简析改性剂对沥青混合料不同时间的动稳定度的影响

通过洁净的集料、结合料，在室内通过车辙试验、标准方法较真实地反映出沥青混凝土在不同的改性沥青及沥青混凝土在同一改性沥青下不同的放置时间内其动稳定度变化规律。     

高压下石墨超硬相的电阻率测量

采用高压下精确的原位电阻率测量技术,利用高浓度硼掺杂的金刚石薄膜制备微电路,在0～34 GPa测量石墨的电阻率随压力的变化规律.结果表明:在第一和第二个压力循环中,石墨超硬相电阻率不连续变化,分别出现在15.1 GPa和17.9 GPa;相存在的最低压力为8 GPa.     

Phase Transition Behavior of LiCr 0.35 Mn0.65O2 under High Pressure by Electrical Conductivity Measurement

The electrical conductivity of powdered LiCr 0.35 Mn0.65O2 is measured under high pressure up to 26.22 GPa in the temperature range 300-413 K by using a diamond anvil cell. It is found that both conductivity and activation enthalpy change discontinuously at 5.36 GPa and 21.66 GPa. In the pressure range 1.10-5.36 GPa, pressure increases the activation enthalpy and reduces the carrier scattering, which finally leads to the conductivity increase. In the pressure ranges 6.32-21.66 GPa and 22.60-26.22 GPa, the activation enthalpy decreases with pressure increasing, which has a positive contribution to electrical conductivity increase. Two pressure-induced structural phase transitions are found by in-situ x-ray diffraction under high pressure, which results in the discontinuous changes of conductivity and activation enthalpy.     

利用电导率测量方法研究不同粒径ZnS高压相变过程

利用在金刚石对顶砧上集成的金属电极,对不同粒径的ZnS材料进行了高压原位电导率测量. 粒径为2 μm的体材料ZnS在15 GPa时,电导率迅速增大5个数量级,表明体材料ZnS此时发生了从闪锌矿到岩盐矿的结构相变. 而粒径6 nm的纳米材料ZnS的结构相变压力为21 GPa. 电导率测量结果还表明纳米 ZnS比体材料ZnS还具有更宽的迟滞区间.     

利用金刚石纳米粉引晶方法制备高硼掺杂金刚石薄膜

利用金刚石纳米粉引晶方法在SiO2衬底上合成了高硼掺杂金刚石薄膜,并利用范德堡法、扫描电镜、激光拉曼方法对不同掺杂量下生长的样品进行了表征.SEM和拉曼谱分析表明,少量掺杂时有利于提高金刚石薄膜的质量,但是随着掺杂量的增加,金刚石薄膜质量开始明显下降;并且拉曼谱峰在500 cm-1和1200 cm-1开始加强,呈现重掺杂金刚石薄膜的典型特征.其电导率随着温度升高而升高,表明导电性质为半导体导电.     

Pressure-Induced Ionic-Electronic Transition in BiVO_4

Electrical transport properties of bismuth vanadate(BiVO_4) are studied under high pressures with electrochemical impedance spectroscopy. A pressure-induced ionic-electronic transition is found in BiVO_4. Below 3.0 GPa, BiVO_4 has ionic conduction behavior. The ionic resistance decreases under high pressures due to the increasing migration rate of O~(2-)ions. Above 3.0 GPa the channels for ion migration are closed. Transport mechanism changes from the ionic to the electronic behavior. First-principles calculations show that bandgap width narrows under high pressures, causing the continuous decrease of electrical resistance of BiVO_4.     

In situ electrical resistance and activation energy of solid C6o under high pressure

The in situ electrical resistance and transport activation energies of solid C60 fullerene have been measured under high pressure up to 25 GPa in the temperature range of 300-423 K by using a designed diamond anvil cell. In the experiment, four parts of boron-doped diamond films fabricated on one anvil were used as electrical measurement probes and a W-Ta thin film thermocouple which was integrated on the other diamond anvil was used to measure the temperature. The current results indicate that the measured high-pressure resistances are bigger than those reported before at the same pressure and there is no pressure-independent resistance increase before 8 GPa. From the temperature dependence of the resistivity, the C60 behaviors as a semiconductor and the activation energies of the cubic C60 fullerene are 0,49, 0.43, and 0.36 eV at 13, 15, and 19 GPa, respectively.     

DAC垫片孔侧壁绝缘程度对电导率测量结果的影响

通过有限元方法,计算了DAC内垫片孔侧壁与样品发生不同程度短路的情况下,范德堡法测量样品电阻率的相对误差. 发现垫片孔侧壁与样品短路面积小于20％时,相对误差可以控制在10％以内. 而当短路面积超过25％时,相对误差迅速增大. 研究中还发现,电极越靠近样品边缘,相对误差越小.     

In situ electrical resistance and activation energy of solid C_(60) under high pressure

The in situ electrical resistance and transport activation energies of solid C60 fullerene have been measured under high pressure up to 25 GPa in the temperature range of 300-423 K by using a designed diamond anvil cell. In the experiment, four parts of boron-doped diamond films fabricated on one anvil were used as electrical measurement probes and a W-Ta thin film thermocouple which was integrated on the other diamond anvil was used to measure the temperature. The current results indicate that the measured high-pressure resistances are bigger than those reported before at the same pressure and there is no pressure-independent resistance increase before 8 GPa. From the temperature dependence of the resistivity, the C60 behaviors as a semiconductor and the activation energies of the cubic C60 fullerene are 0.49, 0.43, and 0.36 eV at 13, 15, and 19 GPa, respectively.     

放电电压对直流热阴极制备金刚石厚膜的影响

利用直流热阴极辉光放电方法制备出了高品质金刚石厚膜,生长速率达到20μm/h,生长厚度达到3mm.为了解其工作特性、优化沉积工艺,本文研究了放电电压对金刚石沉积速率和品质的影响.通过对扫描电镜、拉曼谱和XRD图谱分析得出,随着放电电压的增加,沉积速率呈下降趋势,电压在850～950V范围金刚石中石墨和非晶碳明显减少,晶粒均匀,表面晶向以(110)为主,金刚石薄膜的质量显著提高.