Phase Transformations in Lutetium Borides at Heating in Vacuum
The LuB12 ® LuB4 ® LuB2 phase transformations on annealing in vacuum (T=(1400÷1800) K, p < 10-2 Pa) are investigated with use of the parent single crystals. SEM and X-ray researches of the corresponding lutetium boride single crystals were carried out before and after their annealing. It is shown that the LuB12 → LuB4 phase transformation takes place in surface layer and transition region spreads inwards the single crystal bulk with time. According to the assessed Lu-B phase diagram the LuB4 phase transformation into other individual phases is impossible, and at first it is shown that under corresponding conditions the LuB4 → LuB2 spontaneous phase transformation takes place both on the surface and in the LuB4 single crystal bulk.
Yves Bréchet, Emmanuel Clouet, Alexis Deschamps, Alphonse Finel and Frédéric Soisson
A. Taran et al., "Phase Transformations in Lutetium Borides at Heating in Vacuum", Solid State Phenomena, Vols. 172-174, pp. 464-469, 2011