Fig. 1.

Sound velocities and elastic moduli of Fe₇C₃ up to 154 GPa and at 300 K derived from NRIXS measurements. (A) Debye velocity (v_D); (B) compressional-wave velocity (v_P); (C) shear-wave velocity (v_S); and (D) shear modulus (G) and isothermal bulk modulus (K_T). Solid lines are linear fits to the data, which are represented by open circles with error bars. The dot-dashed lines denote abrupt changes in K_T (gray dashed line) (8); fm, ferromagnetic; nm, nonmagnetic (low-spin state); pm, paramagnetic.