After more than 60 years, a new NaTl type Zintl phase: KTl at high pressure

At 20 kbar the isolated Tl-6 octahedra of four-connected Tl--ions in the Zintl phase KTl are transformed into the four-connected net of the NaTl type structure. It is not possible to quench the high-pressure phase to ambient pressure: in the diamond anvil cell it retransforms into the normal-pressure phase.