8.2. INFRARED FREQUENCY RANGE
201
s
e
8
9
C
CTI
4(
I
I
I
1 0
35bO
3600
2500
2000
1500
10
Wavenumber (cm-1)
0
Figure 8.6. FTlR reflection spectra of gallium nitride nanopowder surfaces after activation at
500°C (tracing a), after subsequent deuteration (tracing b), and difference spectrum of a
subtracted from b (tracing c). [From M.4. Baraton, G. Carlson, and K. E. Gonsalves, Mater.
Sci. Eng. 850, 42 (1 997).]
the OH and OD groups, respectively, on alumina activated at the temperature 600"C,
and spectrum (a) of Fig. 8.9 provides an expanded view of the OD region of Fig. 8.8
for y-alumina activated at 500°C. The analysis of the positions and relative
amplitudes of component lines of these spectra provide information on the distribution of aluminum ions in the octahedral and tetrahedral sites of the atomic layer at
H
H
H
i i I
I
I
A /"\ / o \
0
0
IV AI3+
~ 1 3 +
AI3+ Iv AI3+ AI&
AI3+
A13+VI A13+VI AI3+
Type la
Type Ib
Type Ila
Type Ilb
Type 111
v(0H) > 3750 cm-'
3720 cm-' < v(0H) < 3750 cm-'
v(0H) - 3700 cm-'
Figure 8.7. Five possible configurations of adsorbed hydroxyl groups bonded at tetrahedral
(IvA13+) and octahedral (vlA13+) sites of a 7-alumina surface. [From M.4. Baraton, in Nalwa
(2000), Vol. 2. Chapter 2, p. 116.1