Thermal conductivity of fluorides of alkali earth metals

A linear dependence is obtained between the thermal resistance and the temperatures for the monocrystalline fluorides CaF₂, SrF₂, BaF₂, and MgF₂. Anisotropy in MgF₂ has been discovered.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 30, No. 2, pp. 322–327, February, 1976.     

Thermoluminescence of alkali halides doped with alkaline earth impurities

Doping with alkaline earth impurities converts the alkali halides into very efficient phosphors. LiF doped with Mg is extensively used in radiation dosimetry. However, the phenomenon of thermoluminescence in these materials is far from clear. LiF-tld 100 is artificially separated from the rest of the alkali halide phosphors. The available experimental data are not fully utilised in building a model for thermoluminescence processes. In this review, thermoluminescence properties of LiF-tld 100 and other alkali halide phosphors are discussed. The comparative study which points out several common points could be useful in understanding thetl processes in these phosphors.     

The second and third virial coefficients of simple fluids

The asymptotic behavior of the second B and third C virial coefficients in the low temperature region is analyzed for fluids with a spherical pair-additive potential of interparticle interaction. The temperature dependences B(T) and C(T) are approximated by expressions which convey correctly the behavior of the virial coefficients in the low-and high-temperature limits. The free parameters of approximation formulas for pure nitrogen, argon, and oxygen are determined. The derived virial equations of state are used to calculate the limit of significant instability of the gas phase in a wide temperature range.     

含钇多金属氧酸盐的合成及稀土多元扩渗与电性能

用降解法或直接法合成了未见报道的四种含钇多元杂多配合物.通过化学分析、ICP和TG曲线确定了其化学式为K18-2nH3[Y(Xn+W11O39)2]·mH2O(X=B3+,Si4+,P5+)和K10H3[Y(SiW9Mo2O39)2];利用IR、XRD、183W-NMR、循环伏安等手段对其结构进行了表征,结果表明杂多阴离子为α-型或β2-型Keggin结构.采用稀土多元渗的方法对配合物进行了气相热扩渗,经ICP和XPS测试表明微量的稀土元素La、Sm和Dy可以渗入到配合物的体相,并与组份元素存在键合作用;导电性的测试结果表明室温时,扩渗后试样的电导率提高了约104～106倍,且与中心原子有关.     

On the theory of long water-waves on a rotating earth

Summary The theory of long water-waves in a rotating frame is considered in a general and systematic fashion, and the differential equations concerning the motion of tides are derived to compose well posed boundary value problems. Particular emphasis is given to the linearized equations of long waves which form the basis for the study of tides. Two applications are also given.     

Experimental determination of some nonlinear elements of third sound dynamics

The frequency shifts of third sound resonances during free decay are observed to have a quadratic dependence on the amplitude of the wave motion. An unambiguous measurement of amplitude allows for quantitative comparisons to predictions for the frequency shifts based on a variety of nonlinear influences acting within the superfluid⁴He film and resonator. Dispersive terms play a minor role in this analysis. We conclude that nonlinear terms dictated by a straight forward application of classical hydrodynamics are applicable to superfluid helium films.     

Hydrogen degradation of steels in gas mains after long periods of operation

We study the degradation of the mechanical and corrosion properties of 17G1S steel in gas mains as a result of operation for 28–40 yr. We reveal the simultaneous decrease in its strength and hardness, on the one hand, and impact toughness and crack resistance, on the other hand. The indicated parameters prove to be most sensitive to the in-service degradation of the metal. The degradation of steel leads to the increase in the strain-hardening coefficient and the appearance of the yield plateau in the tensile stress-strain diagram and causes the appearance of sensitivity to hydrogen embrittlement increasing in the process of operation. We analyze the role of absorbed hydrogen affecting the mechanism of strain aging and responsible for the appearance of defects. It is shown that the polarization resistance can be used not only for monitoring of the corrosion state of gas pipelines but also for the prediction of changes in their mechanical properties in the process of operation. __________ Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 43, No. 5, pp. 97–104, September–October, 2007.     

Phase transition of nanostructure zirconias doped with rare earth elements

Nanostructure zirconias doped with rare earth elements were obtained by coprecipitation. The morphology, structure, and phase transition of the as-prepared samples were studied. According to transmission electron microscopy, the particles appear in near spherical shape and have a mean particle sizes of about 150 nm without change with the rare earth elements. From laser Raman and X-ray diffraction results, it is known that the tetragonal phase of zirconia is stabilized by a certain concentration of the rare earth dopants, and the cubic phase is obtained if enough dopants are added. The crystal lattice increases with the increase of dopant concentration. Moreover, the heavy rare earths are better than the light ones in stabilizing effect. According to our study, laser Raman is more sensitive than X-ray diffraction in monitoring the phase transition.     

An equation of state for oxygen vapour—second and third virial coefficients

Based on a selected p, ρ, T data set of oxygen for the range from low to moderate densities an equation of state for oxygen vapour has been established. From this evaluation, new values for the second and third virial coefficients were derived. In addition, correlation equations for the temperature dependence of these virial coefficients are given. Estimations for the fourth virial coefficient were compared with the one predicted by the Lennard-Jones potential.     

荧光传感器在稀土检测方面的研究进展

本文阐述了稀土元素的应用和检测现状,指出荧光传感器在稀土元素检测中具有灵敏度高、选择性好、设备简单等优点,介绍了三类荧光传感器的特点和构建原理,分析了荧光传感器在稀土检测方面的发展方向。     

Estimation of the periods of initiation and propagation of creep-fatigue cracks in thin-walled structural elements

A computational model is proposed for the determination of the service life of structural elements with concentrators under the conditions fatigue and high-temperature creep. The model is based on the energy approach and the representation of the service life of a structural element as the sum of the periods of initiation and subcritical growth of creep-fatigue cracks.     

Mg2Si基热电材料的稀土掺杂优化

采用机械研磨-电场激活压力辅助合成(FAPAS)技术,快速合成了稀土Sc和Y掺杂的Mg2Si基热电材料,所得试样组织均匀、致密,试样的平均晶粒尺寸为1.5～2μcm,微量稀土元素不改变基体材料的组织形貌.分析表明两种稀土元素均在不同程度改善热电性能,其中掺杂0.427%(摩尔分数)Sc和0.173%(摩尔分数)Y的试样...     

稀土元素催化活化制备中孔炭

以线型酚醛树脂为前驱体,采用溶液混合法将Y(NO3)3或Ce(NO3)3掺杂在其中,通过水蒸气活化制备含有大量中孔的酚醛树脂基活性炭。利用红外光谱(IR)、热重(TG)分析、N2吸附、扫描电镜(SEM)等对酚醛树脂以及其相应的活性炭进行表征。结果表明:掺杂Y(NO3)3或Ce(NO3)3可以提高水蒸气活化的速率,促进孔的发展。由于稀土金属盐与酚醛树脂前驱体相容性的限制,Y(NO3)3或Ce(NO3)3的催化效率随着其在树脂中含量的增加先增大后减小。其中,Y(NO3)3可以同时促进中孔和微孔的发展,且促进微孔发展的作用更强一些,而Ce(NO3)3则在促进中孔的发展中显示出较大的优势。     

The determination of the second and third virial coefficients frompVT-X data of binary systems

The compressibility factor of multicomponent systems can be obtained in terms of virial coefficients of the pure components and their binary mixtures. This paper concerns a method with which, for that purpose, the second and third virial coefficients for these binaries have been determined from experimental data. From useful data, second and third virial coefficients are obtained as a quadratic function of the temperature. The density domain for which these results are applicable is discussed. When ample data are available, results for a sample mixture can be obtained in a straightforward manner. Nevertheless, it is shown that under much less favorable conditions—sometimes even when pure-component data are lacking—fairly good results can still be obtained. In that case, the choice for an appropriate combining rule has to be considered carefully. Finally, the involvement of ternary mixture data, both obtained experimentally and predicted by the equation, is considered.Paper presented at the Tenth Symposium on Thermophysical Properties, June 20–23, 1988, Gaithersburg, Maryland, U.S.A.