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1.
Low temperature sintering and microwave dielectric properties of Ba3Ti5Nb6O28 with B2O3 and CuO additions 总被引:1,自引:0,他引:1
Jeong-Ryeol Kim Dong-Wan Kim Sung Hun Yoon Kug Sun Hong 《Journal of Electroceramics》2006,17(2-4):439-443
The low sintering temperature and the good dielectric properties such as high dielectric constant (ε
r
), high quality factor (Q × f), and small temperature coefficient of resonant frequency (TCF) are required for the application of chip passive components
in wireless communication low temperature co-fired ceramics (LTCC). In the present study, the sintering behaviors and dielectric
properties of Ba3Ti5Nb6O28 ceramics were investigated as a function of B2O3-CuO content. The pure Ba3Ti5Nb6O28 system showed a high sintering temperature (1250∘C) and had the good microwave dielectric properties: Q × f of 10,600 GHz, ε
r
of 37, TCF of −12 ppm/∘C. The addition of B2O3-CuO was revealed to lower the sintering temperature of Ba3Ti5Nb6O28, 900∘C and to enhance the microwave dielectric properties: Q × f of 32,500 GHz, ε
r
of 40, TCF of 9 ppm/∘C. From the X-ray photoelectron spectroscopy (XPS) and X-ray powder diffraction (XRD) studies, these phenomena were explained
in terms of the reduction of oxygen vacancies and the formation of secondary phases having the good microwave dielectric properties. 相似文献
2.
Monazite-type compounds, BiPO4 polymorphs were prepared by the solid-state reaction method. The phase transformation and microwave dielectric properties
of sintered ceramics were investigated using the X-ray powder diffraction (XRD) and a network analyzer, respectively. The
low-temperature phase of BiPO4 has monoclinic structure, and was transformed into the high-temperature phase with a slight distortion of monoclinic when
it is heated above 600∘C. The effect of the transformation on the microwave dielectric properties was examined. It was found that the dielectric
properties of each phase were significantly different. In particular, the high-temperature phase sintered at 950∘C has good microwave dielectric properties; the relative dielectric constant (ε
r
) = 22, the quality factor (Q× f) = 32,500 GHz and the temperature coefficient of resonant frequency (τ
f
) = − 79 ppm/ ∘C. 相似文献
3.
BaO ⋅ Nd2O3 ⋅ 4TiO2—based ceramics were prepared by the mixed oxide route. Specimens were sintered at temperatures in the range 1200–1450∘C. Microstructures were investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM); microwave
dielectric properties were determined at 3 GHz by the Hakki and Coleman method. Product densities were at least 95% theoretical.
The addition of up to 1 wt% Al2O3 to the starting mixtures reduced the sintering temperatures by at least 100∘C. Incorporation of small levels of Al into the structure (initially Ti sites) led to an increase in Q × f values, from 6200 to 7000 GHz, a decrease in relative permittivity (εr) from 88 to 78, and moved the temperature coefficient of resonant frequency (τf) towards zero. The addition of 0.5 wt% Al2O3 with 8 wt% Bi2O3 improved densification, increased both εr (to 88) and Q× f (to 8000 GHz) and moved τf closer to zero.
Ceramics in the system (1 − x)BaO ⋅ Nd2O3 ⋅ 4TiO2 + xBaO ⋅ Al2O3 ⋅ 4TiO2 exhibited very limited solid solubility. The end member BaO ⋅ Al2O3 ⋅ 4TiO2 was tetragonal in structure with the following dielectric properties: εr = 35; Q× f = 5000 GHz; τf = −15ppm/∘C. Microstructures of the mixed Nd-Al compositions contained two distinct phases, Nd-rich needle-like grains and large Al-rich,
lath-shaped grains. Products with near zero τf were achieved at compositions of approximately 0.14BaO ⋅ Nd2O3 ⋅ 4TiO2 + 0.86BaO ⋅ Al2O3 ⋅ 4TiO2, where Q× f = 8200 GHz and εr = 71. 相似文献
4.
Jong-Yoon Ha Ji-Won Choi Chong-Yun Kang Seok-Jin Yoon Doo Jin Choi Hyun-Jai Kim 《Journal of Electroceramics》2006,17(2-4):399-403
The effect of the addition of glass on the densification, low temperature sintering, and microwave dielectric properties of
the Ca[(Li1/3Nb2/3)1−x
Tix]O3−δ(CLNT) was investigated. Addition of glass (B2O3-ZnO-SiO2-PbO system) improved the densification and reduced the sintering temperature from 1150∘C to 900∘C of Ca[(Li1/3Nb2/3)1−x
-Tix]O3−δ microwave dielectric ceramics. As increasing glass contents from 10 wt% to 15 wt%, the dielectric constants (εr) and bulk density were increased. The quality factor (Q⋅f0), however, was decreased slightly. The temperature coefficients of the resonant frequency (τf) shifted positive value as increasing glass contents over Ti content is 0.2 mol. The dielectric properties of Ca[(Li1/3Nb2/3)0.75Ti0.25]O3−δ with 10 wt% glass sintered at 900∘C for 3 h were εr = 40 Q·f0 = 11500 GHz, τf = 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). 相似文献
5.
Chien-Min Cheng Ying-Chung Chen Cheng-Fu Yang Chao-Chin Chan 《Journal of Electroceramics》2007,18(1-2):155-160
1,500 °C−sintered MgTa2O6 ceramic exhibits microwave dielectric characteristics of ɛ
r = 30.5, Q × f = 56,900 GHz, and τ
f = 28.3 ppm/°C, whereas 1,400 °C-sintered MgNb2O6 ceramic exhibits microwave dielectric characteristics of ɛ
r = 21.7, Q × f = 89,900 GHz, and τ
f = −68.5 ppm/°C. In order to find the dielectric resonators with τ
f value close to 0 ppm/°C, the effects of sintering condition and composition on the microwave dielectric characteristics of
Mg(Ta1−x
Nb
x
)2O6 ceramics (0.25 ≦ x ≦ 0.35) prepared under sintering temperature of 1,300–1,450 °C are investigated. The results show that as the sintering temperature
increases from 1,300 to 1,450 °C, the ɛ
r, Q × f and τ
f values of Mg(Ta1−x
Nb
x
)2O6 ceramics all increase and saturate at 1,450 °C. On the other hand, as the Nb2O5 content decreases, the τ
f values of Mg(Ta1−x
Nb
x
)2O6 ceramics will shift to near 0 ppm/°C. The optimized sintering conditions and composition to obtain the Mg(Ta1−x
Nb
x
)2O6 dielectrics with τ
f close to 0 ppm/°C are sintering temperature of 1,450 °C, sintering duration of 4 h, and composition of x = 0.25, which exhibits the microwave dielectric characteristics of ɛ
r = 27.9, Q × f = 33,100 GHz, and τ
f = −0.7 ppm/°C. 相似文献
6.
Juhyun Yoo Jungmin Hwang Sangho Lee Kwanghyun Chung Hyunggyu Lee 《Journal of Electroceramics》2006,17(2-4):525-529
In this study, in order to develop the composition ceramics for multilayer piezoelectric actuator, PNN substituted PMN-PZT
ceramics were fabricated using Li2CO3 and Na2CO3 as sintering aids, and their piezoelectric and dielectric characteristics were investigated. With the increase of the amount
of PNN substitution, dielectric constant (εr), electromechanical coupling factor (k
p), and piezoelectric constant (d
33) of specimens showed the maximum value at each sintering temperature, and crystal structure changed from tetragonal to rhombohedral.
At the sintering temperature of 950∘C, the density, εr, k
p, d
33, Qm and Tc of 12 mol% PNN substituted PMN-PNN-PZT composition ceramics showed the optimal values of 7.79 g/cm3, 1160, 0.599, 419pC/N, 894 and 332∘C, respectively, for low loss multilayer piezoelectric actuator application. 相似文献
7.
Ceramics of 0.2CaTiO3-0.8Li0.5Nd0.5TiO3) have been prepared by the mixed oxide route using additions of Bi2O3-2TiO2 (up to 15 wt%). Powders were calcined 1100∘C; cylindrical specimens were fired at temperatures in the range 1250–1325∘C. Sintered products were typically 95% dense. The microstructures were dominated by angular grains 1–2 μm in size. With increasing
levels of Bi2O3-2TiO2 additions, needle and lath shaped second phases developed. For Bi2Ti2O7 additions up to 5 wt%, the relative permittivity increased from 95 to 131, the product of dielectric Q value and measurement frequency increased from 2150 to 2450 GHz and the temperature coefficient of resonant frequency (τ
f
) increased from −28pp/∘C to +22pp/∘C. A product with temperature stable τ
f
could be obtained at ∼2 wt% Bi2Ti2O7 additions. For high levels of additives, there is minimal change in relative permittivity, the Qxf values degrade and τ
f
becomes increasingly negative. 相似文献
8.
Modification of Pb0.6Ca0.4Zr0.6(Fe1/2Nb1/2)0.4O3 dielectric ceramics was performed by Zr substitution for (Fe, Nb). The XRD patterns showed that the single phase with orthorhombic distortion unit cell was obtained in the present ceramics. The decreasing dielectric constant by Zr substitution was due to its smaller value of /r
3
ion. The calculated polarizability was compared with the observed one, and the results showed a good fit, considering the polarizability of oxygen dependent on the V
ox. The Zr substitution on B-site reduced the temperature coefficient of dielectric constant effectively due to the reduced dielectric constant. The effects of tilting transition on the temperature coefficient of dielectric constant were also discussed. The modified microwave dielectric properties were obtained in Pb0.6Ca0.4Zr0.6+x
(Fe1/2Nb1/2)0.4–x
O3 for x = 0.3:
r
= 100, Q × f = 3,300 to 3,600 GHz,
f
= 6–8 ppm/°C. 相似文献
9.
Jong-Bong Lim Sahn Nahm Hyo-Tae Kim Jong-Hee Kim Jong-Hoo Paik Hwack-Joo Lee 《Journal of Electroceramics》2006,17(2-4):393-397
The effect of B2O3 and CuO on the sintering temperature and microwave dielectric properties of BaTi4O9 ceramics was investigated. The BaTi4O9 ceramics were able to be sintered at 975∘C when B2O3 was added. This decrease in the sintering temperature of the BaTi4O9 ceramics upon the addition of B2O3 is attributed to the formation of BaB2O4 second phase whose melting temperature is around 900∘C. The B2O3 added BaTi4O9 ceramics alone were not sintered below 975∘C, but were sintered at 875∘C when CuO was added. The formation of BaCu(B2O5) second phase could be responsible for the decrease in the sintering temperature of the CuO and B2O3 added BaTi4O9 ceramics. The BaTi4O9 ceramics containing 2.0 mol% B2O3 and 5.0 mol% CuO sintered at 900∘C for 2 h have good microwave dielectric properties of εr = 36.3, Q× f = 30,500 GHz and τf = 28.1 ppm/∘C 相似文献
10.
The effects of CuO and TiO2 additives on the microstructure and microwave dielectric properties of Al2O3 ceramics were investigated. Al2O3 ceramics with CuO and TiO2 additions can be well sintered to achieve 93∼98% theoretical densities below 1,360 °C due to Ti4Cu2O liquid phase sintering effect. The Qf values decreased with increasing CuO and TiO2 content, due to the formation of the second phase Ti4Cu2O. However, the varying behaviors of the dielectric constant (ɛ
r
) and temperature coefficients (τ
f
) were associated with phase constitutions, as a result of the change of CuO and TiO2content. The τ
f
can be shifted close to 0 ppm/°C by controlling the content of CuO and TiO2. The specimens with 0.5 wt.% CuO and 7 wt.% TiO2 sintered at 1,360 °C for 4 h showed ɛ
r
of 11.8, Qf value of 30,000 GHz, and τ
f
of −7 ppm/°C. 相似文献
11.
K. Pengpat S. Hanphimol S. Eitssayeam U. Intatha G. Rujijanagul T. Tunkasiri 《Journal of Electroceramics》2006,16(4):301-305
The important properties of lead-free piezoelectric ceramics have been investigated from Bismuth Sodium Lanthanum Titanate
and Barium Titanate system: (1 − y)(Bi0.5Na0.5)(1 − 1.5x)La
x
TiO3(BNLT)—yBaTiO3(BT) where x = 0.017 and y = 0 − 0.2, respectively. The morphotropic phase boundary (MPB) was found to be around y = 0.1 by the x-ray diffraction and dielectric measurement at various amount of BT. The temperature dependence of dielectric
constant (ε
r
) at various value of y showed the diffuse phase transition exhibiting the relaxor type ferroelectrics. The degree of diffuseness
increased at a high doping content of about y = 0.15 where the second phase transition (T2) of the ferroelectric to antiferroelectric phase disappeared. Moreover, this sample had the maximum piezoelectric coefficient
(d
33) of about 112 pC/N with relatively low dielectric constant. The optimum sintering temperatures and the microstructures of
the dense BNLT-BT ceramics were also examined. 相似文献
12.
The possibility of formation of a solid solution in the system BaSn1−x
Cr
x
O3 has been explored upto x ≤ 0.20. It has been confirmed that single phase solid solution forms upto x ≤ 0.10. Dielectric and conduction behaviour of single phase samples have been studied in the temperature range 400–610 K
and frequency range 10 Hz–2 MHz. Two dielectric relaxation processes in two different frequency ranges have been observed.
The temperature dependence of both dc and ac resistivity obey relation ρ = ρ
o exp(B/T1/4), indicative of variable range hopping conduction mechanism. The activation energy for dc conduction is higher than that
for relaxation time (τ) of low frequency dielectric relaxation process. It has been observed that activation energy for dielectric relaxation matches
with activation energy for ac conductivity (at 100 kHz) for both the dielectric relaxation processes. Seebeck coefficient
‘α’ of the samples have been measured in the temperature range 350–650 K. Negative value of ‘α’ in the entire range of temperature measurement shows that conduction species are negatively charged. On the basis of value
of activation energy for dc conduction and sign of Seebeck coefficient, conduction in the low temperature region (below 500 K)
is attributed to hopping of weakly bonded electrons among Sn2+ ⇔ Sn4+ or Sn3+ ⇔ Sn4+ and that in the high temperature region (above 500 K) to hopping of doubly ionized oxygen vacancies . 相似文献
13.
Jeong-Ryeol Kim Geun-Kyu Choi Dong Kyun Yim Jong-Sung Park Kug Sun Hong 《Journal of Electroceramics》2006,17(1):65-69
Glasses in the ZnO-B2O3-MO3(M = W, Mo) ternary were examined as potential replacements to PbO-B2O3-SiO2-ZnO glass frits with the low firing temperature (500–600∘C) for the dielectric layer of a plasma display panels (PDPs). Glasses were melted in air at 950–1150∘C in a narrow region of the ternary using standard reagent grade materials. The glasses were evaluated for glass transition
temperature (T
g
), softening temperature (T
d
), the coefficient of thermal expansion (CTE), dielectric constant (ε
r
), and optical property. The glass transition temperature of the glasses varied between 470 and 560∘C. The coefficient of thermal expansion and the dielectric constant of the glasses were in the range of 5–8 × 10− 6/∘C and 8–10, respectively. The addition of MO3to ZnO-B2O3binary could induce the expansion of glass forming region, the reduction of T
g
and the increase in the CTE and the dielectric constant of the glasses. Also, the effect of the addition of MO3to ZnO-B2O3binary on the transmittance in the visible-light region (350–700 nm) was investigated. 相似文献
14.
Microwave dielectric properties of low temperature sintering ZnNb2O6 ceramics doped with CuO-V2O5-Bi2O3 additions were investigated systematically. The co-doping of CuO, V2O5 and Bi2O3 can significantly lower the sintering temperature of ZnNb2O6 ceramics from 1150 to 870C. The secondary phase containing Cu, V, Bi and Zn was observed at grain boundary junctions, and the amount of secondary phase increased with increasing CuO-V2O5-Bi2O3 content. The dielectric properties at microwave frequencies (7–9 GHz) in this system exhibited a significant dependence on the relative density, content of additives and microstructure of the ceramics. The dielectric constant ( r) of ZnNb2O6 ceramics increased from 21.95 to 24.18 with increasing CuO-V2O5-Bi2O3 additions from 1.5 to 4.0 wt%. The quality factors (Q× f) of this system decreased with increasing CuO-V2O5-Bi2O3 content and ranged from 36118 to 67100 GHz for sintered ceramics, furthermore, all Q× f values of samples with CuO-V2O5-Bi2O3 additions are lower than that of un-doped ZnNb2O6 ceramics sintered at 1150C for 2 h. The temperature coefficient of resonant frequency ( f) changed from –33.16 to –25.96 ppm/C with increasing CuO-V2O5-Bi2O3 from 1.5 to 4.0 wt% 相似文献
15.
Lead zirconium titanate (PZT) films (Zr/Ti=45:55) with a high dielectric constant are prepared successfully on the low-resistance
Si substrate in sol–gel dip-coating process with PT film used as the buffer layer. The dielectric and ferroelectric properties
of the films as well as the relationship between crystallization and preparing condition are studied. It is shown that the
PZT ferroelectric thin films with a (110) preferred orientation and a well-crystallized perovskite structure could be obtained
after annealing at 800°C for 15 min. The particle size of the sample is about 14–25 nm. The P–E hysteresis loops are measured by means of the Sawyer-Tower test system with a compensation resistor at room temperature.
The remanent polarization (P
r) and coercive electric field (E
c) of the measured PZT thin films are 47.7 μC/cm2 and 18 kV/cm, respectively. The relative dielectric constant ε
r and the dissipation factor tgδ of the PZT thin films were measured with an LCR meter and were found to be 158 and 0.04–0.005, respectively.
Translated from “Preparation and Characterization of PZT Films Fabricated on Si Substrates” published in Chinese Journal of Semiconductors, 2004, 25(4): 404–409 (in Chinese) 相似文献
16.
New lead-free piezoelectric ceramics of ABO3 perovskite type, Bi1/2Na1/2[Ti1−x
(Sb1/2Nb1/2)
x
]O3, were synthesized by conventional solid state reaction. The effect of the replacement of complex ions of (Sb1/2Nb1/2)4+ in the B cationic site on structural and electrical properties was investigated. The XRD analysis showed that all samples
exhibited a single phase of perovskite structure. Piezoelectric and dielectric measurement revealed that the substitution
of (Sb1/2Nb1/2)4+ ions lead to an increase in piezoelectric constant(d
33), electromechanical coupling factor(k
t), relative dielectric constant(ɛ
r),and loss tangent (tanδ), while excess of (Nb1/2Sb1/2)4+ ions results in a decrease in d
33, k
t, ɛ
r, but an increase in tanδ. Temperature dependence of dielectric constant ɛ
r measurement indicated these compounds were relaxor ferroelectric. At low frequency and high temperature, dielectric constant
increased sharply attributed to the superparaelectric clusters after (Sb1/2Nb1/2)4+ ions substitution. 相似文献
17.
The influence of complex dopants including donor and acceptor ions on microstructure and electrical properties of PZT (Zr/Ti
= 53/47) ceramics was investigated. The prepared PZT ceramics modified with complex soft dopants, La+3 and Nb+5, showed that the piezoelectric properties were enhanced and stable with the compositional variations, which made it possible
to establish the higher reliability and reproducibility of the piezoelectric performances. For 1.0 mol% La and 1.2 mol% Nb
doped composition, the maximum value, k
P
= 0.66, was obtained. Unlike single element doping, the complex doping of both the donor and acceptor ions caused various
compensation effects for the piezoelectric properties of the PZT ceramics. The improved piezoelectric properties, i.e., enhanced
Q
m
with remaining higher k
p
, were obtained in the PZT composition complexly doped with La+3 and Fe+3. For 1.0 mol% La and 2.0 mol% Fe doped PZT composition, relatively high Q
m
and k
p
values of 580 and 0.53, respectively, were obtained. It was also shown that the PZT composition had the rather lowered dielectric
constant, ε
r
= 800, and considerably low loss, tanδ = 0.003. By changing the dopants compositions, the properties can also be tailored
over wider range. 相似文献
18.
Electrical properties and sintering behaviors of (1 − x)Pb(Zr0.5Ti0.5)O3-xPb(Cu0.33Nb0.67)O3 ((1 − x)PZT-xPCN, 0.04 ≤ x ≤ 0.32) ceramics were investigated as a function of PCN content and sintering temperature. For the specimens
sintered at 1050∘C for 2 h, a single phase of perovskite structure was obtained up to x = 0.16, and the pyrochlore phase, Pb2Nb2O7 was detected for further substitution. The dielectric constant (ε r), electromechanical coupling factor (Kp) and the piezoelectric coefficient (d
33) increased up to x = 0.08 and then decreased. These results were due to the coexistence of tetragonal and rhombohedral phases in the composition
of x = 0.08. With an increasing of PCN content, Curie temperature (Tc) decreased and the dielectric loss (tanδ) increased. Typically, εr of 1636, Kp of 64% and d33 of 473pC/N were obtained for the 0.92PZT-0.08PCN ceramics sintered at 950∘C for 2 h. 相似文献
19.
The fabricated micro machined ultrasonic transducers (pMUT) was based on piezoelectric laminated plates operating at flexural
modes. The fabricated bimorph pMUT transducers were composed of 5-layers. A 4 μm thick lead zirconate titanate (PZT) thin
film deposited by a sol–gel method was used. The piezoelectric layer exhibited a capacitance corresponding to a permitivity
of ɛ
r = 1,200. The electromechanical coupling coefficient (k
2) and quality factor (Q) were measured as k
2 = 4.4% and Q = 145 in air for a low frequency transducer (240 kHz). The effect of DC bias voltage on frequency and k
2 has been studied. The 16.9 MHz transducer yielded values of Q = 25 in air and k
2 = 3%. 相似文献
20.
M.-S. Yoon Y.-M. Kim S.-Y. Kweon T.-W. Hong Y.-G. Lee S.-L. Ryu I.-H. Kim H.-J. Kim S.-C. Ur 《Journal of Electroceramics》2006,17(2-4):635-637
Perovskite-types 0.05Pb(Mn1/3Sb2/3)O2-0.95Pb- (Zr0.5Ti0.5)O3 (PMS-PZT) was synthesized by conventional bulk ceramic processing technique. ZnO as a dopant up to 0.5 mol% was incorporated
into the PMS-PZT system, and the effects on piezoelectric properties were investigated. Pyrochlore phase was not detected
to form during the synthesis of the PMS-PZT system with 0–0.5 mol% ZnO addition. The highest density of 7.92 g/cm3 was obtained when sintered at 1200∘C for 2 h. Piezoelectric properties as a function of ZnO content were evaluated using a gain phase analyzer. Piezoelectric
charge constant (d
31) and piezoelectric voltage output coefficient (g
31) increased up to −130 pC/N and −24.9 × 103Vm/N, respectively, with increasing ZnO content. Mechanical quality factor (Q
m) was shown to reduce considerably with increasing ZnO content. When 0.3 mol% of ZnO was added into the system, electromechanical
coupling factor (k
p) and relative dielectric constant (ε33
T
/εo) reached to the maximum of 56% and 1727, respectively. 相似文献