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叶大年 《中国科学B辑(英文版)》1989,(3)
The optical anisotropy index is a new conception which has been proposed by the author of this paper on the basis of the Gladstone refractivity (i.e. specific energy by Larsen). The conception is very useful for studying the structural-optical mineralogy. The polarizability ellipsoid of atom groups in minerals may be obtained from the optical anisotropy index; conversely, when the crystal structure, orientation, and the polarizability ellipsoid of atom groups are known, the optical anisotropy index of the minerals may be calculated, and then three principal refractive indices, and the optical axis angles may be calculated, too. The calculated values of optical properties are in very good agreement with the experimental values. This calculation method is much simpler thanBragg's for the carbonates, and the precision of calculated values is much higher than that of Bragg's. The principle of calculation method is suitable for all the minerals containing some strong anisotropic atom groups, besides carbonat 相似文献
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本文从晶体结构的角度,证明等结构化合物晶胞边长、晶胞体积与离子半径之间存在以下关系:(1)多元化合物A_mB_m…X_p的晶胞体积V与某种阳离子如A的半径之间有关系式:V=(a+br_A)(r_X+r_A)~3 (a,b为常数)。(2)对于二元化合物关系式为:V=K(r_X+r_A)~3 (K为常数)。(3)由以上关系式可推得二元化合物V与_A~3r成近似直线关系,多元化合物V与r_A~3之间易表现为曲线关系,但r_A变化不大时仍近似为直线,另外V与r_A也成近似线性关系。(4)二元化合物品胞边长与r_A成线性关系,多元化合物无此线性关系。 相似文献
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过冷结晶效应是硅酸盐熔体在常压过冷态结晶时出现的一种特殊的效应。即当过冷却达到一定程度时,体系中物相可分为两部分(与平衡状态结晶时对比),一部分是类似于静高压产物的相对“收缩相”,另一部分是相对“膨胀相”(常为玻璃态)。但是,过冷却结晶时,体系中各相的总克分子体积一般略大于平衡态结晶时的总克分子体积。因它既类似于静高压效应,同时又必然伴随相对膨胀相,故亦称它为假高压效应。 冲击变质作用形成的物相特点与过冷结晶效应相似,也是膨胀相与收缩相的对立统一,并且冲击变质作用也引起体系的总克分子体积增大。推测这两种效应可能是用昂色格倒易关系联系起来的。 相似文献
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The present paper discusses some characteristics of the molecular volumes of phosphates, arsenates and vanadates. In the salts, the volumes of per acid radical ((?)) quantitatively depend on the radii, charges, numbers of cations and anions. The functional relations between the (?) values of phosphates, arsenates, vanadates and the factors mentioned above are obtained. The molecular volumes of these salts are equal to the sum of the topological volumes of cations and anions. The authors have got a series of universally united topological volume values of cations and anions. It confirms that the topological molecular volume of the crystal water (H_2O) in the hydrates of the salts approximates to a constant, 244 (?)~3 with σ_(n-1)= 2.1. The topological volume of the hydroxide ion (OH~-) approximates to a constant too. The average value is 16.89 (?)~3 with σ_(n-1)=1.68. 相似文献
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The relation between cell-edges or unit-cell volumes of isostructural compounds and theionic radii has wide applications in crystal chemistry. The authors have proved: (1) For a series of multiple isostructural compounds such as A_mB_n…X_p, when the anionand other cations are fixed, there exists the following relation between the unit-cell volume Vand the radius r_A of a certain cation such as A: V = (a + br_A)(r_X + r_A)~3 (a and b are constants). (2) For binary isostructural compounds A_mX_p, the above relation is reduced to V = k(r_X + r_A)~3 (k is a constant). (3) For binary isostructural compounds the relation between V and r_A~3 is approximatelylinear, and for multiple compounds, it is often curvilinear but still approximately linear whenthe variation of r_A is slight. As another approximation, a linear relation also exists betweenV and r_A for isostructural compounds. (4) The relation of ce1l-edge a vs. r_A is linear for binary isostructural compounds. Butno such a good linear relation exists fo 相似文献
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The present paper discusses some characteristics of the molecular volumes of carbonates, nitrates and borates. It confirms that the molecular volume of H_2O in the hydrates of this kind of salts approximates to a constant. When the coordination numbers of cations in mixed salts are identical with those in the single salts, the additivity of the molecular volume is quite accurate. Over 100 sets of data demonstrate that a general additivity is true, the average relative error being ±2.31%. The concept of the topological molecular volume is proposed based, on the additivity. For salts with the same radical and equally charged cations, the molecular volume varies linearly with the cation radius. The volume effects of CO_3~(2-) NO_3~- and BO_3~(3-) in packing can be obtained by extrapolation. They are equal to a large sphere whose volume is the sum of those of three O~(2-). This paper also discusses the possibility of compiling a table of ionic volumes. 相似文献
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本文研究了磷酸盐、砷酸盐、钒酸盐及硼酸盐分子体积(V)的若干特点,此类盐中单位酸根占有体积(V)定量地取决于阳离子的半径、电价和数目以及阴离子团的种类,文中给出了磷酸盐、砷酸盐、钒酸盐和硼酸盐的V值与上述因素之间的解析函数式,这些盐类的分子体积等于阴离子团的拓扑体积和阳离子的拓扑体积之和,并得到了一套普适的阴、阳离子拓扑体积数值,其中结晶水分子体积近似为一常数,平均值为24.4 ,σ_(n-1),=2.1;氢氧根(OH)-的拓扑体积也近似为一常数,平均值为16.89,σ_(n-1)=1.68。 相似文献
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Through the calculation of the VPOs (volume per oxygen) of 1698 rocks and minerals, the authors reach the following conclusion: the mean VPO of glassy extrusive rocks is 22.5. The mean VPO of semicrystalline extrusive rocks is 21.5. Crystalline extrusive and all intrusive rooks from granite to gabbro have a mean VPO of 20.6. According to the models of the earth's layers, the VPO of the upper crust is 20.8. If the lower crust is composed of gabbro, the VPO is about the same as that of the upper crust. If it consists of amphibolite or dioritic garnet granulite, the VPO is 18.8. Based on the data of mantle inclusions and high pressure and high temperature experiments, the calculated VPO of the upper mantle is 17.7. All these are constants in each layer and correspond to the packing concentrations in the packing of equal spheres. 相似文献