从软锰矿到锰同位素：锰元素的发现及其概念的发展

1771年，瑞典化学家托伯恩·伯格曼明确提出软锰矿中含有新元素的假说，并将之初步命名为manganese(锰)。1774年，瑞典矿物学家甘恩首次制取出锰单质，锰元素假说得以验证。同年，瑞典化学家舍勒对锰单质的性质进行了表征，并确认manganese(锰)一词为该元素命名，锰元素的概念正式形成。同位素化学兴起后，1923年至今共发现25种锰的同位素，锰元素被明确定义为质子数为25的所有原子的总称。锰元素的发现浓缩了19世纪初系统分析法形成以前早期分析化学的发展，其概念的演变渗透出系统分析法的形成以及同位素化学的兴起，在定性到定量的研究过程中体现了科学思想和方法的进步。     

硼元素概念的发展史

通过对硼元素概念的发展史考证分析可知,硼元素概念的发展大致可划分为3个时期,即硼元素假说的形成、硼元素概念的形成与发展、现代硼元素概念的建立.18世纪,拉瓦锡预言了硼元素的存在.19世纪初,硼单质的制取成功标志着硼元素概念正式形成.20世纪,随着原子结构理论的建立和同位素的发现,人们对硼元素有了新的认识.硼元素概念的发...     

钨元素的发现及其概念的发展

1781年,瑞典化学家舍勒在白钨矿中发现了钨酸,预测其中一定含有一种新金属元素,并将其命名为钨(Tungsten)。1783年,西班牙化学家德鲁亚尔兄弟从黑钨矿中成功提取出了舍勒所说的新金属单质,将其命名为钨(Wolfram)。1803年,英国化学家道尔顿原子论的提出,赋予钨元素新的含义:具有一定质量的钨原子。1930年以后,钨同位素的发现使人们对钨元素有了新认识,并逐渐形成了现代钨元素的概念。关于钨元素的认识经历了从假说到客观存在、从定性到定量、从宏观到微观的发展历程。钨元素概念的演变体现了科学思想和科学方法的进步。     

氟元素的发现:从假说到客观实在

通过从科学认识论、科学方法论、化学思想等方面对氟元素的发现历程考证分析可知,氟元素的发现不是先发现元素物质,后形成元素概念,而是一个从假说到客观实在的验证过程。科学家以实践为基础,运用逻辑思维和直觉思维预见了氟元素的存在,并不断探索、创新研究方法、自制实验仪器,最终证实了氟元素假说,同时也验证了元素周期律,使卤族元素概念走向成熟,使化学元素观得以演进。     

从类铝到镓同位素:镓元素的发现及其概念的历史演变

1871年门捷列夫基于元素周期律预见“类铝”,1875年布瓦邦德朗基于实证研究分离出镓单质,直至20世纪镓同位素的发现,镓元素概念的发展经历了假说、形成和新的认识等3个时期。伴随着科学思想的演变与科学技术的进步,镓元素的概念不断发展。人们对镓元素的认识也经历了从宏观现象到微观本质,从假说到客观实在的发展过程。镓元素的发现过程体现了科学方法的重要性。镓元素的发现也促进了周期律思想的传播。     

钛元素的发现及其概念发展

1791年,英国矿物学家格雷戈尔发现钛矿石并意识到一种新元素的存在。至1795年,普鲁士化学家克拉普罗特进一步预言了该元素,并将之正式命名为钛(Titanium)。1910,美国化学家亨特制取了纯净的钛单质,钛元素的概念正式形成。20世纪20年代以后,钛同位素的发现使人们对钛元素概念有了新认识,并逐渐形成现代钛元素概念。钛元素概念的发展使人们在科学认知上发生了转变,促进了化学元素观的演进。     

原子吸收法间接测定微量锆

间接原子吸收光谱法的研究受到人们的普遍重视,主要有利用杂多酸的“化学放大”效应间接测定磷、砷、锗;沉淀反应间接测定氯离子、硫酸根,化学干扰效应间接测定钛、铝及络合效应间接测定钒、硼、硝酸根等,但在间接测锆方面未见报道,本文用Mg-8-羟基喹啉(MgL_2)沉淀锆置换出定量的镁,通过测镁间接测锆,建立了空气-乙炔火焰原子吸收光谱法间接测定锆的新体系,方法的特征浓度为0.018mg/L/1%,较氧化亚氮乙炔火焰(10mg/L/1%)提高500倍,该方法灵敏、快速、体系稳定,经萃取分离除去干扰元素,用于实际样品中氧化锆的测定,结果满意.2 实验部分     

电感耦合等离子体发射光谱法测定二硼化锆中26种杂质

建立微波消解样品,电感耦合等离子体发射光谱法测定二硼化锆中26种杂质元素含量的方法。根据二硼化锆的化学组成对杂质检测的影响,确定了各元素最佳分析线;通过考察不同浓度的锆基体对待测元素的影响来确定最佳锆基体浓度;通过萃取法分离硼元素,消除硼对杂质检测的干扰;采用基体匹配法、多谱拟和技术消除了锆基体的干扰。在选定的仪器工作条件下,各待测元素的质量浓度与信号强度成良好的线性关系,线性相关系数均大于0.999。测定结果的相对标准偏差不大于6%(n=11),样品加标回收率为94%~101%。该方法操作简便,测定结果准确,可用于二硼化锆中26种杂质元素的测定。     

铪元素及其同位素的发现：技术进步和思想发展的共同结晶

1869年，门捷列夫在第一张元素周期表中的锆元素后留出原子量为180的元素位置，预测铪与锆同族。1913年，原子序数和莫斯莱定律的提出揭示了铪元素在周期表中位置排列的实质，为铪元素的发现提供理论基础。20世纪20年代，玻尔理论的发展证实铪与锆同族，指导科学家从锆矿石中寻找铪元素。1923年，赫维西和科斯特借助X射线光谱技术发现铪元素，彰显了X射线光谱技术的独特价值。20世纪30年代以后，同位素理论和质谱技术促成了铪同位素的发现，使人们对铪元素有了新的认识。总之，铪元素及其同位素的发现是技术进步和思想发展的共同结晶。     

锆钼蓝杂多酸的极谱行为及其应用

研究了锆钼蓝杂多酸在碱性溶液中的极谱行为 ,提出了测定微量锆的极谱法新体系。在0.04mol/L盐酸及抗坏血酸溶液中 ,锆 (Ⅳ)与钼酸铵反应形成锆钼蓝杂多酸 ,在pH8.5～10.5的NH3-NH4Cl缓冲溶液中 ,于-1.18V产生灵敏的极谱波,导数波高与锆(Ⅳ)的质量浓度在0.005～0.3mg/L范围内呈线性关系。研究了极谱波性质 ,证明其为吸附波 ,方法已用于岩石样品中微量锆的测定。     

Thermal Decomposition of Several Layered Zirconium Salts

The thermal decomposition of zirconium molybdate, tungstate and arsenate were investigated. The total mass losses of the investigated materials were 12.5, 11 and 8.5%, respectively. Despite having different crystal dimensions and structure the thermal decomposition of the samples takes place in a similar way. During heating two main endothermic processes with mass loss were observed. At the end of the thermal decomposition, oxides of the original materials were observed. The mentioned mass losses originate partly from the crystal water loss of the materials. The calculated crystal water content in the original molecule was 1.3 and 1 mole/molecule unit, respectively. Furthermore, for zirconium arsenate, a sublimation process was recorded above 960 K.This revised version was published online in November 2005 with corrections to the Cover Date.     

Changes in the zirconium local surrounding on ligand substitution in solutions

EXAFS and SAXS methods have been used to examine zirconium hydroxide and oxychloride aqueous solutions in the presence of sulfuric acid in a wide range of concentrations, as well as a zirconium sulfate aqueous solution. The structure of the complexes and their transformation regularities were determined. Structures of the given complexes and structures of zirconium hydroxide and zirconium oxychloride and hydroxide complexes in aqueous solutions were compared. Complexes in zirconium hydroxide and oxychloride aqueous solutions have identical structures in the presence of sulfuric acid. When the concentration ratio of sulfuric acid and the initial compound is low (20–30), the complex is an open trimer with zirconium atoms bonded by sulfate groups. Bridge sulfate groups form Zr-O-S-O-Zr bonds. Apart from the bridge sulfate groups, there are three terminal sulfate groups and three terminal hydroxyl groups for each zirconium atom. When the concentration of sulfuric acid is increased (up to a ratio of 40–100), closed trimers are observed in the solution.     

Structure of zirconium butoxide complexes in n-butanol solutions

EXAFS and SAXS were used for structure elucidation of zirconium butoxide complexes in n-butanol at concentrations from 0.3 g to 0.015 g ZrO₂ in 1 ml. The basic structural unit of the complex is a tetramer. It has two equal sides with zirconium atoms linked by double oxygen bridges and with zirconium-zirconium distances of 3.5 Å. The other sides in the tetramer are 3.3 Å and 3.9 Å. This difference in bond lengths is explained by the different numbers of double or single ligand bridges between zirconium atoms. The tetramers are apt to undergo oligomerization to form particles with a diameter of 80 Å in solution.     

锆氧杂环络合物合成方法探索

邻甲氧基苯基锂和 6,6-二甲基富烯 (或 6,6-二乙基富烯 )反应得配体锂盐 ( Cp′ Li) ,Cp′ Li直接和 Cp Zr Cl3· DME反应生成 2个新的锆络合物 Cp′ Cp Zr Cl2 。 BBr3和 Li Br分别用来使 Cp′ Cp Zr Cl2 环化 ,发现在相同条件下 BBr3比 Li Br3更有效。Cp′ Cp Zr Cl2 通过和 BBr3反应得到 2个新的锆氧杂环络合物。 4个新的锆络合物经元素分析、1 H NMR和 MS确证     

Seeding and the Non-Hydrolytic Sol-Gel Synthesis of ZrW2O8 and ZrMo2O8

The unseeded non-hydrolytic sol-gel synthesis of ZrW₂O₈ and ZrMo₂O₈ produces trigonal ZrM₂O₈ (M = W, Mo) at 740 and 300–400°C, respectively. Cubic ZrW₂O₈ can be prepared using non-hydrolytic sol-gel methods by seeding with small amounts of preprepared cubic material, and the formation of the trigonal polymorph can be suppressed completely. Seeds with a small particle size are necessary for the preparation of cubic ZrW₂O₈. In contrast, seeding of ZrMo₂O₈ gels with either cubic ZrMo₂O₈ or cubic ZrW₂O₈ only lowers the temperature at which the trigonal phase crystallizes.     

The thermal decomposition of zirconium oxyhydroxide

The thermal decomposition of zirconium oxyhydroxides prepared by the mixture of aqueous zirconium oxychloride solutions and aqueous solutions of sodium hydroxide or ammonium hydroxide under various conditions has been examined by thermogravimetry, differential thermal analysis, X-ray diffraction study and infrared spectrophotometry. As a result, it is seen that the thermal decomposition of zirconium oxyhydroxide, in which the composition is ZrO_2-x(OH)_2xyH₂O where x2 and 1y<2, proceeds according to the following process:

Thermoanalytical Investigation of Several Layered Zirconium Salts and their Derivatives Part II

The comparison of data of thermal analysis partly with XRD and/or analytical results permits determination of the exact quantity of crystal water of the investigated samples having quite different behaviour. The compositions of the samples were determined from the results of thermal analysis. Furthermore, the data help elucidate the behaviour of various crystalline materials and also their intercalates during heat treatment. This revised version was published online in July 2006 with corrections to the Cover Date.     

一些晶态层状有机-无机混合磷酸锆的制备、表征和层间距分析

酸氢锆和有机磷酸锆是一类具有层状结构的多功能材料 ,具有较高的热稳定性和较好的耐酸碱性能 ,可用作离子交换剂、催化剂及催化剂载体、吸附剂和色谱填充剂等 [1,2]。典型的α-磷酸氢锆具有数十至数百 m2· g-1的比表面 [3]。且无论是晶态、半晶态或是非晶态 ,所有有机基团均位于其表面或层间面上 ,这一优点可以充分发挥活性基团的配位作用。利用有机合成化学的丰富多样性 ,合成含有不同种类有机活性基团的有机膦酸 ,从而将不同种类的有机活性基团引入有机-无机混合磷酸锆层状结构材料 [4～ 6]。这些膦酸盐的另一优点是有机基团的含量比是…     

Modification of highly dispersed silica with zirconium acetylacetonate

The chemisorption of Zr(acac)₄ and the formation of nanoparticles of ZrO₂ on the surface of silica were studied by IR spectroscopy, thermogravimetry, thermal and X-ray phase analysis. The composition was established and the hydrolytic and thermal properties of ≡SiOZr(acac)₃ groups were investigated. __________ Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 44, No. 3, pp. 191–195, May/June, 2008.