Heterotrimetallic lanthanide-substituted bismuth titanate (BLT, where lanthanide is neodymium) with stoichiometry Nd0.75Bi3.25Ti3O12 has been obtained in both highly homogenized crystalline and amorphous thin film forms using three different multicomponent precursors, A (formed from Nd(OC3H7i)(3), Bi(OOC.CH3)(3), and Ti(OC3H7i)(4) taken in the desired stoichiometry), B (formed from Nd(OC3H7i)(2)(acac), Bi(OOC.CH3)(3), Ti(OC3H7i)(3)(acac)), and C (formed from Nd(OC3H7)(acac)(2), Bi(OOC.CH3)(3), Ti(OC3H7)(3)(acac), in the desired stoichiometry), and employing controlled acidic hydrolysis during the sol-gel method. Paramagnetic Nd(III), an f(3) metal ion, gives characteristic 4f-4f transition spectra in the visible and near infrared region. The sensitivity of 4f-4f transitions to minor coordination changes around paramagnetic Nd3+ has been used to monitor hydrolysis during the progress of the sol-gel process of the multicomponent BLT precursors. The variation of intensities (oscillator strengths) of 4f-4f bands during hydrolysis, as well as the variation of Judd-Ofelt intensity parameters, has helped in following the preliminary kinetics of hydrolysis. Highly complex polycondensation reactions occurred during sol-gel hydrolysis of three BLT precursors. Rates of hydrolysis with respect to five 4f-4f transitions of Nd(III) were determined. The different types of multicomponent BLT precursors have shown different rates of hydrolysis, following the reactivity trend A > B > C. (C) 2003 Elsevier Inc. All rights reserved.