低阻值In掺杂CdZnTe晶体的退火改性

以Cd_(1-y)Zn_y合金作退火源,对采用改进的垂直布里奇曼法(MVB)生长的In掺杂的Cd_(0.9)Zn_(0.1)Te晶片进行退火改性.结果表明:与退火前相比,退火后晶片的成分均匀性提高,Cd、Zn和Te三种元素的含量更接近理想的化学计量比,平均红外透过率由12;提高到59;,电阻率从3.5×10~6 Ω·cm提高到5.7×10~9 Ω·cm,且在PL谱中出现了代表晶体质量的(D~0,X)发光峰.在合适的条件下对低阻值In掺杂的CdZnTe晶体进行退火改性可较好的提高晶体的性能.     

不同Ti/Ba比钛酸钡纳米粉体及其陶瓷的制备和介电性能研究

采用溶胶-凝胶(Sol-gel)法制备了不同Ti/Ba比的钛酸钡纳米粉体及其陶瓷。通过XRD、SEM和TEM对钛酸钡粉体及陶瓷进行了表征,并测试了陶瓷的介电性能,研究了Ti/Ba比对陶瓷微观结构和介电性能的影响。结果表明:通过溶胶-凝胶工艺制备的纳米粉体主要为立方相钛酸钡,平均粒径约19~33 nm:随Ti/Ba比的增加,钛酸钡纳米粉体平均粒径呈先稍递减后增大的趋势,当粉体平均粒径大于30 nm吋,四方相在混合相中所占比例逐渐增大;Ti/Ba=1.01~1.03时,陶瓷中异常长大的晶粒较多,室温介电常数降低;1300℃烧结2 h的Ti/Ba=1.04的钛酸钡陶瓷具有较好的介电性能。     

CdZnTe晶体光致发光谱"负热淬灭"现象研究

采用改进的垂直布里奇曼法生长了直径为60 mm的CdZnTe晶体,测试了其在10 K～150 K范围的PL谱.对760 nm和825 nm处的峰积分强度随温度变化关系进行研究发现,在30～50 K范围内,PL谱峰的强度呈现反常温度依赖现象,即随着温度的升高而减小,也就是所谓的"负热淬灭"现象,这在CdZnTe晶体中属首次观察到.进一步分析表明,随着温度的增加,其PL谱强度变化的过程包含了三个无辐射过程和一个负热淬灭过程.与没有发生"负热淬灭"现象的CdZnTe晶体对比,两者XRD图谱呈现明显差异.讨论了发生负热淬灭现象的原因以及可能路径.     

溶胶-凝胶法制备掺锰钛酸钡纳米粉体及其陶瓷

The Mn-doped barium titanate nanosized powders and ceramics were prepared via the sol-gel process. The powders and ceramics were characterized by XRD， SEM and TEM. The dielectric properties of the ceramics were also measured. The influences of calcination temperature and Mn concentration on the microstructure， dielectric properties and phase composition of BaTiO₃ nano-powders and ceramics were discussed. The results indicated that the BaTiO₃-based powders doped with 1.0mol% Mn were mainly in cubic BaTiO₃ phase， but the tetragonal phase became more evident when the calcination temperature increased. After sintering， Mn-doped ceramics were mainly composed of cubic BaTiO₃. Specially， a new phase of hexagonal crystal BaTiO₃ and BaMnO₃ existed in the ceramics doped with 5.0mol% Mn and the ceramic grains were in ‘clintheriform’. The structure of ‘clintheriform’ led to the poor densification of ceramics， reducing the dielectric constant obviously. The dielectric constants of BaTiO₃ ceramics first increased and then decreased as the Mn concentration increased. The room temperature dielectric constant was 2 290 and the lowest dielectric loss was 0.004 when the Mn concentration was 0.5mol%.     

蛋花香

我的奶奶住在风景秀美的乡下.星期天我到奶奶家去玩.奶奶的院子里有花有草还有蟋蟀,可好玩了.我在奶奶家的院子里同小猫咪玩,听到邻居李爷爷"咯咕咯咕"地唤他的鸡,于是我好奇地跑过去看.     

氢氧化镧钠米线对多倍斯伏安响应的增敏作用及其应用

氢氧化镧钠米线修饰碳糊电极对多倍斯伏安响应有明显的增敏作用,其特征是多倍斯一对氧化还原峰的峰电流增大和峰电位差减小。这种增敏作用是由于氢氧化镧钠米线修饰电极有效面积的增大以及氢氧化镧钠米线与多倍斯间的化学作用。基于多倍斯在氢氧化镧钠米线修饰碳糊电极上灵敏的氧化峰,用线性扫描伏安法测定多倍斯,线性范围是3.0×10^-10～1.0×10^-8 mol·L^-1,检测限达5×10^-11mol·L^-1。