Development of a high pressure stirring cell up to 2 GPa: a new window for chemical reactions and material synthesis

Abstract

A new method for stirring under high pressure conditions has been developed and tested. The key component is a Teflon cell assembly equipped with magnetic stirring function, which is capable to operate across a wide pressure range, up to at least 2 GPa, in a large volume press. The setup enables adjustable stirrer rotation rate and detection of stirring in a sample, e.g. to observe liquidsolid phase transitions at high pressure. The viscosity limit of stirring is ca. 500 times that of water at room temperature (i.e. ∼500 mPas). Moreover, we show that zinc oxide nanoparticles hydrothermally synthesized at 0.5 GPa and 100°C under stirring conditions show an order of magnitude smaller size (100 nm) compared to those synthesized under non-stirring conditions (1 μm). The wide pressure range for stirring of viscous media opens interesting possibilities to produce novel materials via hydrothermal synthesis and chemical reactions.

Phase Diagram of Binary Alloy Nanoparticles under High Pressure

“…Daou et al synthesized Fe 3 O 4 nanoparticles using a hydrothermal process in which high pressure was applied at elevated temperatures [ 64 ]. Hsu et al synthesized wurtzite-ZnO nanoparticles under pressures as high as 2 GPa [ 65 ]. In order to understand the phase stability of nanoparticles at high pressure and high temperature, the phase diagram of nanoparticles should be established at high pressure.…”