Institute of Mineralogy and Crystallography, Bulgarian Academy of Sciences, Acad. G. Bonchev Street, Block 107, Sofia 1113, Bulgaria; Institute for Energy, Joint Research Centre, European Commission, P.O. Box 2, NL-1755 ZG Petten, The Netherlands
Institute of Mineralogy and Crystallography, Bulgarian Academy of Sciences, Acad. G. Bonchev Street, Block 107, Sofia 1113, Bulgaria;Institute for Energy, Joint Research Centre, European Commission, P.O. Box 2, NL-1755 ZG Petten, The Netherlands