Dense Nano-structured and Preferentially-oriented Anatase Synthesized by Pulsed High Current Heating

Abstract

Dense nano-structured bulk anatase was synthesized with pulsed high current heating (PHC) method. Nano-powder anatase compact was successfully consolidated up to 90%TD (TD; theoretical density) with preferential orientation and no transformation to rutile, with suppressing the grain growth below about 300 nm. Nearly full densification over 95%TD was attained in the condition of coexisting both anatase and rutile phases. Remarkable preferential orientation was observed in the anatase consolidated at the temperature ranging from 700°C to 850°C. The preferential orientation depended on the angle (z) of crystallographic plane of anatase to the direction of current (and pressure). Degree of the orientation linearly increased with the increase of pressure and the angle in ranging from 45° to 90°, resulting in the appearance of strong preferential orientation in the (004) and (105) XRD peaks. While preferential orientation was not found in the crystallographic planes of anatase observed at the angle z less than 45°.