Development of an experimental set-up for electroresistance measurements of materials under high pressure and temperature

We present an original experimental set-up designed to measure the electroresistance of materials under extreme conditions of pressure (0-10 GPa) and temperature (25-1500 degrees C). Electroresistance can be recorded automatically by a data acquisition board which controls the heating power using a fast feedback algorithm and collects the experimental data. The set-up has been put to the test by carrying out a set of preliminary measurements on Bi and Sn samples up to about 5 GPa and 500 degrees C. The samples have been confined inside pyrophyllite gaskets fitting the 'Paris-Edinburgh' non-toroidal open geometry and connected directly to a power supply. This advanced automated data acquisition system has been found to be very sensitive to tiny resistance variations, allowing for an accurate investigation of phase diagrams of materials, and can be potentially employed for the study of electroresistance anomalies of the liquid phase. The possibility of coupling this set-up with an x-ray source to carry out simultaneous x-ray diffraction measurements is emphasized.