A Novel Low Temperature Synthesis of Pure LaB₆ Powder by Solid-State Reduction Reactions Involving La₂O₃ and B₂O₃

The present study investigates a novel approach for generating lanthanum hexaboride (LaB₆) at low temperatures using lanthanum oxide (La₂O₃), boron trioxide (B₂O₃), and magnesium (Mg) via a solid-state reduction followed by innovative leaching process. In this investigation, the powder blends (La₂O₃, B₂O₃, and Mg) have been ball milled for varied times ranging from 10 min to 25 h. The resultant powder blends are then compressed into pellets and subsequently sintered at various temperatures (ranging from 500 to 900 °C) and time intervals (ranging from 5 to 20 h). It has been observed that the solid-state reduction reaction at lower temperatures produces magnesium oxide (MgO), lanthanum borate (LaBO₃), and magnesium borate (Mg₃B₂O₆) in addition to LaB₆. However, leaching process (using HCl and H₂SO₄) has been carried out to remove the intermediary phases and produce pure LaB₆. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier transformation infrared spectroscopy, and Raman spectroscopy have been carried out to confirm the formation of LaB₆ and its high purity. The purity of the LaB₆ is found out to be ~ 97%.