断续流动-氢化物发生原子荧光法测定浓缩苹果汁中的砷

用断续流动－氢化物发生原子荧光法测定了浓缩萍果汁中的砷含量。确定了仪器的最佳条件，探讨了酸介质，硫脲－抗坏血酸用量，硼氢化钾加入量对测定As的影响。在选定的操作条件下，砷的检限为0．43ng/mL，相对标准偏差为3．4％－6．3％，加标回收率为94．0％－101．5％本方法简便，快速，灵敏，准确，应用于浓缩苹果汁中As的测定，得到满意的结果。     

KxCoO2·yH2O(x《0.2,y≤0.8)的晶体结构、输运及磁学性质

利用熔融KOH和Co3O4在较低温度(480℃)下反应制备出K0.36CoO2,然后用高锰酸钾溶液和饱和的过硫酸钾溶液进行氧化处理.氧化的同时伴随有水分子嵌入.K0.36CoO2用高锰酸钾和过硫酸钾溶液处理后分别得到K0.12CoO2·0.8H2O和K0.16CO2·0.6H2O.这两种化合物都属于六角晶系,表现出金属行为,脱水后主相变为正交结构并且呈现出半导体特性.K0.16CoO2·0.6H2O在56K附近可能存在自旋玻璃转变行为或其他涨落.随着钾含量的减少和水含量的增多,样品的自旋玻璃行为受到抑制或发生磁性相分离.样品K0.12CoO2·0.8H2O在零场冷却和有场冷却曲线上的分叉现象基本上消失.还讨论了产生KxCoO2与NaxCoO2体系结构和物性差别的原因.     

La掺杂Bi-2201单晶中宏观相分离迹象的发现及研究

在对系列Ｌａ 掺杂的Ｂｉ２Ｓｒ２ － ｘＬａｘＣｕＯ６ ＋ δ单晶的研究中,我们发现在极度Ｌａ 掺杂（ 空穴极度欠掺杂） 的样品中有高达３６Ｋ 的超导相出现．Ｘ 射线衍射图（ＸＲＤ） 和电镜照片都表明这种极度空穴欠掺的样品有很好的单相性,从而排除了样品化学不纯的可能．另外,对这种样品进行脱氧处理后,此超导电性相应消失,说明了这种高Ｔｃ 的超导电性是由活动性空穴掺杂引起的．虽然对相应样品在正常态的磁测量没有测出反铁磁峰（Ｎｅｅｌ 峰） ,但对系列样品的拉曼散射研究发现样品随着Ｌａ 含量的增多,其反铁磁交换作用明显加强．所以,我们认为这种高Ｔｃ 超导电性的出现是在Ｂｉ２２０１ 体系中存在宏观相分离的明显迹象     

Preparation and the physical properties of antiperovskite-type compounds Cd1_xInxNNi3（n〈x〈0.2）and Cd1-yCuyNNi3（0〈y〈0.2）

Two series of Cdl-xInxNNi3 （0 〈 x 〈 0.2） and Cd1_yCuyNNi3 （0 〈 y 〈 0.2） samples were prepared from CdO, In203, CuO, and nickel powders under NH3 atmosphere at 773 K. The structural and physical properties were investigated by means of X-ray powder diffraction temperature-dependent resistivity and magnetic measurements. X-ray powder diffraction results showed that the Cd1-xInxNNi3 and Cd1_yCuyNNi3 compounds have a typical antiperovskite structure, and the CdNNi3, Cd0.9In0.1NNi3, and Cd0.9Cu0.1NNia compounds show metallic temperature-dependent resistivity and exhibit a Fermi liquid behavior at low temperature. In contrast to the paramagnetism previously reported, the CdNNi3 sample exhibits very soft and weak ferromagnetism, and no superconductivity was found in the Cd1-xInxNNi3 and Cdl-yCuyNNi3 samples down to 2 K. Each sample exhibited very soft and weak ferromagnetism, and the temperature dependence of the magnetization of the Cd1-xInxNNi3 and Cd1_yCuyNNi3 samples can be well fitted to the combination of a Bloch term and a Curie-Weiss term.     

Preparation and the physical properties of antiperovskite-type compounds Cd_1-xIn_x NNi₃（0 ≤x≤ 0.2） and Cd_1-yCu_yNNi₃（0≤y≤0.2）

Two series of Cd1-xInx NNi3(0 ≤x≤ 0.2) and Cd1-yCuyNNi3(0≤y≤0.2) samples were prepared from CdO, In2O3 , CuO, and nickel powders under NH3 atmosphere at 773K. The structural and physical properties were investigated by means of X-ray powder diffraction temperature-dependent resistivity and magnetic measurements. X-ray powder diffraction results showed that the Cd 1 x In x NNi 3 and Cd 1 y Cuy NNi 3 compounds have a typical antiperovskite structure, and the CdNNi3, Cd0.9 In 0.1 NNi3 , and Cd0.9Cu0.1NNi3 compounds show metallic temperature-dependent resistivity and exhibit a Fermi liquid behavior at low temperature. In contrast to the paramagnetism previously reported, the CdNNi 3 sample exhibits very soft and weak ferromagnetism, and no superconductivity was found in the Cd 1 x In x NNi 3 and Cd 1 y Cu y NNi 3 samples down to 2 K. Each sample exhibited very soft and weak ferromagnetism, and the temperature dependence of the magnetization of the Cd 1-xInx NNi 3 and Cd1-y Cu y NNi 3 samples can be well fitted to the combination of a Bloch term and a Curie–Weiss term.     

磁性离子Fe和Ni替代YBCO体系的结构特征和载流子局域化

为阐明磁性离子在不同替代位置对YBCO体系超导电性的影响机制，利用正电子湮没及相关实验手段结合数值模拟，系统研究了Fe和Ni掺杂的YBa₂Cu₃O_7-δ体系. 结果表明，Fe和Ni离子在替代过程中均以离子团簇的形式进入晶格. 当离子进入CuO₂面时，由于团簇改变了周围的电子结构，造成电子的局域化，并直接影响了电子对的配对和输运，因而强烈抑制了体系的超导电性.而当掺杂离子进入Cu-O链区时，它们同样通过团簇的形式改变周围 关键词： YBCO超导体 磁性离子替代 正电子湮没 数值模拟     

邻二甲苯氧化制苯酐催化剂的研究I.V2O5-TiO2的组成、物性和反应性能

用XPS,IR,TG和脉冲色谱法考察了V_2O_5-TiO_2复合氧化物催化剂中V_2O_5与TiO_2的相互作用,V_2O_5的分散状态和释氧活性,以及催化剂对邻二甲苯氧化的活性和生成苯酐的选择性。阐明了该催化剂组成对活性和选择性的影响。XPS和TG结果表明,V_2O_5含量<10wt%时,它与TiO_2可形成有V_2O_5与TiO_2相互作用和释氧活性的表面层;在V_2O_5含量～10wt%时,该表面层形成得最充分。IR研究证实表面层的释氧活性是由V_2O_5的V=O键松弛引起。V_2O_5>10wt%时,样品中除有释氧活性的V_2O_5外,还有不具有释氧活性的V_2O_5,前者对催化活性和选择性有主要贡献,后者则有不利影响。     

用Cu_2O合成Y－123超导体的研究

用Ｃｕ_２Ｏ合成Ｙ－１２３超导体的研究兰玉成中国科学院物理研究所车广灿，吴非，陈红，贾顺莲，董成，赵忠贤中国科学院物理所超导实验室，北京１０００８０１９９５年１１月２７日收到一、引言众所周知，在高Ｔｃ氧化物超导体中，［ＣＵ－Ｏ］ｐ层或［Ｃｕ－Ｏ］ｐ链?..     

ELECTROCHEMICAL OXIDATION OF La2CuO4 SINGLE CRYSTALS

Bulk superconducting La₂CuO_4+δ single crystals are obtained by using electrochemical intercalation technique from the as-grown insulating samples. Oxidation is carried out by constant current I=10μA at temperature T=70℃ and room temperature, respectively. Structure and magnetic properties are studied by low-temperature X-ray diffraction and susceptibility measurements. A superconducting phase with T_c of 19K and δ-0.12 can be attributed to the formation of oxygen clusters. Room temperature oxidation is inhomogeneous: two superconducting phases with T_c1 of 24K and T_c2 of 8K and an antiferromagnetic phase are coexisting in the crystal. It is found that the appearance of T_c in this system has the "step" tendency.     

一个方便实用的粉末衍射数据处理和结构分析程序

重点介绍了最近开发的粉末Ｘ射线衍射数据处理和结构分析软件“ＰｏｗｄｅｒＸ”．“ＰｏｗｄｅＸ在Ｗｉｎｄｏｗｓ９５／９８平台下工作,有使用方便的图形界面和连机帮助,具有数据平滑、扣除背景、扣除α２、寻峰、指标化、晶格参数精修等多种功能,可以输入多种格式的衍射数据,可以方便地进行数据格式转换,非常适合多晶结构分析和精修的需要,程序中包含有独特的衍射仪零点、样品偏心系统误差样正功能和精确ＣｕＫα２扣除功能