Search products using our product search function

The Fusion Flux Products Available from XRF Scientific

Borate fusion is a technique used to prepare near-homogenous or highly pure heterogenous samples for x-ray fluorescence (XRF) and inductively-coupled plasma (ICP) analysis. It involves the dissolution of oxidized minerals in a molten fusion flux product at temperatures exceeding 1000°C (1832°F). Specialized furnaces are used to elevate the sample temperature within a platinum crucible and agitate the mixture, encouraging sample molecules to dissolve in the molten borate flux. This mixture is then transferred to a platinum mould and cooled. Typically, this method is used to prepare samples as fused discs, beads, or heterogenous liquid fusions for ICP analysis.

The primary raw materials used as fusion flux products are mixtures of lithium tetraborate (Li2B4O7) and lithium metaborate (LiBO2), although oxidizing additives and release agents are often required to protect platinum labware from chemical attack and to ensure optimal sample purity.

This blog post will explore the fusion flux products available from XRF Scientific in more detail:

Fusion Flux Products: Borate Mixtures

Borates are chemical compounds derived from boric acid (BH3O3), which contain one or more boron atoms. These salts include lithium tetraborate and lithium metaborate, both of which can be used to dissolve oxidized materials at elevated temperatures. The scientific consensus is that tetraborate reacts well with base oxides while metaborate reacts well with acidic oxides, but these fusion flux products are rarely used in isolation. More often, mixtures of the two are used to dissolve oxides into a eutectic mixture.

Our range of fusion flux products includes 100% lithium metaborate, which exhibits a high-reactivity with acidic oxides such as silicon dioxide (SiO2). It is not typically used for XRF but is ideal for wet chemistry applications. Lithium tetraborate of 100% purity is used for spectrochemical sample preparation, displaying good reactivity with base oxides such as calcium oxide (CaO) and magnesium oxide (MgO).

The acidity or basicity of a material is critical for determining the appropriate fusion flux products for sample preparation. Borate fusion is intended to alter the chemical properties of the sample so that the homogenous disc or heterogenous solution is as close to neutral as possible – hence the prevalence towards borate mixtures of varying consistencies.

Our fusion flux mixtures include:

  • Lithium tetraborate 66% : lithium metaborate 34%, which is routinely used for fusion of geological samples such as limestone and cement.
  • Lithium tetraborate 50% : lithium metaborate 50%, a general purpose fusion flux product with a relatively low melting point of 870°C (1598°F).
  • Lithium tetraborate 35.3% : lithium metaborate 64.7%, an alkaline borate mixture for sample preparation of more acidic samples, though it is commonly considered a universal fusion flux product and is suitable for the preparation of iron ore, mineral sands, nickel, etc.

Fusion Flux Products: Non-Wetting Additives

These mixtures can be augmented with additional compounds to improve the non-wetting or release characteristics of the fused material, or to oxidize sample compounds. We provide fusion flux mixtures with non-wetting lithium bromide (LiBr) or lithium iodide (LiI) at concentrations of up to 1.5%. This reduces the risk of sample discs fusing to platinum labware and enables easy release after cooling. We also supply lithium bromide assay separately at purity of up to 99.5%.

Alternative release agents include ammonium iodide anhydrous powder, and ammonium iodide tablets.

Fusion Flux Products from XRF Scientific

XRF Scientific is a world leading manufacturer of borate flux products for XRF and ICP sample preparation. We provide a robust method development service to ensure our formulations are optimized to ensure quantitative results in your specific field.

If you need any further information about our fusion flux products or services, please do not hesitate to contact us.