Formation of Borides

The present status of information about phase equilibria and the formation of borides is summarized in Table 2 (binary borides) and in Figure 2a, b (ternary systems) ". ... 

The stabilizing influence of B atoms in sites is well known from MJ5M33B, borides (Mn5Si3 type), e.g., in the formation of boride interstitials by filling metal host lattices that develop from binaries. Boron occupancy (octahedral metal... 

Finally, the high-pressure synthesis favors the formation of borides that are difficult to prepare under standard conditions. In this way SmBj with the AlB2-type structure and GdB,2 and ThB,2 with the UB,2-type structure are prepared. ... 

Experimental work can be difficult owing to both the high volatility of the metals and their reactivity toward O2 (e.g., alkali-metals, alkali-earth metals, rare earths). Once reaction begins it often is highly exothermic judging by the enthalpies of formation of borides. ... 

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