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Structural stability and electrical properties of AIB2-type MnB2 under high pressureStructural stability and electrical properties of AIB2-type MnB2 under high pressureStructural stability and electrical properties of AIB2-type MnB2 under high pressureStructural stability and electrical properties of AIB2-type MnB2 under high pressure 下载免费PDF全文
The structural stability and electrical properties of A1B2-type MnB2 were studied based on high pressure angle- dispersive x-ray diffraction, in situ electrical resistivity measured in a diamond anvil cell (DAC) and first-principles calcu- lations under high pressure. The x-ray diffraction results show that the structure of A1B2-type MnB2 remains stable up to 42.6 GPa. From the equation of state of MnB2, we obtained a bulk modulus value of 169.9~3.7 GPa with a fixed pressure derivative of 4, which indicates that A1B2-type MnB2 is a hard and incompressible material. The electrical resistance un- dergoes a transition at about 19.3 GPa, which can be explained by a transition of manganese 3d electrons from localization to delocalization under high pressure. 相似文献
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High-performance 4H-SiC junction barrier Schottky diodes with double resistive termination extensions 下载免费PDF全文
4H-SiC junction barrier Schottky (JBS) diodes with a high-temperature annealed resistive termination extension (HARTE) are designed, fabricated and characterized in this work. The differential specific on-state resistance of the device is as low as 3.64 m ·cm2 with a total active area of 2.46×10-3 cm2 . Ti is the Schottky contact metal with a Schottky barrier height of 1.08 V and a low onset voltage of 0.7V. The ideality factor is calculated to be 1.06. Al implantation annealing is performed at 1250℃ in Ar, while good reverse characteristics are achieved. The maximum breakdown voltage is 1000 V with a leakage current of 9×10-5 A on chip level. These experimental results show good consistence with the simulation results and demonstrate that high-performance 4H-SiC JBS diodes can be obtained based on the double HARTE structure. 相似文献
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薄膜沉积过程中TiO_2的金红石相向锐钛矿相转变 总被引:6,自引:0,他引:6
用RF磁控放电方法以纯金属钛做靶材在氩氧混合气体中制备了TiO2薄膜,Raman光谱测量表明,在2Pa工作气压下制备的TiO2薄膜为锐钛矿结构,而在02Pa工作气压下制备的是金红石结构。工作气压的改变引起了TiO2薄膜沉积中的相转变。 相似文献
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β胡萝卜素是典型的线性多稀分子,重要的光电材料,在医学上也有重要的作用,研究它在外场作用下分子结构和性能的变化及机理有很重要的理论和应用价值。分别测量了β胡萝卜素在二甲基亚砜中温度为81~25 ℃范围和β胡萝卜素在二硫化碳中压力为0.04~0.60 GPa范围的紫外-可见吸收和共振拉曼光谱。发现了两种不同的的光谱现象,随温度降低,二甲基亚砜中的β胡萝卜素分子的紫外-可见吸收、拉曼光谱都红移,拉曼散射截面增大;而随压强增加二硫化碳中β胡萝卜素分子的紫外-可见吸收峰也红移,但拉曼散射峰却蓝移,拉曼散射截面减小。两种实验现象不能同时用线性多烯分子的“有效共轭长度”“弱阻尼相干振动”等理论模型给予明了解释。电子—声子耦合常数,可以表征分子中的原子和电子在外界环境作用下的相互振动耦合程度的强弱。该研究依据电子—振动相互作用规律,通过分析和计算得出结论:二种实验现象都是π电子与碳碳键振动相互作用产生的,即由于温度、压力作用对β胡萝卜素分子结构及电子—振动耦合影响不同, 引起电子-声子耦合常数不同,是电子能隙对碳碳振动的调制作用而产生的两种实验结果。 相似文献
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通过真空Ar+离子刻蚀获得理想清洁的(110)表面,采用低能电子衍射(LEED)观察了(110)面表面原子结构,观察到(110)面表面未发生重构.采用光电子能谱技术验证了(110)面表面原子结构发生了弛豫.采用角分辨光电子谱(angle-resolved photoemission spectropy)实验测量出在费米能级以下0.9eV处存在峰宽约为0.8eV的表面态.并估算出其表面电荷密度约为6.9×1014cm-2,亦即表面Te和Cd(Zn)原子各有一个悬键. 相似文献
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氮化硼薄膜内应力的红外光谱研究 总被引:13,自引:0,他引:13
用射频(RF)磁控溅射制备了立方氮化硼(c-BN)薄膜。FTIR光谱和电子衍射实验表明:该薄膜是纯的,其结晶度很高。FTIR光谱研究指出,基板负偏压是c-BN相形成的重要因素,但也由此产生了c-BN薄膜的应力,且负偏压越高,产生的应力越大。比较透射谱和反射谱的结果,c-BN薄膜表面层的应力小于内部的。按照c-BN形成的压力模型,表面应力小到一定程度可能影响c-BN的继续生长。一个特制的分层结构BN薄膜保留了由于应力造成的c-BN的裂纹,这个裂纹分布在一些同心圆上,中心是缺陷或杂质,同心圆之间有明显的分界线,把c-BN表层分割成许多应力区。 相似文献
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In the High-Pressure Synergetic Measurements Station(HP-SymS) of the Synergic Extreme Condition User Facility(SECUF), we will develop ultrahigh-pressure devices based on diamond-anvil cell(DAC) techniques, with a target pressure up to 300 GPa. With the use of cryostat and magnet, we will reach 300 GPa–4.2 K–9 T and conduct simultaneous measurements of the electrical-transport property and Raman/Brillouin spectrascopy. With resistance heating and laser heating,we will reach temperatures of at least 1000 and 3000 K, respectively, coupled with Raman/Brillouin spectroscopy measurements. Some designs of supporting devices, such as a femtosecond laser gasket-drilling device, electrode-deposition device, and the gas-loading device, are also introduced in this article. Finally, we conclude by providing some perspectives on the applications of the DAC in related research fields. 相似文献
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建立了同时测定植物组织中玉米素(ZT)、吲哚乙酸(IAA)、赤霉素类(GA1、GA3、GA4)、脱落酸(ABA)、茉莉酸(JA)7种植物激素的超高效液相色谱-三重四级杆串联质谱法(UHPLC-QqQ-MS/MS)。采用C18色谱柱(50×2.1mm,1.8μm)分离,以甲醇-0.1%甲酸水溶液为流动相,梯度洗脱,在多反应监测(MRM)模式下进行定性定量分析,外标法定量。7种植物激素的检出限为0.01~8.77ng·mL~(-1),定量限为0.02~29.23ng·mL~(-1),在实验所采用的浓度范围内线性相关系数(R2)在0.9870~0.9990之间。植物样本前处理采用C18-SPE小柱进行富集和纯化,极大地减少了基质干扰。在辣椒叶片基质中,7种植物激素在低、中、高3个加标水平下的平均回收率为65.8%~90.9%,相对标准偏差(RSDs,n=5)为2.1%~5.5%。该方法简单、快速,灵敏,准确,适用于对植物组织中多种激素的同时测定。 相似文献