Formation of organic ion cocrystals, phase transition and ion conduction

Abstract

Organic ionic plastic crystals (OIPCs) are increasingly drawing attention recently owing to their many practical applications. In this study, seven organic salts [Cat1][Cat2][Ni(mnt)2] were prepared, herein mnt2− = maleonitriledithiolate, Cat1+...

Structural, magnetic and phase transition properties in S = ½ radical solid solutions of [FxCl1−x-BzPy][Ni(mnt)2] (x = 0.07–0.87)

“…41 On the basis of the above findings, we suppose that, around T C , the contribution of Coulomb interactions to the formation energy of the lattice is comparable, and however, the contribution of magnetic couplings to the formation energy of the lattice is significantly different for the HTP and the LTP in the [F x Cl 1− x -BzPy][Ni(mnt) 2 ] ( x = 0–1) crystals. Taking [F-BzPy][Ni(mnt) 2 ] as an example, the magnetic coupling energy is estimated to be ∼0.13 kJ mol −1 (= J / k B × 8.31 × 10 –3 kJ mol −1 ) in the HTP and ∼1.87 kJ mol −1 ( = Δ /(2 k B ) × 8.31 × 10 –3 kJ mol −1 ) in the LTP, and the magnetic coupling energy is close to the intermolecular van der Waals interaction energy (generally, less than 5 kJ mol −1 ) in the LTP, 42 but it is much higher than that in the HTP, and this leads to the crystal structure being more thermodynamically stable in the LTP than that in the HTP, and the lattice vibrations assist the transformation between the HTP and the LTP in [F-BzPy][Ni(mnt) 2 ], and this case is similar to that in the spin-Peierls transition.…”

“…as an example, the magnetic coupling energy is estimated to be ∼0.13 kJ mol −1 (=J/k B × 8.31 × 10 -3 kJ mol −1 ) in the HTP and ∼1.87 kJ mol −1 ( = Δ/(2k B ) × 8.31 × 10 -3 kJ mol −1 ) in the LTP, and the magnetic coupling energy is close to the intermolecular van der Waals interaction energy (generally, less than 5 kJ mol −1 ) in the LTP, 42 but it is much higher than that in the HTP, and this leads to the crystal structure being more thermodynamically stable in the LTP than that in the HTP, and the lattice vibrations assist the transformation between the HTP and the LTP in [F-BzPy] [Ni(mnt) 2 ], and this case is similar to that in the spin-Peierls transition.…”

Tunable thermotropic phase transition triggering large dielectric response and superionic conduction in lead halide perovskites

“…This is because the globularshaped cations gain more thermal energy at high temperature, and the rotational freedom degrees of cations are much increased, leading to plastic crystal behavior. 43,49 Actually, the crystals of 1 show plastic deformation in the HT phase (Fig. S6 †).…”