Ionic motion in Li3In2(PO4)3
Abstract The Li + ion distribution over non-equivalent positions and the conductivity due to Li + ion motion in the superionic conductor Li 3 In 2 (PO 4 ) 3 have been studied with 7 Li and 31 P NMR, impedance spectroscopy and DTA. It is shown that there are two phase transitions, at ∼380 and ∼420 K, in the vicinity of which a redistribution of Li + ions among several different crystallographic sites is observed. Characteristic parameters of the Li + ion motion are determined from the 7 Li spin-lattice relaxation data. The 7 Li NMR spectra and spin-lattice relaxation indicate that there are Li + Li + contact pairs in a crystalline lattice. A model is suggested for the Li + ion transport based on the concept of a motion of an interstitial configuration as Li + cation metastable pairs.