Glass-Free Zn2Te3O8Microwave Ceramic for LTCC Applications (original) (raw)
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Journal of Materials Science: Materials in Electronics, 2014
h can reach a high relative density of 97.5 % and exhibits good microwave dielectric properties, i.e., relative dielectric constant (e r ) = 19.1, quality factor (Q) = 7083.5 at 9 GHz, and temperature coefficient of resonant frequency (s f ) = -48.9 ppm/°C. In addition, the ceramic could be co-fired well with an Ag electrode, which is made it as a promising dielectric ceramic for low temperature co-fired ceramics technology application.
Microwave Dielectric Properties of ATe3O8 (A = Sn, Zr) Ceramics
ATe3O8 (A = Sn, Zr) ceramics were investigated as a promising dielectric materials for low temperature cofired ceramics (LTCC) applications. The ATe3O8 ceramics were synthesized using solid state reaction method by sintering in the temperature range 600 to 800 C. The structure and microstructure of the ceramics were investigated using X-ray diffraction (XRD) and scanning electron microscopy (SEM) methods. The dielectric properties of the ceramics were studied in the frequency range 4– 6 GHz. The SnTe3O8 ceramic has a dielectric constant ("r) of 37.3, quality factor (Qu f ) of 9600 GHz, and temperature coefficient of resonant frequency (f ) of 223 ppm/C, respectively. Ceramics with the composition 0.9TeO2– 0.1SnTe3O8 has "r of 26.7, Qu f of 10000 GHz, and a f of 32 ppm/C when sintered at 650 C/2 h. ZrTe3O8 has relatively high "r of 67.5, Qu f of 1800 GHz, and high positive f of 362 ppm/
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.
Crystal structure and microwave dielectric properties of Zn0.9Ti0.8−xSnxNb2.2O8 ceramics
Ceramics International, 2012
The crystal structure and microwave dielectric properties of apatite-type LiRE 9 (SiO 4 ) 6 O 2 ceramics (RE = La, Pr, Nd, Sm, Eu, Gd, and Er) have been investigated. The densification of lithium apatites has been greatly improved with the addition of 1 wt% LiF. Selected area electron diffraction and X-ray diffraction (XRD) Rietveld analysis confirm that these compounds belong to the P6 3 /m (No. 176) space group with hexagonal crystal symmetry. The porosity-corrected relative permittivity was found to decrease with decreasing ionic polarizability of RE 3+ ions. Relationships between the structural parameters and microwave dielectric properties have been examined. The observed variation in the quality factor of LiRE 9 (SiO 4 ) 6 O 2 + 1 wt% LiF ceramics (RE = La, Pr, and Nd) was correlated with average cation covalency (%). The temperature coefficient of resonant frequency was found to depend on the bond valence sum of cations. LiEr 9 (SiO 4 ) 6 O 2 + 1 wt% LiF ceramics showed good microwave dielectric properties with e r = 12.8, Q u 3 f = 13000 GHz and τ f = +17 ppm/°C. All the compositions showed low coefficient of thermal expansion with thermal conductivity in the range 1.3-2.8 W (m K) À1 .
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.
Low loss, temperature stable dielectric ceramics in ZnNb2O6–Zn3Nb2O8 system for LTCC applications
Abstract (1 - x)ZnNb2O6–xZn3Nb2O8 mixed phase ceramics have been prepared by conventional solid state ceramic route by both mixing ZnO with Nb2O5 and by ZnNb2O6 with Zn3Nb2O8, respectively. The sintered ceramics have high relative permittivity (er = 23–25), high quality factor (Quxf) up to 95,500 GHz and temperature coefficient of resonant frequency (sf) in the range -55 to -73 ppm/C. The quality factors are higher for the mixtures when prepared from ZnNb2O6 and Zn3Nb2O8. The 0.5ZnNb2O6–0.5Zn3Nb2O8 has Quxf = 95,500 GHz (at 5.16 GHz), er = 22.7 and sf = -65 ppm/C when sintered at 1200 C. The sf of the ceramic has been tuned close to zero by the addition of ZnTa2O6, which has a positive sf. The ceramic composition (1 - y)[0.5ZnNb2O6–0.5Zn3Nb2O8]– yZnTa2O6 with y = 0.91 shows er = 34.7 and Quxf = 41,950 GHz (at 4.63 GHz) and zero sf. In order to lower the sintering temperature of 0.5ZnNb2O6–0.5Zn3Nb2O8 ceramic for low temperature co-fired ceramic applications, low melting additives such as CuO, B2O3 and ACuB2O5 (A—Ba, Sr, Zn, Ca) have been added. 12 wt% ZnCuB2O5 added 0.5ZnNb2O6–0.5Zn3Nb2O8 ceramic sintered at 875 C has Quxf = 39,750 GHz (at 5.89 GHz), er = 18.3 and sf = -88 ppm/C.
R.F. and microwave dielectric properties of (Zn0.95M0.05)2TiO4 (M=Mn2+, Co2+, Ni2+ or Cu2+) ceramics
Materials Science and Engineering: B, 2010
Here, we report our results on the synthesis and properties of pure and 3d transition metal substituted zinc ortho-titanate (Zn 1−x M x ) 2 TiO 4 dielectrics. Polycrystalline (Zn 0.95 M 0.05 ) 2 TiO 4 (M = Mn 2+ , Co 2+ , Ni 2+ or Cu 2+ ) samples of sintered density ≥94%, were prepared by ceramic powder mixing and solid state reaction followed by sintering (in air) between 1060 and 1180 • C. The XRD patterns of the furnace cooled samples revealed single ortho-titanate tetragonal inverse spinel phase. The SEM micrographs showed fairly uniform grains between 5 and 25 m depending upon the composition. Dielectric measurements on the samples were made at low frequencies (1 kHz to 1 MHz) from 30 to 450 • C. The dielectric constant (ε r ) and dielectric loss (tan ı), at all the frequencies, were found to rise with progressive increase in sample's temperature albeit the rise being less at higher frequencies (≥100 kHz). The room temperature values of ε r were between 21 and 26 (depending on the 3d M 2+ ion) and remained almost constant in the entire low frequency range ≤100 kHz. Both ε r and tan ı were found to decrease with increasing frequency at higher temperatures (>200 • C). At microwave frequencies (7.0-7.5 GHz), the room temperature values of ε r for all the (Zn 0.95 M 0.05 ) 2 TiO 4 samples were found to be in the range 18-20 and the unloaded quality factor (Q u ·f) values ranged between 2100 and 9650 GHz. The (Zn 0.95 M 0.05 ) 2 TiO 4 (M = Mn 2+ or Cu 2+ ), samples exhibited over four times improvement in quality factor vis-à-vis pure Zn 2 TiO 4 , which is attributed to relative increase in grain size and density in case of Cu 2+ , and reduction in tetragonality of the unit cell for Mn 2+ substitution.
The 0.83ZnAl2O4-0.17TiO2 (ZAT) ceramics were synthesized by solid state ceramic route. The effect of 27B2O3-35Bi2O3- 6SiO2-32ZnO (BBSZ) glass on the microwave dielectric properties of ZAT was investigated. The crystal structure and the microstructure of the ceramic-glass composites were studied by X-ray diffraction and scanning electron microscopic techniques. The low frequency dielectric loss was measured at 1 MHz. The dielectric properties of the sintered samples were measured in the microwave frequency range by the resonance method. Addition of 0.2 wt% of BBSZ improved the dielectric properties with quality factor (Qu f) > 120,000 GHz, temperature coefficient of resonant frequency (tf) = 7.3 ppm/8C and dielectric constant (er) = 11.7. Addition of 10 wt% of BBSZ lowered the sintering temperature to about 950 8C with Qu f > 10,000 GHz, er = 10 and tf = 23 ppm/8C. The reactivity of 10 wt% BBSZ added ZAT with silver was also studied. The results show that ZAT doped with suitable amount of BBSZ glass is a possible material for low-temperature co-fired ceramic (LTCC) application
Microwave Dielectric Properties and Low-Temperature Sintering of Cerium Oxide for LTCC Applications
were added to CeO 2 powder. The crystal structure of the ceramic-glass composites was studied by X-ray diffraction, microstructure by scanning electron microscopy, and phase composition using the energy-dispersive X-ray analysis technique. The microwave dielectric properties such as relative permittivity (e r ), quality factor (Q u xf), and coefficient of temperature variation of resonant frequency (s f ) of the ceramics have been measured in the frequency range 4-6 GHz. Addition of B 2 O 3 and Bi 2 O 3 -ZnO-B 2 O 3 -SiO 2 lowered the sintering temperature of ceria to about 9001C. The 20 wt% B 2 O 3 and 10 wt% Bi 2 O 3 -ZnO-B 2 O 3 -SiO 2 -added CeO 2 and sintered at 9001 and 9501C showed: Q u xf 5 24 200 and 12 000 GHz, e r 5 13.2 and 22.4, and s f 5 À46 and -57.2 ppm/1C, respectively.