In situ high‐pressure synchrotron X‐ray diffraction study of the structural stability in the intermetallic compound Mn₂Sb

Abstract

Cu2Sb‐type (Strukturbericht designation: C38) intermetallic compound Mn2Sb was studied up to 25.7 GPa at room temperature using the in situ synchrotron powder X‐ray diffraction (XRD) technique. Our results from the XRD analysis showed that the (C38)‐type Mn2Sb undergoes a pressure‐induced structural phase transition near 22.4 GPa. In the low‐pressure (LP) phase of Mn2Sb, an anisotropic compressibility was observed with greater compressibility along the a‐axis than the c‐axis. And the mechanism for the anisotropy of compressibility was discussed in terms of the stacking of crystallography. Fitted to a third‐order Birch–Murnaghan equation of state (BM‐EOS), the pressure–volume data of Mn2Sb yielded the stable lattice volume V0 = 109.45(3) Å3, bulk modulus B0 = 50.1(5) GPa, and its derivative $B'_{{\rm 0}} $ = 7.0(2) for the LP phase. We propose that the distortion of Mn(I)Sb4 tetrahedra may give rise to the structural instability of Mn2Sb under high pressure (HP).

Elucidating the Phase Transformation and Metallization Behavior of Zinc Phosphide under High Pressure

“…Figure a,b shows the pressure dependences of lattice constants of LP and HP phases, respectively. The slopes of the fitting lines somehow account for the compressibility of crystal plane in Zn 3 P 2 . In the LP phase, d a /d P = 0.0268 Å × GPa –1 and d c /d P = 0.0375 Å × GPa –1 , which are ∼10 times larger than that in the HP phase (d a /d P = 0.0056 Å × GPa –1 , d b /d P = 0.0055 Å × GPa –1 , d c /d P = 0.0049 Å × GPa –1 ), indicating that the HP phase is more difficult to compress than the LP phase.…”