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Binary As–Se glasses with different amounts of As content have been prepared and scanned with different heating rates (3 ≤ ψ ≤ 48 K min−1) over temperatures ranging from 300 to 450 K. Both the glass transition temperature (Tgl) and the temperature peak of crystallization (Tpc) increase as a function of As and/or the ψ values. A good correlation between Tgl and Tpc has been investigated. The observed increase in Tgl and Tpc by increasing the ψ values or as a function of As is well discussed in accordance with Lasocka’s relationship and using the average coordination number Acn, the viscosity at glass transition μ(Tgl) and the overall mean bond energy E. The glass transition Egl and crystallization activation energies (Egl and Epc) were determined based on the changes in Tgl and Tpc values due to the heating rate (ψ). The increase in the values of Egl and Epc with increasing the As content is expected due to the increase in Tgl and Tpc values. The kinetic exponent n and the crystal dimensionality m have been determined.
相似文献In the present work, radon concentrations were measured in surface and underground water samples in Faridabad District of Southern Haryana, India using an active radon monitor based on alpha scintillation technique and results have been inter-compared. The average radon concentration in the underground water samples was observed to be 4 times higher than in the surface water samples. The estimated annual effective dose varied from 5.7 to 58.5 μSvy?1 with an average of 24.2 μSvy?1 for underground water samples and 1.1 to 12.5 μSvy?1 with an average of 6.7 μSvy?1 for surface water samples. The estimated annual effective dose for both type of samples was found to be less than 0.1 mSvy?1, which is the safe limit as suggested by World Health Organisation and EU Council.
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