Nanoparticles readily agglomerate, especially during nucleation, growth, and calcination processes. In this work, modified carbon black (MCB) has been used to prevent particle agglomeration during the nucleation step in the preparation of a highly dispersed nano-La(OH)(3) precursor by a coprecipitation reaction. The surface carboxyl groups formed on MCB after modification can adsorb and fix positively charged La3+ ions on the surface. Therefore nano-La(OH)(3) nuclei can be uniformly deposited on the MCB surface. After nucleation, La(OH)(3) particles with a size of about 20 nm With a positive surface charge still interact strongly With the negatively charged MCB surface, which effectively prevents their agglomeration during the subsequent aging process. Furthermore, due to the release of CO2 over a wide temperature range from 400 to 700 degrees C during a subsequent calcination process, La2O3 particles obtained by calcination of the La(OH)(3) precursor can be effectively isolated at high temperature and prevented from agglomerating. By using MCB as an agglomeration inhibitor in this way, highly dispersed La2O3 nanoparticles with a size of 50 nm having excellent photoluminescence ability can be prepared.