Synthesis of morphologically controlled lanthanum carbonate particles using ultrasound irradiation

Lanthanum carbonate particles, which can be used as precursors to lanthanum oxide, have been synthesised from lanthanum nitrate and urea in the presen ce and absence of ultrasound irradiation. The use of ultrasound irradiation was found to have a remarkable effect on the morphology of the lanthanum c arbonate particles formed. Needle-shaped particles were found to be formed in the presence of ultrasound irradiation, whereas spherical carbonate part icles were produced in the absence of ultrasound irradiation. Characterizat ion by powder X-ray diffraction, transmission electron microscopy, scanning electron microscopy, thermogravimetric analysis, differential scanning cal orimetry, FT-IR spectroscopy, as well as elemental analysis was carried out on the materials synthesised. The effect of heating on the chemistry and t he morphology of the carbonate particles was also investigated. The carbona te particles were found to be completely converted into lanthanum oxide at ca. 725 degreesC. In the case of the needle-shaped lanthanum carbonate part icles, the shape was found to be deformed to a small extent on heating, whe reas a larger degree of deformation was observed for the spherical lanthanu m carbonate particles.