Thermal hysteresis loop in the elastic incoherent scattering function of vinylidene fluoride and trifluoroethylene ferroelectric copolymers

2005 ◽  
Vol 71 (18) ◽  
Author(s):  
E. Lopez Cabarcos ◽  
A. F. Braña ◽  
B. Frick ◽  
F. Batallan
Keyword(s):  
Hysteresis Loop ◽  
Vinylidene Fluoride ◽  
Thermal Hysteresis ◽  
Incoherent Scattering ◽  
Scattering Function ◽  
Incoherent Scattering Function ◽  
Thermal Hysteresis Loop

Magnetic, Spectral and Structural Aspects of Spin Transitions in Iron(II) Complexes of 2-(Pyrazol-3-yl)pyridine and 3-(Thiazol-2-yl)pyrazole

1999 ◽  
Vol 52 (2) ◽  
pp. 109 ◽  
Author(s):  
Lucia S. Harimanow ◽  
Kristian H. Sugiyarto ◽  
Donald C. Craig ◽  
Marcia L. Scudder ◽  
Harold A. Goodwin
Keyword(s):  
Hydrogen Bonding ◽  
Hysteresis Loop ◽  
Room Temperature ◽  
Thermal Hysteresis ◽  
Structural Data ◽  
Monoclinic Space Group ◽  
Space Group ◽  
Thermal Hysteresis Loop ◽  
Lower Temperature ◽  
Structural Aspects

Tris(ligand)iron(II) complexes of 2-(pyrazol-3-yl)pyridine (3ppH) and 3-(thiazol-2-yl)pyrazole (3tpH) undergo temperature-induced singlet (1A1) ⇔ quintet (5T2) transitions. The transition in [Fe(3ppH)3] [CF3SO3]2.2H2O is continuous and centred above room temperature while that in the anhydrous triflate salt is discontinuous and is centred below room temperature. The latter transition occurs via a thermal hysteresis loop of width 12 K, Tc↓ and Tc↑ being 229 and 241 K, respectively. The displacement of the transition to lower temperature in the anhydrous salt is believed to be associated with the loss of hydrogen bonding involving the uncoordinated pyrazole >NH group and solvate water. In [Fe(3tpH)2(3tp)] [ClO4].2H2O and [Fe(3tpH)2(3tp)] [BF4].2H2O (3tp is the deprotonated ligand) continuous transitions are observed, centred below room temperature. In these instances the displacement is consistent with the intrinsically weaker field of the bidentate system containing two five-membered heterocycles. Structural data were obtained for [Fe(3ppH)3][CF3SO3]2.2H2O, [Fe(3tpH)3] [BF4]2.1·5H2O and [Ni(3tpH)3] [BF4]2.2(3tpH). The average metal–nitrogen distances in the complexes are 1·97, 2·18 and 2·09 Å, severally. The large difference in the distances for the two iron complexes arises from the different ground states: a singlet for the 3ppH complex and a quintet for the 3tpH complex. In all three salts there is extensive hydrogen bonding involving the pyrazole >NH groups, the anions and the solvate molecules. [Fe(3ppH)3] [CF3SO3]2.2H2O: monoclinic, space group P21/c, a 12·33(1), b 24·44(1), c 12·55(1) Å, β 115·27(4)°, Z 4. [Fe(3tpH)3] [BF4]2.1·5H2O: monoclinic, space group C 2/c, a 41·56(2), b 16·418(3), c 18·154(7) Å, β 106·94(2)°, Z 8. [Ni(3tpH)3] [BF4]2.2(3tpH):P bcn, a 14·928(2), b 15·310 (3), c 17·882 (3) Å, Z 4.

Dynamical control of the spin transition inside the thermal hysteresis loop of a spin-crossover single crystal

2016 ◽  
Vol 486 ◽  
pp. 187-191 ◽  
Author(s):  
Kamel Boukheddaden ◽  
Mouhamadou Sy ◽  
Miguel Paez-Espejo ◽  
Ahmed Slimani ◽  
François Varret
Keyword(s):  
Single Crystal ◽  
Hysteresis Loop ◽  
Spin Crossover ◽  
Thermal Hysteresis ◽  
Spin Transition ◽  
Thermal Hysteresis Loop ◽  
Dynamical Control

Bidirectional photo-switching of the spin state of iron(II) ions in a triazol based spin crossover complex within the thermal hysteresis loop

2009 ◽  
Vol 477 (1-3) ◽  
pp. 156-159 ◽  
Author(s):  
Nawel Ould Moussa ◽  
Denis Ostrovskii ◽  
Victor Martinez Garcia ◽  
Gábor Molnár ◽  
Koichiro Tanaka ◽  
...  
Keyword(s):  
Hysteresis Loop ◽  
Spin State ◽  
Spin Crossover ◽  
Thermal Hysteresis ◽  
Thermal Hysteresis Loop
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