Fast ion conductors with rotating sulphate ions

Abstract

RBsumk.-Des ttudes de diffraction des rayons X et des neutrons par Li2S04 c.f.c. (entre 575 O C et 860 O C pour Li2S04 pur) montrent la grande facilite des ions sulfates a prendre toutes les orientations. Ces mouvements de rotation fortement couplte entrainent un changement permanent de la position des cations. Cela explique pourquoi tous les cations mono-et divalents ont, jusqu'a maintenant, montre une grande mobilitt dans plusieurs phases sulphates, contrairement au cas d'autres types d'tlectrolytes solides. Ces phases sulfates sont plastiques avec des proprittts qui ressemblent a celles d'autres types de mattriaux plastiques. Des Btudes de diffusion BrilIouin montrent des difftrences notables entre les phases plastiques c.f.c. et liquide Li2S04 alors que l'indice de refraction change a peine au point de fusion.

Structure and dynamics of the plastic crystal tetramethylammonium dicyanamide—a molecular dynamics study☆

“…); for a material to exhibit plastic mechanical properties, its final entropy of melting, ΔS f , should be less than 20 J K −1 mol −1 [6]. In the 1980s, some inorganic salts were also found to exhibit rotator phases as well as plastic behaviour, for example, Li 2 SO 4 and Na 3 PO 4 , where a "paddle-wheel" rotation of the anions while fixed on their lattice sites was suggested as the cause of the long-range translational motion of the Li + and Na + cations [7,8].…”

Plastic crystal behaviour in tetraethylammonium dicyanamide

“…This became known as Timmermans' criteria [6]. In later years, interest grew in plastic crystal behaviour in inorganic salts such as Li 2 SO 4 [5,11,12] and Na 3 PO 4 [13][14][15], which were investigated briefly as possible electrolyte materials. Studies on a range of organic molecular plastic crystals have further investigated the contributions to the entropy changes at the solid to plastic and plastic to liquid transitions.…”

Thermal analysis, nuclear magnetic resonance spectroscopy, and impedance spectroscopy of N,N-dimethyl-pyrrolidinium iodide: An ionic solid exhibiting rotator phases

“…3 Certain inorganic salts have also been found to exhibit rotator phases and sometimes also plastic behavior. Examples include Li 2 SO 4 and Na 3 PO 4 , where "paddle-wheel" rotation of the anions while fixed on their lattice sites has been suggested as the cause of the long-range translational motion of the Li + and Na + cations. 4,5 Other organic-based materials with multiple phase transitions and rotator phases include families of quaternary-ammonium cations, imidazolium cations, and pyrrolidinium cations.…”

“…Examples include Li 2 SO 4 and Na 3 PO 4 , where "paddle-wheel" rotation of the anions while fixed on their lattice sites has been suggested as the cause of the long-range translational motion of the Li + and Na + cations. 4,5 Other organic-based materials with multiple phase transitions and rotator phases include families of quaternary-ammonium cations, imidazolium cations, and pyrrolidinium cations. [6][7][8][9][10][11] The salts based on the N-alkyl-N-methyl-pyrrolidinium cations ͑Fig.…”