Micro-Nano powder particle size and morphology of the requirement varies depending on use. Ferric chloride α, β, γ are three Crystal forms. Water gas reaction, butane dehydrogenation catalyst with ferric chloride requirement for α-crystalline, and Superfine iron oxide magnetic particles for magnetic recording media requirements as the γ Crystal, particle size is less than 0.3pm, the shape is the needle of length-diameter ratio greater than 8. Pigments with alpha-Fe2O3
Best bars, plates, sheet-like.
A12O3 alpha, gamma, theta, ETA of eight kinds of grain, alumina catalysts and catalyst carriers should be for η-A12O3 or γ--A12O3 and α--A12O3 of ceramic materials is important. There are three main types of alumina hydrate trihydrate and two monohydrate, requirements for flame retardant materials are three hydrates, and fine particle size, reasonable gradation, good transparency, flaky, fine particle shape edges.
For Ni-MH battery material of spherical nickel hydroxide powder requires distribution of its size have a certain width, so that small particles can fill the holes of the large particles, and improve the energy density and used as a manufacture of nickel oxide powder calcination of precursor, the required grain size distribution of submicron and as narrow as possible.
Table 2.1 lists some requirements for particle shape of industrial products, there are special requirements on application of nano-powder in.