ε r) and bulk density were increased. The quality factor (Q•f 0), however, was decreased slightly. The temperature coefficients of the resonant frequency (τ f) shifted positive value as increasing glass contents over Ti content is 0.2 mol. The dielectric properties of Ca[(Li 1/3 Nb 2/3) 0.75 Ti 0.25 ]O 3−δ with 10 wt% glass sintered at 900 • C for 3 h were ε r = 40 Q•f 0 = 11500 GHz, τ f = 8 ppm/ • C. The relationship between the microstructure and dielectric properties of ceramics was studied by X-ray diffraction (XRD), and scanning electron microscope (SEM).