Microwave dielectric properties of Ca[(Li1/3Nb2/3)1−x Tix]O3−δ ceramics with glass (original) (raw)
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The Ca[(Li1/3Nb2/3)1−xTix]O3−ı (x = 0.2 and 0.25) (CLNT) ceramics with lithium borosilicate (LBS) and lithium magnesium zinc borosilicate (LMZBS) glasses were prepared by conventional solid state ceramic route. The effect of glass addition on the densification, microstructure and microwave dielectric properties of the CLNT ceramics was investigated. The addition of LBS and LMZBS glasses improved the densification and lowered the sintering temperature of CLNT ceramics from 1175 ◦C to 950 ◦C and 900 ◦C, respectively. The Ca[(Li1/3Nb2/3)0.8Ti0.2]O3−ı ceramics with 5 wt% of LBS glass sintered at 950 ◦C has εr = 30.5, Quf = 14,700GHz (f = 4.6 GHz) and f =−18 ppm/◦C. Addition of 12 wt% of LMZBS glass in Ca[(Li1/3Nb2/3)0.8Ti0.2]O3−ı ceramics sintered at 900 ◦C showed εr = 26.2, Quf = 13,000GHz (f = 4.8 GHz) and f =−21 ppm/◦C. The f value decreased to below 10 ppm/◦C by increasing the titanium content in the Ca[(Li1/3Nb2/3)0.8Ti0.2]O3−ı ceramics. The Ca[(Li1/3Nb2/3)0.75Ti0.25]O3−ı ceramics with 5 wt% of LBS and sintered at 950 ◦C/4 h has εr = 32.8, Quf = 11,500GHz (f = 4.5 GHz) and f =−2 ppm/◦C. The 12 wt% LMZBS glass added Ca[(Li1/3Nb2/3)0.75Ti0.25]O3−ı ceramics sintered at 920 ◦C/4 h has εr = 28.52, Quf = 11,000GHz (f = 4.8 GHz) and f =−3 ppm/◦C.
Abstract- The Ca[(Li1l3Nb2/3)1-xTix]0 3-3 (x=0.2 and 0.25) (CLNT) ceramics with Lithium Magnesium Zinc Borosilicate (LMZBS) glasses were prepared by conventional solid state ceramic route. The crystal structure and microstructure of the glass added and sintered CLNT ceramics were studied using X-ray diffractometer and Scanning electron microscope. The addition of LMZBS glasses improved the densification and lowered the sintering temperature of CLNT ceramics from 1175°C to 900°C without degrading the microwave dielectric properties. The value is tuned by increasing the titanium content in the Ca[(Li1l3Nb2/3)o.sTiO.2]0 3-3 ceramics. The Ca[(Li1l3Nb2/3)o.75Tio.25103-3 ceramics with 12 wt°A» of LMZBS and sintered at 900°C/4h has r =28.52, Quxf=11000 GHz and = ppm/°C. This results shows that the Ca[(Li1l3Nb2/3)o.75 Tio.25]03-3 ceramics with suitable amount of LMZBS glass addition can find application in LTCC based devices
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
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.
Microwave dielectric properties of Li2ZnTi3O8 ceramics prepared by reaction-sintering process
Journal of Materials Science: Materials in Electronics, 2014
Li 2 ZnTi 3 O 8 (LZT) microwave dielectric ceramics prepared by reaction-sintering process were investigated. Li 2 CO 3 , ZnO and TiO 2 powders were mixed, pressed and sintered directly into ceramic pellets without any calcination stage involved. Pure LZT phase was obtained after sintering at temperatures above 1,100°C for 2 h. LZT ceramic with the maximum bulk density of 3.81 g/cm 3 (96.2 % of the theoretical value) and excellent microwave dielectric properties of e r = 25.8, Q 9 f = 78,216 GHz and s f = -10.5 ppm/°C was obtained after sintering at 1,100°C for 2 h. The results show that the reaction-sintering process is a simple and effective method to produce LZT ceramics.
Low-Temperature Sintering and Microwave Dielectric Properties of Li2ATi3O8 (A5Mg, Zn) Ceramics
New temperature-stable low-loss ceramic–glass composites based on Li2ATi3O8 (A5Mg, Zn) ceramics have been prepared by the conventional solid-state ceramic route. The effect of lithium magnesium zinc borosilicate (LMZBS) glass addition on the sinterability, phase purity, microstructure, and microwave dielectric properties of Li2MgTi3O8 (LMT) and Li2ZnTi3O8 (LZT) dielectric ceramics has been investigated for low-temperature co-fired ceramic applications. The LMT13 wt% of LMZBS glass sintered at 9251C/4 h has er524.5, Quf544,000 GHz, and tf5(1)0.2 ppm/1C. Addition of LZT ceramics with 3 wt% of LMZBS glass sintered at 9001C/4 h has er523.2, Quf531,300 GHz, and tf5()15.6 ppm/1C. The LMT and LZT ceramic–glass composites do not react with the commonly used silver electrode material.
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.
Microwave dielectric properties of temperature stable Li2ZnxCo1−xTi3O8 ceramics
Journal of Alloys and Compounds, 2011
The Li 2 Zn x Co 1−x Ti 3 O 8 (x = 0.2-0.8) solid solution system has been synthesized by the conventional solidstate ceramic route and the effect of Zn substitution for Co on microwave dielectric properties of Li 2 CoTi 3 O 8 ceramics has also been investigated. The microwave dielectric properties of these ceramics show a linear variation between the end members for all compositions. The optimized sintering temperatures of Li 2 Zn x Co 1−x Ti 3 O 8 ceramics increase with increasing content of Zn. The specimen with x = 0.4 sintered at 1050 • C/2 h exhibits an excellent combination of microwave dielectric properties with ε r = 27.7, Q u × f = 57,100 GHz and f = −1.0 ppm/ • C.