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.

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.

LOW-TEMPERATURE TRANSITION METAL-SEMICONDUCTOR IN CdCr2Se4 SINGLE CRYSTALS DOPED WITH INDIUM AND GALLIUM

1980 ◽  
Vol 41 (C5) ◽  
pp. C5-155-C5-156 ◽  
Author(s):  
T. G. Aminov ◽  
K. P. Below ◽  
V. T. Kalinnikov ◽  
L. I. Koroleva ◽  
L. N. Tovmasjan
Keyword(s):  
Low Temperature ◽  
Transition Metal ◽  
Single Crystals ◽  
Temperature Transition

Anthracene fluorescence at low temperatures. I. Purified single crystals

1972 ◽  
Vol 25 (7) ◽  
pp. 1411 ◽  
Author(s):  
LE Lyons ◽  
LJ Warren
Keyword(s):  
Low Temperature ◽  
Single Crystals ◽  
Fluorescence Spectrum ◽  
Low Temperatures ◽  
Free Exciton ◽  
Deformation Bands ◽  
Exciton Emission ◽  
Polarized Emission ◽  
Impurity Bands ◽  
Phonon Structure

The low-temperature fluorescence spectrum of purified vapour-grown anthracene single crystals is presented and the free-exciton emission distinguished from a number of defect or impurity bands present even in the purest crystals. In assigning the observed bands the symmetry of the active vibrations and the origin of background fluorescence and deformation bands are discussed. The phonon structure in the region of the fluorescence origin was found to be almost completely b-polarized. Emission of electronic origin (25103 cm-1) was too weak to be observed. Polarization ratios of the principal vibronio bands at 5.6 K are given.

Dielectric Loss in Li- and Na-Swept α-Quartz and the Effect of Irradiation

1983 ◽  
Vol 24 ◽  
Author(s):  
J. Toulouse ◽  
A.S. Nowick
Keyword(s):  
Dielectric Loss ◽  
Low Temperature ◽  
Low Temperatures ◽  
Quantum Effects ◽  
Frequency Stability ◽  
Distorted Tetrahedron ◽  
High Quality ◽  
Quartz Crystals ◽  
Alkali Ions ◽  
Synthetic Crystals

ABSTRACTAlkali ions, which compensate for substitional Al3+, play an important role in the frequency stability of α-quartz crystals. In this work, low temperature dielectricloss measurements (between 2.9 and 300 K) are carried out on crystals that have been “swept” so as to introduce either Li+ or Na+. High quality synthetic crystals as well as natural crystals are employed. The well known loss peaks due to Al-Na pairs are further explored and similar peaks due to Al-Li are sought after but not found. It is concluded that the Al-Li pair is oriented along the C2 -axis of the A104 distorted tetrahedron. After irradiation, large peaks are observed at very low temperatures both in Li+- and Na+-containing crystals. These peaks, which are distorted below ∼6 K due to the onset of quantum effects, may originate in alkali centers produced when alkali ions are liberated by the irradiation.

scholarly journals The Stability of Icosahedral Cd-Yb

2003 ◽  
Vol 805 ◽  
Author(s):  
Günter Krauss ◽  
Sofia Deloudi ◽  
Andrea Steiner ◽  
Walter Steurer ◽  
Amy R. Ross ◽  
...  
Keyword(s):  
Low Temperature ◽  
Ambient Temperature ◽  
Mechanical Stress ◽  
Single Crystals ◽  
High Temperatures ◽  
Low Temperatures ◽  
Ambient Pressure ◽  
X Ray Diffraction ◽  
X Ray ◽  
The Stability

ABSTRACTThe stability of single-crystalline icosahedral Cd-Yb was investigated using X-ray diffraction methods in the temperature range 20 K ≤ T ≤ 900 K at ambient pressure and from ambient temperature to 873 K at about 9 GPa. Single-crystals remain stable at low temperatures and in the investigated HP-HT-regime. At high temperatures and ambient pressure, the quasicrystal decomposes. The application of mechanical stress at low temperatures yields to the same decomposition, the formation of Cd. A reaction of icosahedral Cd-Yb with traces of oxygen or water causing the decomposition seems reasonable, but a low-temperature instability of this binary quasi-crystal cannot be ruled out totally.

PERSISTENT PHOTOCONDUCTIVITY IN La0.7CaxBa1-xMnO3 THIN FILMS

1999 ◽  
Vol 13 (29n31) ◽  
pp. 3786-3791 ◽  
Author(s):  
R. CAURO ◽  
J. C. GRENET ◽  
A. GILABERT ◽  
M. G. MEDICI
Keyword(s):  
Thin Films ◽  
Low Temperature ◽  
Visible Light ◽  
Low Temperatures ◽  
Transport Mechanism ◽  
Persistent Photoconductivity ◽  
Temperature Range ◽  
Insulator Metal Transition ◽  
First Time

We report, for the first time, experiments of persistent photoconductivity (PPC) in thin films of manganese perovskites La 0.7 Ca 0.25 Ba 0.05 MnO 3 and La 0.7 Ca 0.2 Ba 0.1 MnO 3 showing a persistent decrease of a few percent of the resistance after illumination with visible light. These persistent photoinduced effects are seen only in a range of low temperatures (<25 K) well below the insulator-metal transition at respectively T c=173 K and T c=120 K. In this low temperature range, the transport mechanism is rather of activated hopping type regime.

The Design and Use of Special-Purpose Attachments for the Horizontal Diffractometer

1963 ◽  
Vol 7 ◽  
pp. 302-313
Author(s):  
William L. Baun ◽  
John J. Renton
Keyword(s):  
Thermal Expansion ◽  
Low Temperature ◽  
Single Crystals ◽  
Low Temperatures ◽  
Coefficient Of Thermal Expansion ◽  
Semicrystalline Polymers ◽  
Organic Liquids ◽  
Crystalline Materials ◽  
Full Circle ◽  
Beryllium Window

AbstractSeveral special-purpose attachments have been designed and built for the Siemens horizontal diffractometer. Design details and experimental results are shown for the following equipment: (1) Low-temperature mount for poly crystalline materials—examples are shown illustrating identification of organic liquids crystallized at low temperatures, and results are presented on coefficient of thermal expansion of alloys in the binary system copper—platinum from −185 to 25°C. (2) Low-temperature mount for single-crystal studies—this design allows recording of higher-level layer lines by use of a domed beryllium window. Illustrations are shown for organic single crystals and for organic liquids crystallized in the lowtemperature mount. (3) Focusing attachment—this attachment uses a curved specimen mounted on the focusing circle (Seeman-Bohlin mounting). Comparisons of dispersion are made and examples such as the (400) reflection from molybdenum are shown using both curved and flat specimens. (4) Full-circle goniometer—this device has been used primarily for determining distribution of intensity in amorphous and semicrystalline polymers, but is applicable to study of single crystals. Examples of both of these applications are discussed.

The ferromagnetic domain structure in haematite

1967 ◽  
Vol 297 (1449) ◽  
pp. 269-274 ◽  
Keyword(s):  
Domain Structure ◽  
Transformation Temperature ◽  
Detailed Account ◽  
Antiferromagnetic State ◽  
Ferromagnetic Domain ◽  
Synthetic Crystals ◽  
Natural And Synthetic

The domain structure in crystals of natural and synthetic haematite has been examined using the colloid method. A special acetone based colloid was developed which allowed the domain structure to be observed down to -30 °C. In the case of the synthetic crystals, the domain structure disappeared below -14 °C (the transformation temperature to the antiferromagnetic state), whereas no change was observed for haematite crystals from Elba. A detailed account is given of the stages leading to the disappearance of the domain structure for one of the synthetic crystals.

Domain structure on U3P4 single crystals at low temperatures

Physica B+C ◽  
1985 ◽  
Vol 130 (1-3) ◽  
pp. 548-550 ◽  
Author(s):  
A. Szewczyk ◽  
R. Szymczak ◽  
Z. Henkie
Keyword(s):  
Single Crystals ◽  
Domain Structure ◽  
Low Temperatures

Thermogravimetric study of sequential carbonation and decarbonation processes over Na2ZrO3 at low temperatures (30–80 °C): relative humidity effect

RSC Advances ◽  
2016 ◽  
Vol 6 (71) ◽  
pp. 66579-66588 ◽  
Author(s):  
J. Arturo Mendoza-Nieto ◽  
Heriberto Pfeiffer
Keyword(s):  
Solid State ◽  
Relative Humidity ◽  
Low Temperature ◽  
Low Temperatures ◽  
Humidity Effect ◽  
Temperature Range ◽  
Thermogravimetric Study ◽  
Relative Humidity Effect

Na2ZrO3 was synthetized via solid-state and tested in a low temperature range (30–80 °C) for carbonation and decarbonation processes using RH values between 0 and 80%. Results confirm that it is possible to accomplish successively at least 8 cycles.

Sign in / Sign up

Export Citation Format

Share Document