Reactivity of NASICON with water and interpretation of the detection limitof a NASICON based Na+ ion selective electrode

The leaching of Na+ ions from NASICON of composition Na3Zr2Si2PO12 to the a queous solution was evidenced. The origin of the Na+ leaching was studied u sing Na+ concentration and pH measurements as well as solution and X-ray an alyses. The Na+ released was mainly attributed to the dissolution of a seco nd phase, predominantly amorphous. The rate of Na+ release was found to be dependent on the inverse of the square of the particle size. It is proposed that it is controlled by diffusion within the particle. An effective diffu sion coefficient was deduced to be of the order of 5 x 10(-10) cm(2) s(-1). The nature of the detection limit of the NASICON based Na+ ion selective e lectrodes is discussed. (C) 1999 Elsevier Science B.V. All rights reserved.