等结构化合物中离子半径的晶胞体积效应

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。     

EFFECT OF IONIC RADII ON UNIT-CELL VOLUMES OF ISOSTRUCTURAL COMPOUNDS

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     

PACKING OF IONS IN SILICATE GLASSES

Any silicate glass can be regarded as the relaxation of SiO_2 glass and the volumeis composed of two parts. One is the topological volume of O~(2-), which is equal to thevolume per oxygen of SiO_2 glass, the other is the topological volumes of cations. Thetopological volume of a monovalent cation equals the volume shared by each sphere indense haphazard packing of equal spheres of the cation's size. The charges of bivalentcations cause a decrease of volume, the decrement being the packing volume of Ca~(2+). Anequation is reached for the calculation of the volume per oxygen of silicate glasses. Alot of calculations show that the equation is accurate, so accurate that the densities canbe calculated. The study reveals some characters of the glass structure and clearly ex-presses the contributions of various cations to the volumes of glasses.     

硅酸盐玻璃中的离子堆积

硅酸盐玻璃可视为松驰的SiO_2玻璃,其体积由两部分组成,一部分为O~(2-)的拓扑体积,等于SiO_2玻璃的氧平均体积,另一部分为阳离子的拓扑体积。对于一价阳离子相当于做等大球密任意堆积时的平均占有体积,对于二价阳离子须减去电荷引起的体积收缩,其减量等于Ca~(2+)的堆积体积,由此得到计算硅酸盐玻璃氧平均体积的公式。该公式表明了各种阳离子对玻璃体积的贡献,从一个侧面揭示了玻璃结构的特点,并可用来计算玻璃密度。     

MOLECULAR VOLUMES OF SALTS. WITH TRIANGULAR RADICALS

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.     

CONSTANT VOLUMES PER OXYGEN OF THE EARTH''''S LAYERS

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.     

含三角形酸根盐类的分子体积

本文研究了碳酸盐、硝酸盐、硼酸盐分子体积的若干特点。该类盐中结晶水分子体积近似为一常数。当复盐中阳离子配位数与单盐中相同时,分子体积加和性精度很高。100多组数据证明一般性的加和仍然成立,平均相对误差±2.31％,由此提出拓扑体积的概念。将分子体积与阳离子半径的直线关系外推可得到CO_3~(2-),NO_3~-,BO_3~(3-)在堆积时的体积效应,相当于体积为三个O~(2-)体积之和的大球。文中还论证了建立离子体积表的可能性。     

CM200透射电子显微镜保护关机的故障分析及维修

介绍了CM200透射电子显微镜电镜保护(LPR)的工作原理,分析了电镜保护关机的故障原因并介绍了几个维修实例.     

地球圈层氧平均体积的守恒性

本文计算了1698个岩石和矿物的氧平均体积,从中得出结论,玻璃质喷出岩V_0为22.5 ~3,半晶质喷出岩V_0为21.5 ~3,金晶质喷出岩和从花岗岩到辉长岩的侵入岩V_0平均为20.6 ~3。按照地球圈层模型,上地壳V_0为20.8 ~3下地壳若为辉长岩,则V_0与上地壳基本相同,若为角闪岩或闪长岩成分的石榴石麻粒岩,则V_0为18.8 ~3,根据地幔包体和高温高压实验资料,计算出上地幔V_0为17.7 ~3。这些都是分层守恒的常数,并与等大球任意堆积的各个堆积系数相对应。