Thermal behavior of ammonium octafluorodirhenate(III)

The thermal behavior of (NH4)(2)[Re2F8]center dot 2H(2)O salt was studied in the temperature range 150-700 degrees C under flowing nitrogen gas. The decomposition products were studied by powder X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. Results are consistent with the formation of (NH4)(2)[Re2F8] salt at 150 degrees C, amorphous rhenium metal at 300 and 400 degrees C, and crystalline rhenium metal at 500 and 700 degrees C. A mechanism of formation of rhenium metal from (NH4)(2)[Re2F8]center dot 2H(2)O was proposed. The effect of crystallite size and lattice strain was evaluated at 500 and 700 degrees C from powder XRD peak broadenings using both Williamson-Hall and the modified Scherrer methods.

Automated summary

The thermal behavior of (NH4)(2)[Re2F8]·2H2O salt was studied, and the decomposition products were analyzed using different techniques. Different metal forms were observed at different temperatures, and a mechanism for the formation of metal from the salt was proposed. The effects of crystallite size and lattice strain were evaluated using different methods.