采用脉冲激光沉积方法,在制备有LaNiO3(LNO)底电极的LaAlO3(LAO)衬底上,分别在500,600℃和700℃的沉积温度下制备了锆钛酸钡Ba(Zr0.2Ti0.8)O3(BZT)薄膜。通过X射线衍射表征薄膜的结构特性,原子力显微镜和扫描电子显微镜分别用来表征样...采用脉冲激光沉积方法,在制备有LaNiO3(LNO)底电极的LaAlO3(LAO)衬底上,分别在500,600℃和700℃的沉积温度下制备了锆钛酸钡Ba(Zr0.2Ti0.8)O3(BZT)薄膜。通过X射线衍射表征薄膜的结构特性,原子力显微镜和扫描电子显微镜分别用来表征样品的表面和断面形貌。结果表明:BZT薄膜与LNO具有c轴取向,并以cube-on-cube方式排列生长。BZT薄膜表面致密无裂缝,具有柱状生长的晶粒。薄膜的介电性能测试显示:600℃下沉积的BZT薄膜具有较高的介电可调性(49.1%)和较低的介电损耗(2.5%)。在600℃下沉积的BZT薄膜的优值因子(figure of merit,FOM)达到19.8。展开更多
β-SiC ceramic powders were obtained by pyrolyzing polycarbosilane in vacuum at 800-1200 °C. The β-SiC ceramic powders were characterized by TGA/DSC, XRD and Raman spectroscopy. The dielectric properties of β-S...β-SiC ceramic powders were obtained by pyrolyzing polycarbosilane in vacuum at 800-1200 °C. The β-SiC ceramic powders were characterized by TGA/DSC, XRD and Raman spectroscopy. The dielectric properties of β-SiC ceramic powders were investigated by measuring their complex permittivity by rectangle wave guide method in the frequency range of 8.2-18 GHz. The results show that both real part ε′ and imaginary part ε″ of complex permittivity increase with increasing pyrolysis temperature. The mechanism was proposed that order carbon formed at high temperature resulted in electron relaxation polarization and conductance loss, which contributes to the increase in complex permittivity.展开更多
The dielectric constant of the lunar regolith can directly influence the reflection coefficient and the trans-mission coefficient of the Moon′s surface, and plays an important role in the Moon research. In order to s...The dielectric constant of the lunar regolith can directly influence the reflection coefficient and the trans-mission coefficient of the Moon′s surface, and plays an important role in the Moon research. In order to study the di-electric properties of the lunar regolith, the lunar regolith simulant was made according to the making procedure of the CAS-1 simulant made by Chinese Academy of Sciences. Then the dielectric constants of the lunar regolith simulant were measured with 85070E Aiglent Microwave Network Analyzer in the frequency ranging from 0.2 GHz to 20.0 GHz and at temperature of 25.1℃, 17.7℃, 13.1℃, 11.5℃, 9.6℃, 8.0℃, 4.1℃, -0.3℃, -4.7℃, -9.5℃, -18.7℃, -27.7℃, and -32.6℃, respectively. The Odelevsky model was employed to remove the influence of water in the air on the final effective dielectric constants. The results indicate that frequency and temperature have apparent influences on the dielectric constants of the lunar regolith simulant. The real parts of the dielectric constants increase fast over the range of 0.2 GHz to 3.0 GHz, but decrease slowly over the range of 4.0 GHz to 20.0 GHz. The opposite phenomenon occurs in the imaginary parts. The influences of the frequency and temperature on the brightness temperature were also estimated based on the radiative transfer equation. The result shows that the variation of the frequency and temperature results in great changes of the microwave brightness temperature emitting from the lunar regolith.展开更多
Electrical conductivity and dielectric properties of bismuth aluminate, Bi12.47Al0.53O19.5 （BAO）, were investigated in the frequency range from 1 Hz to 1 MHz in the temperature range from 420 K to 5 K. In the temper...Electrical conductivity and dielectric properties of bismuth aluminate, Bi12.47Al0.53O19.5 （BAO）, were investigated in the frequency range from 1 Hz to 1 MHz in the temperature range from 420 K to 5 K. In the temperature range from 360 K to 220 K the real part of the complex ac electrical conductivity and dielectric constant follow the universal dielectric response （UDR）, being typical for hopping or tunneling of localized charge carriers. A detailed analysis of the temperature dependence of the UDR parameter s in terms of the theoretical model for tunneling of small polarons revealed that below 360 K this mechanism governs the charge transport in this material. The characteristic parameters for polarons, W∞, ιo, and ι0 were determined.展开更多
基金supported by Youth Foundation of Southwest University of Science and Technology No09zx3112~~
文摘采用脉冲激光沉积方法,在制备有LaNiO3(LNO)底电极的LaAlO3(LAO)衬底上,分别在500,600℃和700℃的沉积温度下制备了锆钛酸钡Ba(Zr0.2Ti0.8)O3(BZT)薄膜。通过X射线衍射表征薄膜的结构特性,原子力显微镜和扫描电子显微镜分别用来表征样品的表面和断面形貌。结果表明:BZT薄膜与LNO具有c轴取向,并以cube-on-cube方式排列生长。BZT薄膜表面致密无裂缝,具有柱状生长的晶粒。薄膜的介电性能测试显示:600℃下沉积的BZT薄膜具有较高的介电可调性(49.1%)和较低的介电损耗(2.5%)。在600℃下沉积的BZT薄膜的优值因子(figure of merit,FOM)达到19.8。
基金Project (50572090) supported by the National Natural Science Foundation of ChinaProject (KP200901) supported by the Fund of the State Key Laboratory of Solidification Processing, China
文摘β-SiC ceramic powders were obtained by pyrolyzing polycarbosilane in vacuum at 800-1200 °C. The β-SiC ceramic powders were characterized by TGA/DSC, XRD and Raman spectroscopy. The dielectric properties of β-SiC ceramic powders were investigated by measuring their complex permittivity by rectangle wave guide method in the frequency range of 8.2-18 GHz. The results show that both real part ε′ and imaginary part ε″ of complex permittivity increase with increasing pyrolysis temperature. The mechanism was proposed that order carbon formed at high temperature resulted in electron relaxation polarization and conductance loss, which contributes to the increase in complex permittivity.
基金Under the auspices of National Natural Science Foundation of China (No. 40901159, 40901187)Doctoral Fund of Ministry of Education of China (No. 20090061120055)+1 种基金the Fundamental Research Funds for the Central Universities (No. 200903047)National High Technology Research and Development Program of China (No. 2010AA122203)
文摘The dielectric constant of the lunar regolith can directly influence the reflection coefficient and the trans-mission coefficient of the Moon′s surface, and plays an important role in the Moon research. In order to study the di-electric properties of the lunar regolith, the lunar regolith simulant was made according to the making procedure of the CAS-1 simulant made by Chinese Academy of Sciences. Then the dielectric constants of the lunar regolith simulant were measured with 85070E Aiglent Microwave Network Analyzer in the frequency ranging from 0.2 GHz to 20.0 GHz and at temperature of 25.1℃, 17.7℃, 13.1℃, 11.5℃, 9.6℃, 8.0℃, 4.1℃, -0.3℃, -4.7℃, -9.5℃, -18.7℃, -27.7℃, and -32.6℃, respectively. The Odelevsky model was employed to remove the influence of water in the air on the final effective dielectric constants. The results indicate that frequency and temperature have apparent influences on the dielectric constants of the lunar regolith simulant. The real parts of the dielectric constants increase fast over the range of 0.2 GHz to 3.0 GHz, but decrease slowly over the range of 4.0 GHz to 20.0 GHz. The opposite phenomenon occurs in the imaginary parts. The influences of the frequency and temperature on the brightness temperature were also estimated based on the radiative transfer equation. The result shows that the variation of the frequency and temperature results in great changes of the microwave brightness temperature emitting from the lunar regolith.
文摘Electrical conductivity and dielectric properties of bismuth aluminate, Bi12.47Al0.53O19.5 （BAO）, were investigated in the frequency range from 1 Hz to 1 MHz in the temperature range from 420 K to 5 K. In the temperature range from 360 K to 220 K the real part of the complex ac electrical conductivity and dielectric constant follow the universal dielectric response （UDR）, being typical for hopping or tunneling of localized charge carriers. A detailed analysis of the temperature dependence of the UDR parameter s in terms of the theoretical model for tunneling of small polarons revealed that below 360 K this mechanism governs the charge transport in this material. The characteristic parameters for polarons, W∞, ιo, and ι0 were determined.
