Calculation of the diffusion coefficients of alkali and alkali-earth metal vapor in helium by exchange perturbation analysis

1991 ◽  
Vol 61 (5) ◽  
pp. 1405-1410
Author(s):  
K. M. Aref'ev ◽  
N. B. Balashova
Keyword(s):  
Perturbation Analysis ◽  
Diffusion Coefficients ◽  
Earth Metal ◽  
Metal Vapor ◽  
Alkali Earth Metal ◽  
Alkali Earth

scholarly journals SBA-15 with Crystalline Walls Produced via Thermal Treatment with the Alkali and Alkali Earth Metal Ions

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5270
Author(s):  
Sung Soo Park ◽  
Sang-Wook Chu ◽  
Liyi Shi ◽  
Shuai Yuan ◽  
Chang-Sik Ha
Keyword(s):  
Metal Ions ◽  
Pore Size ◽  
Metal Ion ◽  
Pore Diameter ◽  
Earth Metal ◽  
Silica Matrix ◽  
Alkali Earth Metal ◽  
Alkali Earth ◽  
Large Pore ◽  
Large Pore Size

Crystalline walled SBA-15 with large pore size were prepared using alkali and alkali earth metal ions (Na+, Li+, K+ and Ca2+). For this work, the ratios of alkali metal ions (Si/metal ion) ranged from 2.1 to 80, while the temperatures tested ranged from 500 to 700 °C. The SBA-15 prepared with Si/Na+ ratios ranging from 2.1 to 40 at 700 °C exhibited both cristobalite and quartz SiO2 structures in pore walls. When the Na+ amount increased (i.e., Si/Na increased from 80 to 40), the pore size was increased remarkably but the surface area and pore volume of the metal ion-based SBA-15 were decreased. When the SBA-15 prepared with Li+, K+ and Ca2+ ions (Si/metal ion = 40) was thermally treated at 700 °C, the crystalline SiO2 of quartz structure with large pore diameter (i.e., 802.5 Å) was observed for Ca+2 ion-based SBA-15, while no crystalline SiO2 structures were observed in pore walls for both the K+ and Li+ ions treated SBA-15. The crystalline SiO2 structures may be formed by the rearrangement of silica matrix when alkali or alkali earth metal ions are inserted into silica matrix at elevated temperature.

Crystallization Behavior and Microstructure of B2O3-Al2O3-SiO2 Glass-Ceramics

2008 ◽  
Vol 51 ◽  
pp. 149-154
Author(s):  
Han Ning Xiao ◽  
Tao Sun ◽  
Hua Bin Liu ◽  
Yin Cheng
Keyword(s):  
Activation Energy ◽  
Metal Oxides ◽  
Crystalline Phase ◽  
Crystallization Behavior ◽  
Glass Ceramics ◽  
Earth Metal ◽  
Crystallization Activation Energy ◽  
Alkali Earth Metal ◽  
Alkali Earth ◽  
Bulk Crystallization

The influences of B2O3/SiO2 ratio and different alkali earth metal oxides MO (M= Ba, Mg, Ca) on the crystallization behavior of B2O3-Al2O3-SiO2 (BAS) glass were investigated by means of DSC, XRD and SEM. With the reduction of B2O3/SiO2 ratio, the crystallization activation energy increases at first and then decreases, reaching the minimum value of 375.4 kJ·mol-1 when the B2O3/SiO2 ratio is 2.2. The crystalline indices (n) are all more than 4, which indicates that the glass is in bulk crystallization. When the glass was heated to 800°C, the primary precipitated crystalline phase was Al4B2O9. With the increase of temperature up to 1100°C, Al18B4O33 and Al5BO9 appeared and became the major crystalline phases in BAS glass-ceramics.

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