Use molybdenum grids for TEM studies when high temperature and inertness are needed. "Moly" grids are sometimes used in conjunction with certain ion milling recipes since the etching rate under ion milling conditions is very low. The carbon coating of molybdenum grids typically is a bit more of a challenge, especially to the inexperienced, and therefore, SPI Supplies offers a complete grid coating service, providing grids custom coated with carbon, holey carbon, Formvar, etc. All grids shown on this page are made to a specification for the outer diameter of 3.05 mm.
Grids are available in both square hole and also, circular hole style mesh. All grids have a thickness of 0.03 mm (30 µm/0012"). This thickness corresponds to the lowest cost production (and highest yield) and is quite an acceptable thickness for most users. However, on occasion, we are asked if we can produce thinner grids. And the answer is "yes, but", meaning that yes, we can make thinner grids, but the yield goes down and the cost goes up. The thinnest grids we can make are 0.01 mm (10µm/0.0004"). Such grids are made on special order, minimum of twenty vials of 100 grids, and the cost is typically 35% higher than the 10+ vial pricing. Such special order grids requirement payment in advance as once started there are no changes or cancellations permitted. Let us know your requirements so that we can help you sort this out!
Are you doing ion milling?
While some of the SPI TEM grid patterns in molybdenum have applications in ion milling, the product that has been developed specifically for this application would be the SPI "moly rings".
Are you doing Tripod polishing?
For the support of the specimen, we recommend the SPI "Moly" half rings.
Are you doing cryo-TEM?
The use of molybdenum grids has been well documented by those doing cryo-TEM work. Since the coefficient of contraction for a carbon coating is almost identical with that of molybdenum metal, it is possible to avoid the frustrating phenomenon of "cryo-crinkling". This means that thin molecular crystals, both natural as well as synthetic, will really be "flat" and normal to the beam and one would expect to get far more reflections than would otherwise be the case. See the publication by J. Vonck, Ultramicroscopy 5, 123-129 (2000).
Not all moly grids are the same!
In the case of moly TEM grids, thinner is almost always better. This is especially true for those doing tilting experiments. For example, if you are using the 30 µm thick SPI moly grids, and are doing work that requires tilting of the specimen, you have have much more area available for viewing than if you are using 50 µm thick grids, which would come from other sources. It is more difficult to make the thinner grids, yields are lower, but we offer only the best moly grids, those that are only 30 µm thick. Note that the thickness of the 300 and 400 mesh square mesh grids are only 22 µm thick. There is also the question of purity: The molybdenum foils used to make the grids are 99.9% pure molybdenum.
All grids on this page have an outside diameter of 3.05 mm.