Low-temperature direct synthesis of CeO2-ZrO2 solid solution nanoparticles by a hydrothermal method

Well-crystallized CeO2-ZrO2 solid solution nanoparticles were successfully prepared by a hydrothermal method in a single step at 120 degreesC, for 6 h without any post heat treatment. The particle sizes of 6 +/- 3 nm by surface area measurements are in good agreement with crystallite sizes of 6 +/- 3 nm by X-ray diffraction. Transmission microscopy also confirmed the formation of crystals of 5-8 nm in the products. In the formation of the homogeneous solid solutions the complete oxidation of Ce3+ to Ce4+ in the precipitated gels seems to be one of the important steps. The solid solutions contained several wt % water, but it was expelled by calcining greater than or equal to600 degreesC. The heating of the samples brought about grain growths, but did not change the phases. The specific areas of 120-200 m(2)/g of as-prepared samples were decreased to 4-14 m(2)/g by heating at 900 degreesC for 4 h.