Transformation at Increased Pressure

The transformation of h-BN into c-BN (at 6.5 GPa) and the reverse transformation of c-BN to h-BN (from 0.6 to 2.1 GPa) were investigated in a Li3N-BN catalyst system [40], Synchrotron radiation was used to check the phases and to examine reactions between the BN-phases and the catalyst. 

The reverse transformation was investigated in a temperature range from 800 to 1200 °C. The reaction started at the same time at which a melt was formed. The experiments described showed that the transformation from c-BN to h-BN took place within minutes. These experiments revealed that c-BN is the stable phase at standard conditions in the presence of a Li-catalyst [41]. 

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