Study of Synthesis and Temperature Dependence of DC Conductivity in the Low Temperature Range for Poly(N-Methylaniline)

2011 ◽  
Vol 40 (6) ◽  
pp. 1364-1368
Author(s):  
Atul Kapil ◽  
Subhash Chand
2003 ◽  
Vol 217 (6) ◽  
pp. 707-722 ◽  
Author(s):  
A. A. Ruth ◽  
H. Lesche ◽  
B. Nickel

AbstractThe dynamic viscosity (η) of the glass-forming 50:50 mixture of cis-1,4/trans-1,3-dimethylcyclohexane (ct-DMCH) was measured from 293 K down to ≈ 126 K where η ~ 1.2 × 106 mPas. The viscosity measurements of several other commonly used solvents cover the range from 293 K down to ≈ 148 K (η ~ 1.4 × 104 mPas) for 1-propanol (1-Prop), to ≈118 K (η ~ 2.5 × 102 mPas) for 2-methylpentane (2-MP), to ≈ 167 K (η ~ 10.0 mPas) for isooctane (Isooct), to ≈ 183 K (η ~ 2.8 mPas) for cyclopentane (CP) and down to ≈ 98 K (η ~ 4.6 × 102 mPas) for the 30:70 mixture of cyclopentane/isopentane (CP/IP). The density (ρ) of all solvents was measured correspondingly over appropriate temperature ranges. For the solvents studied here, the temperature dependence of the viscosity can be represented by a single Arrhenius term down to ~180 K. Over a wider temperature range down to ~118K the sum of two Arrhenius terms is required, and in the low temperature regime a Vogel–Tammann–Fulcher expression is necessary to adequately describe the temperature dependence of the dynamic viscosity.


2011 ◽  
Vol 679-680 ◽  
pp. 567-570 ◽  
Author(s):  
Duy Minh Nguyen ◽  
Gontran Pâques ◽  
Nicolas Dheilly ◽  
Christophe Raynaud ◽  
Dominique Tournier ◽  
...  

Avalanche diodes have been fabricated on 4H-SiC substrate. These diodes show an abrupt avalanche voltage of about 59 V which corresponds to the calculated theoretical one using our previously determined impact ionization coefficients. This avalanche voltage increases by as small as 3.7 mV/K over the investigated temperature range (150K-420K).


In this work, we studied the low-temperature plasticity, elastic and dissipative characteristics, as well as the microstructural evolution of the Fe40Mn40Co10Cr10 high-entropy alloy in a wide temperature range of 300 - 0.5 K. The temperature dependences of yield strength, strain hardening, strength and ductility, as well as acoustic absorption and dynamic Young's modulus are obtained. It was found that the structure of Fe40Mn40Co10Cr10 alloy in the initial state is single-phase with fcc lattice, and in the deformed state at low temperatures it becomes two-phase due to the deformation-induced phase transition. In addition, EBSD analysis of the alloy structure revealed a change in grain morphology and the appearance of twin dislocations after plastic deformation at all investigatedtemperatures. Acoustic studies showed that the transition from the initial to the deformed state changes the character of the temperature dependence of the dynamic Young's modulus from almost linear to exponential, and reduces the absolute values. The Fe40Mn40Co10Cr10 alloy has excellent strength and ductility at a high strain hardening rate, which is explained by the significant contribution of the twinning process. With a decrease in temperature from 300 to 4.2 K, a strong temperature dependence of the yield strength is observed, which indicates the thermal activation of the nature of the plastic deformation of the alloys in this temperature range. In the temperature range of 0.5-4.2 K, an anomaly of the yield strength was observed, namely a decrease in the value of the yield strength with decreasing temperature from 4.2 K to 0.5 K. The anomalous dependence of the yield strength is due to a change in the mechanism of overcoming local barriers from thermoactivated to inertial one, when part of the local obstacles is overcome by dislocations without activation. This leads to a decrease in yield strength with decreasing temperature. At a temperature of 4.2 K and below, the smooth nature of the plastic deformation changes from smooth to serrated. The jumps begin immediately after the yield strength and gradually increase from 40 MPa to ~ 160 MPa. The results obtained are important for practical applications of high-entropy alloys at low temperatures.


2018 ◽  
Vol 60 (6) ◽  
pp. 1147
Author(s):  
И.А. Барабан ◽  
А.В. Емельянов ◽  
П.Н. Медведская ◽  
В.В. Родионова

AbstractThis work presents results of investigations of low temperature magnetic properties of microwires, fabricated by the Ulitovsky–Taylor method from Fe–Si–B alloy. Influence of the glass coating presence on the magnetostatic properties was shown at room temperature and at 2 K. Conclusions about the peculiarities of temperature dependence of the magnetic moment, measured in low and high magnetic fields (10 Oe–5 kOe) in the temperature range from 2 to 300 K for a sample with partially reduced fabricated processinduced stress by removing the glass, were made.


1979 ◽  
Vol 28 (312) ◽  
pp. 852-856 ◽  
Author(s):  
Yoichiro TAKEUCHI ◽  
Naotake NODA ◽  
Shigeru KOMORI ◽  
Takuo YAMATO

Author(s):  
Peter P. Knox ◽  
Vladimir V. Gorokhov ◽  
Boris N. Korvatovsky ◽  
Nadezhda P. Grishanova ◽  
Sergey N. Goryachev ◽  
...  

1996 ◽  
Vol 442 ◽  
Author(s):  
J.-M. Spaeth ◽  
S. Greulich-Weber ◽  
M. März ◽  
E. N. Kalabukhova ◽  
S. N. Lukin

AbstractThe electronic structure of nitrogen donors in 6H-, 4H- and 3C-SiC is investigated by measuring the nitrogen hyperfine (hf) interactions with electron nuclear double resonance (ENDOR) and the temperature dependence of the hf split electron paramagnetic resonance (EPR) spectra. Superhyperfine (shf) interactions with many shells of 13C and 29Si were measured in 6H-SiC. The hf and shf interactions are discussed in the framework of effective mass theory. The temperature dependence is explained with the thermal occupation of the lowest valley-orbit split A1 and E states. It is proposed that the EPR spectra of P donors observed previously in neutron transmuted 6H-SiC at low temperature (<10K) and high temperature (>60K) are all due to substitutional P donors on the two quasi-cubic and hexagonal Si sites, whereby at low temperature the E state is occupied and at high temperature the A1 state. The low temperature spectra are thus thought not to be due to P-vacancy pair defects as proposed previously.


2003 ◽  
Vol 17 (27n28) ◽  
pp. 1453-1460
Author(s):  
ILEANA LUPSA

The magnetic properties of U 1-x Dy x Al y Ni 5-y (y=0,1) systems were investigated in the 2(5)–600 K temperature range and for fields up to 80 kOe. The systems having x≥0.2 are magnetically ordered with low transition temperatures and magnetization mainly due to the Dy contribution. The nickel exhibits magnetic moments, very weak in the low temperature range and well-defined effective moments over transition temperatures. The nickel behavior is discussed in terms of the spin fluctuation model.


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