Effects of Thermal History on the Nucleation in Silicate Melts

热历史对硅酸盐熔体成核的影响

• 批准号: 61470052
• 负责人: AOKI Yoshikazu
• 金额: $ 3.58万
• 依托单位: Kyushu University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (B)
• 财政年份: 1986
• 资助国家: 日本
• 起止时间: 1986 至 1988
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-61470052/
• 关键词: diopside; anorthite; NMR; trimethylsilylation; metastable phase; silicate anion; セクター構造; 核形成頻度; 結晶成長速度; TTT図; 均一核形成; 不均一核形成; 珪酸塩メルト; An-Di-Fo系; 珪酸塩ガラスの構造; 結晶化過程; 結晶化の活性化エネルギー; トリメチルシリル化

1. ^<29>Si MASS NMR spectroscopy of glasses with diopside composition indicates that all Si are tetrahedrally coordinated to oxygen. Estimates of the average Si-O bond length and average Si-O-Si bond angle determined from empirical correlations of ^<29>Si chemical shift with bond length and angle indicate that these parameters are 1.63^゜_ and 130゜C respectively.2. The improved trimethylsilylation method reveals that poly-silicate anions present along with a small amount of monomer, dimer, and three-chain in diopside glass.3. The crystallization kinetics of quenched and annealed glasses with diopside composition were investigated by DTA. X-ray diffretion confirmed that diopside and mixture of diopside and Mg-wollastonite crystallized from quenched and annealed glasses, respectively. The effective activation energy of crystallization of quenched and annealed glasses was derived from DTA curves obtained at various heating rates.4. The kinetics of crystal nucleation in anorthite melt have been betermined over the range of supercooling between 250゜and 625゜C. Two metastable phases, P2_1 and C2, first nucleate heterogeneously at supercoolings of from 270゜ to 620゜C, depending on the duration. both phases are suddenly transformed to the stable phase, l1^^-, at supercoolings of from 350゜ to 450゜C after the duration of 100 min.

1. ^<29>Si质量核磁共振光谱与透辉石组成的玻璃表明，所有的Si都是四面体配位的氧。根据^<29>Si化学位移与键长和键角的经验相关性估算的平均Si- o键长和平均Si- o -Si键角表明，这些参数分别为1.63^ _和130 C。改进的三甲基硅基化方法表明，在透辉石玻璃中，聚硅酸盐阴离子与少量单体、二聚体和三链同时存在。采用差热分析方法研究了透辉石组成的淬火和退火玻璃的结晶动力学。x射线衍射证实，透辉石和透辉石与镁硅灰石的混合物分别在淬火和退火玻璃中结晶。根据不同升温速率下的差热分析曲线，得到了淬火和退火玻璃的有效结晶活化能。钙长石熔体中结晶成核的动力学已在250至625摄氏度的过冷范围内测定。两个亚稳相P2_1和C2首先在270至620摄氏度的过冷（取决于持续时间）下非均匀成核。在350至450摄氏度的过冷温度下，持续100分钟后，两相突然转变为稳定相l1^^-。

项目成果

Y. AOKI; N. IYATOMI: "Crystallization kinetics of anorthite composition" Journal of Crystal Growth.

Y.青木;

Y.Aoki: American Mineralogist.

Y.Aoki：美国矿物学家。

青木義和: 鉱物学雑誌.

青木芳一：矿物学杂志。

Y.,AOKI;N.,IYATOMI: Journal of Crystal Growth.

Y.，AOKI；N.，IYATOMI：晶体生长杂志。

Y.AOKI;N.IYATOMI: Journal of Crystal Growth.

Y.AOKI；N.IYATOMI：晶体生长杂志。