NH3BH3 as an internal hydrogen source for high pressure experiments

Aminoborane NH3BH3 is proposed as an appropriate material to produce hydrogen in the high-pressure cells designed for the synthesis of hydrides in sizeable amounts at pressures of a few GPa and elevated temperatures. Aminoborane is a non-hydroscopic material and it does not noticeably react with air that permits assembling the high-pressure cells under ambient conditions without any precautions. If heated to 300 °C at any pressure from 0.6 to 9 GPa, aminoborane decomposes to H2 gas and chemically inert amorphous BN and does not further absorb the liberated hydrogen. Experiments using NH3BH3 and AlH3 alternatively as the internal hydrogen source gave coinciding isotherms of hydrogen solubility in rhodium at 600 °C and pressures up to 9 GPa therefore demonstrating that the partial pressure of impurities (if any) in the H2 gas generated by NH3BH3 is well below the accuracy ±0.3 GPa of determination of the total gas pressure.