High-pressure studies of a biphasic NiTiSn/Ni2TiSn Heusler alloy by in situ X-ray diffraction and first principle calculations.

The present work studies the effect of hydrostatic pressure on a biphasic Heusler alloy using in situ X-ray diffraction. A nanostructured biphasic NiTiSn/Ni2TiSn Heusler alloy was synthesized by four hours of me-chanical alloying using a vibrational high-energy mill and characterized by x-ray diffraction measurements and Rietveld method. The sample was submitted to high-pressure conditions (up to 11.9 GPa) using a diamond anvil cell (DAC) loaded with He, and the structural evolutions were followed by in situ synchrotron x-ray diffraction. The results validate the stability of the half and full-Heusler alloys, as no pressure-induced structural phase transition was observed over the entire pressure range. The behavior of the crystal-lographic parameters, equation of state and the compressibility factors for both the Heusler phases were obtained from the experimental results as well from the density functional theory (DFT) calculations. The second-order Birch-Murnaghan equation of state determined from our experimental results yields bulk moduli of 143(9) GPa and 156(6) GPa for the Half and Full Heusler phases, respectively. According to the DFT calculations, the corresponding values are 131.0(9) GPa and 161.8(8) GPa. (c) 2022 Elsevier B.V. All rights reserved.

Automated summary

The effect of hydrostatic pressure on a biphasic Heusler alloy was studied using in situ X-ray diffraction. The stability of the alloy phases under high-pressure conditions was confirmed, and no pressure-induced structural phase transition was observed. The experimental results were in good agreement with the density functional theory calculations.