A reactor for <i>in situ</i> , time-resolved neutron diffraction studies of microwave-induced rapid solid-state chemical reactions

Utilizing direct microwave- (MW)-induced heating in solid-state synthesis yields the clear benefits of greatly reduced reaction times and lower energy requirements as compared with conventional methods. Here, we describe a bespoke single-mode cavity (SMC) MW reactor designed to operate within a neutron beamline that allowed powder diffraction data to be collected from materials <i>in situ</i> as they were heated using MWs. The unique set-up was used to investigate the rapid solid-state synthesis of the binary metal chalcogenide thermoelectric (TE) materials Bi₂Se₃, Bi₂Te₃, Sb₂Se₃ and Sb₂Te₃. The resultant time-resolved diffraction data from each synthesis were time-sliced post-reaction into segments covering periods of tens of seconds, enabling the reaction progression to be visualized as colourmap plots. This technique enabled the accurate tracking of polycrystalline structure formation and a quantitative analysis of phase fractions during the accelerated heating and subsequent cooling stages of each reaction. Our investigations have also revealed some of the present limitations of rapid <i>in situ</i> neutron diffraction techniques and how these might be remedied.This article is part of the discussion meeting issue 'Microwave science in sustainability'.