250-450 ℃에서 3시간 동안의 수열반응을 통해 1-10 ㎛의 평균입경을 갖는 능면체 모양의 α-SiO₂ (α-quartz) 단결정 분말을 제조하였다. 실험결과 광화제 농도를 증가시켜 결정성장이 시작되는 수열합성온도를 낮출 수 있었으며, 입자의 크기가 작고 입도분포의 폭이 좁은 분말을 얻을 수 있었다. 한편, 성장기질의 농도나 반응시간을 증가시키면 입자의 크기가 작고 입도분포의 폭이 넓은 분말을 얻을 수 있었다. 또한 반응온도가 증가하면 핵생성이나 결정성장이 모두 빨라지고 입자의 크기도 커짐을 알 수 있었다. 위의 내용을 총괄적으로 표현하기 위하여 결정화 특성을 해석함으로써 평균입경(S)에 관한 특성방정식, S≈1.57 exp(-E_a/RT)·t^0.11·C_M^-0.33·C_M^0.22·C_S^0.08를 제안할 수 있었으며, 이 식에서 활성화에너지(E_a)는 8.15 kJ/g㏖K 였다.

Powders of crystalline α-SiO₂(α-quartz), having the mean particle size of 1-10μm with shapes of rhombohedron, were prepared by hydrothermal synthesis in the temperature range of 250-450℃ for a 3h reaction. The reaction temperature could be reduced as the concentration of a mineralizer increased. Experimental results showed that the particle size became smaller with its narrow distribution as the concentration of a mineralizer increased. However, the particle size became larger with its wide distribution as the concentration of nutrients and the reaction temperature increased. Both of the nucleation and the crystal growth rate also became faster and the particle size became larger as the reaction temperature increased. The above results were expressed as a characteristic equation for the weight mean particle diameter(S) of synthetic powders, such as S≈1.57exp(-E_a/RT)·C_M^-0.33·C_N^0.22·C_S^0.08 with the activation energy, E_a, was 8.15kJ/gmolK.

α-Quartz Powders Hydrothermal Synthesis Crystal Growth Rate Characteristic Equation

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