Investigation of MBH4–VCl2, M = Li, Na or K

Systematic investigations of MBH4−VCl2, M = Li, Na, or K, 2:1 or 3:1, samples prepared by mechano-chemistry and different milling time in order to gain insight in the phase stability and search for novel borohydrides. The samples were investigated using powder X-ray diffraction and Raman spectroscopy. Subsequently, the samples were exposed to heat treatment and investigated by in-situ synchrotron radiation powder X-ray diffraction (SR-PXD). These studies reveal formation of numerous compounds during decomposition of the samples, which contrasts with previous investigations. In several cases the formed compounds were in a less well-crystalline state, which did not allow identification. One of the unidentified compounds was observed both in the LiBH4−VCl2 and NaBH4−VCl2 systems and appeared to decompose at T ∼ 190 °C and is assumed to be a new vanadium borohydride. Crystalline Li2VCl4 was observed, but a major fraction of the decomposition products appeared to be amorphous. The KBH4−VCl2 system revealed formation of well-crystalline solid solutions of K(BH4)1−xClx.