A review on the advancements in the characterization of the high-pressure properties of iodates

The goal of this work is to report a systematic and balanced review of the progress made in recent years on the high-pressure behavior of iodates, a group of materials with multiple technological applications and peculiar behaviors under external compression. This review article presents results obtained from multiple characterization techniques which include: X-ray diffraction, Raman and infrared spectroscopy, optical-absorption, resistivity, and second-harmonic generation measurements. The discussion of the results from experiments will be combined with density-functional theory calculations which have been shown to be a very useful tool for the interpretation of experimental data. Throughout the manuscript many of the phenomena observed will be connected to the presence of a lone electron pairs of the iodine atoms in the studied iodates. The presence of the lone electron pairs plays a crucial role in the high-pressure behavior of iodates and it is associated with many of the phenomena discussed here, in particular with the pressure-induced changes in the character of iodine-oxygen bonds, which causes many physical properties to behave nonlinearly. Towards the end of this review, a discussion of current problems that remain unsolved is presented as well as proposals for possible avenues for future studies.