La_0.67Ce_0.03Sr_0.3MnO₃-coupled microwave assisted ultra-fast synthesis of nanocrystalline Cobalt oxide and Bismuth oxide

Bismuth hydroxide and Cobalt hydroxide gels were freshly prepared by adding aqueous sodium hydroxide to their corresponding nitrates under basic conditions. Then they were oven dried at 373 K and found to be amorphous in X-ray diffraction (XRD) study. They crystallized into their respective oxides by microwave irradiation (2.45 GHz) in merely 2 min using La_0.67Ce_0.03Sr_0.3MnO₃ (LCSMO) as couplant in a microwave domestic oven (~ 100 W). This is the lowest temperature treatment and synthesis time so far reported in the literature for the formation of these systems. Formation of nanocrystallites of Bi₂O₃ (10 nm) and Co₃O₄ (15 nm) has been confirmed by XRD. Normally these hydroxides produce oxides only on heating at temperature > 673 K or digesting them at 373 K for 4 - 6 hours as reported by us earlier. Microwave assisted heating proves to be a novel technology whose applications can be carefully harnessed due to its unique effects compared to the conventional heating, such as rapid volumetric heating, shortened reaction time and energy saving.