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Revealing the elusive role of water vapor in the oxidation behavior of a Mn-Si containing NiCr alloy at 950 °C
Detailed nanoscale characterizations revealed the formation of a considerably higher fraction of SiO 2 particles in the external Cr 2 O 3 layer on a NiCr alloy. In addition, atom probe tomography revealed substantially lower segregation of Mn at the Cr 2 O 3 grain boundaries in wet air compared to dry air exposures, where the intriguing formation of Mn-rich clusters was observed in the Cr 2 O 3 grains for the very first time. These findings provided additional evidence regarding the impact of distinct transport processes through the Cr 2 O 3 layer on the resulting oxidation rates and subsurface alloy compositional changes.
The lithiation process and Li diffusion in amorphous SiO 2 and Si from first-principles
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The critical role of Si doping in enhancing the stability of M[subscript 6]C carbides
Abstract not provided
The beneficial effect of Ce additions to high Fe-containing secondary Al-Si-Mg cast alloys
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Probing the local structure of LaFe11.4Si1.6 by pair distribution function analysis
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Practical considerations for using K3 cameras in CDS mode for high-resolution and high-throughput si
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The ferromagnetic to antiferromagnetic crossover in chromium-based pyroxenes tuned via the Ge to Si ratio
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High pressure behaviors and novel high-pressure phase of Si 3 N 4 and TiN
Abstract not provided
Pressure-driven density match nucleates metastable r8 phases from amorphous Si and Ge
The pressure–temperature phase behavior of covalent disordered solids such as amorphous silicon and germanium is complex. Questions remain on possible glass transitions, on polyamorphism via amorphous–amorphous transitions, on connections with liquid–liquid transitions, on structure-behavior relationships, and on their potential as precursor for novel methods for material discovery. Here we demonstrate experimentally the nucleation of a metastable, four-fold coordinated rhombohedral r8 phase from pure amorphous silicon and germanium upon room temperature compression at pressures below 10 GPa. Accompanying theory reveals a strong pressure-driven distortion of the bond angle transforming the starting tetrahedral low-density amorphous network to a distorted four-fold coordinated medium-density state. This state is of lower density than metallic high-density networks, resembles the crystalline r8 phase and initiates its nucleation. Our finding shows that polyamorphism is not the only possible transformation mode for these amorphous solids and that instead nucleation of interesting functional phases at potentially useful pressures is possible. Such novel access modes to metastable structures are critical for future exploitability and could be useful for other tetrahedral materials including carbon, where the related (bc8) post-diamond phase remains elusive. Our observed density match between an amorphous and a metastable crystalline phase clearly allows for a new phase transition pathway, while corresponding theory demonstrates how carefully validated atomistic simulations can guide prediction, discovery and synthesis of novel material structures.