Thanks - but I would say you are also right, that nanocrystalline is an adjective referring to a material which is crystalline on a nanoscale, whereas a nanocrystal, as a noun, refers to a nano sized crystal!!!
Yesterday I gave exactly the same answer as Dr. Byrne but more wide, which unfortunately for some reason (maybe due to a failure in the network) is not reflected in RG. Although the actuality of my answer has already fallen, I dare to bring their additional explanations and arguments. The words "crystal" or nanocrystal are relevant (applied, used) to separate independent objects. Adjectives “crystalline” act as attribute (gram.-attributive) and may apply not only to individual objects (particles, crystallites), but also to objects that contain a lot of crystals. Thus, the nanocrystal is a nanosized crystal, nanoscale particle. Nanocrystalline = having the structure, form and size of a nanocrystal, nanocrystal-like or consisting of nanoscale crystallites.