High-pressure synthesis, crystal structure and anisotropic thermal/compressive behaviors of pseudo-ternary (V,Cr,Mo)P4

Pseudo-ternary CrP 4 -type (V,Cr,Mo)P 4 was successfully synthesized at the conditions of 4 GPa and 900 °C by using a large volume multi-anvil-type press. SEM-EDS and STEM analyses revealed that the synthesized pseudo-ternary (V,Cr,Mo)P 4 contains almost equimolar amounts of transition metals . The lattice parameters and unit cell volume of (V,Cr,Mo)P 4 yield the average value of its end-members. The low-temperature (133 K–333 K) in-situ synchrotron XRD measurements demonstrated that the c -axis showed the highest coefficient of thermal expansion, followed by the b -axis and the a -axis. These thermal behaviors are the same as the binary end-members and pseudo-binary (V,Cr)P 4 . While from the high-pressure (P < 10 GPa) in-situ synchrotron XRD measurements, it was found that (V,Cr,Mo)P 4 showed no phase transition and compression behaviors in which the c -axis was more compressible than the other two axes ( b and a ) and the b -axis was slightly compressible more than the a -axis. The zero-pressure bulk modulus of 106 (1) GPa and 122.1 (7) GPa were obtained for (V,Cr)P 4 and (V,Cr,Mo)P 4 , respectively. MoP 6 octahedral is highly distorted in comparison with VP 4 and CrP 4 , thus the incorporation of MoP 4 greatly yields incompressible behaviors of CrP 4 -type phosphides with respect to temperature and pressure. Homogeneous pseudo-ternary transition-metal phosphide (V,Cr,Mo)P 4 was synthesized using a high-pressure technique via a rection between ternary metal and phosphorus. These thermal behaviors are the same as the binary end-members and pseudo-binary (V,Cr)P 4 . While from the high-pressure in-situ synchrotron XRD measurements, it was found that (V,Cr,Mo)P 4 showed no phase transition and compression behaviors in which the c -axis was more compressible than the other two axes ( b and a ) and the b -axis was slightly compressible more than the a -axis. The zero-pressure bulk modulus of 122.1 (7) GPa were obtained for (V,Cr,Mo)P 4 . • CrP 4 -type (V,Cr,Mo)P 4 was synthesized under high pressure at 4 GPa and 900 °C. • Pseudo-ternary (V,Cr,Mo)P 4 contains nearly equimolar amounts of transition metal. • CrP 4 -type phosphides are more compressible in the c -axis than the other two axes. • Distorted octahedral sites yield incompressible behaviors for CrP 4 -type phosphides. • High-pressure synthesis of multi-component phosphides would offer new insight.