Summary:The preprint proposes a salt-assisted microwave-induced solid-state combustion route for controlled LaB6 nanoparticle synthesis from La(NO3)3·6H2O, urea, and boron powder. XRD and thermodynamic analysis support the proposed formation mechanism. With NaCl and LaCl3·7H2O added at X1 = 1 and X2 = 0.5, the product consisted of uniform LaB6 nanocubes with a D50 of 70.6 nm. When used in transparent thermal-insulation glass coatings, the sample showed 71.1% visible-light transmittance and reduced the internal temperature of a test chamber by 10.2 °C compared with uncoated glass.