In the field of photo optics, lithium iodate is a crystalline solid used in optical elements. This crystal has wide transparency range and good non-linear, acousto-optical and piezoelectric properties making it suitable for various applications.
The crystal structure is asymmetrically coordinated monodentate iodate groups. The molecular ZnO6 and LiO6 octahedral units are strictly connected by the iodate ligands, which have asymmetric coordination. The distorted IO6 polyhedron is formed by three different short interatomic distances ranging from 1.9037(5) to 2.0833(5) A, and the bond lengths vary between 2.1952(5) and 2.7772(5) A.
Structural Refinement and FTIR Profiles
Fourier transform infrared (FTIR) spectroscopy showed a significant structural change from the original as-obtained crystal structure to that of LiZn(IO3)3 with 81 IR-active modes, corresponding to G = 41A + 40B, which is considerably higher than the 51 IR-active modes in Zn(IO3)2 . In addition, the spectrum of LiZn(IO3)3 exhibited an asymmetrically shifted resonance in the 3500-3400 cm-1 range compared to simple metal iodates, owing to the presence of the distorted IO6 polyhedron, which was previously unknown.
We characterized the electrochemical performance of LPS:0.5LiI in contact with lithium metal through the XPS depth profiling technique. We found that chemical diffusion of iodine to the surface of lithium metal was observed after 12 h in contact with the solid electrolyte. This is evidenced by the I3d peak area and S2p peak area, both showing increased atomic concentrations of iodine.
This result suggests that the iodine molecules diffuse to the lithium metal surface during the compaction process, resulting in an improved lithium deposition on the LPS:0.5LiI electrode. In addition, the iodine-rich interface is capable of resisting stripping, which is crucial for the development of a mechanically robust interfacial barrier between the lithium and the solid electrolyte.