Zur Thermischen Zersetzung von SrPO₃F · H₂O

Abstract

Der thermische Abbau Von SrPO3F · H2O wurde durch komplexe thermische Analyse charakterisiert. Dabei wurden die thermogravimetrischen Untersuchungen sowohl mit simultan als auch parallel durchgeführten massenspektrometrischen Gasanalysen kombiniert. Die thermische Zersetzung beginnt mit dem Verlust Von ∼0,8 mol Wasser, danach setzt partielle Hydrolyse unter Bildung Von HF ein. Die deutlich strukturierte POF3‐Entstehung über 500°C bleibt jedoch weitgehend von der Dehydratisierung unbeeinflußt. Einzelne Teilreaktionen werden formuliert, die über 600°C zum α‐Sr2P2O7 und SrF2 bzw. über 750°C zum α‐Sr2P2O7 und Sr5(PO4)3F führen. Die entsprechend berechneten Massenverluste stimmen mit den experimentellen Werten überein.

Syntheses, Crystal Structures, NMR Spectroscopy, and Vibrational Spectroscopy of Sr(PO3F)·H2O and Sr(PO3F)

“…Unlike the previously mentioned monothiophosphates NaM(PO 3 S) · 9H 2 O (M = Mg, Ca, Sr,7,30 Ba), which decompose by the loss of H 2 S upon mild heating, Sr(PO 3 F) · H 2 O dehydrates without the evaporation of HF to yield phase‐pure Sr(PO 3 F) above 80 °C. In a previous investigation on the thermal behaviour of Sr(PO 3 F) · H 2 O, it was shown by simultaneous thermogravimetry and mass‐spectroscopic measurements that the decomposition of the hydrous phase follows a multistage mechanism until the end‐products α‐Sr 2 P 2 O 7 and the apatite‐type phase Sr 5 (PO 4 ) 3 F form above 750 °C 16. For the intrinsic dehydration, the authors determined a decomposition range of 80–140 °C and a mass loss corresponding to ca.…”

“…The dehydration seems to be controlled kinetically and can be monitored at different heating rates and heating times of the samples. A partial dehydration occurs if the material is heated quickly or only for a short time above the onset of the dehydration temperature (as in the previous thermogravimetric study16 or for the preparation of samples for solid‐state NMR studies, see below), whereas slow heating rates and the retention of the chosen temperature for several hours or even days lead to complete dehydration. The differential weighing of a hydrous sample treated at 115 °C for two weeks under atmospheric conditions revealed a dehydration degree of more than 99 %.…”

Synthesis, Crystal Structure, and Properties of Mn(PO3F)(H2O)2

“…[20,21] The situation in Mn(PO 3 F)(H 2 O) 2 supports the general observation that hydrogen bonds of the type O-H···F are not pronounced or developed at all in water-or OH-containing fluorophosphates, as has been shown for numerous other examples. [6,[22][23][24][25][26][27] Despite of the same chemical formula type M(PO 3 F)(H 2 O) 2 (M = divalent transition metal), Mn(PO 3 F)(H 2 O) 2 crystallizes in a different crystal structure type than Cu(PO 3 F)(H 2 O) 2 . [14] The latter has a monoclinic structure with four formula units and consists of a [CuO 4 It is interesting to note that for Mn(PO 3 F)(H 2 O) 2 no corresponding dihydrate has been described in sulfate chemistry so far.…”

The characterization of the thermal behaviour of inorganic fluorides using quasi-static thermoanalytical methods

“…At 5 kPa another pathway of decomposition is observed. HP is the main component of the gas phase after the evaporation of more than 0.7 mol H20 and then a continuous mass loss between 150 ~ and 450~ was observed [11]. Also the following decomposition of SrPO3F is influenced: in contrast to the two reaction steps at 5 kPa, only one decomposition step is observed at higher partial pressures.…”

“…The thermal decomposition of these compounds was investigated several years ago [10][11][12]. It was impossible to separate the thermal dissociation and the hydrolysis at that time.…”