Large-volume diamond cells for neutron diffraction above 90 GPa

Abstract

Quantitative high pressure neutron-diffraction measurements have traditionally required large sample volumes of at least ∼25 mm3 due to limited neutron flux. Therefore, pressures in these experiments have been limited to below 25 GPa. In comparison, for X-ray diffraction, sample volumes in conventional diamond cells for pressures up to 100 GPa have been less than 1×10−4 mm3. Here, we report a new design of strongly supported conical diamond anvils for neutron diffraction that has reached 94 GPa with a sample volume of ∼2×10−2 mm3, a 100-fold increase. This sample volume is sufficient to measure full neutron-diffraction patterns of D2O–ice to this pressure at the high flux Spallation Neutrons and Pressure beamline at the Oak Ridge National Laboratory. This provides an almost fourfold extension of the previous pressure regime for such measurements.