Nanosized with grain size

The estimated value of -67 nm (no lattice strains) [6] is at the border of nanocrystallinity if one defines it as the grain size smaller than 100 nm [7]. Our result correlates very well with the grain size of 78 nm reported very recently by Kojima et al. [8] for their commercial MgH. Both resnlts suggest that certain commercial varieties of MgH could be subjected to either ball milling or other type of postdeformation in the proprietary mannfactnring process, which results in the final nearly nanosize grains (crystallites). 

In the majority of cases when one deals with nanosize superparamagnetic grains, polydispersity seems to be an inherent feature. The independent measurement of the size distribution function, such as by electron micrography, is a painstaking and rare opportunity. Besides, even when it is done, from the statistical viewpoint a set of available measurements (103 — 104 grains) for the particle number concentration even as small as 1010 — 1018, that is, 0.01% by volume at the particle size 10 nm, is far from being statistically representative. 

The highest remanence available is achieved in Nd2Fei4B/a-Fe nanocomposite materials with typical grain size 20 - 30 nm jU()Mr = 0.98 T, juoHc = 1.1 T, and BHW = 127 kJ/m3 [133], However, due to the difficulty in material processing, the commercial development of these materials remains very limited. Anisotropic NdFeB powders are produced by the HDDR process. Nanosize grains form within micron sized powder particles and they are therefore protected against corrosion. Thanks to the induced texture... 

Zhu et al. prepared nanosized La2Cu04 perovskite oxide using an amorphous heteronuclear complex La2Cu(DTPA)i 6 6H20 as a precursor at a low temperature of 650 °C (Zhu et al., 2000). The grain size was in nano-scale even though the precursor was calcined at 900 °C. The crystal size barely changes with calcination temperature above 650 °C and the calcination time. 

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