Thermal expansion of ChS-139 steel in temperature range 20–720 °C

The article presents the results of investigation of thermal expansion of ChS-139 steel in the temperature range 20–720 °C. Measurements were carried out by dilatometric method with DIL-402C unit manufactured by NETZSCH (Germany) with the error (1.5–2)×10^?7 K^?1. The approximation dependences of thermal coefficient of linear expansion on temperature have been obtained and reference tables have been calculated. The abnormal change of expansion coefficient above 550 °C is shown, and the explanation of the phenomenon is given.     

Thermal and electrical resistivities of rhenium from 2°K to 20°K

Measurements of the thermal and electrical resistivities of highly pure monocrystals of rhenium have been made at temperatures between 2°K and 20°K. The ideal resistivities can be described by ρ_i ∞ T^m (in the electrical case) and by ω_i ∞ Tⁿ (in the thermal case) only if m and n are allowed to vary with temperature. The values of m and n fall smoothly from 5.1 and 3.3 at 20°K and become 2 and 1, respectively, at the lowest temperatures. The anisotropy at all temperatures is found to be approximately ρ_i⊥/ρi∥ ~ 1.3 and ω_i⊥/ω_i∥ ~ l.1, where the parallel orientation is along the c axis of the hexagonal-close-packed lattice of rhenium. Below about 11°K the ideal resistivities obey a Wiedemann-Franz law with a Lorenz number of roughly 0.5 × 10^{− 8}V²/deg².     

Thermal expansion of artificial graphites in the temperature range 293–1650 K

The article presents the results of studying the thermal expansion of MPG-6 and AXF-5Q graphites and graphite composite based on ¹³C isotope in the temperature range 293–1650 K. Measurements were performed with dilatometric method in DIL-402C unit manufactured by NETZSCH (Germany), with the accuracy of (1÷4)×10^?7 K^?1. Approximation dependences of average integral coefficient of linear expansion on temperature have been obtained and reference tables calculated. It is shown that the coefficient of thermal expansion of ¹³C composite is much lesser than for MPG-6 and AXF-5Q. The explanation of this phenomenon is provided in the paper.     

Dielectric study of natural inyoite in the frequency range from 10−1 to 107 Hz and the temperature range from −50 to 140°C

For the first time, the method of dielectric dispersion in the 10^?1–10⁷ frequency range is applied to study temperature the dependences of permittivity, conductivity, and dielectric modulus of natural inyoite in the temperature range from ?50 to 140°C. An anomalous increase in the parameters under consideration is observed at temperatures between 87 and 98°C. According to thermal gravimetrical measurements, this range is characterized by an anomaly resulting from a partial loss of crystallization water.     

Thermal conductivity of Pb-Mg-Zr alloys and the thermal resistance of the interface between alloys and EP-823 steel in the temperature range of 300–900°C

A technique for measuring the thermal resistance of the liquid metal–structural steel interface is proposed. The results ofmeasurements of the thermal resistance of the interface between Pb-Mg-Zr alloys and EP-823 steel and the thermal conductivity of Pb-Mg-Zr alloys in the temperature range of 350–900 °C are presented.     

Inelastic scattering of cold neutrons by polycrystalline beryllium oxide in the temperature range from 100°K to 1000°K

The total cross-section of beryllium oxide for cold neutrons of mean wavelength 5.55 Å has been measured in the temperature range from 100 to 1000°K. The results are satisfactorily interpreted in terms of the incoherent approximation using the Placzek expansion. The values of the Debye temperature obtained from these measurements in the low and high temperature ranges are compared with those got by specific heat measurements. A method of choosing the effective mass and effective neutron cross-section of a molecule in a diatomic lattice is suggested.     

Thermal expansion anisotropy of β-TlInS2 crystals in the course of phase transitions

Basing on the thermal expansion studies performed for β-TlInS₂ crystals in the course of their phase transitions, we have found that the crystals aged for one year are composed from at least two polytypes, which undergo phase transitions at different temperatures. The detailed analysis of anisotropy of the thermal expansion demonstrates that all of the diagonal components of the thermal expansion tensor associated with the eigensystem have almost the same modules but differ by their signs. This leads to appearance of an elliptical conical surface of zero thermal expansion. The orientation of this surface does not depend on the temperature in the temperature interval under study. We have also found that the thermal expansion coefficients along the crystallographic a and b axes are close to zero.     

Thermal conductivity and thermal diffusivity of samarium in the temperature range of 293–1773 K

The thermal conductivity and the thermal diffusivity coefficients of samarium have been measured by the laser flash method in the temperature interval of 293–1773 K in solid and liquid states including the regions of phase transitions. The measurement errors of the heat transfer coefficients were ±(3–6)%. The approximation equations and the tables of reference data for the temperature dependence of properties have been obtained. The obtained results have been compared with the available literature data.     

Measurements of the specific volume of carbon dioxide in the range of 700 to 4000b and 50 to 475°C

The paper presents the results of p, v, t measurements of CO₂ in the range of 700 to 4000 b, 50 to 475°C. An analysis of the method of measurement and a comparison of the measured data with those of Kennedy and Michels indicate that the measurements have been performed with the following limit errors: pressure ±20 b, temperature ±0.2°C, specific volume ±0.3%.     

Change in the modulus of elasticity of copper after deformation in the temperature range from 4.2–78°K

Pure polycrystalline copper has been deformed at 4.2°K, 20°K and at 78°K. The decrease in the modulus of elasticity E was measured as a function of the extension and after deformation also as a function of the temperature. After an extension of more than 5% at either 4.2°K or 78°K the value of -ΔE/E is about 7% measured at 4.2°K and about 13% measured at 78°K. This change in the decrease is nearly reversible. The reversible change was measured as a function of the annealing temperature.     

Shubnikov-De Haas effect in the temperature range between T = 2°K and T = 77.4°K

SdH oscillations are shown to occur up to the liquid Nitrogen temperature range. This behaviour, observed in highly doped Bi₉₅Sb₅ (n = 1.45 × 10¹⁹ cm⁻³), is explained by the theory of ionized impurity scattering. Heavy mass electrons, located in a subsidiary conduction band minimum, give rise to a screening effect, drastically reducing the impurity scattering of the light electrons.     

Thermal expansion of CuInSe2 in the 11–1,073 K range: an X-ray diffraction study

Structural and elastic properties of chalcopyrite-type CuInSe₂ are determined in almost full stability range of temperature from 11 to 1,073 K, by in situ X-ray diffraction, employing a synchrotron-radiation source. The studied polycrystalline sample was prepared from a stoichiometric single crystal. Phase analysis reveals the formation of a trace amount of indium oxide impurity phase at the highest temperatures studied. From the obtained smooth lattice-parameter dependencies on temperature, the temperature dependencies of thermal expansion coefficients are derived. These coefficients are found to follow the trends previously reported for narrow temperature intervals. The present results provide a clear experimental evidence that the linear expansion coefficient is slightly negative below 47 K in both, a and c, directions; this temperature limit is in between the previously reported theoretical value (35 K) and the experimental ones (60 and 80 K) of such limit.     

Some doping studies on the oxidation of zinc in the temperature range 200–390°C

The effect of doping the gas phase on the oxidation rate of evaporated zinc films has been investigated. The experiments were carried out in the temperature range 200–390°C at an oxygen pressure of 1 atm. The concentration of the dopant, iodine, was approximately 0.1 mole %. It was found that below an oxidation temperature of about 375°C, iodine accelerated the rate of the reaction; above this temperature, iodine reduced the growth rate of the oxide. The effect on the conductivity of zinc oxide films heated in pure and iodine-doped oxygen atmospheres was also studied. The results of these experiments are discussed together with some previously published results on the effect of applying an electric field across a growing zinc oxide layer. It is concluded that the oxidation of zinc in the temperature range 200–390°C is probably controlled by a reaction occurring at the oxygen/oxide interface. There is a change in the rate controlling step at 375°C. These conclusions are discussed in the light of existing theories of metal oxidation.     

Order structure of methanol along the 200-bar isobar in the temperature range of 60–320°C according to IR spectroscopy

The topology and energetic characteristics of hydrogen bonded clusters in methanol and methanol-heptane mixtures are investigated by IR spectroscopy over a wide temperature range. The average number of hydrogen bonds per methanol molecule was calculated. Based on an analysis of changes in the spectral parameters of O...H intramolecular bonds, conclusions on structural rearrangements in the mixture under study at elevated temperatures are drawn.