Stability and Superconductivity of TiPHn (n = 1−8) under High Pressure

Titanium exhibits high affinity to hydrogen and the Ti-H compounds are thermodynamically stable. We introduced the Ti elements in the P-H compounds to deal with the thermodynamic-instability issue of the P-H compounds. In this work, ternary hydrogen-rich compounds TiPHn (n = 1-8) were studied and calculated using the density function theory (DFT) method. The results showed that the TiPH4 and TiPH8 had high superconducting critical temperatures (Tc) as well as better stability. Among TiPHn (n = 1-8), the TiPH and TiPH4 were most stable at 50-200 and 250-300 GPa, respectively. For the R-3m-TiPH4 structure, the predicted Tc's are 52 and 62 K at 100 and 250 GPa, respectively, and its larger Young's modulus suggested that it might be potentially synthetized in experiment.