Bis(ammonium) fluorophosphate at room temperature

Area of Science:

• Crystallography
• Solid-state chemistry
• Materials science

Background:

• The ammonium fluorophosphate ((NH4)2(PO3F)) crystal structure and its phase transitions are not well-characterized.
• Understanding the structural properties of such compounds is crucial for potential applications in materials science.

Purpose of the Study:

• To determine the room-temperature crystal structure of ammonium fluorophosphate ((NH4)2(PO3F)).
• To investigate the phase transitions of ammonium fluorophosphate.

Main Methods:

• X-ray diffraction analysis was used to elucidate the crystal structure.
• Differential scanning calorimetry was employed to detect phase transitions.

Main Results:

• The room-temperature phase of (NH4)2(PO3F) was identified as orthorhombic with space group Pna2(1).
• The structure comprises ammonium cations (NH4+) and fluorophosphate anions (PO3F2-) linked by N-H.O hydrogen bonds.
• Two distinct phase transitions were observed at approximately 251 K (cooling) and 274 K (heating).

Conclusions:

• Ammonium fluorophosphate ((NH4)2(PO3F)) exhibits an orthorhombic structure related to the beta-K2SO4 family at room temperature.
• The compound undergoes reversible phase transitions, indicating temperature-dependent structural changes.