scholarly journals Tri-Hexagonal charge order in kagome metal CsV3Sb5 revealed by 121Sb NQR

2021 ◽  
Author(s):  
Chao Mu ◽  
Qiangwei Yin ◽  
Zhijun Tu ◽  
Chunsheng Gong ◽  
Ping Zheng ◽  
...  
Keyword(s):  
Density Wave ◽  
Charge Order ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
S Wave ◽  
First Order ◽  
First Order Phase Transition ◽  
Quadrupole Resonance ◽  
A Charge ◽  
First Order Phase

Abstract We report 121Sb nuclear quadrupole resonance (NQR) measurements on kagome superconductor CsV3Sb5 with T c = 2.5 K. 121Sb NQR spectra split after a charge density wave (CDW) transition at 94 K, which demonstrates a commensurate CDW state. The coexistence of the high temperature phase and the CDW phase between 91 K and 94 K manifests that it is a first order phase transition. The CDW order exhibits Tri-Hexagonal deformation with a lateral shift between the adjacent kagome layers, which is consistent with 2×2×2 superlattice modulation. The superconducting state coexists with CDW order and shows a conventional s-wave behavior in the bulk state.

High Temperature Phase Transitions in BiFeO3

2009 ◽  
Vol 1199 ◽  
Author(s):  
Donna Arnold ◽  
Christopher M Kavanagh ◽  
Philip Lightfoot ◽  
Finlay Doogan Morrison
Keyword(s):  
Phase Transition ◽  
High Temperature ◽  
Order Phase Transition ◽  
Structure Type ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
First Order ◽  
Β Phase ◽  
First Order Phase Transition ◽  
First Order Phase

AbstractThe high temperature phases of BiFeO3 have courted much controversy with many conflicting structural models reported, in particular for the paraelectric β-phase. High temperature powder neutron diffraction (PND) experiments indicate that the ferroelectric (R3c) α-phase transforms to the paraelectric β-phase at approximately 820 °C via a first order phase transition. We demonstrate that this phase is unambiguously orthorhombic, adopting the GdFeO3 structure-type with a space group Pbnm. On further heating BiFeO3 undergoes another first order phase transition (β-γ) at approximately 930 °C which is marked by a discontinuous decrease in cell volume consistent with an insulator-metal transition. Close inspection of the PND data show no evidence of any symmetry change, with the postulated γ-phase remaining orthorhombic Pbnm. In addition we present PND and impedance spectroscopy data for BiFeO3 which suggest that the so-called ‘Połomska’ transition observed by some authors at approximately 185 °C is not intrinsic.

Synthesis and Lattice Distortion of Ferroelectric/Antiferroelectric Bi(III)-containing Perovskites

2002 ◽  
Vol 755 ◽  
Author(s):  
Yoshiyuki Inaguma ◽  
Atsushi Miyaguchi ◽  
Tetsuhiro Katsumata
Keyword(s):  
Phase Transition ◽  
High Temperature ◽  
Order Phase Transition ◽  
Lattice Distortion ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
First Order ◽  
First Order Phase Transition ◽  
Lattice Distortions ◽  
First Order Phase

ABSTRACTBi(III)-containing perovskites Bi1/2Ag1/2TiO3 and Bi(M1/2Ti1/2)O3 (M= Co, Mg, and Ni) were synthesized under oxygen pressure as high as approximately 1 MPa and under a pressure as high as 6 GPa, and the lattice distortions were investigated. It was found that ferroelectric Bi1/2Ag1/2TiO3 may be rhombohedrally distorted. In constrast, Bi(M1/2Ti1/2)O3 (M= Co, Mg, and Ni), the structure of which is different from GdFeO3-type compound, is monoclinically distorted. The ratio of lattice parameters of the monoclinic perovskite-subcell for Bi(M1/2Ti1/2)O3 (M= Co, Mg, and Ni), am/bm is larger than that of GdFeO3-type perovskites, though the tolerance factor is close. In addition, it was found that Bi(Ni1/2Ti1/2)O3 undergoes a first-order phase transition from a GdFeO3-type phase(high-temperature phase) at around 490 K. These results indicate that the Bi3+ character in Bi(III)-containing perovskites strongly influences the structure distortion.

In Situ Measurement of Phase Transition of Layered Perovskite BaLn2Mn2O7

2010 ◽  
Vol 67 ◽  
pp. 113-117 ◽  
Author(s):  
Hiromi Nakano ◽  
Nobuo Ishizawa ◽  
Hirohisa Sato ◽  
Naoki Kamegashira
Keyword(s):  
Phase Transition ◽  
High Temperature ◽  
Order Phase Transition ◽  
High Temperature Phase ◽  
Layered Perovskite ◽  
Temperature Phase ◽  
First Order ◽  
First Order Phase Transition ◽  
First Order Phase

The BaLn2Mn2O7 (Ln = rare earth) has a Sr3Ti2O7-type structure with double block oxygen octahedra belonging to the Ruddlesden-Popper-Type homologous series AO(ABO3)2. In-situ measurement of the phase transition for BaLn2Mn2O7 was performed using single-crystal X-ray diffraction and a high-temperature transmission electron microscope (TEM). Two types of transitions were observed in BaPr2Mn2O7: the transition from primitive tetragonal (P42/mnm) to body-centered tetragonal (I4/mmm) at around 400 K and the first-order phase transition at around 1040 K. Multiple phase transitions were also observed in BaEu2Mn2O7, with one from P42/mnm to I4/mmm at around 400 K and another, above 550 K, as a first-order phase transition. The high-temperature phase had a 1.5% lattice mismatch along the c-axis compared with the low-temperature phase. We succeeded in recording for the first time in-situ structural change in BaGd2Mn2O7 as a movie by high-temperature TEM. The high-temperature phase nucleated parallel to the (00l) plane as a layer above 550 K and grew until covering the entire inspected region at around 1023 K. The first-order phase transition was caused by the structural and/or electrical distortion of the layered perovskite structure composed of Jahn-Teller ion Mn3+.

Parameterization of the coupling between strain and order parameter for LuF[SeO3]

2014 ◽  
Vol 47 (2) ◽  
pp. 701-711 ◽  
Author(s):  
Oxana V. Magdysyuk ◽  
Melanie Müller ◽  
Robert E. Dinnebier ◽  
Christian Lipp ◽  
Thomas Schleid
Keyword(s):  
Phase Transition ◽  
Order Parameter ◽  
Structural Phase ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
Time Resolved ◽  
Synchrotron Powder Diffraction ◽  
First Order Phase Transition ◽  
Temperature Phase Transition ◽  
First Order Phase

The high-temperature phase transition of LuF[SeO3] has been characterized by time-resolved high-resolution synchrotron powder diffraction. On heating, a second-order structural phase transition was found at 393 K, while on cooling the same phase transition occurs at 371 K, showing a large hysteresis typical for a first-order phase transition. Detailed analysis using sequential and parametric whole powder pattern fitting revealed that the coupling between the strain and the displacive order parameter determines the behaviour of the material during the phase transition. Different possible coupling mechanisms have been evaluated and the most probable rationalized.

scholarly journals 127I NQR and Crystal Structure Studies of [N(CH3)4]2 CdI4

2000 ◽  
Vol 55 (1-2) ◽  
pp. 225-229 ◽  
Author(s):  
Hideta Ishihara ◽  
Keizo Horiuchi ◽  
Thorsten M. Gesing ◽  
Shi-qi Dou ◽  
J.-Christian Buhl ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
Order Phase Transition ◽  
Intensity Ratio ◽  
Room Temperature ◽  
Liquid Nitrogen Temperature ◽  
Temperature Phase ◽  
First Order ◽  
First Order Phase Transition ◽  
First Order Phase

The temperature dependence of 127I NQR and DSC as well as the crystal structure at room temperature of the title compound were determined. This compound shows a first-order phase transition of an order-disorder type at 245 K. Eight 127I(v1:m = ±1/2 ↔ ±3/2) NQR lines of 79.57, 81.86, 82.56, 83.36, 84.68, 87.72, 88.34, and 88.86 MHz, and corresponding eight 127I(v2: m = ±3/2 ↔±5/2) NQR lines were observed at liquid nitrogen temperature. Three 127I(υi) NQR lines wfth an intensity ratio of 1:1:2 in the order of decreasing frequency were observed just above the transition point and two NQR lines except for the middle-frequency line disappeared around room temperature. This temperature behavior of NQR lines is very similar to that observed in [N(CH3)4]2Hgl4. Another first-order phase transition takes place at 527 K. The structure of the room-temperature phase was redetermined: orthorhombic, Pnma, Z = 4, a = 1342.8(3), b = 975.7(2), c = 1696.5(3) pm. The NQR result of three lines with an intensity ratio of 1:1:2 is in agreement with this structure. The thermal displacement parameters of atoms in both cations and anions are large.

Room-Temperature First-Order Phase Transition in a Charge-Disproportionated Molecular Conductor (MeEDO-TTF)2PF6

2008 ◽  
Vol 20 (24) ◽  
pp. 7551-7562 ◽  
Author(s):  
Xiangfeng Shao ◽  
Yoshiaki Nakano ◽  
Masafumi Sakata ◽  
Hideki Yamochi ◽  
Yukihiro Yoshida ◽  
...  
Keyword(s):  
Phase Transition ◽  
Order Phase Transition ◽  
Room Temperature ◽  
First Order ◽  
Molecular Conductor ◽  
First Order Phase Transition ◽  
A Charge ◽  
First Order Phase

Determination of the low-temperature structure of hexamethylbenzene

2005 ◽  
Vol 61 (2) ◽  
pp. 200-206 ◽  
Author(s):  
John A. Stride
Keyword(s):  
Low Temperature ◽  
Temperature Phase ◽  
Temperature Structure ◽  
Thermally Induced ◽  
First Order ◽  
Neutron Powder Diffraction Data ◽  
First Order Phase Transition ◽  
First Order Phase

The low-temperature structure of hexamethylbenzene has been determined from neutron powder diffraction data and found to differ from the room-temperature phase predominantly by a translation of molecular planes to a form a cubic close-packed type structure. By performing measurements as a function of temperature, the role of thermally induced agitation of the molecular units in the first-order phase transition is clearly demonstrated.

Reversible dimerization of C60 molecules in the crystal structure of the bis(arene)chromium fulleride [Cr(C7H8)]2C60

2002 ◽  
Vol 58 (3) ◽  
pp. 482-488 ◽  
Author(s):  
Andreas Hönnerscheid ◽  
Robert Dinnebier ◽  
Martin Jansen
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
First Order Phase Transition ◽  
Cscl Type ◽  
Reversible Dimerization ◽  
First Order Phase ◽  
Low Temperature Phase ◽  
Positively Charged

Bis(toluene)chromium fulleride, [Cr(C7H8)2]C60, has been synthesized as a black microcrystalline powder from C60 and [Cr(C7H8)2] in toluene. [Cr(C7H8)2]C60 is an ionic compound in which the fullerene is negatively charged and the bis(toluene)chromium molecule positively charged. At T = 250 K a reversible first-order phase transition from a primitive cubic high-temperature phase to a triclinic low-temperature phase occurs. The high-temperature phase [Pm\overline 3m, a = 9.9840 (1) Å, T = 295 K] is composed of dynamically disordered fulleride anions and bis(toluene)chromium(I) cations in a CsCl-type arrangement. The triclinic low-temperature modification [P\overline 1, a = 13.6414 (8), b = 13.8338 (7), c = 13.8548 (7) Å, α = 91.830 (3), β = 116.776 (2), γ = 119.333 (2)°, T = 235 K] consists of ordered C60 dimers and two crystallographically distinct bis(toluene)chromium entities.

scholarly journals Components Influence On Dielectric Properties Of Ferroelectric Composite Materials

2016 ◽  
Vol 1 (1) ◽  
pp. 51
Author(s):  
O.V. Efimova ◽  
E.V. Stukova ◽  
E.Yu. Koroleva
Keyword(s):  
Phase Transition ◽  
Dielectric Properties ◽  
Ferroelectric Phase ◽  
Volume Fraction ◽  
Temperature Phase ◽  
Cooling Mode ◽  
First Order ◽  
First Order Phase Transition ◽  
Temperature Phase Transition ◽  
First Order Phase

<p>The dielectric properties of ferroelectric composite (NH<sub>4</sub>HSO<sub>4</sub>)<em><sub>x</sub></em>/(PbTiO<sub>3</sub>)<em><sub>1-x</sub></em> is studied for x ranging from 0,00 to 0,50. Measurements of permittivity were performed by heating-cooling mode temperature range from 130 K to 380 K. The value of the temperature interval of existence of the ferroelectric phase increases by ~5 degrees and independent at the volume fraction of particulate inclusions in composites. It is shown that the inclusion of PbTiO<sub>3</sub> particles gives rise to hysteresis upper temperature phase transition, which may indicate a change in the type of phase transition of the second order on the first-order phase transition.</p>

THE SPECTRUM OF THE $\mathcal{T}$-MATRIX AND THE SURFACE TENSION IN THE SU(3) GAUGE THEORY

1992 ◽  
Vol 03 (05) ◽  
pp. 947-960 ◽  
Author(s):  
T. TRAPPENBERG
Keyword(s):  
Phase Transition ◽  
Surface Tension ◽  
Gauge Theory ◽  
Finite Size ◽  
Temperature Phase ◽  
Finite Size Effects ◽  
First Order ◽  
First Order Phase Transition ◽  
Temperature Phase Transition ◽  
First Order Phase

The transfer matrix method to describe finite size effects due to tunneling are worked out for Z(2)- and Z(3)-symmetric models. We used this method to extract the surface tension σ in the SU(3) gauge theory at the finite temperature phase transition on lattices with an extent T=2 in the euclidean time direction. We also discuss if the confined phase completely wets the deconfined phase at this first order phase transition.

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