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. We also show that both transitions are irreversible and are not accompanied by a latent heat.
Structural phase transitions and adduct release in calcium borohydride
2011
Abstract
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. We also show that both transitions are irreversible and are not accompanied by a latent heat.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
