Melt-assisted synthesis to lanthanum hexaboride nanoparticles and cubes

Lanthanum hexaboride ( LaB 6 ) nanocrystals and cubes were successfully synthesized at 700 ∘ C for 2 h under argon atmosphere by a melt-assisted method using LaCl 3 and NaBH 4 as reactants, NaCl–KCl or zinc or NaCl–KCl–zinc as reaction melt. The obtained products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Raman spectroscopy. XRD patterns and Raman spectra confirmed the formation of LaB 6 with high purity. TEM and SEM results showed LaB 6 powders prepared in mixed molten salts of NaCl–KCl were mainly composed of nanoparticles with sizes of ca. 8 nm. The morphology of LaB 6 presented as regular cubes (100–300 nm) when metal zinc was used as reaction melt. Photothermal conversion test indicated that nanoparticles had a better photothermal conversion performance than cubes.