MICROWAVE IRRADIATION-ASSISTED METHOD FOR THE RAPID SYNTHESIS OF FINE PARTICLES OF α-Al_2O_3 AND α-(Al_(1-x)Cr_x)_2O_3 AND THEIR COATINGS ON Si(100)

摘要

Chromium-substituted p-diketonatc complexes of aluminium have been synthesized and employed as precursors for a novel "soft chemistry" process, wherein microwave irradiation of a solution of the complex yields, within minutes, well-crystallized needles of α-(Al_(1-x)Cr_x)_2O_3 measuring 20-30 nm in diameter and 50 nm long. By varying the microwave irradiation parameters and using a surfactant such as polyvinyl pyrrolidone, the crystallite size and shape can be controlled and their agglomeration prevented. These microstructural parameters, as well as the polymorph of the Cr-substituted Al_2O_3 formed, may also be controlled by employing a different complex. Samples of α-(Al_(1-x)Cr_x)_2O_3 have been characterized by XRD, FTIR, and TEM. The technique results in material of homogeneous metal composition, as shown by EDAX, and can be adjusted as desired. The technique has been extended to obtain coatings of α-(Al_(1-x)Cr_x)_2O_3 on Si(100).