I think that preparing with microwaves is good and yields nano particles, simply because microwaves give speedy heating and reaches the desired temp in short time. Dr. Sami Al-Shell (in Virginia) did works on that. With microwaves and fast heating you get fast precipitation and get many nuclei, This is a condition to form many particles with nano-size.
A normal microwave oven can be used provided that it is modified to do the job. Safety should be carefully considered while using microwave ovens. Must ask experts also. Metals inside microwave ovens are believed to cause sparks, again be careful please.
There is a nice review article on microwave assisted synthesis of all kinds of nanoparticle in Ange. Chemie. forgot the volume/issue. You may get it from the reference of our paper by Sangeeta et al . in the recent issue of journal of nanofluid.