Chemistry

It's normal for crystals to have changes in their size when you replace atoms.

The material they talk about here is a metal oxide, not just a metal. These are much more brittle than metals but they can still take some minor squashing or stretching (like ceramic bowls ringing). You're correct that this takes a lot of pressure to sustain.

It's a bit too soon to say no one has recreated it quickly, the paper was only uploaded a week ago. I'm also skeptical but we should see some responses from other physicists soon.