scholarly journals Phonons, electrons and thermal transport in Planckian high Tc materials

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Connie H. Mousatov ◽  
Sean A. Hartnoll
Keyword(s):  
Thermal Diffusivity ◽  
Room Temperature ◽  
Phonon Scattering ◽  
Temperature Phase ◽  
Temperature Derivative ◽  
High Tc ◽  
Optimal Doping ◽  
Strong Scattering ◽  
Measured Strength ◽  
Temperature Phase Diagram

AbstractThe room-temperature thermal diffusivity of high Tc materials is dominated by phonons. This allows the scattering of phonons by electrons to be discerned. We argue that the measured strength of this scattering suggests a converse Planckian scattering of electrons by phonons across the room-temperature phase diagram of these materials. Consistent with this conclusion, the temperature derivative of the resistivity of strongly overdoped cuprates is noted to show a kink at a little below 200 K that we argue should be understood as the onset of a high-temperature Planckian T-linear scattering of electrons by classical phonons. This kink continuously disappears toward optimal doping, even while strong scattering of phonons by electrons remains visible in the thermal diffusivity, sharpening the long-standing puzzle of the lack of a feature in the T-linear resistivity at optimal doping associated with the onset of phonon scattering.

C60 UNDER PRESSURE

1992 ◽  
Vol 06 (19) ◽  
pp. 1153-1158 ◽  
Author(s):  
MANUEL NÚÑEZ-REGUEIRO
Keyword(s):  
Phase Diagram ◽  
High Pressure ◽  
High Temperatures ◽  
Room Temperature ◽  
Fullerene Cage ◽  
Temperature Phase ◽  
Bonded Phase ◽  
Temperature Phase Diagram

The high pressure experiments done on fullerenes are reviewed. C 60 has found to be stable up to about 20 GPa at room temperature and hydrostatic conditions. Application of stronger, or non-hydrostatic, pressures at room temperature can induce the formation of a partially sp3 bonded phase, that apparently conserves the fullerene cage. Extreme non-hydrostatic compressions above about 15 GPa can, though, break down the cage and produce amorphous or cubic diamond. Destruction of the cage at high temperatures has also been observed, but the resulting product is amorphous sp2 material. A preliminary pressure-temperature phase diagram for C 60 is proposed.

scholarly journals On the Dimorphism and the Pressure-Temperature State Diagram of Racemic m-Nisoldipine, a Dihydropyridine Calcium Ion Antagonist

2018 ◽  
Author(s):  
Ivo Rietveld ◽  
Kangli Li ◽  
Gabin Gbabode ◽  
Gérard Coquerel ◽  
René Céolin
Keyword(s):  
Phase Diagram ◽  
Calcium Ion ◽  
Room Temperature ◽  
Phase Relationship ◽  
State Diagram ◽  
Stable Phase ◽  
Temperature Phase ◽  
Temperature State ◽  
Temperature Phase Diagram

The pressure-temperature phase diagram of the dimorphism of racemic m-nisoldipine is constructed using temperatures and enthalpies of fusion of forms A and B. At ordinary pressure, the transition from form B to form A is found to occur around 192 K, which indicates that these polymorphs are enantiotropically related and that form A is stable at room temperature. Nevertheless, the phase relationship turns to be monotropic when pressures become greater than about 100 MPa, which indicates that form B becomes the sole stable phase.<br>

scholarly journals Low Temperature Phase Diagram of NH3BH3

2011 ◽  
Vol 1309 ◽  
Author(s):  
Bertil Sundqvist ◽  
Ove Andersson ◽  
Issam Quwar ◽  
Alexandr Talyzin
Keyword(s):  
Phase Diagram ◽  
Low Temperature ◽  
Atmospheric Pressure ◽  
Room Temperature ◽  
Temperature Phase ◽  
Conductivity Measurements ◽  
Phase Boundaries ◽  
T Phase ◽  
Low Temperature Phase ◽  
Temperature Phase Diagram

ABSTRACTThe pressure-temperature (p-T) phase diagram of NH3BH3 has been investigated by thermal conductivity measurements up to 1.5 GPa at temperatures between 100 and 300 K, and the phase boundaries between the three known structural phases have been identified. The transformation between the room temperature tetragonal I4mm phase and the low temperature orthorhombic Pmn21 phase (Tc = 218 K at p = 0) shows only a small hysteresis. The transformation into the high pressure orthorhombic Cmc21 phase (at 1.0 GPa near 292 K) has a very strong hysteresis, up to Δp = 0.5 GPa, and below 230 K a fraction of this phase is metastable even at atmospheric pressure.

scholarly journals On the Dimorphism and the Pressure-Temperature State Diagram of Racemic m-Nisoldipine, a Dihydropyridine Calcium Ion Antagonist

2018 ◽  
Author(s):  
Ivo Rietveld ◽  
Kangli Li ◽  
Gabin Gbabode ◽  
Gérard Coquerel ◽  
René Céolin
Keyword(s):  
Phase Diagram ◽  
Calcium Ion ◽  
Room Temperature ◽  
Phase Relationship ◽  
State Diagram ◽  
Stable Phase ◽  
Temperature Phase ◽  
Temperature State ◽  
Temperature Phase Diagram

The pressure-temperature phase diagram of the dimorphism of racemic m-nisoldipine is constructed using temperatures and enthalpies of fusion of forms A and B. At ordinary pressure, the transition from form B to form A is found to occur around 192 K, which indicates that these polymorphs are enantiotropically related and that form A is stable at room temperature. Nevertheless, the phase relationship turns to be monotropic when pressures become greater than about 100 MPa, which indicates that form B becomes the sole stable phase.<br>

Electron Microscope study of commensurate-incommensurate phase transition in BaZnGeO4

1990 ◽  
Vol 48 (4) ◽  
pp. 172-173
Author(s):  
Naoki Yamamoto ◽  
Makoto Kikuchi ◽  
Tooru Atake ◽  
Akihiro Hamano ◽  
Yasutoshi Saito
Keyword(s):  
Phase Transition ◽  
Electron Microscope Study ◽  
Room Temperature ◽  
Hexagonal Lattice ◽  
Ferroelectric Materials ◽  
Temperature Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Periodic Arrays ◽  
Modulation Wave Vector

BaZnGeO4 undergoes many phase transitions from I to V phase. The highest temperature phase I has a BaAl2O4 type structure with a hexagonal lattice. Recent X-ray diffraction study showed that the incommensurate (IC) lattice modulation appears along the c axis in the III and IV phases with a period of about 4c, and a commensurate (C) phase with a modulated period of 4c exists between the III and IV phases in the narrow temperature region (—58°C to —47°C on cooling), called the III' phase. The modulations in the IC phases are considered displacive type, but the detailed structures have not been studied. It is also not clear whether the modulation changes into periodic arrays of discommensurations (DC’s) near the III-III' and IV-V phase transition temperature as found in the ferroelectric materials such as Rb2ZnCl4.At room temperature (III phase) satellite reflections were seen around the fundamental reflections in a diffraction pattern (Fig.1) and they aligned along a certain direction deviated from the c* direction, which indicates that the modulation wave vector q tilts from the c* axis. The tilt angle is about 2 degree at room temperature and depends on temperature.

scholarly journals Field-temperature phase diagram of the enigmatic Nd2(Zr1−xTix)2O7 pyrochlore magnets

2021 ◽  
Vol 103 (21) ◽  
Author(s):  
M. Léger ◽  
E. Lhotel ◽  
E. Ressouche ◽  
K. Beauvois ◽  
F. Damay ◽  
...  
Keyword(s):  
Phase Diagram ◽  
Temperature Phase ◽  
Field Temperature ◽  
Temperature Phase Diagram

scholarly journals Structure and Properties of Ln2MoO6 Oxymolybdates (Ln = La, Pr, Nd) Doped with Magnesium

Crystals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 611
Author(s):  
Ekaterina Orlova ◽  
Elena Kharitonova ◽  
Timofei Sorokin ◽  
Alexander Antipin ◽  
Nataliya Novikova ◽  
...  
Keyword(s):  
Rare Earth ◽  
Infrared Spectroscopy ◽  
Room Temperature ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
Spectroscopy Data ◽  
Structure And Properties ◽  
Hygroscopic Properties ◽  
Thermogravimetric Studies ◽  
Mg Doped

The literature data and the results obtained by the authors on the study of the structure and properties of a series of polycrystalline and single-crystal samples of pure and Mg-doped oxymolybdates Ln2MoO6 (Ln = La, Pr, Nd) are analyzed. Presumably, the high-temperature phase I41/acd of Nd2MoO6 single crystals is retained at room temperature. The reason for the loss of the center of symmetry in the structures of La2MoO6 and Pr2MoO6 and the transition to the space group I4¯c2 is the displacement of oxygen atoms along the twofold diagonal axes. In all structures, Mg cations are localized near the positions of the Mo atoms, and the splitting of the positions of the atoms of rare-earth elements is found. Thermogravimetric studies, as well as infrared spectroscopy data for hydrated samples of Ln2MoO6 (Ln = La, Pr, Nd), pure and with an impurity of Mg, confirm their hygroscopic properties.

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