scholarly journals Spin-induced negative thermal expansion and spin–phonon coupling in van der Waals material CrBr3

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
D. P. Kozlenko ◽  
O. N. Lis ◽  
S. E. Kichanov ◽  
E. V. Lukin ◽  
N. M. Belozerova ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Van Der Waals ◽  
Negative Thermal Expansion ◽  
Building Blocks ◽  
Phonon Coupling ◽  
X Ray Diffraction ◽  
Interatomic Distances ◽  
Lattice Volume ◽  
Physical Phenomena ◽  
Strong Spin

AbstractThe two-dimensional van der Waals (vdW) magnets retaining magnetic order in atomically thin limit demonstrate challenging physical phenomena and they are considered as prospective building blocks for construction of advanced spintronics and nanoelectronics devices. Here, we present experimental evidence for negative thermal expansion of lattice volume and vdW layers and strong spin–phonon coupling effects, caused by formation of the long-range ferromagnetic order in the vdW material CrBr3. The neutron and X-ray diffraction measurements revealed anomalous temperature variation of lattice parameters and interatomic distances and angles in the vicinity of Curie temperature (TC). A pronounced rise of the frequencies of the most of the observed vibrational modes and unusual reversal broadening of their full widths at half maximum below TC was found from Raman spectroscopy measurements.

Effect of Annealing Temperature and External Tensile Stress on Negative Thermal Expansion to Cold Rolled Ti–23Nb–0.7Ta–2Zr Alloy

2020 ◽  
Vol 12 (9) ◽  
pp. 1409-1412
Author(s):  
Jeong-Tae Moon ◽  
Tae-Hyun Nam
Keyword(s):  
Thermal Expansion ◽  
Annealing Temperature ◽  
Negative Thermal Expansion ◽  
Constant Load ◽  
External Stress ◽  
Expansion Rate ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cold Rolled ◽  
The Difference

The effect of annealing temperature and external stress on the thermal expansion of a Ti–23Nb–0.7Ta–2Zr alloy were investigated by means of thermal expansion tests under constant load and X-ray diffraction (XRD). Negative thermal expansion (NTE), which is a shrinkage during heating, was observed in both a cold rolled and annealed specimens. The intensity of (200)β peak decreased while that of (211)β peak increased as the annealing temperature increased. The difference in expansion rate between 50 °C and 250 °C is found to decrease with an increasing annealing temperature from 600 °C to 800 °C, above which it kept almost constant. The expansion rate decreased as the applied stress increased.

Thermally boosted upconversion and downshifting luminescence in Sc2(MoO4)3:Yb/Er with two-dimensional negative thermal expansion

2021 ◽  
Author(s):  
Jinsheng Liao ◽  
Minghua Wang ◽  
Fulin Lin ◽  
Zhuo Han ◽  
Datao Tu ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Near Infrared ◽  
Negative Thermal Expansion ◽  
Thermal Quenching ◽  
Relative Sensitivity ◽  
Strong Temperature Dependence ◽  
Two Dimensional ◽  
X Ray Diffraction ◽  
Higher Temperature

Abstract Lanthanide (Ln3+)-doped phosphors generally suffer from thermal quenching, in which their photoluminescence (PL) intensities decrease at the higher temperature. Herein, we report a class of unique two-dimensional negative-thermal-expansion phosphor of Sc2(MoO4)3:Yb/Er. By virtue of the reduced distances between sensitizers and emitters as well as confined energy migration with increasing the temperature, a 45-fold enhancement of green upconversion (UC) luminescence and a 450-fold enhancement of near-infrared downshifting (DS) luminescence of Er3+ are achieved from 25 to 500 ˚C. The thermally boosted UC and DS luminescence mechanism is systematically investigated through in situ temperature-dependent Raman spectroscopy, synchrotron X-ray diffraction and PL dynamics. Moreover, the luminescence lifetime of 4I11/2 of Er3+ in Sc2(MoO4)3:Yb/Er displays a strong temperature dependence, enabling ratiometric thermometry with the highest relative sensitivity of 13.4%/K at 298 K. These findings may gain a vital insight into the design of negative-thermal-expansion Ln3+-doped phosphors for versatile applications.

Variable-Temperature Microcrystal X-ray Diffraction Studies of Negative Thermal Expansion in the Pure Silica Zeolite IFR

2001 ◽  
Vol 123 (23) ◽  
pp. 5453-5459 ◽  
Author(s):  
Luis A. Villaescusa ◽  
Philip Lightfoot ◽  
Simon J. Teat ◽  
Russell E. Morris
Keyword(s):  
Thermal Expansion ◽  
Variable Temperature ◽  
Negative Thermal Expansion ◽  
X Ray Diffraction ◽  
X Ray ◽  
Pure Silica

scholarly journals Structural and Thermal Unusual Properties in Invar Behavior of Ni-Mn Alloys

2020 ◽  
Vol 17 (2(SI)) ◽  
pp. 0629
Author(s):  
Salih Darweesh et al.
Keyword(s):  
Thermal Expansion ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Lattice Distortion ◽  
Negative Thermal Expansion ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ferromagnetic Metals ◽  
Invar Effect

The Invar effect in 3D transition metal such as Ni and Mn, were prepared on a series composition of binary Ni1-xMnx system with x=0.3, 0.5, 0.8 by using powder metallurgy technique. In this work, the characterization of structural and thermal properties have been investigated experimentally by X-ray diffraction, thermal expansion coefficient and vibrating sample magnetometer (VSM) techniques. The results show that anonymously negative thermal expansion coefficient are changeable in the structure. The results were explained due to the instability relation between magnetic spins with lattice distortion on some of ferromagnetic metals.    

Negative Thermal Expansion of Gd2Fe16.5Cr0.5 Compound with Th2Ni17-Type Structure

2011 ◽  
Vol 299-300 ◽  
pp. 47-50
Author(s):  
Yan Ming Hao ◽  
Fei Fei Liang ◽  
Xiao Hong He ◽  
Wu Yan Zhao ◽  
Yue Ting Qin ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Curie Temperature ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Linear Thermal Expansion Coefficient ◽  
Linear Thermal Expansion ◽  
Negative Thermal Expansion ◽  
Type Structure ◽  
X Ray Diffraction ◽  
Temperature Range

The thermal expansion and the Curie temperature of Gd2Fe16.5Cr0.5 compound have been investigated by means of x-ray diffraction and magnetization measurements. The result shows that the Gd2Fe16.5Cr0.5 compound annealed at 1243°C has a hexagonal Th2Ni17-type structure. Cr atom substituting for Fe atom can increase the Curie temperature obviously. In magnetic state, an anisotropic anomolous thermal expansion was observed. Along the c-axis, the average linear thermal expansion coefficient αc=-2.79×10-6/K in the temperature range 294-472K, and αc =-3.09×10-5/K in 472-592K. Along the a-axis, the average linear thermal expansion coefficient αa =9.22×10-6/K in 294-552K, and αa =-1.41×10-5/K in 552-592K. In the temperature range 472-592K, the average volume thermal expansion coefficient αv =-2.14×10-5/K. The mechanism of the thermal expansion anomaly of Gd2Fe16.5Cr0.5 compound was discussed in this paper.

Structural phase transition and negative thermal expansion in Cu1.8Zn0.2V2–x P x O7 solid solutions

2022 ◽  
Author(s):  
Koshi Takenaka ◽  
Masato Kano ◽  
Ryota Kasugai ◽  
Kohei Takada ◽  
Koki Eto ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Structural Phase ◽  
Negative Thermal Expansion ◽  
Peak Position ◽  
Crystallographic Analysis ◽  
Resin Matrix ◽  
Matrix Composites ◽  
X Ray Diffraction ◽  
Lower Dielectric Constant ◽  
Microstructural Effects

Abstract Negative thermal expansion (NTE) is exhibited over the entire x range for Cu1.8Zn0.2V2–xPxO7. In particular, dilatometric measurements using epoxy resin matrix composites containing the spray-dried powder demonstrated that the thermal expansion suppressive capability was almost unchanged for x≤0.1. With increasing x, the x-ray diffraction peak position moves systematically, but some peaks are extremely broad and/or asymmetric, suggesting disorder in the internal structure. The crystallographic analysis confirmed NTE enhancement by microstructural effects at least for x=0.2. Preliminary measurements suggest higher resistivity and lower dielectric constant than that of pure vanadate, which is suitable for application to electronic devices.

Polymorphism in the negative thermal expansion material magnesium hafnium tungstate

2008 ◽  
Vol 23 (1) ◽  
pp. 210-213 ◽  
Author(s):  
Amy M. Gindhart ◽  
Cora Lind ◽  
Mark Green
Keyword(s):  
Phase Transition ◽  
Thermal Expansion ◽  
Variable Temperature ◽  
Negative Thermal Expansion ◽  
Orthorhombic Phase ◽  
High Energy ◽  
X Ray Diffraction ◽  
Space Group ◽  
Smooth Change ◽  
Energy Ball

Magnesium hafnium tungstate [MgHf(WO4)3] was synthesized by high-energy ball milling followed by calcination. The material was characterized by variable- temperature neutron and x-ray diffraction. It crystallized in space group P21/a below 400 K and transformed to an orthorhombic structure at higher temperatures. The orthorhombic polymorph adopted space group Pnma, instead of the Pnca structure commonly observed for other A2(MO4)3 materials (A = trivalent metal, M = Mo, W). In contrast, the monoclinic polymorphs appeared to be isostructural. Negative thermal expansion was observed in the orthorhombic phase with αa = −5.2 × 10−6 K−1, αb = 4.4 × 10−6 K−1, αc = −2.9 × 10−6 K−1, αV = −3.7 × 10−6 K−1, and αl = −1.2 × 10−6 K−1. The monoclinic to orthorhombic phase transition was accompanied by a smooth change in unit-cell volume, indicative of a second-order phase transition.

scholarly journals Negative thermal expansion and electronic structure variation of chalcopyrite type LiGaTe2

RSC Advances ◽  
2018 ◽  
Vol 8 (18) ◽  
pp. 9946-9955 ◽  
Author(s):  
V. V. Atuchin ◽  
Fei Liang ◽  
S. Grazhdannikov ◽  
L. I. Isaenko ◽  
P. G. Krinitsin ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Electronic Structure ◽  
Diffraction Analysis ◽  
First Principles ◽  
Cell Parameter ◽  
Negative Thermal Expansion ◽  
First Principles Calculations ◽  
X Ray Diffraction ◽  
Structure Variation ◽  
X Ray

The LiGaTe2 crystals were grown by the Bridgman–Stockbarger technique and the cell parameter dependence on temperature in the range of 303–563 K was evaluated by the X-ray diffraction analysis and first principles calculations.

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