Investigating the electronic properties of novel titanium oxonitridophosphate, Ti₅P₁₂N₂₄O₂, through structural distortions at the titanium sites

Introducing new elements into binary transition metal compounds can cause crystal distortion at the transition metal site. The newly synthesized high-temperature and high-pressure titanium oxonitridophosphate Ti5P12N24O2 is an example of such a compound. We analyze the structural distortion at the titanium sites by applying X-ray absorption spectroscopy (XAS) and resonant inelastic X-ray scattering (RIXS) techniques at the Ti L-2,L-3-edge. We verify the two distinct titanium sites in the lattice, each exhibiting a specific valence state. We confirm that these are both Ti3+ and Ti4+ with a dominant presence of the Ti3+ cation. The degree of lattice distortion within the crystal is extracted and quantified by employing ligand field multiplet theory (LFMT) in a distorted octahedral crystal field (D-4h). Using the calculated distortion values, we establish a correlation between the distorted parameters (Ds, Dt) and the crystallographic bond length of Ti-N at each titanium site. There is good agreement between the calculated and measured splitting energy (Delta e(g)) of the e(g) orbitals and Ti4+ is identified as the more distorted titanium site, while the Ti3+ occupies the less distorted site in the polyhedral structure.