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Microwave dielectric properties of glass–ceramic composites for low temperature co-firable ceramics
Materials Chemistry and Physics 79 (2003) 129–134
Microwave dielectric properties of glass–ceramic composites for low temperature co-firable ceramics Cheng-Sao Chen a,∗ , Chen-Chia Chou a , Wei-Jan Shih b , Kuo-Shung Liu b , Chang-Shun Chen c , I-Nan Lin d a
Department of Mechanical Engineering, National Taiwan University of Science and Technology, Taipei 106, Taiwan, ROC b Department of Materials Science and Engineering, National Tsing-Hua University, Hsinchu, Taiwan, ROC c Department of Mechanical Engineering, Hwa-Hsia College of Technology and Commerce, Taipei 235, Taiwan, ROC d Materials Science Center, National Tsing-Hua University, Hsinchu, Taiwan, ROC
Abstract The densification behavior and the microwave dielectric properties of RBS–(MgCa)TiO3 (R: MgO, CaO, SrO or BaO, B: B2 O3 and S: SiO2 ) glass–ceramic composite materials were systemically examined. The BaBS glass materials possess highest dielectric constant (K) and quality factor (Q) among the RBS glass materials and the BaBS–(Mg,Ca)TiO3 composites materials also exhibited largest K- and Q-value among the RBS–(Mg,Ca)TiO3 glass–ceramic composite materials. Comparison on the measured K-(Q-) values from the calculated K-(Q-) composition lines implies that the formation of additional crystalline phase other than (Mg,Ca)TiO3 materials markedly modifies the Q-value, but is insignificantly altering the K-value for the composite materials. © 2002 Elsevier Science B.V. All rights reserved. Keywords: Densification; Glass–ceramic composite; Low temperature co-firable ceramics; Microwave dielectric property
1. Introduction Low temperature co-firable ceramics (LTCC) possessing good microwave dielectric properties have recently been widely investigated, due to the necessity for miniaturization of microwave devices to reduce the size of wireless communication system [1–3]. However, the microwave dielectric materials, which possess high quality factor and large dielectric constant, usually need very high sintering temperature and long soaking time to achieve high enough density. On the other hand, using the Ag material as conducting materials for transmission lines and ground planes is needed in order to minimize the microwave absorption loss. Reduction on the sintering temperature for the microwave material to a level co-firable with Ag-electrode materials is thus called for. Generally, low softening temperature glass materials were mixed with the ceramic materials to reduce the firing temperature needed [4–9]. However, network formers contained in the glass materials may absorb the microwave power profoundly in high frequency regime, degrading the quality factor for the materials [10]. In this paper, the microwave dielectric properties of the ∗ Corresponding author. E-mail address: [email protected] (C.-S. Chen).
glass materials and the effect of processing parameters on the characteristics of the glass-to-ceramic composites were investigated.
2. Experiments Pure (Mg0.95 Ca0.05 )TiO3 , MCT, materials were first prepared by mixed oxide process. MgO, CaO and TiO2 with a molar ratio of nominal composition (Mg0.95 Ca0.05 )TiO3 were mixed and then calcined at 1000 ◦ C (2 h). Thus obtained powders were then pulverized down to about 0.5 m size by a dynomill. The glass powders of the composition shown in Table 1 was then mixed with (Mg0.95 Ca0.05 )TiO3 in 50/50 vol.%, followed by pelletization and then sintering at 800–1000 ◦ C for 1 h. The sintered density was measured using Achimedes method. The crystal structure and the microstructure of the sintered MCT samples were examined by X-ray diffraction analysis (XRD, Rigaku D/max-II B) and scanning electron microscopy (SEM, Joel JSM-840A), respectively. The microwave dielectric properties were measured using H.P.8722A network analyzer in a resonant cavity or parallel plate test fixture [11–13]. The microstructure of the materials were examined using transmission electron microscopy (Joel, 200CX-2).
0254-0584/02/$ – see front matter © 2002 Elsevier Science B.V. All rights reserved. PII: S 0 2 5 4 - 0 5 8 4 ( 0 2 ) 0 0 2 8 1 - X
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Table 1 The composition of RBS glass (R: MgO, CaO, SrO or BaO, B: B2 O3 and S: SiO2 in vol.%) Materials
Materials
RBS
MgBS CaBS SrBS BaBS
Al2 O3
B2 O3
SiO2
MgO
45 45 52.09 45
13 13 15.05 13
42
CaO
SrO
BaO
42 32.85 42
Table 2 The characteristics of RBS glass materials (R: MgO, CaO, SrO or BaO, B: B2 O3 and S: SiO2 ) Materials
Tg (◦ C)
Mg (◦ C)
α (10−6 /◦ C)
TD (gw/c.c)
K
f (GHz)
Q×f
MgBS CaBS SrBS BaBS
613 613 583 560
642 669 653 623
5.43 6.17 5.48 5.9
2.32 2.77 2.29 2.71
6.64 7.47 7.12 7.63
6.88 6.24 6.98 6.65
2137 2384 3608 4107
3. Results and discussion The characteristics of the metal–boron-silicates (RBS) glass materials are summarized in Table 2, indicating that all the glass materials possess high quality factor (Q × f ≥ 2000) and are suitable for applications as glass–ceramic composites. These glass materials possess similar microwave dielectric constant (K ∼ = 6 ∼ 8) and thermal expansion coefficient (α ∼ = 4.6–6.2 × 10−6 ◦ C−1 ). The MgBS possess the smallest Q × f -value, whereas the BaBS possess the largest Q × f -value among the RBS-series materials. Moreover, the BaBS materials have lowest softening temperature (Tg ) among the RBS glass materials. Both the high Q × f -value and small Tg -value are desirable for the applications in glass–ceramic composites, viz. the Ba–B–Si–O glass materials are expected to perform better than the other RBS materials.
Fig. 1. X-ray diffraction patterns of the RBS glasses post-annealed at 800 ◦ C for 2 h, indicating that MgBS glasses are most susceptible, while the BaBS glasses are least susceptible to crystallization.
Fig. 2. X-ray diffraction patterns of MCT–RBS glass–ceramics composites sintered at 900 ◦ C for 2 h (R: MgO, CaO, SrO or BaO, B: B2 O3 , S: SiO2 and MCT: (Mg0.95 Ca0.05 )TiO3 ).
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Fig. 3. (a) TEM micrographs showing the presence of glass aggregates, MgTiO3 crystals and CaTiO3 nano-crystalline/glass composite phase; (b) SAD of MgTiO3 in BaBS glass indicates that the interaction between MgTiO3 and BaBS glass is insignificant.
X-ray diffraction patterns of the glass materials heattreated at 800 ◦ C (2 h) are shown in Fig. 1 to indicate that MgBS materials are most susceptibe to crystallization, whereas the BaBS materials are least susceptible to crystal-
lization. The crystallization behavior of 50 MCT–50 RBS glass–ceramic materials are illustrated as XRD patterns in Fig. 2, revealing that crystallization of the glass materials is easily induced at the presence of (MgCa)TiO3 ceramics.
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Fig. 4. Variation of sintered density of MCT–RBS glass–ceramic composites with the densification temperature (R: MgO, CaO, SrO or BaO, B: B2 O3 , S: SiO2 and MCT: (Mg0.95 Ca0.05 )TiO3 ).
Fig. 3a illustrates the typical TEM micrographs of the 50 MCT–50BaBS glass–ceramic composites, which contain mixture of three phases. Electron diffraction analyses shown as inset (a) and (b) indicate that large proportion of the materials are glass aggregates and MgTiO3 crystals, whereas these shown in inset (c) inferred that the CaTiO3 constituents of the materials react with glass materials rigorously, such that a nano-crystal incorporated glass phase is resulted. In contrast, large number of MgTiO3 crystalline grains are observed to distribute uniformly over the composite materials, implying that the interaction between MgTiO3 and glass is less serious. Fig. 3b shows the selected area diffraction patterns (SAD) of crystalline MgTiO3 grains. Whether the crystallization of glass materials are beneficial or detrimental to microwave dielectric properties of the glass–ceramic composites will be discussed shortly. Fig. 4 shows the densification behavior of these glass– ceramic composites, where the theoretical density was calculated by assuming that the glass materials and the (Mg,Ca)TiO3 ceramics are mixed without multual interaction. These figures indicated that BaBS materials could achieve highest relative density among the RBS glass materials, whereas the CaBS materials are always of lower density in these series of materials, which is due to the presence of bubbles during glass forming process. Microwave dielectric properties for the MCT–RBS glass– ceramic composite materials are shown in Fig. 5a and b for dielectric constant (K) and quality (Q × f ), respectively. The microwave dielectric constant (K) of the RBS–MCT glass ceramic composites varies insignificantly with glass composites and densification temperature, i.e. K ∼ = 11 ± 0.5 (Fig. 5a). The BaBS materials possess slightly larger K-value
Fig. 5. Variation of dielectric constants (K) and quality factors (Q × f ) of MCT–RBS glass–ceramic composites as a function of the densification temperature.
(K ∼ = 13). In contrast, Fig. 5b reveals that the Q × f -value of these composite materials varies markedly with both the glass composition and the densification temperature. Among the RBS–MCT composites, the BaBS–MCT materials shows the highest Q×f -value (Q×f = 7000–10, 000), whereas the CaBS–(MgCa)TiO3 exhibits the lowest Q × f -value (Q × f = 2500–4000). Moreover, the K- and Q-values of BaBS–MCT composites are relatively insensitive to the processing temperature, viz. (Q × f )900 = 10, 000, (Q × f )1000 = 9, 500 and (K)900 = 13.2 and (K)1000 = 13.5 for those densified at 900 and 1000 ◦ C, respectively. It has been shown that all the RBS–(Mg,Ca)TiO3 composites materials contain larger proportion of crystalline phase other than (Mg,Ca)TiO3 ceramics. Whether the presence of such an additional crystalline phase enhances or degrades the microwave dielectric properties of the composite materials is examined by comparing the measured K- and Q-values
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Fig. 6. Comparison on of experimental derived K- and Q-values of MCT–RBS glass–ceramic composites with the theoretically calculated curves (R: MgO, CaO, SrO or BaO, B: B2 O3 , S: SiO2 and MCT: (Mg0.95 Ca0.05 )TiO3 ).
with the theoretical value calculated by using mixing rule, i.e. Kd Vm Km 23 + 3K + V d Kd m K= (1a) Kd + V Vm 23 + 3K d m and 1 Vm Vd = + Q Qm Qd
(1b)
where the Vm and Vd are the volume fraction of glass and (Mg,Ca)TiO3 materials, respectively; Km and Qm are the dielectric constant and quality factor of glass materials, respectively, and Kd and Qd are those of
(Mg,Ca)TiO3 materials. The calculated value are plotted as solid curves in Fig. 6a and b for K- and Q-value of BaBS–(Mg,Ca)TiO3 composite materials, respectively. The measured K- and Q-value of these materials are also shown as discreted symbols in these figures. The measured K-values fit the calculated K-lines reasonably well, whereas the measured Q-values deviate from the calculated ones pronouncedly. Most of the measured Q-value are larger then the calculated ones. The deviation of measured K- and Q-values from the calculated ones is presumably due to the formation of crystalline phase other than (Mg,Ca)TiO3 . These results infer that the formation of additional phase is beneficial to the quality factor, but insignificantly alters the dielectric constant of the composite materials.
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4. Conclusion
References
Glass characteristics of metal–boron-silica (RBS) and the densification behavior the microwave dielectric properties of RBS–(Mg,Ca)TiO3 glass–ceramic composite materials were systemically examined. The BaBS glass materials possess highest K- and Q-values among the RBS glass materials and the BaBS–(Mg,Ca)TiO3 composites materials also exhibite largest K- and Q-values among the RBS–(Mg,Ca)TiO3 materials. Deviation of measured K-value from the calculated K-composition line is insignificant, whereas that of the measured Q-values from the calculated Q-composition line is large. These results imply that the formation of additional crystalline phase other than (Mg,Ca)TiO3 ceramics is beneficial for Q-value, but is insignificantly altering the K-value of the composite materials.
[1] S.B. Chon, Microwave bandpass filters containing high Q dielectric resonator, IEEE Trans. Microwave Theory Tech. MTT-16 (1968) 218. [2] K. Wakine, Ferroelectrics 91 (1989) 69. [3] D.L. Wilcox Sr, R.F. Huang, S.X. Dai, J. Am. Ceram. Soc., Ceram. Trans. 97 (1999) 201. [4] T. Takada, et al., Effect of glass addition on BaO-TiO2 -WO3 microwave ceramics, J. Am. Ceram. Soc. 77 (7) (1994) 1909. [5] T. Takada, et al., J. Am. Ceram. Soc. 77 (9) (1994) 2485. [6] M.H. Lewis, Glasses and Glass–Ceramics, Chapman & Hall, 1989, p. 120. [7] H. Jantunen, R. Rautioaho, A. Uusimäki, S. Leppävuori, J. Eur. Ceram. Soc. 20 (2000) 2331. [8] C.F. Yang, S.H. Lo, J. Mater. Sci. Lett. 17 (1998) 1029. [9] J.M. Wu, H.L. Huang, J. Mater. Res. 15 (1) (1998) 222. [10] L. Navias, R.L. Green, J. Am. Ceram. Soc. 29 (10) (1946) 267. [11] B.W. Hakk, P.D. Coleman, A dielectric resonator method of measuring inductive capacities in the millimeter range, IEEE Trans. Microwave Theory Tech. 8 (1960) 402. [12] W.E. Courtney, Analysis and evaluation of a method of measuring the complex permittivity and permeability of microwave insulators, IEEE Trans. Microwave Theory Tech. 18 (1970) 476. [13] Y. Kobayashi, M. Katohy, Microwave measurement of dielectric properties of low-loss materials by the dielectric rod resonator method, IEEE Trans. Microwave Theory Tech. 33 (7) (1985) 586.
Acknowledgements The financial support of National Science Councils, ROC through Project no. NSC 89-2622-E-007-001 is gratefully appreciated by the authors.
Microwave dielectric properties of glass–ceramic composites for low temperature co-firable ceramics Cheng-Sao Chen a,∗ , Chen-Chia Chou a , Wei-Jan Shih b , Kuo-Shung Liu b , Chang-Shun Chen c , I-Nan Lin d a
Department of Mechanical Engineering, National Taiwan University of Science and Technology, Taipei 106, Taiwan, ROC b Department of Materials Science and Engineering, National Tsing-Hua University, Hsinchu, Taiwan, ROC c Department of Mechanical Engineering, Hwa-Hsia College of Technology and Commerce, Taipei 235, Taiwan, ROC d Materials Science Center, National Tsing-Hua University, Hsinchu, Taiwan, ROC
Abstract The densification behavior and the microwave dielectric properties of RBS–(MgCa)TiO3 (R: MgO, CaO, SrO or BaO, B: B2 O3 and S: SiO2 ) glass–ceramic composite materials were systemically examined. The BaBS glass materials possess highest dielectric constant (K) and quality factor (Q) among the RBS glass materials and the BaBS–(Mg,Ca)TiO3 composites materials also exhibited largest K- and Q-value among the RBS–(Mg,Ca)TiO3 glass–ceramic composite materials. Comparison on the measured K-(Q-) values from the calculated K-(Q-) composition lines implies that the formation of additional crystalline phase other than (Mg,Ca)TiO3 materials markedly modifies the Q-value, but is insignificantly altering the K-value for the composite materials. © 2002 Elsevier Science B.V. All rights reserved. Keywords: Densification; Glass–ceramic composite; Low temperature co-firable ceramics; Microwave dielectric property
1. Introduction Low temperature co-firable ceramics (LTCC) possessing good microwave dielectric properties have recently been widely investigated, due to the necessity for miniaturization of microwave devices to reduce the size of wireless communication system [1–3]. However, the microwave dielectric materials, which possess high quality factor and large dielectric constant, usually need very high sintering temperature and long soaking time to achieve high enough density. On the other hand, using the Ag material as conducting materials for transmission lines and ground planes is needed in order to minimize the microwave absorption loss. Reduction on the sintering temperature for the microwave material to a level co-firable with Ag-electrode materials is thus called for. Generally, low softening temperature glass materials were mixed with the ceramic materials to reduce the firing temperature needed [4–9]. However, network formers contained in the glass materials may absorb the microwave power profoundly in high frequency regime, degrading the quality factor for the materials [10]. In this paper, the microwave dielectric properties of the ∗ Corresponding author. E-mail address: [email protected] (C.-S. Chen).
glass materials and the effect of processing parameters on the characteristics of the glass-to-ceramic composites were investigated.
2. Experiments Pure (Mg0.95 Ca0.05 )TiO3 , MCT, materials were first prepared by mixed oxide process. MgO, CaO and TiO2 with a molar ratio of nominal composition (Mg0.95 Ca0.05 )TiO3 were mixed and then calcined at 1000 ◦ C (2 h). Thus obtained powders were then pulverized down to about 0.5 m size by a dynomill. The glass powders of the composition shown in Table 1 was then mixed with (Mg0.95 Ca0.05 )TiO3 in 50/50 vol.%, followed by pelletization and then sintering at 800–1000 ◦ C for 1 h. The sintered density was measured using Achimedes method. The crystal structure and the microstructure of the sintered MCT samples were examined by X-ray diffraction analysis (XRD, Rigaku D/max-II B) and scanning electron microscopy (SEM, Joel JSM-840A), respectively. The microwave dielectric properties were measured using H.P.8722A network analyzer in a resonant cavity or parallel plate test fixture [11–13]. The microstructure of the materials were examined using transmission electron microscopy (Joel, 200CX-2).
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Table 1 The composition of RBS glass (R: MgO, CaO, SrO or BaO, B: B2 O3 and S: SiO2 in vol.%) Materials
Materials
RBS
MgBS CaBS SrBS BaBS
Al2 O3
B2 O3
SiO2
MgO
45 45 52.09 45
13 13 15.05 13
42
CaO
SrO
BaO
42 32.85 42
Table 2 The characteristics of RBS glass materials (R: MgO, CaO, SrO or BaO, B: B2 O3 and S: SiO2 ) Materials
Tg (◦ C)
Mg (◦ C)
α (10−6 /◦ C)
TD (gw/c.c)
K
f (GHz)
Q×f
MgBS CaBS SrBS BaBS
613 613 583 560
642 669 653 623
5.43 6.17 5.48 5.9
2.32 2.77 2.29 2.71
6.64 7.47 7.12 7.63
6.88 6.24 6.98 6.65
2137 2384 3608 4107
3. Results and discussion The characteristics of the metal–boron-silicates (RBS) glass materials are summarized in Table 2, indicating that all the glass materials possess high quality factor (Q × f ≥ 2000) and are suitable for applications as glass–ceramic composites. These glass materials possess similar microwave dielectric constant (K ∼ = 6 ∼ 8) and thermal expansion coefficient (α ∼ = 4.6–6.2 × 10−6 ◦ C−1 ). The MgBS possess the smallest Q × f -value, whereas the BaBS possess the largest Q × f -value among the RBS-series materials. Moreover, the BaBS materials have lowest softening temperature (Tg ) among the RBS glass materials. Both the high Q × f -value and small Tg -value are desirable for the applications in glass–ceramic composites, viz. the Ba–B–Si–O glass materials are expected to perform better than the other RBS materials.
Fig. 1. X-ray diffraction patterns of the RBS glasses post-annealed at 800 ◦ C for 2 h, indicating that MgBS glasses are most susceptible, while the BaBS glasses are least susceptible to crystallization.
Fig. 2. X-ray diffraction patterns of MCT–RBS glass–ceramics composites sintered at 900 ◦ C for 2 h (R: MgO, CaO, SrO or BaO, B: B2 O3 , S: SiO2 and MCT: (Mg0.95 Ca0.05 )TiO3 ).
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131
Fig. 3. (a) TEM micrographs showing the presence of glass aggregates, MgTiO3 crystals and CaTiO3 nano-crystalline/glass composite phase; (b) SAD of MgTiO3 in BaBS glass indicates that the interaction between MgTiO3 and BaBS glass is insignificant.
X-ray diffraction patterns of the glass materials heattreated at 800 ◦ C (2 h) are shown in Fig. 1 to indicate that MgBS materials are most susceptibe to crystallization, whereas the BaBS materials are least susceptible to crystal-
lization. The crystallization behavior of 50 MCT–50 RBS glass–ceramic materials are illustrated as XRD patterns in Fig. 2, revealing that crystallization of the glass materials is easily induced at the presence of (MgCa)TiO3 ceramics.
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Fig. 4. Variation of sintered density of MCT–RBS glass–ceramic composites with the densification temperature (R: MgO, CaO, SrO or BaO, B: B2 O3 , S: SiO2 and MCT: (Mg0.95 Ca0.05 )TiO3 ).
Fig. 3a illustrates the typical TEM micrographs of the 50 MCT–50BaBS glass–ceramic composites, which contain mixture of three phases. Electron diffraction analyses shown as inset (a) and (b) indicate that large proportion of the materials are glass aggregates and MgTiO3 crystals, whereas these shown in inset (c) inferred that the CaTiO3 constituents of the materials react with glass materials rigorously, such that a nano-crystal incorporated glass phase is resulted. In contrast, large number of MgTiO3 crystalline grains are observed to distribute uniformly over the composite materials, implying that the interaction between MgTiO3 and glass is less serious. Fig. 3b shows the selected area diffraction patterns (SAD) of crystalline MgTiO3 grains. Whether the crystallization of glass materials are beneficial or detrimental to microwave dielectric properties of the glass–ceramic composites will be discussed shortly. Fig. 4 shows the densification behavior of these glass– ceramic composites, where the theoretical density was calculated by assuming that the glass materials and the (Mg,Ca)TiO3 ceramics are mixed without multual interaction. These figures indicated that BaBS materials could achieve highest relative density among the RBS glass materials, whereas the CaBS materials are always of lower density in these series of materials, which is due to the presence of bubbles during glass forming process. Microwave dielectric properties for the MCT–RBS glass– ceramic composite materials are shown in Fig. 5a and b for dielectric constant (K) and quality (Q × f ), respectively. The microwave dielectric constant (K) of the RBS–MCT glass ceramic composites varies insignificantly with glass composites and densification temperature, i.e. K ∼ = 11 ± 0.5 (Fig. 5a). The BaBS materials possess slightly larger K-value
Fig. 5. Variation of dielectric constants (K) and quality factors (Q × f ) of MCT–RBS glass–ceramic composites as a function of the densification temperature.
(K ∼ = 13). In contrast, Fig. 5b reveals that the Q × f -value of these composite materials varies markedly with both the glass composition and the densification temperature. Among the RBS–MCT composites, the BaBS–MCT materials shows the highest Q×f -value (Q×f = 7000–10, 000), whereas the CaBS–(MgCa)TiO3 exhibits the lowest Q × f -value (Q × f = 2500–4000). Moreover, the K- and Q-values of BaBS–MCT composites are relatively insensitive to the processing temperature, viz. (Q × f )900 = 10, 000, (Q × f )1000 = 9, 500 and (K)900 = 13.2 and (K)1000 = 13.5 for those densified at 900 and 1000 ◦ C, respectively. It has been shown that all the RBS–(Mg,Ca)TiO3 composites materials contain larger proportion of crystalline phase other than (Mg,Ca)TiO3 ceramics. Whether the presence of such an additional crystalline phase enhances or degrades the microwave dielectric properties of the composite materials is examined by comparing the measured K- and Q-values
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Fig. 6. Comparison on of experimental derived K- and Q-values of MCT–RBS glass–ceramic composites with the theoretically calculated curves (R: MgO, CaO, SrO or BaO, B: B2 O3 , S: SiO2 and MCT: (Mg0.95 Ca0.05 )TiO3 ).
with the theoretical value calculated by using mixing rule, i.e. Kd Vm Km 23 + 3K + V d Kd m K= (1a) Kd + V Vm 23 + 3K d m and 1 Vm Vd = + Q Qm Qd
(1b)
where the Vm and Vd are the volume fraction of glass and (Mg,Ca)TiO3 materials, respectively; Km and Qm are the dielectric constant and quality factor of glass materials, respectively, and Kd and Qd are those of
(Mg,Ca)TiO3 materials. The calculated value are plotted as solid curves in Fig. 6a and b for K- and Q-value of BaBS–(Mg,Ca)TiO3 composite materials, respectively. The measured K- and Q-value of these materials are also shown as discreted symbols in these figures. The measured K-values fit the calculated K-lines reasonably well, whereas the measured Q-values deviate from the calculated ones pronouncedly. Most of the measured Q-value are larger then the calculated ones. The deviation of measured K- and Q-values from the calculated ones is presumably due to the formation of crystalline phase other than (Mg,Ca)TiO3 . These results infer that the formation of additional phase is beneficial to the quality factor, but insignificantly alters the dielectric constant of the composite materials.
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4. Conclusion
References
Glass characteristics of metal–boron-silica (RBS) and the densification behavior the microwave dielectric properties of RBS–(Mg,Ca)TiO3 glass–ceramic composite materials were systemically examined. The BaBS glass materials possess highest K- and Q-values among the RBS glass materials and the BaBS–(Mg,Ca)TiO3 composites materials also exhibite largest K- and Q-values among the RBS–(Mg,Ca)TiO3 materials. Deviation of measured K-value from the calculated K-composition line is insignificant, whereas that of the measured Q-values from the calculated Q-composition line is large. These results imply that the formation of additional crystalline phase other than (Mg,Ca)TiO3 ceramics is beneficial for Q-value, but is insignificantly altering the K-value of the composite materials.
[1] S.B. Chon, Microwave bandpass filters containing high Q dielectric resonator, IEEE Trans. Microwave Theory Tech. MTT-16 (1968) 218. [2] K. Wakine, Ferroelectrics 91 (1989) 69. [3] D.L. Wilcox Sr, R.F. Huang, S.X. Dai, J. Am. Ceram. Soc., Ceram. Trans. 97 (1999) 201. [4] T. Takada, et al., Effect of glass addition on BaO-TiO2 -WO3 microwave ceramics, J. Am. Ceram. Soc. 77 (7) (1994) 1909. [5] T. Takada, et al., J. Am. Ceram. Soc. 77 (9) (1994) 2485. [6] M.H. Lewis, Glasses and Glass–Ceramics, Chapman & Hall, 1989, p. 120. [7] H. Jantunen, R. Rautioaho, A. Uusimäki, S. Leppävuori, J. Eur. Ceram. Soc. 20 (2000) 2331. [8] C.F. Yang, S.H. Lo, J. Mater. Sci. Lett. 17 (1998) 1029. [9] J.M. Wu, H.L. Huang, J. Mater. Res. 15 (1) (1998) 222. [10] L. Navias, R.L. Green, J. Am. Ceram. Soc. 29 (10) (1946) 267. [11] B.W. Hakk, P.D. Coleman, A dielectric resonator method of measuring inductive capacities in the millimeter range, IEEE Trans. Microwave Theory Tech. 8 (1960) 402. [12] W.E. Courtney, Analysis and evaluation of a method of measuring the complex permittivity and permeability of microwave insulators, IEEE Trans. Microwave Theory Tech. 18 (1970) 476. [13] Y. Kobayashi, M. Katohy, Microwave measurement of dielectric properties of low-loss materials by the dielectric rod resonator method, IEEE Trans. Microwave Theory Tech. 33 (7) (1985) 586.
Acknowledgements The financial support of National Science Councils, ROC through Project no. NSC 89-2622-E-007-001 is gratefully appreciated by the authors.