Basic Types of Ultrafine Powders and Prospects

　    1980s , gradually developed ultra-fine powder , has increasingly become the focus of national research so-called ultra-fine powder is the scale ranged between molecules, atoms and bulk materials , usually refers to small solid within 1 ~ 100nm range particles , including a variety of material particles of metal , non-metallic , organic, inorganic and biological .
　    With superfine material , the surface electronic structure and crystal structure has changed , resulting in a bulk material does not have the surface effect, small size effect , quantum effect and macroscopic quantum tunneling effect , so that the ultrafine powder with conventional compared with a series of excellent particulate material physical and chemical properties.
　    The industry due to the different uses of ultra-fine powder and preparation method , while the ultra- powder to make a different division . Currently, more consistent identity and a more reasonable division :
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　   ( 1 ) fine powder ; ( 2 ) fine powder ; ( 3 ) sub-micron powders ; ( 4 ) nanopowder
　Superfine powder particle size between large 100A to 1000A said ultrafine particles ; particle size 20A to 100A in between called ultrafine particles ; 20A or less in diameter , said small ultrafine particles. Currently preparing ultrafine particles is still relatively small difficulty , so ultra-fine powder material in this section refers to a particle size of between 0.1μm 0.01μm solid particles. Thus , the ultrafine particles is between our intermediate state of matter of a large amount of atoms or molecules and between the small number of atoms or molecules composed of artificial obtained , which maintains the existing chemical substances nature and metastable atoms or a group of molecules , are thermodynamically unstable. So for their research and development is key to understanding how the transition to the microscopic world of macro world. With the high...