scholarly journals Lattice dynamics and negative thermal expansion in the framework compound ZnNi(CN)4 with two-dimensional and three-dimensional local environments

2019 ◽  
Vol 99 (2) ◽  
Author(s):  
Stella d'Ambrumenil ◽  
Mohamed Zbiri ◽  
Ann M. Chippindale ◽  
Simon J. Hibble ◽  
Elena Marelli ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Lattice Dynamics ◽  
Negative Thermal Expansion ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Local Environments

Magnetoelastic coupling, negative thermal expansion, and two-dimensional magnetic excitations in FeAs

2021 ◽  
Vol 103 (9) ◽  
Author(s):  
J. L. Niedziela ◽  
L. D. Sanjeewa ◽  
A. A. Podlesnyak ◽  
L. DeBeer-Schmitt ◽  
S. J. Kuhn ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Negative Thermal Expansion ◽  
Two Dimensional ◽  
Magnetic Excitations ◽  
Magnetoelastic Coupling

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.

Infrared lattice dynamics in negative thermal expansion material in single-crystal ScF3

2019 ◽  
Vol 32 (3) ◽  
pp. 035403
Author(s):  
Sahan U Handunkanda ◽  
Erin B Curry ◽  
Vladimir Voronov ◽  
Jason N Hancock
Keyword(s):  
Thermal Expansion ◽  
Single Crystal ◽  
Lattice Dynamics ◽  
Negative Thermal Expansion

CDW-induced negative thermal expansion in two-dimensional conductor η-Mo4O11

2003 ◽  
Vol 125 (1) ◽  
pp. 45-49 ◽  
Author(s):  
Hiroshi Negishi ◽  
Yoshihiro Kuroiwa ◽  
Hiroyasu Akamine ◽  
Shinobu Aoyagi ◽  
Akikatsu Sawada ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Negative Thermal Expansion ◽  
Two Dimensional

scholarly journals Mechanical and Thermal Properties for Uranium and U–6Nb Alloy from First-Principles Theory

2021 ◽  
Vol 11 (12) ◽  
pp. 5643
Author(s):  
Per Söderlind ◽  
Lin H. Yang ◽  
Alexander Landa ◽  
Amanda Wu
Keyword(s):  
Thermal Expansion ◽  
Electronic Structure ◽  
Lattice Dynamics ◽  
Density Functional ◽  
Elastic Moduli ◽  
Inelastic Neutron Scattering ◽  
Negative Thermal Expansion ◽  
Lattice Parameter ◽  
Ductile Material ◽  
Mechanical And Thermal Properties

Elasticity, lattice dynamics, and thermal expansion for uranium and U–6Nb alloy (elastic moduli) are calculated from density functional theory that is extended to include orbital polarization (DFT+OP). Introducing 12.5 at.% of niobium, substitutionally, in uranium softens all the cii elastic moduli, resulting in a significantly softer shear modulus (G). Combined with a nearly invariant bulk modulus (B), the quotient B/G increases dramatically for U–6Nb, suggesting a more ductile material. Lattice dynamics from a harmonic model coupled with a DFT+OP electronic structure is applied for α uranium, and the obtained phonon density of states compares well with inelastic neutron-scattering measurements. The Debye temperature associated with the lattice dynamics falls within the range of experimentally observed Debye temperatures and it also validates our quasi-harmonic (QH) phonon model. The QH Debye–Grüneisen phonon method is combined with a DFT+OP electronic structure and used to explore the anisotropic thermal expansion in α uranium. The anomalous negative thermal expansion (contraction) of the b lattice parameter of the α-phase orthorhombic cell is relatively well reproduced from a free-energy model consisting of QH-phonon and DFT+OP electronic structure contributions.

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