기계화학적 합성법에 의한 CaTiO3 분말의 형성 및 구조적 열적 특성

Abstract

Anatase(TiO2) is transformed into rutile via brookite within 60min by room temperature of milling under dry atmospheric condition using a planetary ball mill. This polymorphic transformation of anatase leads to the mechanochemical mixture of the crystalline CaTiO3 from the mixture with CaO easier than rutile mixture. In the XRD experiments, 45min milling of the CaO-anatase mixture induce the formation of the fairly crystalline CaTiO3 phase, the crystalline phase is surrounded by an amorphous phase. The CaTiO3 single phase can be formed in the mixture milled for 120min or more. The amount of CaTiO3 in the mixture increases with improving its crystallinity as the milling progresses. According to the TEM observation, the CaTiO3 mixtures milled for about 120min or more consist of many fine particle of about 10-20nm. The CaTiO3 microcrystals are formed in the mixture milled for about 120min or more. One of lattice planes, [121] is clearly observed in the TEM micrograph of the 420min milled mixture, while the lattice image is partly detected in the mixture milled for about 120min or less. The grains grow in size in the prolonged milling, and their sizes reach about 20nm at 420min milling, and the grain boundary and lattice fringe appear clearly as the milling progresses. The size of microcrystals becomes larger with increasing milling time. The structural and thermal properties of the alloys by mechanical alloying was investigated by X-ray Diffraction, Scanning Electron Microscope, Energy Dispersive X-ray Spectrometer, Transmission Electron Microscope, Thermogravimetric/Differential Thermal analysis and Fourier Transform Infrared analysis.