Mechano-chemical synthesis of crystalline superionic conductor CsAg4Br3-xI2+x (x=0.32) and its application for Ag+ ion-beam generation

摘要

The mechano-chemical synthesis of crystalline superionic conductor CsAg4Br3-xI2+x, was performed by the means of high-energy ball-milling using CsI-AgBr-AgI powders as precursors. The phase composition of the synthesized material was determined by X-ray diffraction and its variations versus the milling time and rotation rate were studied. Existence of a two-stage chemical reaction resulting in the production of intermediates CsAgBr2 and Ag(Br, I) was revealed. Almost pure CsAg4Br3-xI2+x phase was obtained at the rotation rate of 450 rpm after 3-h milling, and the x value was estimated to be 0.32 by energy dispersive X-ray spectroscopy (EDS). The structure and morphology of this solid electrolyte was investigated, and the grain size was estimated to be 200-500 nm. The thermal property was examined by DSC analysis, and melting temperature was estimated as 178 degrees C. The ionic conductivity at room temperature measured by AC impedance spectroscopy was approximately 0.14 S/cm and its dependence on temperature was studied. The Ag+ ion-conducting property of the prepared superionic conductor was exploited for ion-beam generation. The ion current of several nA was obtained at a working temperature of 177 degrees C and an accelerating voltage of 20 kV, and the dependences of ion current on temperature and accelerating voltage were studied. EDS and X-ray photoelectron spectra showed that Ag+ was a dominant component of the emitted ions. (C) 2019 Elsevier B.V. All rights reserved.