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1. Phase Stability and Thermal Equation of State of Iron Carbide Fe ₃ C to 245 GPa

   https://doi.org/10.1029/2019GL084545  

   Hu, Xiaojun; Fei, Yingwei; Yang, Jing; Cai, Yang; Ye, Shijia; Qi, Meilan; Liu, Fusheng; Zhang, Mingjian (October 2019, Geophysical Research Letters)

   Abstract We conducted shock wave experiments on iron carbide Fe₃C up to a Hugoniot pressure of 245 GPa. The correlation between the particle velocity (u_p) and shock wave velocity (u_s) can be fitted into a linear relationship,u_s= 4.627(±0.073) + 1.614(±0.028)u_p. The density‐pressure relationship is consistent with a single‐phase compression without decomposition. The inference is further supported by the comparison of the observed Hugoniot density with the calculated Hugoniot curves of possible decomposition products. The new Hugoniot data combined with the reported 300‐K isothermal compression data yielded a Grüneisen parameter ofγ= 2.23(7.982/ρ)^0.29. The thermal equation of state of Fe₃C is further used to calculate the density profile of Fe₃C along the Earth's adiabatic geotherm. The density of Fe₃C was found to be too low (by ~5%) to match the observed density in the Earth's inner core, and Fe₃C is unlikely a dominant component of the inner core. 

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2. Ultracompact 4H-silicon carbide optomechanical resonator with f _m  ·  Q _m exceeding 10 ¹³   Hz

   https://doi.org/10.1364/PRJ.567674  

   Liu, Yuncong; Sun, Wenhan; Abiri, Hamed; Feng, Philip_X-L; Li, Qing (August 2025, Photonics Research)

   Silicon carbide (SiC) has great potential for optomechanical applications due to its outstanding optical and mechanical properties. However, challenges associated with SiC nanofabrication have constrained its adoption in optomechanical devices, as embodied by the considerable optical loss or lack of integrated optical access in existing mechanical resonators. In this work, we overcome such challenges and demonstrate a low-loss, ultracompact optomechanical resonator in an integrated 4H-SiC-on-insulator (4H-SiCOI) photonic platform for the first time, to our knowledge. Based on a suspended 4.3-μm-radius microdisk, the SiC optomechanical resonator features low optical loss (<1  dB/cm), a high mechanical frequencyf_mof 0.95×10⁹  Hz, a mechanical quality factorQ_mof 1.92×10⁴, and a footprint of <1×10⁻⁵  mm². The correspondingf_m·Q_mproduct is estimated to be 1.82×10¹³  Hz, which is among the highest reported values of optomechanical cavities tested in ambient environment at room temperature. In addition, the strong optomechanical coupling in the SiC microdisk enables coherent regenerative optomechanical oscillations at a threshold optical dropped power of 14 μW, which also supports efficient harmonic generation at increased power levels. With such competitive performance, we envision a range of chip-scale optomechanical applications to be enabled by the low-loss 4H-SiCOI platform. 

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3. Multi-phosphine-chelated iron-carbide clusters via redox-promoted ligand exchange on an inert hexa-iron-carbide carbonyl cluster

   https://doi.org/10.1039/D4SC01370K  

   Cobb, Caitlyn R; Ngo, Ren K; Dick, Emily J; Lynch, Vincent M; Rose, Michael J (June 2024, Chemical Science)

   We report the reactivity, structures and spectroscopic characterization of reactions of phosphine-based ligands (mono-, di- and tri-dentate) with iron-carbide-carbonyl clusters. 

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4. Origin and consequences of non-stoichiometry in iron carbide Fe7C3

   https://doi.org/10.2138/am-2019-6672  

   Zhu, Feng; Li, Jie; Walker, David; Liu, Jiachao; Lai, Xiaojing; Zhang, Dongzhou (March 2019, American Mineralogist)
5. A Transient Iron Carbide Generated by Cyaphide Cleavage

   https://doi.org/10.1021/jacs.4c10704  

   Wannipurage, Duleeka C; Yang, Eric S; Chivington, Austin D; Fletcher, Jess; Ray, Debanik; Yamamoto, Nobuyuki; Pink, Maren; Goicoechea, Jose M; Smith, Jeremy M (October 2024, Journal of the American Chemical Society)