|About this Abstract
||2016 TMS Annual Meeting & Exhibition
||Ultrafine Grained Materials IX
||Production of Nanograined Ge Using Severe Plastic Deformation under High Pressure
||Yoshifumi Ikoma, Takamitsu Toyota, Katsuhiko Saito, Qixin Guo, Zenji Horita
|On-Site Speaker (Planned)
Crystalline Ge was subjected to severe plastic deformation using high-pressure torsion (HPT) under a pressure of 24 GPa. The HPT-processed samples consisted of diamond cubic Ge-I phase and tetragonal Ge-III phase. The Ge-III phase reversely transformed to the Ge-I structure by annealing at 573 K. The HPT-processed sample showed no photoluminescence (PL) while a broad PL peak was observed after the annealing. The observation of the PL peak through HPT-processing and subsequent annealing can give rise to the following consequence. When the high pressure was applied to the crystalline Ge, Ge-I transformed to Ge-II. Nanograin refinement occurred in the metallic Ge-II by torsional strain. When unloading, the Ge-II structure transformed not only back to Ge-I but also to Ge-III. No PL was observed from the HPT-processed samples due to high densities of lattice defects. The existence of nanograined Ge-I with a significant decrease in lattice defects led to the PL.