Monitoring the evolution of intracrystalline concentration U. Schemmert, J. Kärger, C. Krause, R. A. Rákoczy and J. Weitkamp Europhys. Lett., 46 2 (1999) 204-210 Published online: 01 September 2002 DOI: 10.1209/epl/i1999-00245-y