研究了以Fe离子（Fe3＋）掺杂取代部分锰（Mn）离子的层状钙钛矿结构化合物LaSr2Mn2-xFexO7（0≤x≤0.3）的电性和磁性。结果发现：Fe3＋的掺杂抑制了LaSr2Mn2-xFexO7低温的反铁磁性交换作用，使Neel温度TN由x=0的138K降至x=0.3的101K。同时，LaSr2Mn2-xFexO7的自旋玻璃态、电荷有序和金属-绝缘体转变温度都由于Fe3＋取代Mn离子而受到抑制。产生上述现象的原因是因为Mn位被取代导致产生无序状态。由于Fe3＋取代Mn粒子，致使双交换作用通道被打破，化合物的电阻率随x的增加而迅速增加。所有化合物的电阻率在低温阶段都可以用Mott的变程跳跃理论来拟合：在高温阶段可以用最近小声子极化理论来拟合。

A new ionic conductor La2-xNdxMo2O9 (x=0.0-2.0) has been synthesized by wet-chemistry method. The precursors and the resultant oxide powders were characterized by DTA/TG, DSC, XRD and XPS techniques. Effect of substituting Nd for La reveals that the phase transition which occurs in La2Mo2O9 around 565℃ disappears when x>0.2. And the maximum amount of Nd stabilized the high temperature phase of β-La2Mo2O9 from cubic to tetragonal is about x =1.6. The measurements of impedance spectroscopy indicate that the ionic conductivity becomes considerably higher in comparison to that of La2Mo2O9.

A new series of oxides, Ce6−xErxMoO15−δ (0.0 x < 1.5), was synthesized using wet-chemistry techniques. The precursors and resultant oxide powders were characterized by differential thermal analysis/thermogravimetry, x-ray diffraction, and IR, Raman and x-ray photoelectron spectroscopy. The formation temperature of the powders was found to be as low as 350℃. Ce6−xErxMoO15−δ crystallized to a fluorite-related cubic structure. The electrical conductivity of the samples was investigated by using ac impedance spectroscopy. This showed that the presence of Er was related to the oxygenion conductivity, and that the highest oxygen-ion conductivity was found in Ce6−xErxMoO15−δ (x = 0.4),ranging from 5.9 × 10−5 Scm−1 at 300℃ to 1.26 × 10−2 Scm−1 at 700℃, respectively. This kind of material shows a potential application in intermediate-temperature solid oxide fuel cells.

The effect of Ti substitution for Mn on magnetic and transport properties has been investigated for layered manganese oxides LaSr2Mn2−xTixO7. Titanium doping hampered the canted antiferromagnetic (AFM) exchange at low temperature and their Neel temperature (TN) decreased from 138K (x=0) to106K(x= 0.1). Meanwhile, spin glass, charge ordering and metal-insulator transition are suppressed by Ti addition. This can be attributed to Mn-site disorder caused by random substitution of Ti4+. The suppression of charge ordering leads to magntetoresistance (MR) ratio increase and MR reaches maximum at x = 0.3. The resistivity increases obviously with x increasing because of double exchange interaction channel broken by Ti4+ addition. The resistivity of all samples in low temperature range fits to the Mott’s variable range hopping (VRH) model, while it fits to nearest neighbor hopping of small polarons model in high temperature range. We also found that both disorder and distortion in A-site and B-site will induce the similar effect to electrical and magnetic properties.

The different morphologies of nanorods have been obtained via a simple wet chemical method in the present of polyethylene glycol (PEG, Mw=4000) by using zinc nitrate hexahydrate (Zn(NO3)2·6H2O) and ammonium hydroxide (NH3·H2O) as the starting materials. Samples were characterized by XRD, EDS, TEM, SEM, ED and PL. XRD results prove the formation of ZnO with wurtzite structure. The ED and HRTEM reveal that single ZnO nanorod is single crystal and preferentially grows up along the[001] direction. The PL spectra showed that the ZnO nanorods have blue emission at 466 nm and green–yellow emission at 542 nm. The influence of reaction temperature, pH in system and evaporation of ammonia on the morphology has been investigated. A possible growth mechanism of ZnO with various morphologies is discussed.