Nanocrystalline metal tungstates [MWO4 (M = Ca, Sr, Ba, Pb)] phosphors, which have scheelite structure, were successfully synthesized at low temperatures via a modified citrate complex route assisted by microwave irradiation. Crystallizations of the MWO4 (M = Ca, Sr, Ba, Pb) phosphors were detected at 400 degrees C and were completed at 500 degrees C. Most of the MWO4 (M = Ca, Sr, Ba, Pb) nanocrystallites heat-treated above 500 degrees C showed primarily spherical and homogeneous morphology with particle size of 20-30 nm. The nanocrystalline MWO4 (M = Ca, Sr, Ba, Pb) phosphors prepared at 600 degrees C exhibited a spread-eagle shape of blue luminescent spectra, which was due to Jahn-Teller effect on [WO42-] tetrahedron. (C) 2005 The Electrochemical Society.