Hebei Messi Biology Co., Ltd. stated that electronic grade magnesium oxide can be used as various additives and electronic parts, raw materials for phosphors, raw materials for various targets, raw materials for superconducting thin film substrates, raw materials for tunnel barrier layers for tunnel magnetoresistance elements (TMR elements), and raw materials for protective films for color plasma display panels (PDPs). It is also used as a raw material for crystalline magnesium oxide layers for PDPs, and has attracted attention as an inorganic material with extremely wide applications. In recent years, magnesium oxide powders with large crystallite diameters, extremely small crystal deviations, and good crystallinity that can fully exert various magnesium oxide characteristics such as insulation properties, fluorescence properties, and transparency are required in various applications.
As methods for preparing magnesium oxide powder, it is known that there are mainly gas phase methods using metal magnesium oxidation for preparation, thermal decomposition methods for preparation by calcining precursors such as magnesium hydroxide or magnesium carbonate at a temperature above the thermal decomposition temperature, and methods for crushing blocks obtained by electric melting. However, in the previous methods, although magnesium oxide powders with single crystal size can be obtained, it cannot be said that their size is sufficient, and magnesium oxide powders with good crystallinity cannot be produced.
As magnesium oxide powder with good crystallinity, magnesium oxide powder with a peak half width of (200) plane in the range of 0.40 to 0.60 degrees in powder X-ray diffraction of Cu-Ka rays is used. Magnesium oxide powder with a peak half width of X-ray diffraction at Bragg angle (2e ± 0.2deg) = 42.9deg ((200) plane) in the range of 0.25 to 0.52deg in powder X-ray diffraction of Cu-Ka rays is used. However, the crystallinity of these magnesium oxide powders has not reached a sufficient level.
After repeated various studies to solve the above problems, it was found that when magnesium oxide precursor is calcined by thermal decomposition to produce magnesium oxide powder, the calcination is carried out in the presence of a specific amount of halide ions and in a closed system different from the usual calcination conditions, which can produce magnesium oxide powder with large crystallite diameter and good crystallinity that cannot be obtained by the previous method.