Development of scandium oxide reference materials by high-temperature melting with lithium-borate flux

Fusion technique was applied for synthesis of scandium oxide reference materials (RMs) to control the content of Fe, Mg, Mn, Y, Zr, Yb, Th, Na, P, Si, Ca and Cu trace elements. The sample to flux ratio was 12.5, the flux was a mixture of lithium tetraborate and lithium metaborate (LiT:LiM = 1:1), the releasing agent was KI in the amount of 0.1 g. Reagents were oxides with a purity higher than 99.9 %. First, a concentrated mixture No. 1 was prepared from analytes oxides and flux with a mass concentration of trace elements 0.1–1.0 wt. % depending on the element. Next, the concentrated mixture No. 1 was diluted with borate flux approximately 10 times yielding in an intermediate mixture No. 2. Finally, the intermediate mixture No. 2 was diluted with borate flux approximately 10 times subsequently getting a dilute mixture No. 3 with a mass concentration of trace elements 0.001–0.01 wt. %. Mixtures Nos. 1, 2 and 3 were employed to create reference materials and provide necessary concentration ranges for the calibration curves. The synthesized RMs are intended to define the composition of scandium oxide with X-ray fluorescence analysis.