[S-CG49] Innovation through the Integration of Solid Earth Science and Materials Science

[SCG49-05] The role of rotational diamond anvil cell in the integration of solid Earth science and materials science

★Invited Papers

*Shintaro Azuma¹, Kenji Ohta¹ (1.Department of Earth and Planetary Sciences, School of Science, Tokyo Institute of Technology)

Keywords:Rotational diamond anvil cell, high temperature and pressure, near-infrared heating method, semiconductors

The recently developed rotational diamond anvil cell (rDAC) has enabled quantitative large-strain deformation experiments at pressures covering the entire lower mantle (Nomura et al., 2017; Azuma et al., 2019). Stable and homogenous high-temperature conditions on deformation samples have also been achieved by introducing a near-infrared focused heating system (Image furnace) to rDAC. These rDAC and heating systems have been optimized for BL47XU, SPring-8 and, in combination with high-brilliance X-rays, allow in-situ measurements of phase transformation, differential stress, and crystallographic preferred orientation (CPO) of samples during deformation (Park et al., 2022). This rDAC system is expected to contribute to our understanding of the deformation properties of lower mantle minerals. On the other hand, large strain deformation experiments under high pressure and high temperature using rDAC are not only contributing to solid Earth science, but also finding potential applications in the field of materials science. High-pressure torsional testing is known as one of the Severe Plastic Deformation (SPD) in the field of materials science, and, for exapmle, previous studies have proceeded to change the mechanical properties of metals by applying large-strain plastic deformation to refine their crystal grains (e.g., Valiev et al., 2000). In addition, indirect bandgap semiconductors, such as silicon (Si) and germanium (Ge), are known to change their electrical conductivity by one order of magnitude or more when subjected to high-pressure, rapid pressure reduction, and annealing. Recently, research to improve semiconductor performances by introducing grain refinement, metastable phases, and dislocations through torsional deformation has also been attracting attention. In Silicon, changes in electrical conductivity of 4-6 orders of magnitude have been observed by applying torsional deformation and heating (e.g., Ikoma 2019). The rDAC has primarily been developed for deep earth science. However, we believe that it can also contribute new insights to the field of materials science, as there are many similarities between rDAC experiments and techniques such as Severe Plastic Deformation (SPD) commonly used in materials science, including torsional deformation, high pressure, and in-situ X-ray measurements. In our presentation, we will introduce experimental techniques and data that can be provided by rDAC, and discuss their application to materials science. We plan to apply torsional deformation and measurement techniques of rDAC to indirect bandgap semiconductors doped with impurities, and to conduct electrical conductivity measurements of the samples.