陈湘明
1)高性能微波介质陶瓷;2)弛豫铁电陶瓷的改性与微波应用、3)电介质陶瓷新体系探索、4)复相功能陶瓷以及5)结构-功能一体化陶瓷等
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- 姓名:陈湘明
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学术头衔:
博士生导师
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学科领域:
材料科学基础学科
- 研究兴趣:1)高性能微波介质陶瓷;2)弛豫铁电陶瓷的改性与微波应用、3)电介质陶瓷新体系探索、4)复相功能陶瓷以及5)结构-功能一体化陶瓷等
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【期刊论文】Structures and properties of dielectrics in Pb(Mg1/3Nb2/3)O3-La(Mg1/2Ti1/2)O3 system
陈湘明, X. Hu and X. M. Chen a)
,-0001,():
-1年11月30日
(1-x)Pb(Mg1/3Nb2/3)O3-xLa(Mg1/2Ti1/2)O3 dielectrics were prepared by a solid-state reaction process and the structures were evaluated together with the dielectric characterization. The pyrochlore-free dielectrics were obtained with increasing La(Mg1/2Ti1/2)O3 content due to the increased electrone gativity difference. The 1/2 (111) superlattice reflection showed 1:1 ordering on the B site in all compositions. Antiphase tilting of oxygen octahedra and B-site cation displacing appeared at x50.9. Low loss (tand; 1024) dielectrics with high dielectric constant (36-900) Were obtained in the present system, and the good microwave dielectric properties were achieved in the compositions with x>0.7. The best combination of microwave dielectric properties was obtained for x50.9: e534, Qf521 280GHz, and t f5260 ppm/℃.
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【期刊论文】High permittivity and low loss dielectric ceramics in the BaO-La2O3-TiO2-Ta2O5 system
陈湘明, X.M. Chen*, Y.H. Sun, X.H. Zheng
Journal of the European Ceramic Society 23(2003)1571-1575,-0001,():
-1年11月30日
Dielectric ceramics were synthesized and characterized in the BaO-La2O3-TiO2-Ta2O5 quaternary system for the three typical compositions: Ba3La3Ti5Ta5O30, Ba4La2Ti4Ta6O30 and Ba5LaTi3Ta7O30, which formed the filled tungsten-bronze structures. The present ceramics indicated high dielectric constant (127.7-148.1) and low dielectric loss tand (in the order of 10-4-10-3 at 1MHz). Meanwhile, the temperature coefficient of dielectric constant varied from -728 to -1347 ppm/C with increasing Ba and Ta and decreasing La and Ti concentration in the temperature range of 20-85 C. The present ceramics are promising candidates for high-and low loss dielectric ceramics, and the suppression of should be the primary issue in the future work.
(, Ba,, La), 6 (, Ti,, Ta), 10 O30, BaO-La2O3-TiO2-Ta2O5, Dielectric properties, Tungsten-bronze structure
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【期刊论文】SrLnAlO4 (Ln Nd and Sm) Microwave Dielectric Ceramics
陈湘明, XIANG MING CHEN*, YANG XIAO, XIAO QIANG LIU & XING HU
Journal of Electroceramics, 10, 111-115, 2003,-0001,():
-1年11月30日
SrLnAlO4 (Ln Nd and Sm) ceramics with K2NiF4 structure were prepared by a solid state reaction approach, and their microwave dielectric characteristics were evaluated together with the microstructures. The single phase dense SrNdAlO4 and SrSmAlO4 ceramics were obtained by sintering at 1450-1475℃ and 1475-1500℃, respectively, and the good microwave dielectric characteristics were achieved: (1) ε = 17.8, Q · f = 25,700GHz, τ f = −9ppm/℃ for SrNdAlO4; and (2) ε = 18.8, Q · f = 54,880GHz, τ f = 2ppm/℃ for SrSmAlO4 dense ceramics. The Q f value significantly increased with increasing sintering temperature.
SrLnAlO4,, microwave dielectric properties,, ceramics,, sintering,, microstructures
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【期刊论文】A-and B Site Cosubstituted Ba6-3xSm8+2xTi18O54 Microwave Dielectric Ceramics
陈湘明, Xiang Ming Chen* and Yi Li
J. Am. Ceram. Soc., 85 [3] 579-84 (2002),-0001,():
-1年11月30日
Tin (Sn) substitution into the B-site and Nd/Sn cosubstitution into the A- and B-sites were investigated in a Ba6-3xSm8+2xTi18O54 solid solution (x=2⁄3). A small amount of tin substitution for titanium improved the temperature coefficient of resonant frequency (f) but led to a decrease of the relative dielectric constant (з) and the quality factor (Qf). The Ba6-3xSm8+2x(Ti1-zSnz)18O54-based tungsten-bronze phase became unstable for compositions with a tin content of >10mol%, where BaSm2O4 and Sm2(Sn,Ti)2O7 appeared, and finally, these phases became the major phases. On the other hand, Nd/Sn cosubstitution led to a good combination of high ε, high Qf, and near-zero Tf. Excellent microwave dielectric properties were achieved in Ba6-3x(Sm1-yNdy)8+2x(Ti1-zSnz)18O54 ceramics with y=0.8 and z =0.05 sintered at 1360℃ for 3h:=82, Qf=10 000GHz, and calculated Tf=+17 ppm/℃. The tolerance factor and electronegativity difference exhibited important effects on the microwave dielectric properties, especially the Qf value. A large tolerance factor and high electronegativity difference generally led to a higher Qf value.
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【期刊论文】3Y-TZP ceramics toughened by Sr2Nb2O7 secondary phase
陈湘明, Xiang Ming Chen a, *, Xiao Qiang Liu a, Fu Liu a, Xiao Bin Zhang a, b
Journal of European Ceramic Society 21(2001)477-481,-0001,():
-1年11月30日
3 mol% yttria stabilized tetragonal zirconia caramics (3Y-TZP) were significantly toughened by a Sr2Nb2O7 ferroelectric secondary phase incorporated into the matrix to serve as toughening agent. A high KIC value, 13.0MPa. M1/2 was achieved in 1mol% Sr2Nb2O7 composite ceramics, while that of the 3Y-TZP matrix was 6.0MP a. m1/2. Energy transformation and consumption due to piexoelectric effects and domain wall motion was suggested as an important toughening mechanism along with that fo phase transformation toughening. Moreover, it should be emphasized that a high KIC value of 12.0MPa. m1/2 was achieved in the present composite ceramics even where the transformation toughening mechanism was inactive.
Ferroelectric properties, Sr2Nb2O7, Toughening, ZrO2
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陈湘明, X.M. Chen, X.H. Zheng, and J. Wang
J. Mater. Res., Vol. 16, No.10, Oct 2001,-0001,():
-1年11月30日
Ba4Nd2Ti4Ta6O30 dielectric ceramics with high-e and low dielectric loss were modified to improve the temperature coefficient of dielectric constant. Through partial substitution of Ti4+ for Ta5+, a significantly reduced temperature coefficient of dielectric constant (te 4 −664p pm/℃) combined with a dielectric constant above 110 and a low dielectric loss (tand-0.0005 to 0.0006 at 1MHz) resulted in the nonstoichiometric dielectric ceramics with nominal compositions Ba4Nd2Ti4+xTa6−xO30−x/2 (x 4 0.8-1.2).
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陈湘明, Yong Jun Wu and Xiang Ming Chen a)
J. Mater. Res., Vol. 16, No.6, Jun 2001,-0001,():
-1年11月30日
The effects of Bi substitution for Nd in Ba6−3xNd8+2xTi18O54 (x 4 2⁄3) solid solution upon the microstructures and microwave dielectric properties were investigated. The solid solubility limit of Bi in Ba6−3xNd8+2xTi18O54 (x 4 2⁄3) solid solution was about 15mol%, the same as that for x 4 0.5, and densification of the present solid solutions could be performed well at lower temperatures. However, the variation tendency of microwave dielectric properties with composition in the present ceramics quite differed from that for x 4 0.5: (1) The temperature coefficient of resonant frequency in the present ceramics showed a continuous variation from positive to negative and did not indicate extreme value at the solid solubility limit. (2) Near-zero temperature coefficient of resonant frequency combined with high-e and high-Qf values could be obtained in the present ceramics, while that for x 4 0.5 had a lower limit of +15 ppm/℃. (3) The dielectric constant also showed a continuous increase for the present compositions, while that in x 4 0.5 had an extreme at solid solubility limit. Ceramics with composition of Ba6−3x(Nd0.85,Bi0.15)8+2xTi18O54 (x 42⁄3) showed excellent dielectric properties of e 4 99.1, Qf4 5290 GHz, and tf4 −5.5 ppm/℃.
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【期刊论文】Sol-Gel Preparation of BaTi4O9 and Ba2Ti9O20
陈湘明, Yebin Xu, Xiang Ming Chen* Liangbin Wang
J. Am. Ceram. Soc., 84 [3] 669-71 (2001),-0001,():
-1年11月30日
BaTi4O9 and Ba2Ti9O20 precursors were prepared via a sol- gel method, using ethylenedi aminetetra acetic acid as a chelating agent. The sol-gel precursors were heated at 700℃-1200℃ in air, and X-ray diffractometry (XRD) was used to determine the phase transformations as a function of temperature. Single-phase BaTi4O9 could not be obtained, even after heating the precursors at 1200℃ for 2h, whereas single-phase Ba2Ti9O20 (as determined via XRD) was obtained at 1200℃ for 2h. Details of the synthesis and characterization of the resultant products have been given.
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【期刊论文】Preparation of Ba6-3xNd8+2xTi18O54 via Ethylenediaminetetraacetic Acid Precursor
陈湘明, Yebin Xu, Xiang Ming Chen* and Yong Jun Wu
J. Am. Ceram. Soc., 83 [11] 2893-95 (2000),-0001,():
-1年11月30日
Ba623xNd812xTi18O54 ceramic powders were synthesized by the modified Pechini method using ethylenediaminetetraacetic acid (EDTA) as a chelating agent. A purplish red, molecularlevel, homogeneously mixed gel was prepared, and transferred into a porous resin intermediate through charring. Singlephase and well-crystallized Ba623xNd812xTi18O54 powders were obtained from pulverized resin at a temperature of 900
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【期刊论文】Bismuth/Samarium Cosubstituted Ba6-3xNd8+2xTi18O54 Microwave Dielectric Ceramics
陈湘明, Yong Jun Wu and Xiang Ming Chen*
J. Am. Ceram Soc. 83 [7] 1837-39 (2000),-0001,():
-1年11月30日
Modification of the microwave dielectric properties in Ba6-3xNd8+2xTi18O54 (x=0.5) solid solutions by Bi/Sm cosubstitution for Nd was investigated. A large increase in the dielectric constant and near-zero temperature coefficient combined with high Qf values were obtained in modified Ba6-3xNd8+2xTi18O54 solid solutions where an enlarged solid solution limit of Bi in Ba6-3xNd8+2xTi18O54 was observed. Excellent microwave dielectric characteristics (e=105, Qf=4110 GHz, and very low tf) were achieved in the composition Ba6-3x(Nd0.7Bi0.18Sm0.12)8+2xTi18O54.
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