Electrical conductivity of slightly reduced rutile between 2° and 370°K

Abstract

The electrical resistivity and the Hall coefficient of slightly reduced rutile crystals were measured in the temperature range between about 2 °K and 370 °K. The time of reduction treatments between 900 °C and 1300 °C was usually as long as 300 hrs, which assures the homogeneous reduction of crystals, The conduction mechanisms in three temperature ranges, i. e. 1. 9～3°K, 3～100°K and 100～250°K, were discussed in terms of lattice defects evidenced by ESR studies.     

A detailed model for the conductivity of magnetite below 119°K

The question of charge transport through the Fe₃O₄ lattice in the ordered state is reexamined. It is shown that only a fairly complicated defect can transfer charge. The implications of this model are compared with the experimental data.     

Dynamic-mechanical study of molecular motions in solid polyoxymethylene copolymers from 4 to 315°K

Variations in four mechanical relaxations in polyoxymethylene copolymers in the temperature range from 4 to 315°K are described as a function of comer size and amount. The 6 relaxation at 50°K is interpreted as being due to limited motions in defect crystals; the γ₂ relaxation, at ca. 175°K, is also associated with defect motion in the crystal; the γ₁ relaxation, at ca. 205°K, is suggested to involve motion of short segments in disordered regions; aad the β relaxation, at ca. 270°K, involving motion of long segments, can be considered to be the glass transition.     

Dynamic mechanical behavior of poly[ethylene terephthalate] from 4.2 to 300°K

The dynamic shear behavior of poly (ethylene terephthalate) (PET) has been investigated in the 4.2—300°K temperature region using a freely oscillating torsion pendulum at frequencies of 0.4 to 2 cps. Uniaxial stretching (draw ratio 3:1) of an amorphous specimen resulted in the appearance of a definite maximum in both the damping, δ, and the loss modulus, G', at 30°K (0.7 cps). Filled unstretched PET samples exhibited small loss maxima in the 50—90°K region. For biaxially stretched heat-set specimens the splitting of the β-damping peak (220°K, 1 cps) is found to depend on the orientations of molecular chain axes with respect to the torsion axis.     

Piezospectroscopic study (78°K) of radiation- produced absorption bands in Si†

Abstract

A detailed study has been made on two sharp sub-bands, 3.45 μ (2900 cm^?1) and 3.61 μ (2765 cm^?1) of the 3.3 μ broad defect absorption band in irradiated Si. Our results indicate that the 3.45 μ and 3.61 μ bands are observed in all types of Si (n-, p-type, and intrinsic) subjected to fast neutron reactor irradiation. Spectra were measured at 78 °K under the effect of a variable uniaxial compressive stress with polarized light. A relatively large dichroism is observed for all three stress directions ?100?, ?110?, and ?111?. We also confirm that both sharp bands exhibit splitting and energy shifts under the action of stress. The model of the divacancy defect given by Watkins and Corbett⁽⁵⁾ has been utilized to explain the data. The dichroism can be accounted for by the effects of Jahn-Teller alignment which arises from the strong bonding of nearest neighbor atoms of the divacancy. The splittings of the bands are small indicating that the Jahn-Teller distortion is little altered in the ground and excited states. The splittings appear to be most sensitive to stress along the vacancy-vacancy axis and a tentative model for the transitions is given.     

Raman Spectra Concentrational Dependence of Naphthalene - Cyclohexane and Naphthalene-Methanol Solutions Frozen at 77° K

The concentrational dependence of Raman spectra of frozen at 77°K naphthalene solutions in cyclohexane and in methanol is studied. An increase in the naphthalene Raman line intensity is observed for the naphthalene-cyclohexane system in a concentrational range in which a quasilinear fluorescence spectrum is recorded.     

The 220°K defect in electron irradiated p-Type Germanium

Lattice defects introduced in p-type nondegenerate germanium by 1.5 MeV electron irradiation at liquid nitrogen temperature was investigated by means of electrical resistivity and Hall coefficient measurements. The annealing behavior of two kinds of defects, which anneal at about 220 °K, was investigated in detail. Each of them has an electron trap. Making use of trap-filling and emptying processes, the 220 °K defects are separated from other defects.     

Results of measurements of the atmospheric muon flux in the zenith angle range of 85°–95°

The results of the study of the near-horizontal muon flux in the zenith angle range of 85–95 degrees are presented. In particular, the so-called albedo muons (atmospheric muons backscattered in the ground to the upper hemisphere are recorded in this range. The data of measurement series performed at the NEVOD-DECOR experimental complex are analyzed for 30 thousand of “live” time hours. Multiple Coulomb scattering of muons in the ground is simulated by theMonte-Carlo method using various models. The measured muon flux intensity is compared with the simulation results.     

Characteristic of the 60°C-Dipole for CSR

The trimming coils embedded in poles of magnet are applied in the C-dipole prototypes of CSR. They are used to adjust the uniformity of magnetic fields through reducing outside magnetic field and augmenting inside. The impact of trimming currents on the uniformity of field and multipole components is carefully investigated by using the two kinds of magnetic measurements,hall sensor and long coil,respectively. It is proved that the uniformity which is better than ±1.0×10 -3 can be reached easily. At the same time,the quadrupole and sextupole components of fields have decreased to a low level through optimizing the trimming currents,but,unfortunately,the octupole and dodecapole will increase correspondingly. Finally,the two measured and calculated results are compared. There is very small difference between the results of the two measuring methods. However,all of the measured results are alien to the calculated one because of the insufficiency of the TOSCA calculation.     

Anomalies of the natural convection of water near 3.98°C

Natural convection of water in a cylindrical cavity with an open surface at a temperature of about 3.98°C (temperature of the maximum water density) is accompanied by typical anomalies on time dependences of temperatures of water layers. In particular, stabilization of temperature T_st is observed in the bottom region of the cavity and duration of such stabilization t_st may reach several hours depending on the experimental conditions. The results for solutions of sodium chloride and ethanol at a relatively low rate of water cooling show that temperature T_st coincides with temperature T_max corresponding to the maximum density of solutions.     

Design of 180 °Vertical Viewing-angle Rainbow Hologram

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Interferometric measurements of the dipole polarizability α of molecules between 300 K and 1100 K

The temperature dependence of the dipole polarizability α(λ, T) of free atoms and molecules is determined by precise measurements of the refractive index n of gases in the extended temperature range between 300 K and 1100 K for wavelength λ = 632·99 nm, using a specially constructed Michelson twin interferometer. α of the noble gases is observed to be independent of T. α of the molecular gases H₂, N₂, O₂, and CH₄ increases with increasing temperature by an amount of approximately 1 per cent per 1000 K. These results are in excellent agreement with theoretical predictions. They will be compared to previously measured temperature dependent polarizabilities.