Pyroelectricity and Spontaneous Polarization in [111] Oriented 0.955 Pb（Zn1/3Nb2/3）O3-0.045PbTiO3 Single Crystals

We report that the measurements of the pyroelectric current of the pre-poled [111]-oriented 0.955 Pb（Zn1/3Nb2/3） O3-0.045 PbTiO3 （PZN-4.5%PT） single crystals can shed some light on the phase transition and spontaneous polarization characters of this material in a similar way to measures of remanent polarization and dielectric properties. The pyroelectric current is measured and the corresponding spontaneous polarization is calculated as a function of temperature with various poling fields added during cooling the sample from 200℃ to room temperature. Critical electric field of 0.061 k V/cm is found to be essential to induce the intermediate ferroelectric orthorhombic phase between the ferroelectric rhombohedral and tetragonal phases. Below the critical field, the polarization increases almost linearly with the increase of poling field. At the critical field, the polarization at 30OC increases abruptly from 14μC/cm^2 for a poling field of O.06kV/cm to 29.5μC/cm^2 for a poling field of 0.061 kV/cm, and afterwards, increases slowly and saturates to 31 μC/cm^2 for poling fields beyond 0.55 kV/cm.     

TiO2过渡层对BiFeO3薄膜微结构和铁电磁性质的影响

研究了TiO2过渡层对BiFeO3薄膜微结构和铁电磁性质的影响.采用溶胶-凝胶法分别在Si（100）和Pt（111）/Ti/SiO2/Si（100）衬底上制备了BiFeO3薄膜.通过加入约10 nm厚度的TiO2过渡层,在两种衬底上均制备出了纯相BiFeO3薄膜,而未加过渡层的薄膜均有杂相存在.与未加TiO2过渡层相比较,BiFeO3/TiO2薄膜表面颗粒大小更加均匀、致密、平整.在室温10kHz下沉积在Pt/Ti/SiO2/Si衬底上的薄膜的损耗从0.094下降到0.028;而薄膜的介电常数变化不大,分别为177和161.在室温下同时测得了薄膜的电滞回线和磁滞回线.BiFeO3/TiO2薄膜的饱和磁化强度为16.8 emu/cm3,在600kV/cm电场下,剩余极化强度为9.8μC/cm2.研究表明,TiO2过渡层能够有效地抑制Bi FeO3薄膜杂相的生成,提高薄膜的表面平整度以及耐压性.     

电解有机溶液法制备CNx薄膜

在６０℃和常压下，电解甲醇和脲的混合溶液在硅基片上沉积ＣＮｘ薄膜．傅里叶红外和Ｒａｍａｎ测试表明，所得薄膜是非晶态的，碳和氮主要是以Ｃ—Ｎ，Ｃ—Ｃ，ＣＣ和ＣＮ的形式成键，有少量的碳和氮以ＣＮ的形式成键．Ｘ射线光电子能谱测试表明，氮是以ＳＰ２和ＳＰ３杂化形式与碳化学成键来成膜的．测试结果表明通过液相沉积法所得ＣＮｘ薄膜与汽相沉积法所得ＣＮｘ薄膜的结构比较接近     

美国重整军备面临难题

里根总统上台后,提出了一个庞大的重振军备计划,今后5年内国防预算总额达15,000亿美元。但据美国报刊报道,美国军事工业目前面临着一系列问题。首先,美国军事工业所必需的钛、锰、钽、钴、铬、铂等几十种重要     

微波电子回旋共振-化学气相沉积SiN_x薄膜的光学性能研究

研究了微波电子回旋共振－化学气相沉积ＳｉＮｘ薄膜的光学性能，这种ＳｉＮｘ薄膜具有透光谱宽、透光率高的特点，总结了透光谱、折射率、光隙能随微波功率、基片温度的变化关系     

INTERFACE SPIN-WAVE OF COUPLED SEMI-INFINITE MAGNETIC SUPERLATTICE

The interface spin-wave (ISW) modes or coupled semi-in-finitemagnetic superlattices separated by a nonmagnetic layer have been studied, by use of the magnetostatic method. A general expression of the ISW dispersion relation is obtained. Detailed calculations are performed in the special case where the ttwo semi-infinite superlattices is considered to be identical and the external magnetic field, is parallel or perpendicular to the surface of the. layers. Some results about ISW modes are discussed.     

氧气氛低温退火Pt/Ba0.8Sr0.2TiO3Pt引起的低频介电弛豫效应

研究了在不同温度区间氧气氛和氮气氛退火后处理对PtBa0.8Sr0.2TiO3Pt介电特性的影响.经过高温550℃氮气退火处理后,再放入350℃的氧气中退火,发现样品的介电特性出现了非常明显的低频弛豫现象,并且这种低频弛豫现象在350℃的氮气中退火后将会消失.通过在出现低频弛豫现象的样品的上下电极加一偏压,可以发现低频弛豫现象更加明显,并且在撤消偏压后这种增强将会逐渐减弱,直至最终恢复到偏压前的弛豫状态 关键词： 脉冲激光沉积 介电弛豫 动态随机存储器     

施主掺杂浓度对PTC陶瓷材料导电性能和微观结构的影响

本文研究了施主Nb掺杂BaTiO_3PTC陶瓷的微观结构和导电性能。总结了材料电阻、介电、复阻抗、电流电压关系、耗散等特性及微结构随施主浓度变化的实验规律。