scholarly journals Study of internal motions through N.Q.R. in 6-Chloropyridin-2-ol

1982 ◽  
Vol 35 (1) ◽  
pp. 211 ◽  
Author(s):  
SP Basavaraju ◽  
N Devaraj ◽  
A Indumathy ◽  
KR Sridharan ◽  
J Ramakrishna
Keyword(s):  
Temperature Dependence ◽  
Room Temperature ◽  
Internal Motions ◽  
Temperature Dependences ◽  
First Time

Chlorine-35 n.q.r, has been observed for the first time in 6-chloropyridin-2-ol and its temperature dependence has been studied from 77 K to room temperature. The torsional frequencies and their temperature dependences have been calculated by using Bayer's theory with and without Tatsuzaki's modification.

scholarly journals Effect of Mechanical Load on Defects Level in Soft Ferrite Ceramics

2018 ◽  
Vol 186 ◽  
pp. 02010
Author(s):  
A.B. Petrova ◽  
A.V. Malyshev ◽  
A.P. Surzhikov
Keyword(s):  
Temperature Dependence ◽  
Curie Point ◽  
Room Temperature ◽  
Mechanical Load ◽  
Initial Permeability ◽  
Temperature Dependences ◽  
Four Levels ◽  
Magnetic Ring ◽  
Soft Ferrite ◽  
With Screws

The article presents the results of a study of the effect of mechanical load on the temperature dependence of the initial permeability of LiTiZn soft ferrite ceramics. Regimes of mechanical load were created by a steel non-magnetic ring with screws. In this work, four levels of mechanical load were investigated: without load, with 1, 2 and 3 screws. For obtaining temperature dependences and exclude the influence of prehistory on the initial permeability, the samples were heated to a temperature exceeding the Curie point by 50 degrees, after which they slowly cooled to room temperature. The defects level was determined by the ratio of the parameters β / α of the phenomenological expression, which describes the experimental temperature dependences. It is shown that as the mechanical load increases, the defects level of ferrite ceramics increases, and after load removing, it returns to its original level.

Luminescence in Si/Strained Si1−xGex Heterostructures

1995 ◽  
Vol 379 ◽  
Author(s):  
J.C. Sturm ◽  
A. St. Amour ◽  
Y. Lacroix ◽  
M.L.W. Thewalt
Keyword(s):  
Temperature Dependence ◽  
Room Temperature ◽  
Surface Passivation ◽  
Band Edge ◽  
Strained Si ◽  
Edge Luminescence ◽  
Recent Developments ◽  
High Pump ◽  
Band Edge Luminescence ◽  
First Time

ABSTRACTThis paper quickly reviews the structure of band-edge luminescence in Si/strained Si1−xGex heterostructures, and then focusses on two recent developments -- the origin of “deep” sub-bandgap luminescence which is sometimes observed in structures grown by Molecular Beam Epitaxy (MBE) and the understanding of the temperature dependence of the band-edge luminescence (up to room temperature). Strong evidence will be presented that the origin of the deep luminescence is radiation damage, and that generated defects are segregated or trapped in the SilxGex layers. The modelling of the temperature dependence by twocarrier numerical simulation is presented for the first time. The work and experimental data show convincingly that the strength of the luminescence at high temperature is controlled by recombination at the top silicon surface, which in turn can be controlled by surface passivation. At high pump powers and low temperatures, Auger recombination reduces the lifetime in the Si1−xGex layers, and leads to a luminescence vs. temperature which is flat up to 250 K and which is reduced only by a factor of three at room temperature.

Anomaly of Nuclear Quadrupole Relaxation in Cu2O Prepared at Low Temperatures

1986 ◽  
Vol 41 (1-2) ◽  
pp. 382-385 ◽  
Author(s):  
J. Kasprzak ◽  
J. Lus ◽  
J. Pietrzak
Keyword(s):  
Temperature Dependence ◽  
Cuprous Oxide ◽  
Thermal Processing ◽  
Low Temperatures ◽  
Room Temperature ◽  
Quadrupole Relaxation ◽  
Temperature Dependences ◽  
Powder Samples ◽  
Nuclear Quadrupole ◽  
Nuclear Quadrupole Relaxation

The 63Cu and 65Cu NQR transitions in powder samples of cuprous oxide have been investigated from 77 to 500 K and at room temperature after annealing up to 1100 K Significant differences in T1 , NQR linewidth Δv, and their temperature dependences were found among the samples prepared in different ways. For C u20 samples obtained in low temperatures (below 380 K), the temperature dependence of T1 below 380 K is o f activation character with Ea = 0.07 eV. These results are interpreted in terms of an electron hopping mechanism. Thermal processing of these samples permits to obtain irreversible electronic state and then the spectroscopic parameters are the same as for the samples obtained in high temperatures (above 1320 K).

Temperature dependence of the AV3O7 (A = Ca, Sr) structure

2007 ◽  
Vol 63 (6) ◽  
pp. 836-842 ◽  
Author(s):  
Sebastian Prinz ◽  
Karine M. Sparta ◽  
Georg Roth
Keyword(s):  
Single Crystal ◽  
Temperature Dependence ◽  
Crystal Structures ◽  
Room Temperature ◽  
X Ray Diffraction ◽  
X Ray ◽  
Space Groups ◽  
Temperature Ranges ◽  
First Time

The V4+ (spin ½) oxovanadates AV3O7 (A = Ca, Sr) were synthesized and studied by means of single-crystal X-ray diffraction. The room-temperature structures of both compounds are orthorhombic and their respective space groups are Pnma and Pmmn. The previously assumed structure of SrV3O7 has been revised and the temperature dependence of both crystal structures in the temperature ranges 297–100 K and 315–100 K, respectively, is discussed for the first time.

Effect of percolation path on temperature dependence of threshold voltage variability in bulk MOSFETs

2021 ◽  
Author(s):  
Tomoko Mizutani ◽  
Kiyoshi Takeuchi ◽  
Takuya Saraya ◽  
Hiroshi Oka ◽  
Takahiro MORI ◽  
...  
Keyword(s):  
Temperature Dependence ◽  
Threshold Voltage ◽  
Cryogenic Temperature ◽  
Room Temperature ◽  
Constant Current ◽  
Percolation Path ◽  
Temperature Dependences ◽  
Random Dopant Fluctuations ◽  
Random Dopant

Abstract Threshold voltage variability of bulk MOSFETs was measured at room temperature and cryogenic temperature and compared. It is found that the temperature dependences of threshold voltage defined by extrapolation (VTHEX) and threshold voltage defined by constant current (VTHC) show different behaviors and the percolation path in the channel, which is caused by potential valley due to random dopant fluctuations, weakens the temperature dependence of VTHC.

Similarities and peculiarities between the crystal structures of the hydrates of sodium sulfate and selenate

2014 ◽  
Vol 70 (4) ◽  
pp. 714-722 ◽  
Author(s):  
Stoyan Kamburov ◽  
Horst Schmidt ◽  
Wolfgang Voigt ◽  
Christo Balarew
Keyword(s):  
Temperature Dependence ◽  
Crystal Structures ◽  
Sodium Sulfate ◽  
Room Temperature ◽  
Site Occupancy ◽  
Monoclinic Space Group ◽  
Chemical Compositions ◽  
Crystal Nucleus ◽  
Space Group ◽  
First Time

The crystal structures of the two hydrates Na2SeO4·10H2O and Na2SeO4·7.5H2O are studied for the first time. The structures of Na2SO4·10H2O and Na2SO4·7H2O are reinvestigated as a function of temperature with respect to the degree of disorder of the O atoms of {\rm SO}_{4}^{2-} in the decahydrate and the O atom of water in the heptahydrate. For Na2SO4·10H2O, the unit site occupancy factor (SOF) of O atoms of {\rm SO}_{4}^{2-} was determined at 120 K. After the temperature dependence of the lattice parameters was studied from 120 to 260 K, it was shown that SOF decreased from 1.0 at 120 K to 0.247 at room temperature. The interesting fact that two salts with different chemical compositions and different crystal structures (Na2SO4·7H2O, tetragonal, space groupP41212 and Na2SeO4·7.5H2O, monoclinic, space groupC2/c) can act mutually as a crystal nucleus is accounted for by similarities in certain fragments of their crystal structures. This phenomenon is attributed to similarities between particular elements of their structures.

Preparation and Characterization of 3C-SiC Heteroepitaxial Layers on Si(111)

1992 ◽  
Vol 242 ◽  
Author(s):  
Mitsugu Yamanaka ◽  
Keiko Ikoma
Keyword(s):  
Hall Mobility ◽  
Carrier Density ◽  
Room Temperature ◽  
Chemical Vapor ◽  
Similar Temperature Dependence ◽  
Temperature Dependences ◽  
Similar Temperature ◽  
First Time ◽  
Heteroepitaxial Layers

ABSTRACT3C-SiC layers were grown on Si(111) substrates by chemical vapor deposition (CVD) using SiH4-CH3CI-H2 gas mixture. 3C-SiC(111) heteroepitaxial layers were obtained with smooth surfaces and reduced warpage. All the epilayers were n- type, and the carrier density and Hall mobility were 2.1×1016∼2.8×1017 cm-3 and 120∼180 cm2/Vs at room temperature, respectively. Temperature dependences of the electrical properties of the self-supported 3C-SiC(111) epilayers were measured between 15 and 300 K for the first time. 3C-SiC(111) epilayers showed a similar temperature dependence of carrier density to 3C-SiC(001) heteroepitaxial layer. Hall mobility was maximum (∼360 cm2/Vs) around 100 K.

PLASTICITY OF IRON SINGLE CRYSTALS

1967 ◽  
Vol 45 (2) ◽  
pp. 1101-1120 ◽  
Author(s):  
A. S. Keh ◽  
Y. Nakada
Keyword(s):  
Temperature Dependence ◽  
Single Crystals ◽  
Work Hardening ◽  
Room Temperature ◽  
Proportional Limit ◽  
Single Slip ◽  
Hardening Behavior ◽  
The Past ◽  
Temperature Dependences ◽  
Latent Hardening

Results accumulated in the past four years on the plastic deformation of iron single crystals are summarized.The work-hardening behavior of iron single crystals depends very much on orientation and temperature. At room temperature, three-stage hardening was observed for single-slip orientations. The work-hardening rates in stages I and II were correlated with the extent of localized secondary slip.Latent hardening was observed in iron crystals. The latent-hardening ratio is about 1.3 and is relatively independent of temperature and choice of latent system.The yield stress of iron single crystals is very dependent on temperature and is also sensitive to orientation at low temperatures and to interstitial content at all temperatures. By adding interstitials to purified crystals, the athermal portion of the flow stress of iron is raised, but its temperature dependence is not altered. Crystals oriented for single slip on the (101) and (112) planes have different temperature dependences of the proportional limit. Similar but small differences in this temperature dependence of proportional limits were observed in crystals oriented for single, double, and multiple slip on {112} planes. These results are explained on the basis of a Peierls mechanism.

scholarly journals Unusual Temperature Dependence of 35Cl NQR Spin-Lattice Relaxation Time in [(CH3)4N]2[MCl6] (M = Pb, Sn, Te)

1991 ◽  
Vol 46 (9) ◽  
pp. 809-814
Author(s):  
Yoshihiro Furukawa ◽  
Yoshihisa Baba ◽  
Shin-ei Gima ◽  
Makoto Kaga ◽  
Tetsuo Asaji ◽  
...  
Keyword(s):  
Relaxation Time ◽  
Temperature Dependence ◽  
Room Temperature ◽  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
Unit Cell ◽  
Spin Lattice Relaxation ◽  
Spin Lattice Relaxation Time ◽  
Spin Lattice ◽  
Temperature Dependences

Abstract The temperature dependence of the spin-lattice relaxation time (T1H) of 1H NMR measured in tetramethylammonium hexachloroplumbate(IV), (Me4N)2[PbCl6], showed a deep and a shallow minimum near 190 and 115 K, respectively. Since the presence of two kinds of crystallographically nonequivalent cations in the room-temperature Fd 3c unit cell has been reported, the deep T1H minimum was assigned to the overall reorientation of three quarters of the Me4N+ ions and the shallow minimum to that of the remaining cations. Two different temperature dependences of the chlorine NQR spin-lattice relaxation time (T1Q), attributable to a modulated electric-field-gradient by the protonic motion, were observed in (Me4N)2[MCl6] (M = Pb, Sn, Te). One is found in the Pb complex whose T1Q stems from the cationic motion responsible for the deep T1H minimum, and the other one is determined by the cationic motion giving the shallow T1H minimum. Although all room-temperature phases of these complexes are well described by the Fd 3c unit cell, the presence of different temperature dependences of T1Q suggests that the CH3 groups in the respective complexes take different orientations in the crystals

scholarly journals Growth Peculiarities and Properties of KR3F10 (R = Y, Tb) Single Crystals

Crystals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 285
Author(s):  
Denis N. Karimov ◽  
Irina I. Buchinskaya ◽  
Natalia A. Arkharova ◽  
Anna G. Ivanova ◽  
Alexander G. Savelyev ◽  
...  
Keyword(s):  
Single Crystals ◽  
Room Temperature ◽  
Phonon Scattering ◽  
Activation Enthalpy ◽  
Ionic Conductivities ◽  
Potassium Fluoride ◽  
Ion Migration ◽  
The Family ◽  
Temperature Dependences ◽  
First Time

Cubic KR3F10 (R = Y, Tb) single crystals have been successfully grown using the Bridgman technique. Growth of crystals of this type is complicated due to the hygroscopicity of potassium fluoride and melt overheating. The solution to the problem of oxygen-incorporated impurities has been demonstrated through the utilization of potassium hydrofluoride as a precursor. In this study, the crystal quality, structure features, and optical, thermal and electrophysical properties of KR3F10 were examined. Data on the temperature dependences of conductivity properties of KTb3F10 crystals were obtained for the first time. These crystals indicated thermal conductivity equal to 1.54 ± 0.05 Wm−1K−1 at room temperature caused by strong phonon scattering in the Tb-based crystal lattice. Ionic conductivities of KY3F10 and KTb3F10 single crystals were 4.9 × 10−8 and 1.2 × 10−10 S/cm at 500 K, respectively, and the observed difference was determined by the activation enthalpy of F− ion migration. Comparison of the physical properties of the grown KR3F10 crystals with the closest crystalline analog from the family of Na0.5−xR0.5+xF2+2x (R = Tb, Y) cubic solid solutions is reported.

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