Modification of the synthesis of layered titanium chloride nitride

Layered titanium nitride chloride (TiNCl) exhibits a relatively high superconducting transition of ~16 K, and it is a candidate for the unconventional superconductor. To better understand the superconductivity, we modified the synthesis process for TiNCl. Highly crystalline TiNCl was prepared by chemical vapor transport at different transport temperatures and intercalated with sodium (Na) metal. Although the crystallographic parameters obtained through Rietveld refinement are similar, the superconducting properties strongly depend on the treatment temperature of pristine TiNCl. Optical and photoemission spectroscopy revealed an in-gap state below the Fermi level, indicating hydrogen incorporation, similar to the case of beta-ZrNCl. Hydrogen temperature programmed desorption revealed hydrogen emission against the heat treatment of the obtained pristine TiNCl. The in-gap state of hydrogen inhibits the introduction of electron carriers from the intercalated Na metal.

Automated summary

The superconducting properties of layered titanium nitride chloride were investigated, and it was found that the treatment temperature and hydrogen incorporation have significant effects on the superconductivity.