Electron waves were first demonstrated by measuring diffraction from crystals. Davison and Germer observed diffraction of electrons from a Nickel crystal in 1928. They varied the electron energy to measure the electron wavelength, agreeing well with the deBroglie expectation.
First we see diffraction from a single crystal.
Diffraction from crystals is a powerful tool. First we see x-ray diffraction from a single Sodium Crystalwhich has periodic locations of the atoms.
Another example of diffraction is shown below. Here neutrons diffract from a single Sodium crystal.