以Ni-Al为底电极的P(VDF-TrFE)铁电电容器的结构与性能

应用磁控溅射法制备Ni-Al和Pt薄膜,溶胶-凝胶法制备P(VDF-TrFE)铁电共聚物薄膜,在SiO2/Si(001)衬底上首次构架了Pt/P(VDF-TrFE)/Ni-Al异质结电容器。X射线衍射(XRD)结果表明:Ni-Al薄膜为非晶结构,P(VDF-TrFE)薄膜具有较好的结晶质量。研究发现,在20 Hz测试频率下,Pt/P(VDF-TrFE)/Ni-Al电容器具有饱和的电滞回线,在90 V驱动电压下,剩余极化强度与矫顽场分别为7.6μC/cm2和45.7 V。在外加电压为40 V时,薄膜的漏电流密度约为5.37×10-6 A/cm2。漏电机制研究表明,Pt/P(VDF-TrFE)/Ni-Al电容器满足欧姆导电机制。铁电电容器经过109极化反转后没有发现明显的疲劳现象。     

Influence of pH value on properties of YPO4:Tb3+ phosphor by co-precipitation method

A series of Y1–xPO4:x Tb3+(x=0.005–0.1) phosphors were successfully fabricated by using co-precipitation method with NH4H2PO4 as phosphorus source. The structure and morphology characterization of the luminescent material was investigated with X-ray powder diffraction(XRD) and field emission scanning electron microscopy(FESEM). The XRD patterns indicated that the samples belonged to tetragonal phase. Luminescence properties were discussed by measuring the excitation and emission spectra. The phosphor could be excited by UV light(340–390 nm) and emitted green light, with the emission peaks located at 491(5D4→7F6), 550(5D4→7F5), 589(5D4→7F4) and 624 nm(5D4→7F3). In addition, the p H value and activator concentration had great effects on the emission intensity. The results illuminated that this phosphor could be used for UV based white light emitting diodes and co-precipitation method could be used to prepare better appearance phosphor.     

钛掺杂对于YMnO3多铁性能的调控

利用固相反应法制备了钛掺杂的YMn_(1–x)Ti_xO_3 (x=0.1,0.2)固溶体,对掺杂前后体系的晶格结构、磁性以及铁电性进行了研究。结果表明:掺杂后的样品仍然维持六角相结构,在x=0.2时开始有菱形■结构出现,掺杂体系保持着原有的铁电与反铁磁共存的状态,并伴随着弱铁磁性的出现;随着掺杂的增加由Curie-Weiss拟合得到的Weiss温度(负值)逐渐升高,表明反铁磁作用在减弱;体系在低温会发生自旋玻璃态转变,同时冻结温度Tf随着掺杂量的增加逐渐降低;对于体系铁电性测量表明其依然保留着原有的铁电性能,且极化强度会随着掺杂浓度的提高而增强。     

沉积温度对磁控溅射法制备La_(0.5)Sr_(0.5)CoO_3薄膜微结构和导电性能的影响

采用射频磁控溅射法在(001)SrTiO3基片上制备了La0.5 Sr0.5 CoO3薄膜,研究了沉积温度对La0.5Sr0.5CoO3薄膜微结构和导电性能的影响.结果表明:沉积温度低于400℃时,薄膜以非晶状态存在,未发生外延生长,沉积温度为550℃和650℃时,薄膜在基片上实现了外延生长;随着沉积温度的升高薄膜表面粗糙度呈现规律性的变化;薄膜的电阻率随沉积温度的升高单调下降,650℃沉积薄膜的电阻率最小为1.63μQΩ·cm.