well, you will have to be more specific... what is a YSZ crystal? Yttrium-Sulfur-Z???
but anyway, you could simply use the Amorphous Cell module if Materials Studio provides you with a simillar crystal structure, and you just exchange the atoms and reassign the atom types before creating the supercell...
(but for any details on that, you'd have to ask someone else... the last time I used MS is 2 years ago and I'm not up-to-date with the current version...)
Thank you dear Markus. Yttria-stabilized zirconia (YSZ) has a fluorite structure that in its crystal, some sites of Zr substitute with Y and some of Oxygene sites become empty.