Homework 4-solutions

Homework 4-solutions - MAT 33 Fall 2007 Due: 09/24/07...

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MAT 33 – Fall 2007 Homework #4 - Solutions Due: 09/24/07 1.) Calculate the number of vacancies per cubic meter in Au at 1050 o C. The energy for vacancy formation is 0.98 eV per atom. Furthermore, the density and atomic weight of Au are 19.32g cm -3 and 196.9 g mol -1 respectively. Determination of the number of vacancies per cubic meter in gold at 1050 ° C (1323 K) requires the utilization of equations (5.1) and (5.2) as follows: - - kT Q A N kT Q V Au Au A V exp = exp N = N V ρ ( 29 ( 29 ( 29 - - - ) 1323 ( / 10 62 . 8 / 98 . 0 exp / 9 . 196 / 32 . 19 / 10 023 . 6 = 5 3 23 K K atom eV x atom eV mol g cm g mol atoms x = 1.093x10 19 cm -3 = 1.093x 10 25 m -3 2.) It is known that the activation energy for the formation of a copper vacancy is 0.9eV. Calculate the ratio of the copper vacancy concentration at 800 o C to that at 500 o C. The ratio is given by
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Homework 4-solutions - MAT 33 Fall 2007 Due: 09/24/07...

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