arXiv subjects

Shin-ichi Adachi

Publications and source records attributed to Shin-ichi Adachi.

3 recordsLinked to original sources

arXiv2022

Metastable structure of photoexcited WO$_{3}$ determined by the pump--probe extended X-ray absorption fine structure spectroscopy and constrained thorough search analysis

We have determined the local structure of photoexcited metastable WO$_3$ created 150 ps after 400 nm laser irradiation by the pulse pump--probe L$_3$-edge extended X-ray absorption fine structure spectroscopy and the constrained thorough search analysis. We have found a highly distorted octahedral local structure with one of the shortest W=O bonds being further shortened to 1.66 Åwhile the other five bonds were elongated even though theoretical calculations predicted the reverse change. We discuss this contradiction and propose a possible structure for the metastable state.

cond-mat.mtrl-sci↗

arXiv2013

Complex structural dynamics of bismuth under laser-driven compression

With the aid of nanosecond time-resolved X-ray diffraction techniques, we have explored the complex structural dynamics of bismuth under laser-driven compression. The results demonstrate that shocked bismuth undergoes a series of structural transformations involving four solid structures: the Bi-I, Bi-II, Bi-III and Bi-V phases. The transformation from the Bi-I phase to the Bi-V phase occurs within 4 ns under shock compression at ~11 GPa, showing no transient phases with the available experimental conditions. Successive phase transitions (Bi-V->Bi-III->Bi-II->Bi-I) during the shock release within 30 ns have also been resolved, which were inaccessible using other dynamic techniques.

cond-mat.mtrl-sci↗

arXiv2011

Reversible phase transition in laser-shocked 3Y-TZP ceramics observed via nanosecond time-resolved X-ray diffraction

The high-pressure phase stability of the metastable tetragonal zirconia is still under debate. The transition dynamics of shocked Y2O3 (3 mol%) stabilized tetragonal zirconia ceramics under laser-shock compression has been directly studied using nanosecond time-resolved X-ray diffraction. The martensitic phase transformation to the monoclinic phase, which is the stable phase for pure zirconia at ambient pressure and room temperature, has been observed during compression at 5 GPa within 20 ns without any intermediates. This monoclinic phase reverts back to the tetragonal phase during pressure release. The results imply that the stabilization effect due to addition of Y2O3 is negated by the shear stress under compression.

cond-mat.mtrl-sci↗