Effect of Heat Treatment on Acoustic Properties of Chromium Polycrystals at Low Temperatures

2008 ◽  
Vol 137 ◽  
pp. 43-48 ◽  
Author(s):  
P.P. Pal-Val ◽  
L.N. Pal-Val ◽  
S.B. Golovina ◽  
Igor S. Golovin
Keyword(s):  
Room Temperature ◽  
Magnetic Phase ◽  
Acoustic Properties ◽  
Magnetic Phase Transitions ◽  
Preliminary Deformation ◽  
Longitudinal Vibrations ◽  
Bending Vibrations ◽  
Long Time ◽  
Thermoelastic Stresses ◽  
First Time

Acoustic properties of polycrystalline Cr samples of 99.99 % purity are investigated at frequencies of longitudinal vibrations f ~ 75 kHz and of bending vibrations at 0.6 < f < 1.5 kHz when thermocycling within the temperature interval 5 − 330 K. Special attention is paid to the acoustic anomalies in the vicinity of the magnetic phase transitions: the Néel point and the spin-flip transition. In the as-received samples, a significant hysteresis of the acoustic properties has been found for the first time. The effect of heat treatments on internal friction and elastic properties of chromium polycrystals is also investigated. The data obtained are compared with the effect of small preliminary deformation and а long-time ageing at room temperature on the ultrasound anomalies in Cr single crystal. The observed behavior of the acoustic properties may be caused by changes in the antiferromagnetic domain structure in Cr polycrystals under the action of thermoelastic stresses arising from quenching, preliminary plastic deformation or thermocycling.

Magnetic phase transitions around room temperature in Cu9S5

2019 ◽  
Vol 92 (4) ◽  
pp. 385-395
Author(s):  
Annette Setzer ◽  
Pablo D. Esquinazi ◽  
Lukas Botsch ◽  
Oliver Baehre ◽  
Eti Teblum ◽  
...  
Keyword(s):  
Phase Transitions ◽  
Room Temperature ◽  
Magnetic Phase ◽  
Magnetic Phase Transitions

scholarly journals Effect of oxygen nonstoichiometry on magnetic phase transitions in frustrated cobaltites YBaCo4O7+x (x = 0, 0.1, 0.2)

2018 ◽  
Vol 185 ◽  
pp. 06004
Author(s):  
Zoya Kazei ◽  
Vyacheslav Snegirev ◽  
Ludmila Kozeeva ◽  
Margarita Kameneva ◽  
Alexander Lavrov
Keyword(s):  
Short Range ◽  
Room Temperature ◽  
Structural Transition ◽  
Magnetic Phase ◽  
Experimental Studies ◽  
Oxygen Nonstoichiometry ◽  
Magnetic Phase Transitions ◽  
Small Deviations ◽  
Effect Of Oxygen ◽  
Short Range Correlations

Experimental studies were carried out for structural and elastic properties of cobaltites YBaCo4O7+x (x = 0, 0.1, 0.2) obtained by various technologies and distinguished by oxygen content. Correlation was revealed between the structure distortion at room temperature and a hysteresis in a ΔE(T)/T0 curve in the temperature range 80 – 280 K, as well as the anomaly value in the region of TN. It was found, that small deviations from stoichiometry (x = 0.1, 0.2) result in suppression of structural transition, reduce a hysteresis, quickly smooth out and reduce anomalies of the Young’s modulus ΔE(T)/T0 in the range of magnetic phase transition. This behavior indicates that structural and magnetic transitions are suppressed in nonstoichiometric samples and only short range correlations of order parameters are retained

scholarly journals Field-Induced Magnetic Phase Transitions and Rich Phase Diagram of HoMnO3 Single Crystal

Crystals ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 419
Author(s):  
Chao Dong ◽  
Rui Chen ◽  
Yongjie Liu ◽  
Congbin Liu ◽  
Haipeng Zhu ◽  
...  
Keyword(s):  
Phase Diagram ◽  
Magnetic Phase ◽  
Magnetic Phase Transitions ◽  
Magnetic Transitions ◽  
Rich Phase ◽  
Early Results ◽  
Scattering Measurements ◽  
Pulsed Fields ◽  
First Time ◽  
New Phase

An extensive magnetization study in pulsed fields up to 62 T and at temperatures down to ~0.7 K has been performed on the single crystals of hexagonal manganite HoMnO3. For magnetic fields (H) applied along the c-axis, successive magnetic transitions below 10 T and a step-like transition at ~41 T are observed. The phase diagram for H//c is very complex and new phase boundaries are explored below 6 K. This phase diagram is compared with the early results derived from dielectric constant and neutron scattering measurements. For H//a, two magnetic transitions are found below 3 T dome-shaped and the phase diagram is reported for the first time. The variety of magnetic symmetries of the field-induced magnetic phases is discussed.

Direct imaging of charge transfer

1996 ◽  
Vol 54 ◽  
pp. 680-681
Author(s):  
Yimei Zhu ◽  
J. Tafto
Keyword(s):  
Charge Transfer ◽  
Electron Diffraction ◽  
Scattering Amplitude ◽  
High Temperature Superconductors ◽  
Charge Carriers ◽  
Image Charge ◽  
Net Charge ◽  
Long Time ◽  
Electron Holes ◽  
First Time

The electron holes confined to the CuO2-plane are the charge carriers in high-temperature superconductors, and thus, the distribution of charge plays a key role in determining their superconducting properties. While it has been known for a long time that in principle, electron diffraction at low angles is very sensitive to charge transfer, we, for the first time, show that under a proper TEM imaging condition, it is possible to directly image charge in crystals with a large unit cell. We apply this new way of studying charge distribution to the technologically important Bi2Sr2Ca1Cu2O8+δ superconductors.Charged particles interact with the electrostatic potential, and thus, for small scattering angles, the incident particle sees a nuclei that is screened by the electron cloud. Hence, the scattering amplitude mainly is determined by the net charge of the ion. Comparing with the high Z neutral Bi atom, we note that the scattering amplitude of the hole or an electron is larger at small scattering angles. This is in stark contrast to the displacements which contribute negligibly to the electron diffraction pattern at small angles because of the short g-vectors.

Assessment of recreational use of specially protected natural territories of Tatishchevsky district of Saratov region

2019 ◽  
Vol 27 (2) ◽  
pp. 117-127
Author(s):  
Yulia M Andriyanova ◽  
Irina V Sergeeva ◽  
Yulia M Mokhonko ◽  
Natalia N Gusakova
Keyword(s):  
Natural Resources ◽  
Protected Areas ◽  
Saratov Region ◽  
Future State ◽  
Forest Phytocenoses ◽  
Long Time ◽  
Main Components ◽  
First Time ◽  
Recreational Use ◽  
Specially Protected Natural Territories

The influence of recreation being a set of measures to restore health and recreation, on the main components of forest phytocenoses in specially protected natural territories of the Tatishchevsky district of the Saratov region has been studied for the first time. These phytocenoses have been intensively used for tourism for a long time. The intensity and visits activity of protected areas has been determined; the recreational capacity of territorial objects has been studied. The degree of forest landscapes has been revealed in specially protected natural territories. The findings allow predicting the future state of the natural resources of the Saratov region and can be taken into account when assessing their optimal use.

Room-temperature white and color-tunable afterglow by manipulating multi-mode triplet emissions

2021 ◽  
Vol 9 (9) ◽  
pp. 3257-3263
Author(s):  
Jianwei Liu ◽  
Zhimin Ma ◽  
Zewei Li ◽  
Yan Liu ◽  
Xiaohua Fu ◽  
...  
Keyword(s):  
Room Temperature ◽  
Single Component ◽  
Color Tunable ◽  
First Time ◽  
Multi Mode

Two isomers pDCzPyCN and oDCzPyCN are designed and synthesized. Amazingly, oDCzPyCN manifest white afterglow at room temperature. This is the first time that single-component white afterglow has finally been realized.

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