3d—MAGNETISM OF THE RT4B COMPOUNDS

1993 ◽  
Vol 07 (01n03) ◽  
pp. 798-801
Author(s):  
T.T. DUNG ◽  
N.P. THUY ◽  
T.D. HIEN ◽  
N.M. HONG ◽  
D.C. KHAN ◽  
...  
Keyword(s):  
Temperature Dependence ◽  
Cell Volume ◽  
Unit Cell Volume ◽  
Magnetocrystalline Anisotropy ◽  
Close Correlation ◽  
Spin Reorientation ◽  
Lattice Constants ◽  
Spontaneous Magnetostriction ◽  
Relative Value

Spontaneous-magnetostriction and FMR studies are reported for the series Y(CO1−xFex)4B with x=0.00, 0.0125, 0.02 and 0.125. For the samples with composition x=0.00, 0.0125 and 0.02, step-like changes of the lattice constants a and c around the spin reorientation temperature TSR are observed. The relative values of the changes in ∆a/a and ∆c/c are of the order of 10−4 but are of opposite signs. The changes in the unit cell volume ∆V/V around TSR are negligible. In the temperature dependence of the average g-values of these samples, a step-like change with a relative value for ∆g/g of 10−2 has been deduced from FMR studies. These results point to a close correlation between the lattice constants and the magnetocrystalline anisotropy of the 3d-lattice and consequently to the role of the orbital moments in the anisotropic properties of the 3d-magnetism in the considered compounds.

SUPPRESSION OF SUPERCONDUCTIVITY AND STRUCTURAL CHANGES IN R1-xPrxBa2Cu3O7-y (R=Sm, Gd, Er, Tm, Y)

1992 ◽  
Vol 06 (16n17) ◽  
pp. 1069-1074 ◽  
Author(s):  
P. LIU ◽  
W. J. ZHU ◽  
J. L. ZHANG ◽  
S. Q. GUO ◽  
S. L. JIA ◽  
...  
Keyword(s):  
Transition Temperature ◽  
Cell Volume ◽  
Superconducting Transition Temperature ◽  
Unit Cell Volume ◽  
Structural Changes ◽  
Unit Cell ◽  
Superconducting Transition ◽  
Lattice Constants

The compounds R 1-x Pr x Ba 2 Cu 3 O 7-y ( R = Sm , Gd , Er , Tm and Y ) have been prepared and examined for superconductivity and structural changes. It is observed that the superconducting transition temperature Tc of R 1-x Pr x Ba 2 Cu 3 O 7-y decreases monotonically with increasing Pr concentration for all systems. At constant Pr concentration, Tc decreases approximately linearly with increasing radius with R cations while the lattice constants a,b,c and unit cell volume V increase. The correlation of both the Tc and the lattice constants with the radius of R cations is the same as for 1:2:4, 2:4:7, and 1:2:1:2 compounds.

Cell volumes of LaPO4–CePO4 solid solutions

1987 ◽  
Vol 20 (4) ◽  
pp. 319-320 ◽  
Author(s):  
R. S. de Biasi ◽  
A. A. R. Fernandes ◽  
J. C. S. Oliveira
Keyword(s):  
Cell Volume ◽  
Solid Solutions ◽  
Unit Cell Volume ◽  
Unit Cell ◽  
Cube Root ◽  
Lattice Constants ◽  
Vegard’S Law ◽  
Cell Volumes

Lattice constants have been determined for solid solutions of the form La x Ce1−x PO4. A plot of the cube root of the unit-cell volume as a function of x shows that this system follows Végard's law.

Structural Studies of ZnO Calcined with Transition Metal Oxides

2005 ◽  
Vol 891 ◽  
Author(s):  
Lori Noice ◽  
Bjoern Seipel ◽  
Georg Grathoff ◽  
Amita Gupta ◽  
Peter Moeck ◽  
...  
Keyword(s):  
Transition Metal ◽  
Cell Volume ◽  
Transition Metal Oxides ◽  
Unit Cell Volume ◽  
Copper Ion ◽  
Magnetic Semiconductor ◽  
Unit Cell ◽  
X Ray Diffraction ◽  
Lattice Constants ◽  
Zno Powders

ABSTRACTPowder X-ray diffraction analyses of Mn-and Cu-doped ZnO powders calcined at 500˚C, show shifts in the wurtzite type semiconductor's lattice constants and unit cell volume which correspond to the nominal concentrations of transition metal dopants. Marked reductions in the a-lattice constant and unit cell volume for a small concentration of Cu dopants, which is not maintained upon increased Cu concentration, suggest a change in the copper ion hybridization state due to the dopant concentration. In all the samples, only ZnO and CuO phases were detected, aiding the ascertainment of any ferromagnetic response from the samples as arising from the formation of a true dilute magnetic semiconductor.

scholarly journals Negative thermal expansion in YbMn2Ge2 induced by the dual effect of magnetism and valence transition

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Yongqiang Qiao ◽  
Yuzhu Song ◽  
Andrea Sanson ◽  
Longlong Fan ◽  
Qiang Sun ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Intermetallic Compound ◽  
Cell Volume ◽  
Valence State ◽  
Unit Cell Volume ◽  
Negative Thermal Expansion ◽  
Combined Effect ◽  
Dual Effect ◽  
Valence Transition ◽  
Magnetovolume Effect

AbstractNegative thermal expansion (NTE) is an intriguing property, which is generally triggered by a single NTE mechanism. In this work, an enhanced NTE (αv = −32.9 × 10−6 K−1, ΔT = 175 K) is achieved in YbMn2Ge2 intermetallic compound to be caused by a dual effect of magnetism and valence transition. In YbMn2Ge2, the Mn sublattice that forms the antiferromagnetic structure induces the magnetovolume effect, which contributes to the NTE below the Néel temperature (525 K). Concomitantly, the valence state of Yb increases from 2.40 to 2.82 in the temperature range of 300–700 K, which simultaneously causes the contraction of the unit cell volume due to smaller volume of Yb3+ than that of Yb2+. As a result, such combined effect gives rise to an enhanced NTE. The present study not only sheds light on the peculiar NTE mechanism of YbMn2Ge2, but also indicates the dual effect as a possible promising method to produce enhanced NTE materials.

scholarly journals Allanite at high temperature: effect of REE on the thermal behaviour of epidote-group minerals

2021 ◽  
Vol 48 (9) ◽  
Author(s):  
G. Diego Gatta ◽  
Francesco Pagliaro ◽  
Paolo Lotti ◽  
Alessandro Guastoni ◽  
Laura Cañadillas-Delgado ◽  
...  
Keyword(s):  
Cell Volume ◽  
Thermal Behaviour ◽  
Unit Cell Volume ◽  
Unit Cell ◽  
Atomic Scale ◽  
Elastic Behaviour ◽  
Positive Trend ◽  
Cell Parameters ◽  
Thermal Anisotropy ◽  
Different Temperatures

AbstractThe thermal behaviour of a natural allanite-(Ce) has been investigated up to 1073 K (at room pressure) by means of in situ synchrotron powder X-ray diffraction and single-crystal neutron diffraction. Allanite preserves its crystallinity up to 1073 K. However, up to 700 K, the thermal behaviour along the three principal crystallographic axes, of the monoclinic β angle and of the unit-cell volume follow monotonically increasing trends, which are almost linear. At T > 700–800 K, a drastic change takes place: an inversion of the trend is observed along the a and b axes (more pronounced along b) and for the monoclinic β angle; in contrast, an anomalous increase of the expansion is observed along the c axis, which controls the positive trend experienced by the unit-cell volume at T > 700–800 K. Data collected back to room T, after the HT experiments, show unit-cell parameters significantly different with respect to those previously measured at 293 K: allanite responds with an ideal elastic behaviour up to 700 K, and at T > 700–800 K its behaviour deviates from the elasticity field. The thermo-elastic behaviour up to 700 K was modelled with a modified Holland–Powell EoS; for the unit-cell volume, we obtained the following parameters: VT0 = 467.33(6) Å3 and αT0(V) = 2.8(3) × 10–5 K−1. The thermal anisotropy, derived on the basis of the axial expansion along the three main crystallographic directions, is the following: αT0(a):αT0(b):αT0(c) = 1.08:1:1.36. The T-induced mechanisms, at the atomic scale, are described on the basis of the neutron structure refinements at different temperatures. Evidence of dehydroxylation effect at T ≥ 848 K are reported. A comparison between the thermal behaviour of allanite, epidote and clinozoisite is carried out.

Liver cell hydration and integrin signaling

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Michele Bonus ◽  
Dieter Häussinger ◽  
Holger Gohlke
Keyword(s):  
Cell Volume ◽  
Liver Cell ◽  
Cell Function ◽  
The Other ◽  
Signaling Cascades ◽  
Integrin Signaling ◽  
Volume Changes ◽  
The One ◽  
And Oxidative Stress

Abstract Liver cell hydration (cell volume) is dynamic and can change within minutes under the influence of hormones, nutrients, and oxidative stress. Such volume changes were identified as a novel and important modulator of cell function. It provides an early example for the interaction between a physical parameter (cell volume) on the one hand and metabolism, transport, and gene expression on the other. Such events involve mechanotransduction (osmosensing) which triggers signaling cascades towards liver function (osmosignaling). This article reviews our own work on this topic with emphasis on the role of β1 integrins as (osmo-)mechanosensors in the liver, but also on their role in bile acid signaling.

scholarly journals Study of Structural, Magnetic, and Mossbauer Properties of Dy2Fe16Ga1−xNbx (0.0 ≤ x ≤ 1.0) Prepared via Arc Melting Process

2021 ◽  
Vol 7 (3) ◽  
pp. 42
Author(s):  
Jiba N. Dahal ◽  
Kalangala Sikkanther Syed Ali ◽  
Sanjay R. Mishra
Keyword(s):  
Isomer Shift ◽  
Cell Volume ◽  
Intermetallic Compounds ◽  
Unit Cell Volume ◽  
Rietveld Analysis ◽  
Unit Cell ◽  
X Ray Diffraction ◽  
X Ray ◽  
Arc Melting ◽  
Nb Content

Intermetallic compounds of Dy2Fe16Ga1−xNbx (x = 0.0 to 1.00) were synthesized by arc melting. Samples were investigated for structural, magnetic, and hyperfine properties using X-ray diffraction, vibration sample magnetometer, and Mossbauer spectrometer, respectively. The Rietveld analysis of room temperature X-ray diffraction data shows that all the samples were crystallized in Th2Fe17 structure. The unit cell volume of alloys increased linearly with an increase in Nb content. The maximum Curie temperature Tc ~523 K for x = 0.6 sample is higher than Tc = 153 K of Dy2Fe17. The saturation magnetization decreased linearly with increasing Nb content from 61.57 emu/g for x = 0.0 to 42.46 emu/g for x = 1.0. The Mössbauer spectra and Rietveld analysis showed a small amount of DyFe3 and NbFe2 secondary phases at x = 1.0. The hyperfine field of Dy2Fe16Ga1−xNbx decreased while the isomer shift values increased with the Nb content. The observed increase in isomer shift may have resulted from the decrease in s electron density due to the unit cell volume expansion. The substantial increase in Tc of thus prepared intermetallic compounds is expected to have implications in magnets used for high-temperature applications.

A neutron powder diffraction determination of the thermal expansion tensor of crocoite (PbCrO4) between 60 K and 290 K

1996 ◽  
Vol 60 (403) ◽  
pp. 963-972 ◽  
Author(s):  
Kevin S. Knight
Keyword(s):  
Thermal Expansion ◽  
Temperature Dependence ◽  
Powder Diffraction ◽  
Maximum Expansion ◽  
Lattice Constants ◽  
Thermal Expansion Tensor ◽  
Diffraction Determination ◽  
Line Passing ◽  
Neutron Time

AbstractThe thermal expansion tensor of crocoite has been determined from high-resolution neutron time-of-flight powder diffraction data. The temperature dependence of the lattice constants between 4.5 K and 290 K have been fitted to a quasi-harmonic Einstein model, and the temperature dependence of the thermal expansion tensor has been calculated for 60 K ≤ T ≤ 290 K. The magnitudes of the principal expansivities and their orientation exhibit saturation behaviour for temperatures above 300 K. The predicted saturated expansion coefficients are α11 = 33.1(1) × 10−6K−1, α22 = 15.72(3) × 10−6K−1, α33 = 3.36(1) × 10−6K−1, with α22 parallel to b and α11 lying at an angle of −37.86(5)° to c for the P21/n setting of the crystal structure. The direction of maximum expansion is approximately parallel to both and the least-squares line passing through the projection of the chromium atoms on (010). The direction of minimum expansion lies approximately parallel to [101]. No evidence was found for either a structural or magnetic phase transition between 4.5 K and 300 K.

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