Synthesis and properties of the NdSF compound, phase diagram of the NdF₃-Nd₂S_{3 system}

The NdF3-Nd2S3 system attracts attention of researchers due to the possibility of using LnSF compounds (Ln = rare earth element) as possible new p- and n-type materials. The samples of this system were synthesized from NdF3 and Nd2S3. The NdSF compound belongs to the PbFCl structural type, P4/nmm space group, unit cell parameters: a = 3.9331(20) & Aring;, c = 6.9081(38) & Aring;. The experimentally determined direct and indirect NdSF bandgaps are equal to 2.68 eV and 2.24 eV. The electronic band structure was calculated via DFT simulation. The NdSF compound melts congruently at T = 1385 +/- 10 degrees & Scy;, Delta & Ncy;m = 40.5 +/- 10 kJ/mol, Delta S = 24.4 +/- 10 J/mol. The NdSF microhardness is 455 +/- 10 HV. Five phase transformations in the NdF3-Nd2S3 system were recorded by DSC; their balance equations were derived. The liquidus of the system calculated from the Redlich-Kister equation is fully consistent with the DSC data.