Magnetocaloric properties of   the single crystal Mn0.99Fe0.01As

The Stockbargard – Bridgman method yielded single crystals Mn0.99Fe0.01As. The effect of an external magnetic field with an intensity of up to 10 T on phase transitions in the single crystal Mn0.99Fe0.01As is studied. It is established that the magnetostructural phase transition in Mn0.99Fe0.01As is accompanied by a change in the entropy ΔSm, which is due to the transformation of the crystal structure. At temperatures above the temperature of the magnetostructural transition Tu = 290 K, the existence of an unstable magnetic structure is obtained. The magnetocaloric characteristics of the material under study are determined by an indirect calculation method based on the Maxwell thermodynamic relations and the Clapeyron – Clausius equation.

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Monte Carlo Modelling of Phase Transitions in Quasi-One-Dimensional Multiferoic

Materials Science Forum ◽

10.4028/www.scientific.net/msf.845.158 ◽

2016 ◽

Vol 845 ◽

pp. 158-161

Author(s):

S.J. Lamekhov ◽

Dmitry A. Kuzmin ◽

Igor V. Bychkov ◽

I.A. Maltsev ◽

V.G. Shavrov

Keyword(s):

Magnetic Field ◽

Phase Transition ◽

Monte Carlo ◽

Phase Transitions ◽

Monte Carlo Method ◽

External Magnetic Field ◽

Periodic Potential ◽

One Dimensional ◽

Field Modelling ◽

Energy Components

Behavior of quasi-one-dimensional multiferoic Ca3CoMnO6 in external magnetic field was investigated. Modelling by Monte Carlo method was performed to show influence of external magnetic field on appearance of polarization and temperature of phase transition in electric subsystem. Magnetization, polarization and energy components for magnetic and electric subsystems dependencies were achieved for different values of external magnetic field. Modelling showed that periodic potential in form of Frenkel-Kontorova makes influence on maximal values and temperature of phase transitions for magnetization and polarization.

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Structure of tetrakis(dimethylamino)ethene (TDAE) at low temperatures

Zeitschrift für Kristallographie - Crystalline Materials ◽

10.1524/zkri.1995.210.7.521 ◽

1995 ◽

Vol 210 (7) ◽

Cited By ~ 3

Author(s):

J. Bruckmann ◽

C. Krüger ◽

H. Borrmann ◽

A. Simon ◽

H. Bock

Keyword(s):

Crystal Structure ◽

Phase Transitions ◽

Single Crystal ◽

Temperature Dependence ◽

Single Crystals ◽

Low Temperatures ◽

Structure Refinement ◽

Static Disorder ◽

Structural Details ◽

Different Temperatures

AbstractThe single crystal structure of TDAE was redetermined at different temperatures. Phase transitions are observed by warming the samples from low temperatures but never by cooling. Due to this special behavior it was possible to cool single crystals to 90 K. The data collected from such supercooled crystals resulted in a more precise and reliable structure refinement. Interesting structural details of the sterically overcrowded molecule are elucidated. The temperature dependence of the distortions of the nonplanar dimethylamino groups indicates dynamic behavior rather than static disorder.

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Reversible Metal/Dielectric Phase Transition of Metal/Polymer Structures in Magnetic Field: Tuning the Sign of Magnetoresistance

Materials Science Forum ◽

10.4028/www.scientific.net/msf.845.3 ◽

2016 ◽

Vol 845 ◽

pp. 3-6

Author(s):

Natalya V. Vorob'eva ◽

Aleksei N. Lachinov

Keyword(s):

Magnetic Field ◽

Phase Transition ◽

Phase Transitions ◽

External Magnetic Field ◽

Electroactive Polymer ◽

Polymer Layer ◽

Charge Mobility ◽

Dielectric Phase ◽

Magnetic Metal ◽

Metal Polymer

Abrupt phase transitions in the structure of ferromagnet/ electroactive polymer/ non-magnetic metal have been found in the number of studies in magnetic field as huge magnetoresistive effects. The sign of magnetoresistance depends on the conductivity state that the polymer has possessed at the beginning of the experiment.The ways of managing of metal/ dielectric phase transition in the polymer layer with the aid of weak external magnetic field are considered. The model of local conversion of charge mobility in the conductive channels is suggested.

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Synthese, Kristallstruktur und Eigenschaften von 1,1,1,3,3, 3 - Hexaamino - 1λ5,3λ5-diphosphazeniumehlorid [(NH2)3PNP(NH2)3]Cl / Synthesis, Crystal Structure, and Properties of 1,1,1,3,3,3-Hexaamino- 1λ5 ,3λ5-diphosphazenium Chloride [(NH2)3 PNP(NH2)3 ]Cl

Zeitschrift für Naturforschung B ◽

10.1515/znb-1996-1210 ◽

1996 ◽

Vol 51 (12) ◽

pp. 1732-1738 ◽

Cited By ~ 2

Author(s):

Stefan Horstmann ◽

Wolfgang Schnick

Keyword(s):

Crystal Structure ◽

Phase Transition ◽

Temperature Gradient ◽

Single Crystal ◽

Single Crystals ◽

Room Temperature ◽

Acetonitrile Solution ◽

Structure And Properties ◽

X Ray ◽

Ray Methods

[(NH2)3PNP(NH2)3]Cl has been prepared by a three step synthesis. The last step is the ammonolysis of [Cl3PNPCl3]Cl. Single crystals of 1,1,1,3,3,3-hexaamino-1λ5, 3λ5-diphosphazenium chloride were obtained from an acetonitrile solution in a temperature gradient between 60 °C and room temperature. Between room temperature and -100 °C [(NH2)3PNP(NH2)3]Cl is subject to a phase transition. Therefore, the crystal structure was determined by single crystal X-ray methods at room temperature (P1̄, a = 584.7(1) pm, b = 732.1(1) pm, c = 1092.0(2) pm. q = 71.05(3)°, β = 76.36(3)°, γ = 89.83(3)°, Z = 2, R = 4.75 %, wR = 2.47 %). The cation [(NH2)3PNP(NH2)3]+ is built up by two corner sharing PN4 tetrahedra. Remarkably short P-N bonding distances have been observed and both PN4 tetrahedra exhibit a significant distortion resulting in two large and four small N-P-N bond angles.

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Modeling of magneto-conductivity of bismuth selenide: a topological insulator

SN Applied Sciences ◽

10.1007/s42452-021-04397-8 ◽

2021 ◽

Vol 3 (4) ◽

Author(s):

Yogesh Kumar ◽

Rabia Sultana ◽

Prince Sharma ◽

V. P. S. Awana

Keyword(s):

Magnetic Field ◽

Magnetic Fields ◽

Single Crystal ◽

Single Crystals ◽

X Ray Diffraction ◽

Field Range ◽

X Ray ◽

Bulk Carriers ◽

Different Temperatures

AbstractWe report the magneto-conductivity analysis of Bi2Se3 single crystal at different temperatures in a magnetic field range of ± 14 T. The single crystals are grown by the self-flux method and characterized through X-ray diffraction, Scanning Electron Microscopy, and Raman Spectroscopy. The single crystals show magnetoresistance (MR%) of around 380% at a magnetic field of 14 T and a temperature of 5 K. The Hikami–Larkin–Nagaoka (HLN) equation has been used to fit the magneto-conductivity (MC) data. However, the HLN fitted curve deviates at higher magnetic fields above 1 T, suggesting that the role of surface-driven conductivity suppresses with an increasing magnetic field. This article proposes a speculative model comprising of surface-driven HLN and added quantum diffusive and bulk carriers-driven classical terms. The model successfully explains the MC of the Bi2Se3 single crystal at various temperatures (5–200 K) and applied magnetic fields (up to 14 T).

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Two lithium tricyanomethanide compounds: syntheses and single-crystal structure determination of LiK[C(CN)3]2 and Li[C(CN)3]·½ (H3C)2CO

Zeitschrift für Naturforschung B ◽

10.1515/znb-2014-0250 ◽

2015 ◽

Vol 70 (3) ◽

pp. 191-196 ◽

Cited By ~ 1

Author(s):

Olaf Reckeweg ◽

Francis J. DiSalvo

Keyword(s):

Crystal Structure ◽

Single Crystal ◽

Single Crystals ◽

Structure Determination ◽

Monoclinic Space Group ◽

Orthorhombic Space Group ◽

Space Group ◽

Cell Parameters ◽

New Compounds

AbstractThe new compounds LiK[C(CN)3]2 and Li[C(CN)3]·½ (H3C)2CO were synthesized and their crystal structures were determined. Li[C(CN)3]·½ (H3C)2CO crystallizes in the orthorhombic space group Ima2 (no. 46) with the cell parameters a=794.97(14), b=1165.1(2) and c=1485.4(3) pm, while LiK[C(CN)3]2 adopts the monoclinic space group P21/c (no. 14) with the cell parameters a=1265.7(2), b=1068.0(2) and c=778.36(12) pm and the angle β=95.775(7)°. Single crystals of K[C(CN)3] were also acquired, and the crystal structure was refined more precisely than before corroborating earlier results.

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Calcium Carbodiimide Compounds Revisited – Syntheses, Single Crystal Structure Determination and Vibrational Spectra of Ca11N6[CN2]2, Ca4N2[CN2] and Ca[CN2]

Zeitschrift für Naturforschung B ◽

10.1515/znb-2008-0509 ◽

2008 ◽

Vol 63 (5) ◽

pp. 530-536 ◽

Cited By ~ 8

Author(s):

Olaf Reckeweg ◽

Francis J. DiSalvo

Keyword(s):

Crystal Structure ◽

Raman Spectrum ◽

Single Crystal ◽

Single Crystals ◽

Vibrational Spectra ◽

Structure Determination ◽

X Ray ◽

Characteristic Features ◽

Reported Data ◽

Correct Data

Single crystals of Ca11N6[CN2]2 (dark red needles, tetragonal, P42/mnm (no. 136), a = 1456.22(5), and c = 361.86(2) pm, Z = 2), Ca4N2[CN2] (transparent yellow needles, orthorhombic, Pnma (no. 62), a = 1146.51(11), b = 358.33(4), and c = 1385.77(13) pm, Z = 4) and Ca[CN2] (transparent, colorless, triangular plates, rhombohedral, R3̅m (no. 166), a = 369.00(3), and c = 1477.5(3) pm, Z = 3) were obtained by the reaction of Na2[CN2], CaCl2 and Ca3N2 (if demanded by stoichiometry) in arc-welded Ta ampoules at temperatures between 1200 - 1400 K. Their crystal structures were re-determined by means of single crystal X-ray structure analyses. Additionally, the Raman spectra were recorded on these same single crystals, whereas the IR spectra were obtained with the KBr pellet technique. The title compounds exhibit characteristic features for carbodiimide units with D∞h symmetry (d(C-N) = 121.7 - 123.8 pm and ∡ (N-C-N) = 180°). The vibrational frequencies of these units are in the expected range (Ca11N6[CN2]2: νs = 1230, νs = 2008; δ = 673/645/624 cm−1; Ca4N2[CN2]: νs = 1230, νs = 1986; δ = 672/647 cm−1; Ca[CN2]: νs = 1274, νs = 2031, δ = 668 cm−1). The structural results are more precise than the previously reported data, and with the newly attained Raman spectrum of Ca11N6[CN2]2 we correct data reported earlier.

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INFLUENCE OF AN EXTERNAL MAGNETIC FIELD ON THE DYNAMICS OF A NEW-PHASE NUCLEUS IN THE VICINITY OF THE FIRST-ORDER PHASE TRANSITION IN MAGNETS WITH DEFECTS PRESENT

Modern Physics Letters B ◽

10.1142/s0217984912501837 ◽

2012 ◽

Vol 26 (28) ◽

pp. 1250183 ◽

Cited By ~ 5

Author(s):

VLADIMIR NAZAROV ◽

RISHAT SHAFEEV

Keyword(s):

Magnetic Field ◽

Phase Transition ◽

External Magnetic Field ◽

Magnetic Anisotropy ◽

Spin Reorientation ◽

Critical Fields ◽

First Order ◽

Phase Nucleus ◽

First Order Phase Transition ◽

New Phase

Theoretically, with the aid of a soliton model, the evolution of a new-phase nucleus near the first-order spin-reorientation phase transition in magnets has been investigated in an external magnetic field. The influence of an external field and one-dimensional defects of magnetic anisotropy on the dynamics of such nucleus has been demonstrated. The conditions for the localization of the new-phase nucleus in the region of the magnetic anisotropy defect and for its escape from the defect have been determined. The values of the critical fields which bring about the sample magnetization reversal have been identified and estimated.

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