ANALYSIS OF THE CRYSTAL-GRAIN AND GRAIN-B OUNDARY PHASE IN ALUMINUM NITRIDE BY SELECTED DISSOLUTION

A selected-dissolution method was investigated in order to analyze a c rystal-grain and grain-boundary phase in aluminium nitride which was u sed as a high thermal-conductivity substrate. Unreacted Y2O3 in the sa mple was dissolved by 1.5 M hydrochloric acid. A crystal in the residu al sample after hydrochloric acid dissolution was dissolved by 2 M sod ium hydroxide. The residue which was not dissolved by them was used to determine the grain-boundary phase. EDTA titration, acid-base titrati on, ICP-AES and X-ray diffraction were used to analyze the composition of the crystal-grain and grain-boundary phase. In the aluminium nitri de, to which Y2O3 was added, two grain-boundary phases were constructe d (Y3Al5O12 and YAlO3). Also, it was confirmed that they influence the thermal conductivity.