ß-Al2O3 synthesis from m-Al2O3

-Al₂O₃ formation fromm-Al₂O₃ was found by a new convenient technique. By thermal decomposition of a complex compound, trioxalatoaluminate Na _x (NH₄)_3–x Al(C₂O₄)₃]yH₂O(0.091 x 0.333;y= 3), a very fine powder ofm-Al₂O₃ was formed. The decomposition process was examined by thermal analysis and X-ray diffraction and the phase relation of the system Na₂O-Al₂O₃ in the midtemperature region between 600 and 1200° C is discussed briefly. The tablet ofm-Al₂O₃ was fired at 1600° C for 30 min to prepare dense-Al₂O₃ ceramics, the apparent density of which was greater than 95% of the theoretical value. The sintered tablet was examined from the structural point of view and the electrical conductivity was measured by an a.c. method to verify that the procedure of the complex decomposition is a suitable technique for-Al₂O₃ synthesis.