The State and Optical Properties of Crystalline BaTiO₃ Nanoparticles Dispersed in Various Suspension Media

An investigation has been made on the state of barium titanate (BaTiO3; BTO, hereafter) nanoparticles of 10-15 nm in diameter dispersed in various suspension media, such as 2-methoxyethanol (ethylene glycol monomethyl ether: EGMME) with and without acetylacetone (Acac), ethanol, and isopropanol. The state of the nanoparticles dispersed in these suspension media is deduced from the behavior pattern of their optical transmittance (T), in the wavelength (λ) range of 300-900 nm; the concentration (c) of BTO nanoparticles in the suspensions was varied from 0.01 to 0.25 mol/L. T-c plots obtained for EGMME+Acac and EGMME suspensions at various wavelengths indicate that BTO nanoparticles take two and three different states in the suspensions, respectively, from mono-dispersed to agglomerated states with increasing c.