Abstract:
The Merrill-Bassett gem anvil cell with a newly developed anvil polishing technique
and the CO2 laser heated diamond anvil cell was used to search for possible
ultra hard phases of the unstabalized ZrxHf1xO2 (x=0.5) solid-solution. The
pressure-temperature phase diagram of this compound was explored for the rst
time using angle dispersive x-ray di raction. The pressure-temperature behaviour
of this solid-solution was then compared to the di raction data of the end members
ZrO2 and HfO2. The investigative techniques of Raman spectroscopy and x-ray
di raction were used to clarify previous Raman spectroscopy studies. The structural
changes from the sevenfold coordinated monoclinic to orthorhombic-I to the
ninefold orthorhombic-II (cotunnite) structure under high pressure-temperature conditions
were confirmed. Thus the potential for the Zr0:5Hf0:5O2 solid-solution as a
candidate for an ultra-hard ultra-tough \superceramic" was confirmed.
