Ca(BH4)2 compounds were investigated above room temperature by anelastic spectroscopy (AS) and concomitant measurements of thermogravimetry and mass spectrometry (TGA/MS). Both AS and TGA/MS indicate that even after a thermal treatment at 125°C for 20 h, a non-negligible residual of THF adduct is still present in the sample, which can be removed on a subsequent thermal treatment at temperatures lower than 250°C. Above 250° C dehydrogenation takes place. Moreover, AS sensitively detects the occurrence of the ? ???' structural phase transition around 180°C, and the ?' ? ? transformation, which is completed around 330 °C. The two transitions are not detected by differential scanning calorimetry. We also show that both transitions are irreversible and are not accompanied by a latent heat.
Revised: May 28, 2014 |
Published: September 15, 2011
Citation
Paolone A., O. Palumbo, O. Palumbo, P. Rispoli, A. Miriametro, R. Cantelli, and A.T. Luedtke, et al. 2011.Structural phase transitions and adduct release in calcium borohydride.Journal of Alloys and Compounds 509, no. Supplement 2:S691-S693.PNNL-SA-74977.doi:10.1016/j.jallcom.2010.10.115