Spontaneous polarization of non-stoichiometric LiIO3 crystals in the low-temperature region

Measurements of the total charge Q(T) = SΔPs(T) in non-stoichiometric z-cut LiIO3 samples in the temperature range of 4.2–300 K were reported. The measurements were supplemented with the data on thermally stimulated depolarization induced by an external electric field of different magnitude and polarity. For T > 130 K, anomalies in the ΔPs(T,U) dependence were observed, which are commonly caused by the deviation of the crystal composition from stoichiometry. The possible nature of the non-stoichiometry was clarified with magnetic measurements, which allowed us to detect interstitial Li below 100 K, as well as two paramagnetic associates of unknown nature at 25 K and 50 K. Increasing temperature led to ionization of lithium with formation of Li+ ions and associates, (VO+2e)− and (VO++VLi−)+, responsible for ionic conductivity. It cannot be excluded that during the charge measurements at T > 140 K the associates of a different type (VLi-,Li+) are formed, which possess a dipole moment and can be oriented opp...