Sr-doping effects on conductivity,charge transport,and ferroelectricity of Ba_(0.7)La_(0.3)TiO_3 epitaxial thin films

Sr-doped Ba_0.7La_0.3TiO₃(BSLTO)thin films are deposited by pulsed laser deposition,and their microstructure,conductivity,carrier transport mechanism,and ferroelectricity are systematically investigated.The x-ray diffraction measurements demonstrate that Sr-doping reduces the lattice constant of BSLTO thin films,resulting in the enhanced phonon energy in the films as evidenced by the Raman measurements.Resistivity-temperature and Hall effect measurements demonstrate that Sr can gradually reduce electrical resistivity while the electron concentration remains almost unchanged at high temperatures.For the films with semiconducting behavior,the charge transport model transforms from variable range hopping to small polaron hopping as the measurement temperature increases.The metalic conductive behaviors in the films with Sr=0.30,0.40 conform to thermal phonon scattering mode.The difference in charge transport behavior dependent on the A-site cation doping,is clarified.It is revealed that the increasing of phonon energy by Sr doping is responsible for lower activation energy of small polaron hopping,higher carrier mobility,and lower electrical resistivity.Interestingly,the piezoelectric force microscopy(PFM)results demonstrate that all the BSLTO films can exhibit ferroelectricity,especially for the room temperature metallic conduction film with Sr=0.40.These results imply that Sr-doping could be a potential way to explore ferroelectric metal materials for other perovskite oxides.     

多孔氧化铝模板电沉积法制备ZnO纳米结构阵列的研究

利用直流电化学沉积技术,在多孔氧化铝模板内,通过先沉积Zn(OH)2/ZnCO3,然后在300℃下进行热分解,制得了ZnO纳米点阵结构.扫描电镜结果表明多孔氧化铝模板孔道呈六角形分布,孔径约为55 nm,孔间距约为100 nm,且孔道上下贯通平行排列.X射线衍射表明多孔氧化铝模板为非晶结构,孔内组装的ZnO具有多晶纤锌矿结构.光致发光谱表明ZnO/PAM复合体系同空氧化铝模板相比在420 nm处具有较强的蓝光发射.     

圆柱型各向异性弹性力学平面问题

本文对圆柱型各向异性弹性力学平面问题的基本方程进行了改写。在此基础上，导出了应力函数Ｇ和位移函数φ，它们满足相同的控制方程，比文〔１〕的应力函数Ｆ的控制方程要简单，便于求得特解，并有Ｆ＝ｒＧ的关系。还对若干经典问题进行了求解。