The attached DXP file shows a simple Sankey example using d3. The DXP file is for Spotfire 6.5 so it will work on Spotfire 7.0 and 7.5/7.6 etc.
Before opening the DXP file you will need to have the JSViz extension installed. This can be downloaded from here:
See how to reuse this example: https://community.tibco.com/wiki/how-reuse-spotfire-jsviz-example-and-apply-it-your-data