The polarized optical spectra of the ions Ti3+, V3+, Cr3+, Mn3+, Co3+, and Ni3+ in corundum single crystals have been studied at temperatures from 4.2° to 1200°K. A theory of the band strength based on the point‐charge model and p‐d mixing has been developed and applied to the data with results in fair agreement with experiment. The effects of temperature show that the vibrational‐electronic contribution to band strength is quite small at low temperature but may be appreciable at high temperatures. The crystal‐field parameters have been calculated as convergent lattice sums. The observed trigonal‐field parameter has the opposite sign from that calculated by the point‐charge model if the impurity ion is assumed to occupy an Al3+ ion position in the lattice, but has the same sign as calculated for an ion 0.1 Å displaced along the c3 axis toward the empty octahedral site. Details of the spectra have been interpreted as showing that the surroundings of an ion are distorted in some electronic states.

1.
H. Kayser, Tabelle der Schwingungszahlen, revised by W. F. Meggers (J. W. Edwards Company, Ann Arbor, Michigan, 1944).
2.
L.
Pauling
and
S. B.
Hendricks
,
J. Am. Chem. Soc.
47
,
78
(
1925
).
3.
R. Newnham (private communication). The writer wishes to thank Dr. Newnham [Z. Krist. (to be published)] for supplying him with improved values of the lattice constants and the parameters. These values have been used throughout this work.
4.
J. S. Griffith, The Theory of Transition Metal Ions (Cambridge University Press, New York, 1961).
5.
R.
Bersohn
,
J. Chem. Phys.
29
,
326
(
1958
).
6.
R. E. Watson, Tech. Rept. No. 12, June 1959, Solid State and Molecular Theory Group, MIT, Cambridge, Massachusetts. The reduction of Watson’s functions to 〈rn〉 was carried out by Dr. H. A. Weakliem.
7.
T. S.
Piper
and
R.
Carlin
,
J. Chem. Phys.
33
,
1208
(
1960
).
8.
C. J.
Ballhausen
and
E. M.
Ancmon
,
Math.‐fys. Medd. Danske Videnskab. Selskab.
31
, No.
9
(
1958
).
9.
R. G.
Shulman
and
S.
Sugano
,
Phys. Rev. Letters
7
,
157
(
1961
).
10.
H. C.
Longuet‐Higgins
,
U.
Opik
,
M. H. L.
Pryce
, and
R. A.
Sack
,
Proc. Roy. Soc. (London)
A244
,
1
(
1958
).
H.
Hartmann
,
H. L.
Schlafer
, and
K. H.
Hansen
,
Z. anorg. u. allgem. Chem.
289
,
40
(
1957
).
11.
W.
Low
,
Z. physik. Chem.
13
,
107
(
1957
).
12.
M. H. L. Pryce and W. A. Runciman, Discussions Faraday Soc. No. 26, 34 (1958).
13.
C. J.
Ballhausen
,
Z. physik. Chem. (Frankfurt)
17
,
246
(
1958
).
14.
R.
Englman
,
Mol. Phys.
3
,
48
(
1960
).
15.
Y.
Tanabe
and
S.
Sugano
,
J. Phys. Soc. Japan
13
,
880
(
1958
).
16.
R. S.
Krishnan
,
Proc. Indian Acad. Sci.
26A
,
450
(
1947
).
This content is only available via PDF.
You do not currently have access to this content.