Powder samples can be characterized by XRD and FTIR.
For XRD characterization, there are two types of instruments. One is single crystal XRD and the other one powder XRD. Both are used to determine the crystal type and the size. You can give powdered samples to powder XRD. once you get the results, match the peak with the MATCH software or any XRD matching softwares to compare the pak to find the composition.
In FTIR, you have to powder the sample for characterization. The result will give you the detail of functional groups present in your compound (crystal).