A spectrophotometric investigation was made of the diffusion of Ti+ in pure, doped and pre-treated samples (table 88). The pure crystals were obtained from the melt, or were crystallized from aqueous solutions. The dopants were SrCl2 and BaCl2. It was found that the doping, and various other treatments, decreased the diffusivity; as compared with that in the molten sample. This was associated with a large increase in the apparent activation energy for diffusion. It was shown that the assumption of metastable supersaturated solutions of divalent impurity ions in the so-called pure material, led to a consistent and quantitative interpretation of the results.

A.Glasner, R.Reisfeld, A.Linenberg: Physica Status Solidi, 1967, 24[2], 695-706

 

 

Table 88

Diffusion Parameters for Tl+ Ions

in Pure and Doped KCl Powders

 

Sample

Dopant

Content (mol%)

Do (cm2/s)

Q (kcal/mol)

melt-grown

Ba2+

1.59 x 10-3

100

28.7

melt-grown

Ba2+

4.13 x 10-2

22

27.4

melt-grown

Ba2+

6.6 x 10-2

317

29.4

melt-grown

Sr2+

9.6 x 10-2

159

29.2

as-received

-

-

1.26 x 104

32.8

washed

-

-

2.24

25.0

solution-grown

Ba2+

1.16 x 10-2

2 x 105

35.8

solution-grown

Sr2+

1.85 x 10-2

1.0 x 105

35.4

recrystallized

-

-

3.2 x 104

33.8

dried

-

-

6.3 x 105

37.0

dried and washed

-

-

388

29.8

dried

Ba2+

6.4 x 10-3

1.4 x 105

35.6