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The high-temperature phase of sodium ortho-phosphate, A-Na3PO4, is characterized by a dynamic rotational disorder of its polyatomic anions and, at the same time, by a considerable translational mobility of its cations. During the past decade, there has been considerable controversy about the question of whether both kinds of motion are dynamically coupled. To resolve this issue we have probed anionic and cationic motion individually over a wide range of experimental time scales. Coherent quasielastic neutron scattering as well as temperature-dependent 17 O NMR lineshape and relaxation spectroscopy serve to characterize the rotational motion of the anions, whereas the cation motion is probed by high-frequency conductivity and 23 Na NMR relaxation measurements. On the picosecond timescale, the combined interpretation of the neutron scattering and electrical conductivity data suggests strong dynamic coupling between the rotation of the phosphate groups about one of the four threefold P-O axes and the spatial fluctuations of nearby sodium ions. On more extended timescales, the NMR data indicate an additional, slower process, * Corresponding authors.

Professor Hanskarl Mu È ller-Buschbaum zum 70. Geburtstag gewidmet Inhaltsu È bersicht. Nach Guinier-Simon-Untersuchungen ist Kaliumtrifluormethylsulfonat dimorph, mittels DSC wird eine Umwandlungstemperatur von ±33°C und eine Umwandlungsenthalpie von 0.93 ± 0.03 kJ/mol ermittelt. Im Beugungsexperiment erstreckt sich die Phasenumwandlung in die Tieftemperaturmodifikation u È ber einen Temperaturbereich von ±63°C bis ±45°C. Sie ist monoklin mit den Gitterparametern (±120°C) a = 10.300(3) A Ê , b = 6.052(1) A Ê , c = 14.710(4) A Ê , b = 111.83(2)°. Die Raumtemperaturmodifikation kristallisiert monoklin in der Raumgruppe P2 1 mit den Gitterparametern a = 10.679(5) A Ê , b = 5.963(2) A Ê , c = 14.624(5) A Ê und b = 111.57(3)°(Z = 6). Nach den Ergebnissen von Einkristallstrukturanalysen ist Kaliumtrifluormethylsulfonat aus drei verschiedenen Kalium-SauerstoffKoordinationspolyedern aufgebaut, die so angeordnet sind, daû die koordinierenden SO 3 CF 3 -Anionen ovale Kana Èle ausbilden, in die alle lipophilen CF 3 -Gruppen hineinragen. Die Schmelzenthalpie (F p = 237°C) von Kaliumtriflat betra È gt 13.59 kJ/mol, die spezifische Kaliumionenleitfa È higkeit betra È gt 3.68´10 ±6 Scm ±1 bei 205°C. Crystal Structure, Phase Transition, and Potassium Ion Conductivity of Potassium TrifluoromethanesulfonateAbstract. According to the results of temperature dependent powder diffractometry (Guinier-Simon-technique) potassium trifluoromethanesulfonate is dimorphic. The phase transition occurs between ±63°C and ±45°C. The low-temperature modification crystallizes monoclinic with a = 10.300(3) A Ê , b = 6.052(1) A Ê , c = 14.710(4) A Ê , b = 111.83(2)°(±120°C) and the room-temperature modification with a = 10.679(5) A Ê , b = 5.963(2) A Ê , c = 14.624(5) A Ê , b = 111.57(3)°, Z = 6, P2 1 . According to single crystal structure determination, potassium trifluoromethanesulfonate consists of three different potassium-oxygen-coordination polyhedra, linked by sulfur atoms of the trifluoromethanesulfonate groups. This results in a channel structure with all lipophilic trifluoromethane groups pointing into these channels. By means of DSC, the transition temperature and enthalpy have been determined to be ±33°C and 0.93 ± 0.03 kJ/mol, respectively. The enthalpy of melting (237°C) for potassium trifluoromethanesulfonate is 13.59 kJ/mol, the potassium ionic conductivity is 3.68´10 ±6 Scm ±1 at 205°C.

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Inhaltsubersicht. Nach Kiihl-Guinier-Simon-Untersuchungen ist Natriumtrifluormethylsulfonatmonohydrat dimorph. Die Phasenumwandlung erfolgt bei -35 "C. Die Raumtemperaturmodifikation kristallisiert monoklin in der Raumgruppe P2Jc mit den Gitterkonstanten a = 941,6(5) pm, b = 654,3(2) pm, c = 1062,4(5) pm und B = 107,73(2)". In der Kristallstruktur liegen Doppelschichten aus Trifluormethylsulfonatanionen vor, in denen die unpolaren CF3-Gruppen einander zugewandt sind. Natrium wird von jeweils einem Sauerstoffatom aus vier verschiedenen Anionen sowie von zwei Kristallwassermolekulen koordiniert und erreicht eine verzerrt oktaedrische Koordination. Die Tieftemperaturmodifikation kristallisiert orthorhombisch in der Raumgruppe Pnma mit den Gitterkonstanten a = 645,31(9) pm, b = 538,03 (9) pm, c = 1745,3(3) pm. Die Abgabe von einem Mol Kristallwasser erfolgt bei 136 "C. Wasserfreies Natriumtrifluormethylsulfonat zeigt eine Phasenumwandlung in eine Hochtemperaturmodifikation bei 252 "C, die eine gute Natriumionenleitfahigkeit zeigt (a = 4,l . lo-' n-' cm-' bei 250 "C).Abstract. According to the results of temperature dependent powder diffractometry (Guinier-Simon-technique) sodium trifluormethanesulfonate monohydrate is dimorphous. The phase transition occurs at -35 "C. The room-temperature modification crystallizes monoclinic in space group P21/c with the lattice parameters a = 941.6(5) pm, b = 654.3(2) pm, c = 1062.4(5) pm and p = 107.73(2)". The crystal structure consists of double layers of trifluormethanesulfonate anions, the lipophilic CF3-groups pointing at each other. Sodium is coordinated by four oxygen atoms from four different anions and by two molecules of crystal water. The resulting polyhe-dron may be addressed as a distorted octahedron. The lowtemperature modification crystallizes orthorhombic in space group Pnma with the lattice parameters a = 64.5.31(9) pm, b = 538.03(9) pm, c = 174.5.3(3) pm. The loss of crystal water occurs at 136 "C. Anhydrous sodium trifluormethanesulfonate shows a phase transition at 252 "C. The high-temperature modification is a good sodium ionic conductor (a = 4.1 . lo-' &cm-' at 250 "C).