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1. Short- and Intermediate-Range Structure and Dynamics of Fe-Ni-C Liquid Under Compression

   https://doi.org/10.3389/feart.2019.00258  

   Wang, Jianwei; Chen, Bin; Williams, Quentin; Manghnani, Murli H. (October 2019, Frontiers in Earth Science)
2. Viscosity of Fe‐Ni‐C Liquids up to Core Pressures and Implications for Dynamics of Planetary Cores

   https://doi.org/10.1029/2021GL095991  

   Zhu, Feng; Lai, Xiaojing; Wang, Jianwei; Williams, Quentin; Liu, Jiachao; Kono, Yoshio; Chen, Bin (February 2022, Geophysical Research Letters)

   Abstract The viscosity of iron alloy liquids is the key for the core dynamo and core‐mantle differentiation of terrestrial bodies. Here we measured the viscosity of Fe‐Ni‐C liquids up to 7 GPa using the floating sphere viscometry method and up to 330 GPa using first‐principles calculations. We found a viscosity increase at ∼3–5 GPa, coincident with a structural transition in the liquids. After the transition, the viscosity reaches ∼14–27 mPa·s, a factor of 2–4 higher than that of Fe and Fe‐S liquids. Our computational results from 5 to 330 GPa also indicate a high viscosity of the Fe‐Ni‐C liquids. For a carbon‐rich core in large terrestrial body, the level of turbulence in the outer core would be lessened approaching the inner core boundary. It is also anticipated that Fe‐Ni‐C liquids would percolate in Earth's deep silicate mantle at a much slower speed than Fe and Fe‐S liquids. 

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3. Ni-Electrocatalytic C(sp3)–C(sp3) Doubly Decarboxylative Coupling

   https://doi.org/10.1038/s41586-022-04691-4  

   Zhang, Benxiang; Gao, Yang; Hioki, Yuta; Oderinde, Martins S.; Qiao, Jennifer X.; Rodriguez, Kevin X.; Zhang, Hai-Jun; Kawamata, Yu; Baran, Phil S. (April 2022, Nature)
4. Experimental investigation of the effect of nickel on the electrical resistivity of Fe-Ni and Fe-Ni-S alloys under pressure

   https://doi.org/10.2138/am-2020-7301  

   Pommier, Anne (July 2020, American Mineralogist)

   Abstract Electrical resistivity experiments were conducted on three alloys in the iron-rich side of the Fe-Ni(-S) system (Fe-5 wt% Ni, Fe-10 wt% Ni, Fe-10 wt% Ni-5 wt% S) at 4.5 and 8 GPa and up to 1900 K using the multi-anvil apparatus and the 4-electrode technique. For all samples, increasing temperature increases resistivity. At a specified temperature, Fe-Ni(-S) alloys are more resistive than Fe by a factor of about 3. Fe-Ni alloys containing 5 and 10 wt% Ni present comparable electrical resistivity values. The resistivity of Fe-Ni(-S) alloys is comparable to the one of Fe = 5 wt% S at 4.5 GPa and is about three times higher than the resistivity of Fe = 5 wt% S at 8 GPa, due to a different pressure dependence of electrical resistivity between Fe-Ni and Fe-S alloys. Based on these electrical results and experimentally determined thermal conductivity values from the literature, lower and upper bounds of thermal conductivity were calculated. For all Ni-bearing alloys, thermal conductivity estimates range between ~12 and 20 W/(m⋅K) over the considered pressure and temperature ranges. Adiabatic heat fluxes were computed for both Ganymede's core and the Lunar core, and heat flux values suggest a significant dependence to both core composition and the adiabatic temperature. Comparison with previous thermochemical models of the cores of Ganymede and the Moon suggests that some studies may have overestimated the thermal conductivity and hence, the heat flux along the adiabat in these planetary cores. 

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5. Density of Fe‐Ni‐C Liquids at High Pressures and Implications for Liquid Cores of Earth and the Moon

   https://doi.org/10.1029/2020JB021089  

   Zhu, Feng; Lai, Xiaojing; Wang, Jianwei; Amulele, George; Kono, Yoshio; Shen, Guoyin; Jing, Zhicheng; Manghnani, Murli H.; Williams, Quentin; Chen, Bin (March 2021, Journal of Geophysical Research: Solid Earth)

   Abstract The presence of light elements in the metallic cores of the Earth, the Moon, and other rocky planetary bodies has been widely proposed. Carbon is among the top candidates in light of its high cosmic abundance, siderophile nature, and ubiquity in iron meteorites. It is, however, still controversial whether carbon‐rich core compositional models can account for the seismic velocity observations within the Earth and lunar cores. Here, we report the density and elasticity of Fe₉₀Ni₁₀‐3 wt.% C and Fe₉₀Ni₁₀‐5 wt.% C liquid alloys using synchrotron‐based X‐ray absorption experiments and first‐principles molecular dynamics simulations. Our results show that alloying of 3 wt.% and 5 wt.% C lowers the density of Fe₉₀Ni₁₀liquid by ∼2.9–3.1% at 2 GPa, and ∼3.4–3.6% at 9 GPa. More intriguingly, our experiments and simulations both demonstrate that the bulk moduli of the Fe‐Ni‐C liquids are similar to or slightly higher than those of Fe‐Ni liquids. Thus, the calculated compressional velocities (v_p) of Fe‐Ni‐C liquids are higher than that of pure Fe‐Ni alloy, promoting carbon as a possible candidate to explain the elevatedv_pin the Earth's outer core. However, the values and slopes of both density andv_pof the studied two Fe‐Ni‐C liquids do not match the outer core seismic models, suggesting that carbon may not be the sole principal light element in Earth's outer core. The highv_pof Fe‐Ni‐C liquids does not match the presumptivev_pof the lunar outer core well, indicating that carbon is less likely to be its dominant light element. 

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