A series of LaxCoFe2-xO4 prepared by flash method, where x=0.05, 0.1, 0.15, 0.2, 0.25 and 0.3. The
powder samples were characterized by X-ray diffraction, FTIR and TEM (transmission Electron Microscope). The
x-ray analysis shows that the samples have a single phase cubic spinel structure. The lattice constant was founded to
be nearly constant up to x=0.25 and then increase as lanthanum content increase. The FTIR spectra of the sample
were recorded from 200-4000 cm-1, which analyzed the molecular structure of the samples and the formation of
spinel structure in bulk and nano modes. The HRTEM photographs clearly show the presence of cubic nanoparticle
with average diameter of 16nm for flash samples. The high resolution (HRTEM) indicates the presence of lattice
planes which confirm the crystalline nature of the sample. The effect of La3+ ions on dielectric properties are
presented in this paper.