Non ZrO2 Solid-State Rotors

After reading ammrl e-mail for a few years now, I don't think that following has come up (as least not recently).

We are starting to do 91Zr solid-state NMR, however, with the rotor background (ZrO2) it is a bit tricky.  I was wondering if there is a vendor out there that supplies NMR rotors made of silicon nitride or boron nitride for Varian/Chemagnetics probes?  We are looking at using a 5mm or 4mm probe.  Any help would be greatly appreciated.

Cheers

Chris Kirby, PhD
NMR Facility Manager
Department of Chemistry
University of Western Ontario
London, ON N6A 5B7
(519)-850-2905