A Thermodynamic Analysis of Lanthanum Hexaboride Crystal Preparation from Aluminum Flux with the Use of Compound Precursors

The temperature dependencies of the change in Gibbs energy for a series of probable reactions in the aluminothermic reduction of La2O3, LaCl3, and B2O3, borothermic reduction of La2O3, and synthesis of LaB6in an aluminum flux using compound precursors of the boride components have been plotted on the basis of thermodynamic data from the literature. It has been shown that under the experimental conditions of the growth of rare earth boride single crystals by crystallization from high-temperature solutions in molten aluminum, a rare earth oxide and B2O3should be used as precursors instead of the corresponding elements.