High Pressure Properties of a Ba-Cu-Zn-P Clathrate-I

The high pressure properties of the novel tetrel-free clathrate, Ba(8)Cu(13.1)Zn(3.3)P(29.6), were investigated using synchrotron powder X-ray diffraction. The pressure was applied using a diamond anvil cell. No structural transitions or decomposition were detected in the studied pressure range of 0.1–7 GPa. The calculated bulk modulus for Ba(8)Cu(13.1)Zn(3.3)P(29.6) using a third-order Birch-Murnaghan equation of state is 65(6) GPa at 300 K. This bulk modulus is comparable to the bulk moduli of Ge- and Sn-based clathrates, like A(8)Ga(16)Ge(30) (A = Sr, Ba) and Sn(19.3)Cu(4.7)P(22)I(8), but lower than those for the transition metal-containing silicon-based clathrates, Ba(8)T(x)Si(46−x), T = Ni, Cu; 3 ≤ x ≤ 5.