I would try it with normal cross section preparation; see the basics in our old paper:

Article A modular programme for the preparation of inhomogeneous mat...

Hi! I'm just brain storming here but if you can get a small flake of the pottery, maybe you can just crush it up in liquid nitrogen and then drop it on a carbon grid with a syringe. You should have thin enough regions for HRTEM but lack any 'in situ control'

I second FIB-SEM or microtomy