The remanent magnetization of haematite single crystals

1968 ◽  
Vol 303 (1475) ◽  
pp. 511-524 ◽  
Keyword(s):  
Transition Temperature ◽  
Single Crystals ◽  
Low Temperatures ◽  
Remanent Magnetization ◽  
Sharp Reduction ◽  
Narrow Temperature Range ◽  
Temperature Range ◽  
Fast Neutron Irradiation ◽  
Theoretical Predictions ◽  
Synthetic Crystals

The variation of the remanent magnetization with temperature of several synthetic and natural single crystals of haematite has been measured in the temperature range 60 to –90 °C. Particular attention was given to the measurement of the remanence at temperatures close to the transition temperature. The remanent magnetization of the synthetic crystals showed a sharp reduction over a narrow temperature range; the natural crystals showed a much smaller reduction over a wider temperature range. All the specimens were found to be magnetic at low temperatures which is not in accord with theoretical predictions. The effect of annealing at high temperatures on the behaviour of the remanent magnetization was investigated. The results of measurements of the remanent magnetization of specimens which had been subjected to fast neutron irradiation are also reported.

The ferromagnetic domain structure of haematite

1968 ◽  
Vol 303 (1475) ◽  
pp. 525-529 ◽  
Keyword(s):  
Low Temperature ◽  
Single Crystals ◽  
Domain Structure ◽  
Low Temperatures ◽  
Remanent Magnetization ◽  
Temperature Transition ◽  
Small Temperature ◽  
Temperature Range ◽  
Ferromagnetic Domain ◽  
Synthetic Crystals

Observations are reported of the ferromagnetic domain structure of natural and synthetic single crystals, made at temperatures close to the low temperature transition with the aid of an acetone based magnetic colloid. The domain structure of the synthetic crystals was found to change radically over a small temperature range centred around –12 °C. These changes are correlated with the measured remanent magnetization. Fairly extensive colloid patterns were found on the natural crystals at low temperatures but when the natural crystals were annealed at 1200 °C this low temperature colloid structure was no longer found.

Features of radiothermoluminescence of polypropylene and ethylene propylenediene elastomer SKEPT-4044 compositions with nanoscale metal-containing fillers

2020 ◽  
pp. 66-73
Author(s):  
A.M. Magerramov ◽  
◽  
N.I. Kurbanova ◽  
M.N. Bayramov ◽  
N.A. Alimirzoyeva ◽  
...  
Keyword(s):  
Transition Temperature ◽  
Molecular Mobility ◽  
Fe3o4 Nanoparticles ◽  
Low Temperatures ◽  
Frost Resistance ◽  
Relaxation Processes ◽  
Ethylene Propylene ◽  
Temperature Range ◽  
Β Relaxation

Using radiothermoluminescence (RTL), the molecular mobility features in the temperature range of 77-300 K were studied for the polypropylene (PP)/ethylene propylene diene elastomer SKEPT-4044 with NiO, Cu2O and Fe3O4 nanoparticles (NPs) based on ABS-acrylonitrile butadiene or SCS-divinyl styrene matrices. It has been shown that the introduction of nanofillers in PP significantly affects the nature and temperature of γ- and β-relaxation processes, while the region of manifestation of the β-process noticeably shifts to the region of low temperatures. Composites with Cu2O NPs have a higher β-transition temperature Tβ than composites with other NPs. It was found that PP/SKEPT-4044 composites with Cu2O NPs with a dispersion of 11-15 nm and acrylonitrile butadiene thermoplastics have optimal frost resistance compared to other compositions.

Polarized Raman Scattering Study of ZnGeP2 Single Crystals

1997 ◽  
Vol 484 ◽  
Author(s):  
Spirit Tlali ◽  
Howard E. Jackson ◽  
M. C. Ohmer ◽  
P. G. Schunemann ◽  
T. M. Pollak
Keyword(s):  
Raman Scattering ◽  
Single Crystals ◽  
Raman Spectra ◽  
Low Temperatures ◽  
High Quality ◽  
Crystal Orientations ◽  
Gradient Technique ◽  
Theoretical Predictions ◽  
Scattering Study ◽  
Polarized Raman

AbstractRaman scattering experiments on high quality ZnGeP2 single crystals grown by the seeded horizontal dynamic gradient technique have been carried out. Polarized Raman spectra were obtained in the backscattering geometry at both room and low temperatures for several crystal orientations and compared with group theoretical predictions. Raman spectra from as-grown and annealed samples display distinctive differences which were explored by utilizing two different excitation wavelengths: 514.3 nm and 632.8 nm; the observed differences are attributed to a surface interdiffuasion effect.

Temperature dependence of piezoelectric properties of 0.67 Pb(Mg1/3Nb2/3)O3–0.33 PbTiO3 single crystals

2003 ◽  
Vol 18 (2) ◽  
pp. 537-541 ◽  
Author(s):  
Ping-chu Wang ◽  
Xiao-ming Pan ◽  
Dong-lin Li ◽  
Yuan-wei Song ◽  
Hao-su Luo ◽  
...  
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Temperature Dependence ◽  
Single Crystals ◽  
Phase Transition Temperature ◽  
Room Temperature ◽  
Piezoelectric Properties ◽  
Device Design ◽  
Temperature Range ◽  
Approach Zero

Piezoelectric properties k33 and d33 of 0.67 Pb(Mg1/3Nb2/3)O3–0.33 PbTiO3 single crystals grown by a modified Bridgman method were measured in the temperature range of 20–150 °C. Recoverability of the properties after the samples were heated to 110 °C, above the ferroelectric–ferroelectric (F–F) phase transition temperature of the composition, was found. From 20 to approximately 80 °C, k33 increases slightly, while d33 is almost doubled. Between approximately 90 and 100 °C, k33 decreases sharply to roughly a level of PZT-5 ceramics and d33 decreases to about 700 pC/N. They increase again with further increase of temperature; at 140 °C they attain 0.74 and approximately 1300 pC/N, respectively, and then decrease quickly and approach zero at about 150 °C. When heating to 110 °C followed by cooling to room temperature, the property decay is small. After more than one dozen heating–cooling cycles, k33 and d33 tend to be stable at 0.89 and approximately 1220 pC/N, respectively. The results might be helpful for device design and applications of PMN–PT single crystals.

scholarly journals Specific Features of Photoconductivity of Tl1-xIn1-xSnxSe2 Monocrystals at Low Temperatures

2019 ◽  
Vol 20 (1) ◽  
pp. 50-55
Author(s):  
O.V. Novosad ◽  
G.L. Myronchuk ◽  
S.P. Danylchuk ◽  
O.V. Zamurueva ◽  
L.V. Piskach ◽  
...  
Keyword(s):  
Single Crystals ◽  
Thermal Energy ◽  
Low Temperatures ◽  
Relaxation Processes ◽  
Directional Crystallization ◽  
Thermally Stimulated Currents ◽  
Temperature Range ◽  
Thermostimulated Currents

The photoconductivity spectra in the temperature range T≈36-200 K and the spectra of thermostimulated currents in the temperature range T≈70-300 K of Tl1-xIn1-xSnxSe2 single crystals obtained by directional crystallization of Bridgman-Stockbarger have been studied. The induced photoconductivity and long-term photoconductivity relaxation processes have been found. To interpret the found results, a model of two-center recombination has been suggested. It is illustrated that the role of the r-centers of slow recombination are formed by Tl vacancies. On the basis of the studies of the spectra of thermally stimulated currents, the thermal energy of electrons activation with t-levels of adhesion has been determined.

THERMAL EXPANSION OF SINGLE CRYSTALS OF ZINC AT LOW TEMPERATURES

1965 ◽  
Vol 43 (7) ◽  
pp. 1328-1333 ◽  
Author(s):  
D. A. Channing ◽  
S. Weintroub
Keyword(s):  
Experimental Data ◽  
Thermal Expansion ◽  
Single Crystals ◽  
Low Temperatures ◽  
Linear Thermal Expansion ◽  
Optical Interference ◽  
Temperature Range ◽  
Thermal Expansion Coefficients ◽  
Expansion Coefficients ◽  
Good Agreement

The linear thermal expansion coefficients αψ of two single crystals of Zn of orientations ψ = 10.8° and 63.9 ° with the hexad axis were measured over the temperature range of about 20–270 °K using an absolute Fizeau optical interference technique. The two principal coefficients, [Formula: see text] and [Formula: see text], corresponding to ψ = 0° and 90 ° respectively, were calculated from the Voigt relation, and their values are compared with previously reported experimental data. Above 60 °K there is good agreement with previous work, and below 60 °K the results confirm, in general, the data obtained by McCammon and White. The Grüneisen parameter γ is essentially constant at about 2.1 in the range 100–270 °K, but below 100 °K γ rises appreciably with decreasing temperature and reaches the value of about 3.5 at 20 °K.

Effect of Prestraining on the Brittle-To-Ductile Transition of NiAl Single Crystals

1996 ◽  
Vol 460 ◽  
Author(s):  
S. Shrivastava ◽  
F. Ebrahimi
Keyword(s):  
Fracture Toughness ◽  
Transition Temperature ◽  
Crack Initiation ◽  
Single Crystals ◽  
Low Temperatures ◽  
Crack Initiation And Propagation ◽  
Brittle To Ductile Transition ◽  
Initiation And Propagation ◽  
Toughness Testing ◽  
Dislocation Sources

ABSTRACTThe brittle-to-ductile transition (BDT) has been established for NiAl single crystals as evaluated by fracture toughness testing and also the effects of prestraining on the brittle-to-ductile transition temperature (BDTT) have been investigated. Specimens were prestrained to a 10% plastic strain level at 200°C under tension prior to toughness testing. The BDT of the prestrained specimens was compared to that of the as homogenized specimens. The results have revealed the occurrence of two competing effects upon prestraining: (1) an increase in dislocation sources causing a difficulty in micro-crack initiation and resulting in an increase in toughness at low temperatures, and (2) an increase in the flow stress resulting in an increase in BDT temperature. The crack initiation and propagation mechanisms were also analyzed and have been discussed.

In situ Tensile Experiments at Low Temperatures on Niobium Single Crystals by H.V.E.M.

1975 ◽  
Vol 33 ◽  
pp. 58-59
Author(s):  
F. H. Louchet ◽  
L. P. Kubin
Keyword(s):  
Electron Microscope ◽  
Transition Temperature ◽  
Low Temperature ◽  
Slip System ◽  
Low Temperatures ◽  
Tensile Axis ◽  
Image Intensifier ◽  
Screw Dislocations ◽  
Source Operation

Experiments have been carried out on the 3 MeV electron microscope in Toulouse. The low temperature straining holder has been previously described Images given by an image intensifier are recorded on magnetic tape.The microtensile niobium samples are cut in a plane with the two operative slip directions [111] and lying in the foil plane. The tensile axis is near [011].Our results concern:- The transition temperature of niobium near 220 K: at this temperature and below an increasing difference appears between the mobilities of the screw and edge portions of dislocations loops. Source operation and interactions between screw dislocations of different slip system have been recorded.

Dynamic Viscosity of Compressed Water to 10 Kilobar and Steam to 1500°C

1969 ◽  
Vol 11 (2) ◽  
pp. 189-205 ◽  
Author(s):  
E. A. Bruges ◽  
M. R. Gibson
Keyword(s):  
Gaseous Phase ◽  
Dynamic Viscosity ◽  
Low Temperatures ◽  
Pressure Range ◽  
Low Pressure ◽  
Temperature Range ◽  
Inversion Temperature ◽  
Pressure Steam ◽  
Correlating Equations ◽  
First Time

Equations specifying the dynamic viscosity of compressed water and steam are presented. In the temperature range 0-100cC the location of the inversion locus (mu) is defined for the first time with some precision. The low pressure steam results are re-correlated and a higher inversion temperature is indicated than that previously accepted. From 100 to 600°C values of viscosity are derived up to 3·5 kilobar and between 600 and 1500°C up to 1 kilobar. All the original observations in the gaseous phase have been corrected to a consistent set of densities and deviation plots for all the new correlations are given. Although the equations give values within the tolerances of the International Skeleton Table it is clear that the range and tolerances of the latter could with some advantage be revised to give twice the existing temperature range and over 10 times the existing pressure range at low temperatures. A list of the observations used and their deviations from the correlating equations is available as a separate publication.

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