Ceramics-Silikáty 41, (1) 21 - 27 (1997)

Thermal decomposition of basic magnesium carbonate (4MgCO₃.Mg(OH)₂.4H₂O) yields porous pseudomorphoses of the original crystals. The specific surface area of the oxide decreases exponentially with increasing firing temperature. The maximum specific surface area of MgO fired at 500°C amounts to 155 m² g⁻¹, falling down to 20 m² g⁻¹ when fired at 1200°C. Extension of the time of firing affects negligibly the specific surface area. Of the admixtures accompanying magnesium oxide in dolomitic raw materials, the specific surface area of fired magnesia is mostly affected by ferric oxide. Under the same firing conditions, at a content of 2 wt.% of this component, the specific surface area decreases down to one tenth of that of non-doped magnesium oxide.