Rietveld refinement of an urban soil

We can broadly define "urban soils" as those which are located within the cities in park areas, recreation areas, community gardens, green belts, lawns, near multi-story buildings, sediment basins and other such places. Since these soils are also found in watersheds that provide drinking water, food, waste utilization, and natural resources to communities, their periodic analysis is imperative and different agencies (government or private) usually undertake such surveys.

We collected X-ray diffraction data on one such urban soil using Rigaku's Ultima IV multipurpose diffraction system (Figure 1) and identified the most common phases as well as some minor phases as shown in Figure 2.

X-ray diffraction data

Figure 1

most common phases

Figure 2

Rietveld analysis was then performed as shown in Figure 3, using the Whole Pattern Fitting (WPF) module in the Jade software. Figure 3, shows the derived pattern from the model (orange) on top of the raw data (black) and the difference pattern is at the top (blue).

Rietveld analysis

Figure 3

The output from WPF shows the quantitative percentages of each of the phases in Urban Soil (Figure 4). As expected quartz is the major component in all urban soils. The zeolites with a similar chemical composition as quartz and cristobalite may be unique to the geographical location of a particular urban soil.

output from WPF

Figure 4

The Ultima IV represents the state-of-the-art in multipurpose X-ray diffraction (XRD) systems. Incorporating Rigaku's patented cross beam optics (CBO) technology for permanently mounted, permanently aligned and user-selectable parallel and focusing geometries, the Ultima IV X-ray diffractometer can perform many different measurements...fast. Read more...

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