homework6solution

# homework6solution - Solutions to Homework#6 1 Problem 1 To...

This preview shows pages 1–2. Sign up to view the full content.

Solutions to Homework #6 1. Problem 1 To study the diffusion of nickel in the grain boundaries of nickel oxide NiO in the temperature range between 500 o C and 800 o C, polycrystalline nickel oxide samples were prepared by oxidation of pure nickel foils. The material thus obtained had equiaxed grains with an average diameter of about 10 µ m. A thin layer of tracer ( 63 Ni) was deposited on the surface. After diffusion annealing, the penetration profile was determined by a sectioning technique based on RF sputtering. The anneals were carried out at 4 different temperatures (500, 600, 700, 800 o C) under a pressure of one atmosphere of pure oxygen. The data are given in table below T o C t (s) D (cm 2 /s) D δ (cm 3 /s) 800 6.6x10 2 2.1x10 -14 1.4x10 -16 700 7.2x10 3 1.2x10 -15 600 6.05x10 5 3.7x10 -17 1.8x10 -18 500 8.6x10 5 4.5x10 -19 5.6x10 -20 D and D ' are the diffusion coefficients of nickel in the volume and the grain boundaries, respectively. δ is the width of the grain boundaries, taken as δ = 7x10 -8 a. Show that these experiments are indeed in the Harrison B kinetics regime b. The experimental values for the average concentration as a function of depth found at 700 o C, are given in table below z(cm)x10 4 0.1 0.12 0.14 0.16 0.18 0.22 0.24 0.30 0.50 cx10 3 550 340 160 100 29 30 25 15 9 0.68 0.90 1 1.15 1.4 1.6 2.1 2.6 3.1 3.6 5.2 4.6 4 3.8 3.1 3 2.2 1.6 1.05 0.85 Obtain D' δ and the grain boundary diffusion coefficient D '. Is the condition β > 10 fulfilled?

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

## This note was uploaded on 01/19/2010 for the course MAT SCI 503 taught by Professor Chen during the Spring '02 term at Penn State.

### Page1 / 4

homework6solution - Solutions to Homework#6 1 Problem 1 To...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online