18－冠－6修饰碳糊电极测定金的研究

本文研究了１８－冠－６修饰碳糊电极测定金的条件，金在０．５ｍｏｌ／ＬＨＣ１－０．００５ｍｏｌ／ＬＫＣ１底液中富集，介质交换到０．０１ｍｏｌ／ＬＨＣ１中进行测定。金（Ⅲ）浓度在０．１～１．０μｇ／ｍＬ范围内呈线性关系，相对标准偏差为９．７％，检出限为２０ｎｇ／ｍＬ。可不经预先分离直接测定矿样中的金，结果良好。并研究了Ａｕ（Ⅲ）在１８－冠－６碳糊修饰电极上的还原机理。     

YBaCuO缺氧和掺氟效应的从头算研究

应用含自洽晶体场MadeLung势全电子从头算方法计算了模拟缺氧和掺氟的YBaCuO原子簇.结果表明:缺氧效应导致CuO_2面上的电荷浓度增加,空穴数目减少,Cu的化学价降低以及Cu-O共价键严重削弱.掺入的氟占据顶角氧的位置,可使局域电子结构恢复到不缺氧YBA_2CU_3O_7时的状态.借助于计算得到的化学键特征,对前人推测氟取代链上氧空位的观点提出质疑.     

Study on the effects of fluorine and oxygen deficiency on YBa_2Cu_3O_7 by ab initio method

The calculations of clusters modeling the fluorine-doping and oxygen deficiency of YBa2Cu3O2,have been performed by the method of all-electron ab initio Hartree-Fock with self-consistent crystal field Results show that in CuO planes electric charge significantly increases,the chemical valence of Cu decreases and the covalent bonding of Cu-O greatly weakens owing to oxygen deficiency,while the effect of F restores the local electronic structure of YBa2Cu3O7 The reported opinion that F occupied the oxygen vacancy in Cu-O chains seems disputable according to the calculated bonding characteristics.