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1. Light irradiation induced brittle-to-ductile and ductile-to-brittle transition in inorganic semiconductors

   https://doi.org/10.1103/PhysRevB.99.161202  

   Wang, Hongwei; Morozov, Sergey I.; Goddard, William A.; An, Qi (April 2019, Physical Review B)
2. Microscopic defect dynamics during a brittle-to-ductile transition

   https://doi.org/10.1073/pnas.2305667120  

   O’Ghaffari, Hoagy; Peč, Matěj; Mittal, Tushar; Mok, Ulrich; Chang, Hilary; Evans, Brian (October 2023, Proceedings of the National Academy of Sciences)

   Deformation of all materials necessitates the collective propagation of various microscopic defects. On Earth, fracturing gives way to crystal-plastic deformation with increasing depth resulting in a “brittle-to-ductile” transition (BDT) region that is key for estimating the integrated strength of tectonic plates, constraining the earthquake cycle, and utilizing deep geothermal resources. Here, we show that the crossing of a BDT in marble during deformation experiments in the laboratory is accompanied by systematic increase in the frequency of acoustic emissions suggesting a profound change in the mean size and propagation velocity of the active defects. We further identify dominant classes of emitted waveforms using unsupervised learning methods and show that their relative activity systematically changes as the rocks cross the brittle–ductile transition. As pressure increases, long-period signals are suppressed and short-period signals become dominant. At higher pressures, signals frequently come in avalanche-like patterns. We propose that these classes of waveforms correlate with individual dominant defect types. Complex mixed-mode events indicate that interactions between the defects are common over the whole pressure range, in agreement with postmortem microstructural observations. Our measurements provide unique, real-time data of microscale dynamics over a broad range of pressures (10 to 200 MPa) and can inform micromechanical models for semi-brittle deformation. 

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3. VERTIGO: MAKING SENSE OF DISEQUILIBRIUM AT THE BRITTLE-DUCTILE TRANSITION

   https://doi.org/10.1130/abs/2022AM-382812  

   Gottardi, Raphael; Casale, Gabriele; McAleer, Ryan (January 2022, Geological Society of America Abstracts with Programs)
4. Constitutive Behavior of Olivine Gouge Across the Brittle‐Ductile Transition

   https://doi.org/10.1029/2023GL105916  

   Barbot, Sylvain; Zhang, Lei (December 2023, Geophysical Research Letters)

   Abstract The bottom of the lithosphere is characterized by a thermally controlled transition from brittle to ductile deformation. While the mechanical behavior of rocks firmly within the brittle and ductile regimes is relatively well understood, how the transition operates remains elusive. Here, we study the mechanical properties of pure olivine gouge from 100 to 500°C under 100 MPa pore‐fluid pressure in a triaxial deformation apparatus as a proxy for the mechanical properties of the upper mantle across the brittle‐ductile transition. We describe the mechanical data with a rate‐, state‐, and temperature‐dependent constitutive law with multiple thermally activated deformation mechanisms. The stress power exponents decrease from 70 ± 10 in the brittle regime to 17 ± 3 and 4 ± 2 in the semi‐brittle and ductile regimes, respectively. The mechanical model consistently explains the mechanical behavior of olivine gouge across the brittle‐ductile transition, capturing the gradual evolution from cataclasis to crystal plasticity. 

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5. In Situ Nano-thermomechanical Experiment Reveals Brittle to Ductile Transition in Silicon Nanowires

   https://doi.org/10.1021/acs.nanolett.9b01789  

   Cheng, Guangming; Zhang, Yin; Chang, Tzu-Hsuan; Liu, Qunfeng; Chen, Lin; Lu, Wei D.; Zhu, Ting; Zhu, Yong (July 2019, Nano Letters)