zirconium hydroxide coprecipitation e.g. as a result of formation of a separate chemical
compound of scandium and zirconium such as Zr
1-x
Sc
x
O(OH)
y
.
nН
2
О. It can also be
assumed that scandium cations can be absorbed on zirconium hydroxide surface, but
this hypothesis also grounds on possibility of formation surface hydroxo complexes of
zirconium and scandium.
NMR Study of the Processes of Zirconium Compounds of Zr
(1-x)
Sc
x
O
y
Type
Formation. In thermal decomposition of zirconium compounds hydroxo complex
ZrО(ОН)
2
.
nН
2
O [7] is the main intermediate form, its decomposition leads to
formation of zirconium dioxide solid phase. When added to initial solutions, stabilizing
additives in the process of coprecipitation interact with the main matrix, forming
appropriate complexes such as Zr
1-x
Мe
x
O(OH)
y
.
nН
2
О, or surface compounds due to
absorption forces. In the process of thermal treatment precipitates are dehydrated to
form solid replacement solutions such as Zr
(1-x)
Mе
x
О
y.
.
Effects of scandium (III) as well as ligands (H
2
O, OH
-
) on structural and chemical
characteristics of forming the products of hydroxo zirconium complexes thermal
decomposition were studied in samples of Zr
0,92
Sc
0,08
O(OH)
0,5
.
nН
2
О.
The samples were roasted at temperatures 20 - 1200°C for one hour. The study
was made using NMR МAS
1
Н and stationary NMR
45
Sс
.
. NMR spectra were recorded
on a
Bruker Avance 400 spectrometer. Mass loss was determined using the technique
of thermogravimetric analysis. The phase composition was determined by X-ray phase
analysis.
As seen in Fig. 2 NMR МАS
1Н
spectra for zirconium oxides with Sc additive are
significantly changing during thermal treatment of the sample. The initial sample
spectrum consists of a single line shifted towards the high frequencies side at δ =83,6
ppm relative to Larmor frequency and width at half height (∆ν
1/2
=2,4 ppm). Heating
the sample to 100°C causes shifting of the line at δ=84.4 ppm and the sample expansion
(∆ν
1/2
=6,8 ppm). Heating the sample to 150°C results in further shifting of this line
towards the higher frequencies at δ=85.4 ppm, its width remaining unchanged.
Besides, against a wide line background there stand out distinctly at least three
relatively narrow components of equal width (∆ν
1/2
=1 ppm) with chemical shifts
δ
1
=85,66; δ
2
=84,43 and δ
3
=83,26 ppm and intensity relations 6:3:1 accordingly.
Calcination of the sample to 250°C leads to a shift of the whole spectrum towards the
low frequencies side, lessening of the spectrum intensity, retention of multiplicity and
relationship between the intensities of the narrow components. Calcination of the
sample to 400°C causes a further shift towards the low frequencies side, lessening of
triplet which fully disappears in the sample calcined at 500°C.
In proton resonance spectrum of the sample heated in the temperature interval
500-700°C three weakly resolvable components at δ=83,5 ppm are observed. A shift
of the whole spectrum towards the high frequencies side, next towards the low
- 1403 -