Having tried to do this myself, it is almost impossible to light an aluminium/boric oxide mixture easily. I gave up on aluminium and used magnesium
instead. It worked that time. I then chucked the products into dilute acid, which dissolves away everything except the boron. I got an amorphous brown
powder.
Curious... I watched MrHomeScientist's video and he obtained the black, crystalline allotrope. There is an amorphous brown allotrope, but it is not
stated how this is prepared as opposed to the crystalline black.
Assuming the above is amorphous boron, what gave rise to the different allotropy?blogfast25 - 8-1-2014 at 06:32
Curious... I watched MrHomeScientist's video and he obtained the black, crystalline allotrope. There is an amorphous brown allotrope, but it is not
stated how this is prepared as opposed to the crystalline black.
Assuming the above is amorphous boron, what gave rise to the different allotropy?
To get a crystalline product the melting point of the boron must at least be reached (that is a necessary but not necessarily sufficient condition).
So perhaps it was just a question of end-temperature of the reaction.
What makes you conclude his product was crystalline though? The naked eye does not do XRD very well! mkurek - 8-1-2014 at 08:25
With other thermites it becomes a question of heat transfer from the thermite to the boron reaction and of what kind of crucible could withstand such
a thermal shock.
