Publikationsrepositorium - Helmholtz-Zentrum Dresden-Rossendorf

Quality assurance of natural raw materials (e.g. ores) requires thorough studies on concentration and spatial distribution patterns of technologically relevant trace elements within the mineral matrix at the microscale. Obtaining such a goal is yet only possible with the use of beam-based microanalytical methods and a proper set of homogeneous, matrix-matched reference materials (RMs) doped with trace elements relevant to resource technology.
Natural minerals usually exhibit chemical heterogeneity at μg/g sampling masses and are unsuitable as RMs for in-situ chemical microanalysis. On the other hand, available synthetic RMs (e.g. glasses, pressed pellets) fail to satisfy matrix-match criterion.
A collaboration involving several German scientific institutions centered around TU Bergakademie Freiberg proposed a novel strategy for obtaining such RMs through the synthesis of multi trace element doped mineral matrices subsequently tested for chemical and structural homogeneity with both microscopic and spectroscopic (RMs-dependent and absolute) microanalytical methods.
Three mineral matrices vital to resource technology applications – pyrite, tantalite and feldspar – have been synthesized using flux method, Czochralski method and alkoxide-based sol-gel synthesis, respectively and doped with various sets of technologically important trace elements at the concentration range found in corresponding natural minerals. Their spatial chemical micro-homogeneity has been investigated using light and electron microscopy as well as RMs–dependent (EPMA, LA-ICP-MS) and absolute (PIXE, PIGE) analytical methods.
Quantitative and qualitative elemental spatial distribution maps have been obtained for major and trace elements for each matrix. Homogeneity of the matrices was evaluated using petrologically sensitive statistical analysis.
Established homogeneity testing protocol will be employed in the next stages of the project.