钶铁矿型MnNb2O6的熔盐法合成、钒掺杂与磁性研究

采用了熔盐法新工艺制备了纯相与掺钒的MnNb₂O₆粉晶,利用X射线衍射仪(XRD),扫描电子显微镜(SEM),能谱分析(EDX),透射电子显微镜(TEM)、高分辨透射电镜(HRTEM)和电子衍射(SAED)分析了其物相、形貌及微结构.结果表明合成产物为正交晶系钶铁矿型MnNb₂O₆;在不同的熔盐中合成出了棒状、片状与长方体形貌的纯相产物.讨论了温度与掺杂对结构与形貌的影响,HRTEM与SAED分析表明了产物的各向异性生 关键词： 熔盐法 结构与形貌 掺杂 反铁磁性     

Structure, room-temperature magnetic and optical properties of Mn-doped TiO2 nano powders prepared by the sol-gel process

TiO 2 nano powders with Mn concentration of 0 at%-12 at% were synthesized by the sol-gel process,and were annealed at 500 C and 800 C in air for 2 hrs.X-ray diffraction (XRD) measurements indicate that the Mn-TiO 2 nano powders with Mn concentration of 1 at% and 2 at% annealed at 500 and 800 C are of pure anatase and rutile,respectively.The scanning electron microscope (SEM) observations reveal that the crystal grain size increases with the annealing temperature,and the high resolution transmission electron microscopy (HRTEM) investigations further indicate that the samples are well crystallized,confirming that Mn has doped into the TiO 2 crystal lattice effectively.The room temperature ferromagnetism,which could be explained within the scope of the bound magnetic polaron (BMP) theory,is detected in the Mn-TiO 2 samples with Mn concentration of 2 at%,and the magnetization of the powders annealed at 500 C is stronger than that of the sample treated at 800 C.The UV-VIS diffuse reflectance spectra results demonstrate that the absorption of the TiO 2 powders could be enlarged by the enhanced trapped electron absorption caused by Mn doping.     

钙钛矿型纳米BaFeO3的制备、结构表征及铁磁性研究

采用溶胶-凝胶法制备出钙钛矿型纳米BaFeO₃粉末,利用X射线衍射(XRD)、扫描电子显微镜(SEM)和透射电子显微镜(TEM)分析研究了其微观结构及形貌,结果表明：胶体试样经800℃退火处理后,形成了20nm左右的钙钛矿型BaFeO₃粉末,其(110)面晶面间距为0.280nm左右,(100)面晶面间距为0.401nm左右.利用振动样品磁强计(VSM)研究了纳米BaFeO₃粉末的室温铁磁性能,测量结果表明：在室温条件下,纳米BaFeO关键词： 溶胶-凝胶法 3')" href="#">钙钛矿型纳米BaFeO₃ 铁磁性 氧空位     

Physical modeling of direct current and radio frequency characteristics for In P-based InAlAs/InGaAs HEMTs

Direct current(DC) and radio frequency(RF) performances of InP-based high electron mobility transistors(HEMTs)are investigated by Sentaurus TCAD. The physical models including hydrodynamic transport model, Shockley–Read–Hall recombination, Auger recombination, radiative recombination, density gradient model and high field-dependent mobility are used to characterize the devices. The simulated results and measured results about DC and RF performances are compared, showing that they are well matched. However, the slight differences in channel current and pinch-off voltage may be accounted for by the surface defects resulting from oxidized InAlAs material in the gate-recess region. Moreover,the simulated frequency characteristics can be extrapolated beyond the test equipment limitation of 40 GHz, which gives a more accurate maximum oscillation frequency( f_(max)) of 385 GHz.     

Co离子注入TiO2薄膜的显微结构和磁性研究

利用直流磁控溅射技术在玻璃衬底上沉积了TiO₂薄膜,并对其进行了Co离子注入,最后在真空中500 ℃退火50 min,得到系列薄膜样品. 利用剥离-分散方法制备了薄膜的透射电镜样品,并用扫描电镜(SEM)、X射线能量散射谱(EDX)和高分辨透射电镜(HRTEM)对样品做了近似原位观察,研究了薄膜样品中不同Co离子注入深度的成分分布和显微结构. 结果表明,薄膜呈锐钛矿结构,Co元素主要分布在薄膜表层,Co离子的注入使TiO₂薄膜的晶粒被部分破坏,并形成CoO,而5 关键词： 2薄膜')" href="#">Co注入TiO₂薄膜 电镜原位观察 室温铁磁性     

A full W-band low noise amplifier module for millimeter-wave applications

A full W-band Low Noise Amplifier (LNA) Module is designed and fabricated in this letter. A broadband transition is introduced in this module. The proposed transition is designed, optimized based on the results from numerical simulations. The results show that 1 dB bandwidth of the transition ranges from 61 to 117 GHz. For the purpose of verification, two transitions in back-to-back connection are measured. The results show that transmission loss is only about 0.9-1.7dB. This transition is used to interface integrated circuits to waveguide components. The characteristic of the LNA module is measured after assembly. It exhibits a broad bandwidth of 75 to 110 GHz , has a small signal gain above 21 dB. The noise figure is lower than 5dB throughout the entire W-band (below 3 dB from 89 to 95GHz) at a room temperature. The proposed LNA module exhibits potential for millimeter wave applications due to its high small signal gain, low noise, and low dc power consumption     

液晶面板领域的中国专利申请状况分析

对日本、韩国及我国台湾地区主要液晶企业的中国专利申请状况进行了分析,希望能帮助国内液晶企业了解我国液晶领域专利申请概况和国外液晶企业在华专利申请布局信息,为我国液晶面板企业制定技术发展策略提供参考依据,从而制定合适自身的专利申请策略.     

Nb/SnO2复合薄膜的制备、结构及光电性能

用溶胶-凝胶旋涂法在玻璃基底上制备出Nb/SnO₂复合透明导电薄膜,利用XRD,SEM,紫外—可见分光光度计,四探针电阻仪等测试方法对Nb/SnO₂复合薄膜的结构和物性进行了研究.结果表明: 当Nb含量小于0.99at%时,Nb/SnO₂复合薄膜为较纯的四方金红石结构;复合薄膜中晶粒分布均匀,平均尺寸在5—7 nm.当Nb含量小于0.99at%时,Nb/SnO₂复合薄膜的电阻率先减小后增大,当Nb含量为0.37at%时 关键词： 溶胶-凝胶法 2复合薄膜')" href="#">Nb/SnO₂复合薄膜 结构表征 光电性能     

Structures and magnetic anisotropy of β-Mn2V2O7 crystals synthesized by the molten salt method

β-Mn2V2O7 crystals with strip shape are successfully prepared by the molten salt method in a closed crucible,and are characterized by x-ray diffraction (XRD),scanning electron microscopy (SEM),transmission electron microscopy (TEM),selected area of electron diffraction (SAED) and high-resolution transmission electron microscopy (HRTEM).The results indicate that the sample is of the β-Mn2V2O7 crystal with monoclinic symmetry,level natural cleavage facets and directional growth.Magnetic properties are measured by vibration sample magnetometry (VSM) at room temperature,and the magnetic hysteresis loop indicates that the β-Mn2V2O7 has anti-ferromagnetic properties with low coercive force and remnant magnetization.The magnetic measurement results in different directions exhibit that the β-Mn2V2O7 has magnetic anisotropy,which is due to the fact that the magnetic interaction energy of the β-Mn2V2O7 is lowest only when the electron configuration is in a certain direction.     

钙钛矿型纳米BaFeO3的制备、结构表征及铁磁性研究

采用溶胶-凝胶法制备出钙钛矿型纳米BaFeO3粉末,利用X射线衍射(XRD)、扫描电子显微镜(SEM)和透射电子显微镜(TEM)分析研究了其微观结构及形貌,结果表明:胶体试样经800℃退火处理后,形成了20nm左右的钙钛矿型BaFeO3粉末,其(110)面晶面间距为0.280nm左右,(100)面晶面间距为0.401nm左右.利用振动样品磁强计(VSM)研究了纳米BaFeO3粉末的室温铁磁性能,测量结果表明:在室温条件下,纳米BaFeO3粉末具有完整闭合的磁滞回线,具有较小的矫顽力和较低的饱和磁化强度,呈现出明显的弱铁磁性,且铁磁性随退火温度的变化明显.钙钛矿型纳米BaFeO3的铁磁性主要归因于Fe3 _O_Fe4 之间的氧空位.