scholarly journals Paramagnetic ionic plastic crystals containing the octamethylferrocenium cation: counteranion dependence of phase transitions and crystal structures

2018 ◽  
Vol 20 (5) ◽  
pp. 3019-3028 ◽  
Author(s):  
Tomoyuki Mochida ◽  
Mai Ishida ◽  
Takumi Tominaga ◽  
Kazuyuki Takahashi ◽  
Takahiro Sakurai ◽  
...  
Keyword(s):  
Phase Transitions ◽  
Crystal Structures ◽  
Room Temperature ◽  
Plastic Crystals

Octamethylferrocenium salts with various anions exhibit paramagnetic plastic phases at or above room temperature.

Influence of the molecular structures on the high-pressure and low-temperature phase transitions of plastic crystals

2003 ◽  
Vol 59 (1) ◽  
pp. 60-71 ◽  
Author(s):  
Markus Wunschel ◽  
Robert E. Dinnebier ◽  
Stefan Carlson ◽  
Piotr Bernatowicz ◽  
Sander van Smaalen
Keyword(s):  
High Pressure ◽  
Phase Transitions ◽  
Low Temperature ◽  
Room Temperature ◽  
Close Packing ◽  
Molecular Structures ◽  
Temperature Phase ◽  
Plastic Crystals ◽  
First Order ◽  
First Order Phase

The crystal structures of tert-butyl-tris(trimethylsilyl)silane, Si[C(CH_3)_3]_1[Si(CH_3)_3]_3 (Bu1), and di-tert-butyl-bis(trimethylsilyl)silane, Si[C(CH_3)_3]_2[Si(CH_3)_3]_2 (Bu2), at room temperature and at 105 K have been determined by X-ray powder diffraction; the high-pressure behavior for pressures between 0 and 5 GPa is reported. The room-temperature structures have cubic Fm\bar{3}m symmetry (Z = 4) with a = 13.2645 (2) Å, V = 2333.87 (4) Å3 for Bu1 and a = 12.9673 (1) Å, V = 2180.46 (3) Å3 for Bu2. The molecules are arranged in a cubic close packing (c.c.p.) and exhibit at least 48-fold orientational disorder. Upon cooling both compounds undergo a first-order phase transition at temperatures T_c = 230 (5) K (Bu1) and T_c = 250 (5) K (Bu2) into monoclinic structures with space group P2_1/n. The structures at 105 K have a = 17.317 (1), b = 15.598 (1), c = 16.385 (1) Å, \gamma = 109.477 (4)°, V = 4172.7 (8) Å3 and Z = 8 for Bu1and a = 17.0089 (9), b = 15.3159 (8), c = 15.9325 (8) Å, \gamma = 110.343 (3)°, V = 3891.7 (5) Å3 and Z = 8 for Bu2. The severe disorder of the room-temperature phase is significantly decreased and only a two- or threefold rotational disorder of the molecules remains at 105 K. First-order phase transitions have been observed at pressures of 0.13–0.28 GPa for Bu1 and 0.20–0.24 GPa for Bu2. The high-pressure structures are isostructural to the low-temperature structures. The pressure dependencies of the unit-cell volumes were fitted with Vinet equations of state and the bulk moduli were obtained. At still higher pressures further anomalies in the pressure dependencies of the lattice parameters were observed. These anomalies are explained as additional disorder–order phase transitions.

scholarly journals Phase Transitions, Crystal Structures, and Magnetic Properties of Ferrocenium Ionic Plastic Crystals with CF3 BF3 and Other Anions

2019 ◽  
Vol 4 (4) ◽  
pp. 1410-1415 ◽  
Author(s):  
Hironori Kimata ◽  
Takahiro Sakurai ◽  
Hitoshi Ohta ◽  
Tomoyuki Mochida
Keyword(s):  
Magnetic Properties ◽  
Phase Transitions ◽  
Crystal Structures ◽  
Plastic Crystals

scholarly journals Crystal Structures and Phase Sequences of Metallocenium Salts with Fluorinated Anions: Effects of Molecular Size and Symmetry on Phase Transitions to Ionic Plastic Crystals

2016 ◽  
Vol 22 (44) ◽  
pp. 15725-15732 ◽  
Author(s):  
Tomoyuki Mochida ◽  
Yusuke Funasako ◽  
Mai Ishida ◽  
Shingo Saruta ◽  
Takashi Kosone ◽  
...  
Keyword(s):  
Phase Transitions ◽  
Crystal Structures ◽  
Molecular Size ◽  
Plastic Crystals

scholarly journals High-Pressure Spectroscopy Study of Zn(IO3)2 Using Far-Infrared Synchrotron Radiation

Crystals ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 34
Author(s):  
Akun Liang ◽  
Robin Turnbull ◽  
Enrico Bandiello ◽  
Ibraheem Yousef ◽  
Catalin Popescu ◽  
...  
Keyword(s):  
High Pressure ◽  
Phase Transitions ◽  
Synchrotron Radiation ◽  
Infrared Radiation ◽  
Room Temperature ◽  
Far Infrared ◽  
Low Pressure ◽  
Pressure Response ◽  
Spectroscopy Study ◽  
Far Infrared Radiation

We report the first high-pressure spectroscopy study on Zn(IO3)2 using synchrotron far-infrared radiation. Spectroscopy was conducted up to pressures of 17 GPa at room temperature. Twenty-five phonons were identified below 600 cm−1 for the initial monoclinic low-pressure polymorph of Zn(IO3)2. The pressure response of the modes with wavenumbers above 150 cm−1 has been characterized, with modes exhibiting non-linear responses and frequency discontinuities that have been proposed to be related to the existence of phase transitions. Analysis of the high-pressure spectra acquired on compression indicates that Zn(IO3)2 undergoes subtle phase transitions around 3 and 8 GPa, followed by a more drastic transition around 13 GPa.

Room-temperature NaI/H2O compression icing: solute–solute interactions

2017 ◽  
Vol 19 (39) ◽  
pp. 26645-26650 ◽  
Author(s):  
Qingxin Zeng ◽  
Chuang Yao ◽  
Kai Wang ◽  
Chang Q. Sun ◽  
Bo Zou
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Bond Energy ◽  
Room Temperature ◽  
Solute Concentration ◽  
Solute Interaction ◽  
Solute Interactions

H–O bond energy governs the PCx for Na/H2O liquid–VI–VII phase transition. Solute concentration affects the path of phase transitions differently with the solute type. Solute–solute interaction lessens the PC2 sensitivity to compression. The PC1 goes along the liquid–VI boundary till the triple phase joint.

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