采用固相法制备了Ca Cu3Ti4O12多晶块体,研究了其介电常数随温度和频率的变化。结果表明,在温度为300 K、频率为1 k Hz时,多晶块的介电常数高达14 000;频率为1 k Hz时,介电常数基本不随温度的变化而改变。动态变化的极化弛豫使Ca Cu3Ti4...采用固相法制备了Ca Cu3Ti4O12多晶块体,研究了其介电常数随温度和频率的变化。结果表明,在温度为300 K、频率为1 k Hz时,多晶块的介电常数高达14 000;频率为1 k Hz时,介电常数基本不随温度的变化而改变。动态变化的极化弛豫使Ca Cu3Ti4O12多晶块具有巨介电常数,混合价Ti离子导致极化子的热激活使Ca Cu3Ti4O12多晶块的介电特性出现反常效应。展开更多
采用固相烧结法制备了FeV_2O_4多晶块材,采用X射线衍射法和电子显微镜断面扫描对FeV_2O_4多晶块材进行结构表征,并测量其铁电极化强度和交、直流电输运特性.结果表明,制备的FeV_2O_4多晶块材是纯净的,结构较致密.低温(6K)时FeV_2O_4多...采用固相烧结法制备了FeV_2O_4多晶块材,采用X射线衍射法和电子显微镜断面扫描对FeV_2O_4多晶块材进行结构表征,并测量其铁电极化强度和交、直流电输运特性.结果表明,制备的FeV_2O_4多晶块材是纯净的,结构较致密.低温(6K)时FeV_2O_4多晶块材的铁电饱和极化强度达到141.8μC/m2,外加磁场后自发极化强度受到较大的压制,表明样品具有较强的磁电效应,其最大磁阻效应(2.83%)出现在亚铁磁转变温度TN1(110K)处.结合交流阻抗谱辅助等效回路分析法,对测量数据进行拟合.结果显示FeV_2O_4多晶块材的直流和交流输运特性都符合Mott的变程跳跃(variable range hopping,VRH)机制,其能带是近似于原子能级的窄带.展开更多
利用固相烧结法制备了多铁性材料CaMn7O12多晶块材,断面扫描电子显微镜(SEM)形貌图显示样品的结构致密.使用热释电方法测量CaMn7O12多晶块材的铁电极化,说明材料具有铁电性.测量了CaMn7O12多晶块材的直流和交流输运特性,结合交流阻抗谱...利用固相烧结法制备了多铁性材料CaMn7O12多晶块材,断面扫描电子显微镜(SEM)形貌图显示样品的结构致密.使用热释电方法测量CaMn7O12多晶块材的铁电极化,说明材料具有铁电性.测量了CaMn7O12多晶块材的直流和交流输运特性,结合交流阻抗谱辅助等效回路分析法,对测量数据进行拟合.结果显示CaMn7O12多晶块材的直流和交流输运特性都符合Mott的VRH(variable range hopping)机制,其能带是近似于原子能级的窄带.展开更多
The corrosion behaviors of Ti-based and Zr-based amorphous alloys and their corresponding crystallized alloys were studied by electrochemical methods. It is found that the corrosion potentials of Zr-based amorphous al...The corrosion behaviors of Ti-based and Zr-based amorphous alloys and their corresponding crystallized alloys were studied by electrochemical methods. It is found that the corrosion potentials of Zr-based amorphous alloy and its corresponding crystalline counterpart are both lower than those of the Ti-based amorphous alloy in the 1 mol/L H2SO4 solution. In the 3.5% NaCl solution,Zr-based crystallized alloy exhibits the lowest corrosion potential among the experimental samples. No passivation is observed in the corrosion process for the Zr-based crystalline alloy. However, Zr- and Ti-based amorphous alloys both exhibit passivation characteristics. EIS measurements indicate the amorphous alloys exhibit better corrosion resistance than the crystallized one in the NaCl solution. Surface analysis shows that both amorphous alloys in the NaCl solution are eroded by pitting corrosion. In the H2SO4 solution, all the alloys display similar behaviors and their surfaces can mostly keep intact except for some cracks on the corroded surface at local region.展开更多
The growth kinetics of intermetallic compound layer between molten In-Sn alloy and Cu40Zr44Al8Ag8 bulk metallic glass substrate was examined by solid state isothermal aging at the temperature range between 333 and 393...The growth kinetics of intermetallic compound layer between molten In-Sn alloy and Cu40Zr44Al8Ag8 bulk metallic glass substrate was examined by solid state isothermal aging at the temperature range between 333 and 393 K.The aged samples were characterized by scanning electron microscopy and energy dispersive spectrometry.It is found that the intermetallic compound layer is composed of Zr,Cu and Sn.The layer growth of the intermetallic compound is mainly controlled by a diffusion mechanism over the temperature range and the value of the time exponent is approximately 0.5.The apparent activation energy for the growth of total intermetallic compound layers is 98.35 kJ /mol calculated by the Arrhenius equation.展开更多
文摘采用固相法制备了Ca Cu3Ti4O12多晶块体,研究了其介电常数随温度和频率的变化。结果表明,在温度为300 K、频率为1 k Hz时,多晶块的介电常数高达14 000;频率为1 k Hz时,介电常数基本不随温度的变化而改变。动态变化的极化弛豫使Ca Cu3Ti4O12多晶块具有巨介电常数,混合价Ti离子导致极化子的热激活使Ca Cu3Ti4O12多晶块的介电特性出现反常效应。
文摘采用固相烧结法制备了FeV_2O_4多晶块材,采用X射线衍射法和电子显微镜断面扫描对FeV_2O_4多晶块材进行结构表征,并测量其铁电极化强度和交、直流电输运特性.结果表明,制备的FeV_2O_4多晶块材是纯净的,结构较致密.低温(6K)时FeV_2O_4多晶块材的铁电饱和极化强度达到141.8μC/m2,外加磁场后自发极化强度受到较大的压制,表明样品具有较强的磁电效应,其最大磁阻效应(2.83%)出现在亚铁磁转变温度TN1(110K)处.结合交流阻抗谱辅助等效回路分析法,对测量数据进行拟合.结果显示FeV_2O_4多晶块材的直流和交流输运特性都符合Mott的变程跳跃(variable range hopping,VRH)机制,其能带是近似于原子能级的窄带.
文摘利用固相烧结法制备了多铁性材料CaMn7O12多晶块材,断面扫描电子显微镜(SEM)形貌图显示样品的结构致密.使用热释电方法测量CaMn7O12多晶块材的铁电极化,说明材料具有铁电性.测量了CaMn7O12多晶块材的直流和交流输运特性,结合交流阻抗谱辅助等效回路分析法,对测量数据进行拟合.结果显示CaMn7O12多晶块材的直流和交流输运特性都符合Mott的VRH(variable range hopping)机制,其能带是近似于原子能级的窄带.
基金Project (2007CB607603) supported by the National Basic Research Program of ChinaProject (B08040) supported by the "111" Project, China
文摘The corrosion behaviors of Ti-based and Zr-based amorphous alloys and their corresponding crystallized alloys were studied by electrochemical methods. It is found that the corrosion potentials of Zr-based amorphous alloy and its corresponding crystalline counterpart are both lower than those of the Ti-based amorphous alloy in the 1 mol/L H2SO4 solution. In the 3.5% NaCl solution,Zr-based crystallized alloy exhibits the lowest corrosion potential among the experimental samples. No passivation is observed in the corrosion process for the Zr-based crystalline alloy. However, Zr- and Ti-based amorphous alloys both exhibit passivation characteristics. EIS measurements indicate the amorphous alloys exhibit better corrosion resistance than the crystallized one in the NaCl solution. Surface analysis shows that both amorphous alloys in the NaCl solution are eroded by pitting corrosion. In the H2SO4 solution, all the alloys display similar behaviors and their surfaces can mostly keep intact except for some cracks on the corroded surface at local region.
基金Project (2011CB606301) supported by the National Basic Research Program of ChinaProject (20212339) supported by the Doctor Startup Foundation Program of Shenyang University,China
文摘The growth kinetics of intermetallic compound layer between molten In-Sn alloy and Cu40Zr44Al8Ag8 bulk metallic glass substrate was examined by solid state isothermal aging at the temperature range between 333 and 393 K.The aged samples were characterized by scanning electron microscopy and energy dispersive spectrometry.It is found that the intermetallic compound layer is composed of Zr,Cu and Sn.The layer growth of the intermetallic compound is mainly controlled by a diffusion mechanism over the temperature range and the value of the time exponent is approximately 0.5.The apparent activation energy for the growth of total intermetallic compound layers is 98.35 kJ /mol calculated by the Arrhenius equation.
