Microstructural Characterization of Spodumene-Silicon Nitride Complex by Transmission Electron Microscopy

抄録

A spodumene ceramic doped with 23.1 mass% Si₃N₄ exhibited an average thermal-expansion-coefficient of -0.032×10^-6 K^-1 between 293 K and 300 K. The effect of the Si₃N₄ quantity on the microstructure of the ceramics was characterized with a scanning electron microscope (SEM) and a transmission electron microscope (TEM) equipped with an energy-dispersive spectroscope (EDS). Below 11.1 mass% Si₃N₄, a spodumene-Si₃N₄ complex formed as a dense material in the porous spodumene ceramic, like islands. In the complex, a part of the Si₃N₄ dissolved in the spodumene causing a glassy type of spodumene to form around the Si₃N₄ during the liquid-phase-sintering process. With increasing Si₃N₄ content, the dense material region extended homogeneously throughout the ceramic. Above 33.1 mass% Si₃N₄, a poreless ceramic was produced.