Formation and color properties of vanadium doped ZrSiO4 ceramic ...

Pyon a , Kyong-Sop Han b and Byung-Ha Lee a, *
a Kyu-Ri
of Material Science & Engineering, Myongji University, YongIn, Korea
Department
b Department of Material, KIST, Seoul, Korea
doped zircon pigments were prepared by a ceramic method from a mixture of monoclinic zirconia and silica with
Vanadium
fluoride as a mineralizer and the color properties of the pigments were also investigated. The raw composition was
sodium
in order to optimize the synthesis of the final pigments. The color of synthesized pigments observed in the absence and
varied
presence of the NaF was green and blue, respectively. They were characterized by X-ray diffraction, UV-Vis and Raman
the
The color changes produced in the samples during heating are discussed in terms of the valence of the
spectroscopies.
species in the zircon matrix and the yield of the zircon phase. In these zircon pigments, evidence of the intermediate
vanadium
+4 ) in an initial step in the synthesis process is observed by Raman spectroscopy. V -ZrSiO 4
pigments using rice
phase(NaVO 3 o
give rise to a blue coloration at a low temperature (750 C) and they became a more intense blue color with holding
ash husk
structures are frequently found in ceramic
Zircon-doped
and are closely related to properties, such as low
pigments
dissolution resistance and tinctorial strength that
toxicity,
desirable for a wide range of industrial applications.
are
frist commercially introduced zircon pigment was
The
blue(DCMA 14-42-2)” containing vanadium as
“turquoise
chromophore cation. A yellow zircon pigment containing
a
(DCMA 14-43-4) and a pink zircon pigment
praseodymium
14-44-5) containing iron are also commercially
(DCMA
available[1-6].
forms solutions and incorporates into
Vanadium 4+ solid
lattice with a form of V ions that is the origin
zircon the
the blue color of this pigment. But there are some contradictory
of
reports about the limit of the solid solution, the
location and stabilization of the blue color [7]. Eppler
valance,
the mechanism of formation to elucidate the origin
examined
the coloring by zircon pigments, and also proposed the
of
played by mineralizers in the reaction kinetics through
role
ion model and a vapor transport model [8].
an 4+ diffusion
al. [9] confirmed the existence of V in the ZrO 8
et Demiray
in zircon structure using crystal field theory
position 4+ the
spectrum analysis and concluded that V ions
optical through
the octahedral sites since the unit cell parameters in
occupy
zircon are the same as those in undoped zircon.
V-doped
research of the V-ZrSiO 4
system indicates
Structural 4+
[10]
V cation which forms a solid solution with the
the that
author:
*Corresponding
: +82-31-330-6461
Tel
+82-31-330-6457
Fax:
da5raa@naver.com
E-mail:
flux increased the solubility and thermal
and 4+
additions(NaF)
V in zircon but did not affect the valence
of stability
coordination. Raman spectra have been proposed
and
to try to obtain information concerning the position
[11-13]
vanadium(IV) in the zircon lattice. De Waal et al. [11]
of
for the calculation of V-O bond distances in
used
compounds equation of Hardcastle and
vanadium(IV) 4+ the
and indicated that the Si (4b) positions
[13], Waches
4+ chromophores as V from Raman spectra.
accommodate the
previous study [14], rice husk ash was used as a
a In
of silica in the preparation of pr-ZrSiO 4
solid
source
to produce a yellow powder in which a degree
solutions
high reactivity allows a significant increase in the
of
of the process at a lower temperature. Currently
efficiency
Korea, the estimated production of rice husk is approximately
in
800,000 tons per year. Research is continuing to
the feasibility of using rice husk ash which remains
determine
waste after burning, as an industrial raw material [15-17].
as
the present study, the raw composition of vanadium
In
and firing conditions were varied in order to
contents
the synthesis of the final pigments and the Raman
optimize
of undoped zircon powder was compared to that
spectrum
the V-doped zircon pigments using rice husk ash and
of
2
as a source of silica in order to elucidate the state of
SiO
ions in the formation process by means of a
vanadium
temperature processing route.
low
preparation
Sample
preparation of the vanadium-doped zircon pigments
The
carried out using traditional ceramic procedures. Highpurity
was
reagent-grade monoclinic zirconia (Yakuri), rice
J O U R N A L O F
Journal of Ceramic Processing Research. Vol. 12, No. 3, pp. 279~288 (2011)
Ceramic
Processing Research
Formation and color properties of vanadium doped ZrSiO 4 ceramic pigments
time and a suitable turquoise blue at high temperature(~1300 o C) glazes for porcelain wares.
Key words: Rice husk ash, V-ZrSiO 4 pigment, Raman internal mode, Formation process.
Introduction
Experimental
zircon lattice by substituting for both Si 4+ and Zr 4+ cations
husk ash and SiO 2
as a source of silica, V 2
O 5
(99.0%/ Junsei),
279

well as a mineralizer NaF (Duksan) were selected as the
as
materials in the preparation of the pigments. The rice
raw
ash used was obtained by the slowest possible burning
husk
1000 o C. After burning it was washed repeatedly with
at
to remove as much alkali as possible. The average
water
size was 0.56 µm. ZrO 2 and SiO 2 were mixed to
particle
equimolar concentration. 0.1~0.2 mol% of V 2 O 5 ,
an
mol% of NaF were added to the mixture and this was
0.5
milled in acetone. The resulting dried powders were
then
homogenized in an agate mortar and samples of
finally
mixture were placed in alumina crucibles. In order to
the
the V-ZrSiO 4 pigment to be formed in a solid-state
allow
the dried powders were fired in an electric furnace
reaction,
temperatures ranging between 600 and 1000 o C for
at
h. To produce an intense blue pigment and lower the
3
temperature, the firing conditions were designed
synthesis
holding schedules which were varied from 3 h to
with
h at 750 o C. Also to investigate the formation process
10
this pigment, the holding schedules were varied from
in
h to 10 h at 700 o C.
0
of V-ZrSiO 4 pigments
Characteristics
measure the silica content in the rice husk ash, an
To
was carried out using XRF (Shimadzu, XRF -1800).
analysis
particle size analyzer (Shimadzu, SALD-7101) was used
A
an analysis of the particle size. Characterization of the
for
samples was done using an X-ray diffractometer
calcined
Ni-filtered Cu Kα radiation (Shimadzu, XRD 7000).
with
a qualitative analysis, the patterns were recorded on
For
samples in the 10-70 2θ range at room temperature
ground
a scanning rate of 10 o /minute and a step size of 0.2 o .
at
wt% of corundum was added to all samples as an internal
10
The fraction of ZrSiO 4 (αZrSiO 4 = I ZS(200) +
standard.
M(11 ) + I M(111) + I T(111) ) was obtained based on the relative
I
calculated using the four peak areas of ZrSiO 4
intensity
2 (111) that appeared in the 2θ range of 26-32 o in
t-ZrO
X-ray diffraction patterns of the sample powders
the
at each temperature [18].
heat-treated
oxidation state of the vanadium in the pigments
The
at various calcination temperatures was analyzed
synthesized
UV-Vis spectra (Shimadzu, UV-2410 PC). Assignment
using
the zircon frequency and doped V-O bonding frequency
of
confirmed using Raman spectroscopy (Dimention
was
Lambda Solution, Inc, U.S.A.). The Raman spectra
D2,
excited with a semiconductor laser operating at
were
nm and vertical scattered reflection light was analyzed
532
a CCD dispersive Raman spectrometer at a spectral
using
of 3 cm −1 . Raman spectra were recorded at room
resolution
using a vector Raman probe (RP532-US).
temperature
UV-Vis spectra were obtained in the absorption mode
The
the range of 200-800 nm. The colors of the synthesized
in
and their coloring in a lime-barium glaze were
pigments
via UV-Vis spectra. The results were also obtained
analyzed
by means of UV PC optical color analysis
numerically
(Shimadzu, P/N 206-67449) using the CIE L*a*b*
software
of glazes under high-temperature firing
Application
scope of application of the V-ZrSiO 4 pigments
The
in the present study is the range of the ceramics
synthesized
by high-temperature firing (SK 8-10). For the final
created
of the coloring of the synthesized pigments,
evaluation
were conducted by applying the pigments
experiments
lime-barium glazes used in a ceramic made by hightemperature
to
firing. Its Seger formula is as follows:
KNaO
0.297
CaO 0.734 Al 2 O 3 4.682 SiO 2
0.157
MgO
0.018
BaO 0.528
of the synthesized pigments was added to limebarium
Each
glazes (10%) by wet-mixing. Firing was done in
electric furnace by raising the temperature to 1265 o C
an
30 minuite at a rate of 3 K·minuite −1 . The samples
for
then cooled. The characteristics of the colors of the
were
fired glazes using the synthesized
high-temperature
4 pigments were measured by UV-Vis spectroscopy,
V-ZrSiO
these values were then expressed numerically based
and
of raw samples
Characterization
results of the chemical analysis of the rice husk
The
are shown in Table 1. The loss by ignition of the ground
ash
husk ash was 25.75% while that of the silica content
rice
58%. Additionally, the content of the Fe 2 O 3 , which
was
cloth coloring, was extremely low at 1.89%. This
affects
of synthesis parameters
Optimization
changes depending on different calcination tem-
Phase
peratures
the synthesis of V-doped blue zircon pigment
Regarding
rice husk ash, an investigation was carried out
using
the relation of the formation of zircon crystals
between
the coloring of the pigment according to the calcination
and
Fig. 1 shows the calcination temperature-
temperature.
changes of the crystal phases of the V-ZrSiO 4
dependent
synthesized with the addition of 0.2 mol% of
pigment
Table 1. Chemical analysis of the rice husk ash as received
280 Kyu-Ri Pyon, Kyong-Sop Han and Byung-Ha Lee
on the CIE L*a*b* color order system.
Results and Discussion
value for the content of the alkali was 4.04%.
1
(monoclinic) m-ZrO 2 (11 , 111) and (tetragonal)
1
(200),
V 2 O 5 . The holding time at each temperature zone for the
Oxide Composition (%) Oxide Composition (%)
SiO 2 58.16 K 2 O 3.90
Al 2 O 3 3.23 P 2 O 5 2.31
Fe 2 O 3 1.89 MnO 0.26
MgO 1.23
CaO 2.40 Ig.loss 25.75
Na2O 0.14
color system.

1. XRD patterns of samples formed at different temperatures
Fig.
V-doped ZrSiO 4 pigments.(V 2 O 5 0.2, NaF 0.5 mol%) (600, 700,
in
of pigment was 3 hours. In the case where
synthesis o the
temperature was 600 C, the main phase
calcination the
were observed (JCPDS : 30-1259). This observation
NaF
in agreement with the Raman analysis. Raman analysis
is
carried in order to more clearly confirm the presence
was o out
3
produced at 600 C, which therefore had been
NaVO of
before zircon was produced; and the result is
produced
in Fig. 2. The standard in Fig. 2 represents the result
shown
o analysis of the NaVO 3
synthesized at 650 C using
of the
mixture of V 2
O 5
and NaF. The result showed
equimolar an
o pigment synthesized at 600 C showed the appearance
that the
characteristic NaVO 3
bands at 952, 915, 637,
of
−1 248, 225 and 180 cm . Thus it was confirmed
506, 342,
3
is the intermediate phase, the first reaction
NaVO that
during the process of the pigment. Also it was
product
that during the initial period of reaction, vanadium
confirmed
5+ the intermediate phase V , which is a yellow
exists as
reaction between m-ZrO 2
and silica began at
The powder.
o to initiate the active production of zircon crystals.
700 o C
temperature reached 750 C, zircon became
the When
o phase and at 800 C it showed a rapid growth
the main
the relative reduction of the M-ZrO 2
to a
by accompanied
The Hedvall effect [19] has been well known: that
trace.
the synthesis of zircon, the temperature zone for the
during
phase transition or quartz-cristoballite
monoclinic-tetragonal
transition allows a very reactive state, maximizing
phase
reaction rate, and thus resulting in an increase of zircon
the
Fig. 3 shows the changes in the yields of zircon
formation.
m-ZrO 2
according to varying the calcination temperature
and
when a V-ZrSiO 4
pigment is synthesized with
and M-ZrO 2 yields with different temperatures of
Zircon
V doped ZrSiO 4 pigments.
the
o C, thereby maximizing the reaction so as to increase
600
the next step the yield of zircon by the Hedvall effect.
in
the synthesis of zircon pigment, the temperature at which
In
begins to be synthesized as the main phase is very
zircon
because at this stage coloring of the pigment
important
as the chromophore is included into the host
begins
The of zircon was shown to be highest (94.7%)
matrix. o yield
C. The optimum calcination temperature for V
800 at
o doped blue pigment was 800 C for 3 h and the
0.2 mol%
was synthesized at this temperature as
pigment best
in Fig. 3. The color property of this pigment when
shown
to a glaze was L* 62.66 a* -14.66 b*-9.12(H
applied
changes depending on the content of V 2 O 5 and
Phase
holding times
different
Formation and color properties of vanadium doped ZrSiO 4 ceramic pigments 281
Fig. 2. Raman spectra of vanadium 0.2 mol% doped zircon blue
pigments using rice husk ash at 600 o C.
: 3 h keeping) Z : C o 800,1000 750, , 2 ZrO monoclinic : m zircon,
3 NaVO : N quartz, : Q cristobalite. : C
m-ZrO 2
with traces of unreacted silica and NaVO 3
was
vanadium oxide), which is a eutectic of V 2
O 5
and
(sodium
Fig. 3.
of NaF allowed the phase transition of SiO 2
addition
→ cristoballite) at the very low temperature of
(quartz
2.0B V/C 6.2/3.8 ).
the addition of 0.2 mol% V 2
O 5
. The result showed that the
In order to find the optimum V 2
O 5
content for the synthesis

4. XRD patterns of content change of V 2 O 5 at 800 o C(3 h) in
Fig.
ZrSiO 4 pigments.(V 2 O 5 0.2, NaF 0.5 mol%) Z : zircon,
V-doped
V-doped blue zircon pigment using rice husk ash,
of
was carried out at 800 o C for 3 hours with the
calcination
of 0.05, 0.1, 0.2 and 0.25 mol% V 2 O 5 . The results
addition
shown in Fig. 4. During the synthesis of zircon pigment,
are
oxide first forms a eutectic by reacting with NaF
vanadium
it also plays a role as a mineralizer to promote the
while
of zircon. In all the samples the main phase was
formation
but the presence of unreacted M-ZrO 2 exerted a subtle
zircon,
on the completion of pigment synthesis as well as
effect
the intensity of coloring. The addition of more than
on
mol% V 2 O 5 allowed a good production of zircon during
0.1
resulting in the blue coloring of the synthesized
calcination,
In this research, the optimum amount of V 2 O 5 that
pigment.
in the best blue coloring of the pigment was
resulted
mol% when this pigment was applied to a glaze, the
0.2
values were L* 62.66, a* −14.66, b* −9.12 (H 2.0B
color
6.2/3.8).
V/C
holding time at the final temperature has been
The
to be an important synthetic factor that can lower
reported
calcination temperature by reducing the unnecessary
the
nd phase and by stabilizing the growth of the 1 st phase
2
and that can also increase the intensity of coloring
zircon
When pigment samples synthesized at various calcination
[14].
temperatures were applied to a glaze the best
was shown by the sample calcined at 800 o C for
coloring
hours. Whereas the sample calcined at 750 o C for 3 hours
3
a reduction of the 2 nd phase (M-ZrO 2 ) as the zircon
showed
Therefore, in order to obtain the optimum calcination
grew.
of 3, 5 and 10 hours. Fig. 5 shows the change of
times
phases according to the change of holding time.
crystal
results showed that the highest intensity of zircon
The
obtained from the sample calcined at 750 o C for 5 hours,
was
with the best coloring: L* 58.38, a* −12.87, b* −10.63
also
3.7B V/C 5.7/3.9). The best condition for the synthesis
(H
5. XRD patterns for different holding times at 750 o C in V-
Fig.
ZrSiO 4 pigments.(V 2 O 5 0.2, NaF 0.5 mol%) Z : zircon,
doped
the V-ZrSiO 4 pigment using rice husk ash was calcination
of
750 o C for 5 hours with the addition of 0.2 mol% V 2 O 5
at
0.5 mol% NaF. This is because the holding time at
and o C can stabilize the growth of zircon crystals as well
750
the inclusion of V ions, resulting in an improvement
as
the coloring.
of
properties of pigments
Color
analysis of pigments with different calcination
UV-Vis
temperatures
pigments synthesized at 600-1000 o C with the
The
of 0.2 mol% V 2 O 5 were added to a lime-barium
addition
at a concentration of 10%, for an analysis of the
glaze
by UV-Vis spectroscopy and the results are
coloring
in Fig. 6. and Table 2. The pigment synthesized
shown
600 o C gave a yellow color. There was a change in the
at
spectra from 700 o C, the onset temperature of
UV-Vis
6. Optical absorption spectra of glazed samples with V-
Fig.
ZrSiO 4 pigments.(V 2 O 5 0.2, NaF 0.5 mol%) synthesized at
doped
282 Kyu-Ri Pyon, Kyong-Sop Han and Byung-Ha Lee
m : monoclinic ZrO 2 .
m : monoclinic ZrO 2 , Q : low quartz, C : cristobalite, N : NaVO 3 .
at 750 o C, samples containing 0.2 mol% V 2 O 5
condition
0.5 mol% NaF were calcined for varying holding
and
different temperatures.

2. Lab parameters of glazed tiles with synthesized samples
Table
V 0.2mol% doped blue pigments with different temperatures
of
at which active production of zircon begins.
synthesis
is, the characteristic absorption band for a yellow
That
at 435-480 nm moved towards short wavelengths
color
the band at long wavelengths around 650 nm
while
o intensive. From above 700 C, the characteristic
became 4+ more
band of V at 640 nm [20] was observed
absorption
with a clear change in the coloring to blue of the
along
applied to the glaze and the blue coloring was
pigment
enhanced this characteristic band became more
more 5+ as
is due to the conversion of the V species,
This intense.
is in the initial step of pigment synthesis,
which 4+
prevalent
in the final step. The coloring of the pigment
V to
o increase of the blue color property from 750 C
showed an
begins to grow rapidly and the best blue
zircon when
o obtained at 800 C with a b* value of −9.12.
color was
been literature reporting that the characteristic
has There
absorption bands of V 4+
nm. They reported that the band [21] at 290 nm was
640
to 2B 1 → 2A (the dodecahedral transition) and that
due
band at 640 nm is related to 2B 1 → 2 E (the dodecahedral
the
tetrahedral transition) this is in agreement with the
and
of the present research. It has been confirmed that in
result
synthesis of the V-doped zircon pigment using rice
the
4+ the characteristic absorption bands of V which
husk ash
major cause for coloring appears at 290 and 640 nm
the is
to a valence electron transition.
due
7 and Table 2 show the L*a*b* values. When
Fig.
Fig. 7. a*-b* plots of the glazed sample with V-doped ZrSiO 4
to lime-barium glaze the pigments synthesized
added o a
C with the addition of 0.2 mol% V 2 O 5 showed
600-1000 at
following The ion in the pigment
the o coloring. 5+ vanadium
C is in the state of V (NaVO 3 ) which
600 at synthesized
a yellow color so when it was applied to a glaze the
has
value was 19.53 giving a grayish yellow color. The
b*
o the pigment synthesized at 700 C to a glaze
application of
a negative a* value (−13.59) and b* value
in resulted
giving weak blue color. Whereas the application
(−5.08), o a
pigment synthesized at 750 C to a glaze resulted in
the of
and values that are similar to those of the pigment
a* o b*
700 C giving a light bluish green color but
at synthesized
an increase of the L* value to 65.99. As shown in
with
3, the pigment synthesized at a higher calcination
Fig.
showed higher yield of zircon resulting
temperature o a
color property. The pigment synthesized at 800 C
bluer in
the highest yield of zircon and when applied to
showed
glaze it also showed the highest −b* value of −9.12.
a
the mean time, its H/VC value was 2.0B 6.2/3.8 giving
In
best greenish blue color. The pigment synthesized at
the
o C showed a somewhat poor yield of zircon with
1000
re-increase of the M-ZrO 2 yield the coloring of the
a
applied to a glaze also became poor to a pale
pigment
color.
green
the results of applying the pigments synthesized
Thus
various calcination temperatures to glazes showed that
at
o condition was 800 C for 3 hours. The
the optimum
under this condition showed the best
synthesized pigment
blue color(L* 62.66, a* −14.66, b* −9.12, Hue
greenish
2.0B).
value
changes depending on the content of V 2 O 5 and
Color
holding times
different
o synthesized at 800 C for 3 hours with
The pigments
2 O 5 contents (0.1, 0.15, 0.2 and 0.25 mol%)
V varying
added to a lime-barium glaze for an analysis by
were
spectroscopy the result is shown in Fig. 8. The
UV-Vis
8. a*-b* plots of glazed samples with V-doped ZrSiO 4 pigments
Fig.
0.5 mol%) with different V 2 O 5 contents(mol%) at 800 o C and
(NaF
Formation and color properties of vanadium doped ZrSiO 4 ceramic pigments 283
Samples L* a* b* H V/C Color
1000(3 h)68.29 0−7.30 01.78 8.2G0 6.7/1.2 Pale Green
1800(3 h)62.66 −14.66 −9.12 2.0B0 6.2/3.8 Greenish Blue
1750(3 h)65.99 −13.27 −4.31 8.5BG 6.5/2.9 Light Bluish Green
1700(3 h)71.61 −13.59 −5.08 9.5BG 7.1/3.0 Light Bluish Green
1600(3 h)78.93 0−2.69 19.53 5.0Y0 7.8/2.6 Grayish Yellow
appeared at 290 nm and
with different holding times at 750 o C (V 2 O 5 0.2, NaF 0.5 mol%).
pigments.(V 2 O 5 0.2, NaF 0.5 mol%) different temperatures.

sample synthesized with the addition of 0.1 mol%
pigment
2 O 5 and applied to a glaze gave a grayish yellow green
V
Where the V 2 O 5 content was increased to 0.15 mol%
color.
was a remarkable increase of the blue color property
there
with a decrease of the b* value to 1.08. however,
along
L* value was still 70.88 giving a pale green color of a
the
bright and weak tone. The application of the pigment
fairly
with the addition of 0.2 mol% V 2 O 5 to a
synthesized
resulted in a big change of color. That is, the color
glaze
darker along with an increase of the blue color
became
resulting in a light greenish blue color. In the case
property
0.25 mol% V 2 O 5 the color became rather brighter to
of
light blue color. Thus in the experiment with varying V 2 O 5
a
the optimum V 2 O 5 content for an excellent blue
contents,
was 0.2mol% which is also in agreement with
coloring
result of XRD in Fig. 1.
the
pigments synthesized with the addition of 0.2 mol%
The
2 O 5 at 750 o C for various holding times of 3, 5, 7, and
V
hours were applied to a lime-barium glaze for an analysis
10
UV-Vis spectroscopy and the results are is shown in
by
8 and 9. In the experiment with varying holding times
Figs.
750 o C, the sample with 5 hours holding time showed a
at
blue color property than the sample with 3 hours
better
time at the same temperature and also than the
holding
with 3 hours holding time at 800 o C. The sample
sample
7 hours holding time showed almost the same coloring
with
the sample with 5 hours holding time but with a
as
for higher brightness resulting in a L* value
propensity
61.16 and when the holding time was 10 hours, there
of
again an increase of the b* value to −4.25, resulting
was
an even brighter color. The result of the experiments
in
varying holding times showed that the optimum
with
for pigment synthesis was 750 o C with 5 hours
condition
time. The effect of holding time on the synthesis
holding
not so great in the case of the V-ZrSiO 4 pigment
was
to the ZrSiO 4 pigment, however it was possible
compared
lower the highest calcination temperature from 800 o C
to
to 750 o C as well as to more effectively improve
down
blue color property.
the
could be understood as shown in Fig. 9 by the
This
stabilization of the V ion to the state of 4+ which
further
the blue coloring of the pigment. In these
maximizes
the optimum calcination conditions for the
experiments,
of the zircon pigment with the addition of 0.2 mol%
synthesis
2 O 5 was 750 o C for 5 hours and application of this pigment
V
a glaze gave the most vivid and intense light greenish
to
Raman spectra of ZrSiO 4 :V 4+
analysis was carried out in order to investigate
Raman
effect of rice husk ash and the calcination temperature
the
the zircon frequency and doped V-O bonding frequency
on
the synthesis of V- ZrSiO 4 pigment and the results
during
shown in Fig. 10 and Table 3. Assignments were
are
with the results of the researches conducted by
made
et al. [22] and Knittle and Williams [23] as well as
Syme
the zircon and V-O vibration Raman modes of the
with
9. Optical absorption spectrum of a glazed sample with V-doped
Fig.
4 pigments.(V2O5 0.2, NaF 0.5 mol%) different holding time
ZrSiO
spectra of vanadium 0.2 mol% doped zircon blue
Raman
using SiO 2 and RHA at different temperatures. Z : Zircon.
pigments
synthesized in this research.
pigments
10 shows the Raman spectra of the V-ZrSiO 4
Fig.
synthesized using rice husk ash and SiO 2 . Table 4
pigment
the symmetry species mode assignment for each
shows
When rice husk ash was used to synthesize
frequency.
the optimum condition was 750 o C for 5 hours
pigments
zircon was produced at lower temperatures than when
and
2 was used. As shown by the comparison in Table 4
SiO
majority of the bands presented in Fig. 10 are the
the
bands of ZrSiO 4 . In the case of the pigment
characteristic
using rice husk ash at 750 o C, the characteristic
synthesized
bands including the most intensive zircon B 1g mode
zircon
almost the same peak intensity as in the case of
showed
pigment synthesized using SiO 2 at 800 o C. This is due
the
the higher reaction rate of amorphous rice husk ash.
to
result of the Raman analysis on commercial ZrSiO 4
The
and the zircon powder synthesized by Syme et al.
powder
showed almost the same pure zircon assignment at
[22]
g , A 1g and B 1g . In the case of the vanadium-doped pigments,
E
vibrational modes are shown although weak at
unique
284 Kyu-Ri Pyon, Kyong-Sop Han and Byung-Ha Lee
at 750 o C.
Fig. 10.
blue color (L* 58.38, a* −12.87, b* −10.63).
pigments

4 single crystal
V-ZrSiO
et al.[11])
(Wall
ZrSiO 4 Pigment
V-doped
(RHA)
−1
882, 498 and 473 cm . The low intensity bands
950, 912,
Fig. 10 were not observed in the pure zircon
in presented
That is, they are the bands that are presumed
powder.
be the V-O vibration modes of the vanadium in the
to
VO 4
coordination in the zircon structure. As
tetrahedral
in Table 4, these bands were also found in other
shown
2
O 5
. De Waal et al. [11] reported that the new internal
V
not observed with a pure zircon powder were caused
modes
ZrSiO 4 Pigment
V-doped
2 ) (SiO
ZrSiO 4
Commercial
Powder
4 ZrSiO
et al.[22])
(Syme
υ/cm −1 υ/cm −1 υ/cm −1 υ/cm −1 υ/cm −1 υ/cm −1
1007 1003 1005 1005 1009 Zircon B 1g
974 971 971 971 975 Zircon A 1g
953 950 950 V-O a
925 - - 923 925 Zircon E g
918 912 910 V-O a
912 882 876 V-O a
V-O tetrahedral 11)
1 (A1) V
streching
Symmetric
2 (E) V
Bending
3 (F 2 ) V
streching
Asymmetric
4 ( F 2 ) V
Bending
2 B
E
2 B
E
625 625 640 641 Zircon B 1g
473 473 V-O a
434 433 437 439 Zircon A 1g
389 389 408 393 Zircon E g
V-O a
353 353 353 357 Zircon E g
219 219 223 225 Zircon E g
211 214 Zircon B 1g
201 201 201 202 Zircon E g
1g
917
B
908
g E
1g
503
B
473
g E
912
882
498
473
915
-
506
-
699
-
481
-
the D 2d
site in the zircon lattice. That is, as shown in
of
4 the peaks at 950, 912, 882, 498, 473 cm −1 observed
Table
the V-ZrSiO 4
pigment synthesized using rice husk ash
with
confirmed to be the V-O vibration modes (V 1
(A 1
)
were
V 3
(F 2
) asymmetric stretching, and V 4
(F 2
)
stretching,
that are related to Raman active modes at each
bending)
group (A 1g
, A 1g,
B 1g,
E g,
B 1g
and E g
). Therefore the
factor
ions of the zircon pigment synthesized using
vanadium
husk which are responsible for the blue coloring,
rice 4+ ash
to be located at the Si sites of D 2d
symmetry
considered are
Formation and color properties of vanadium doped ZrSiO 4 ceramic pigments 285
Table 3. Raman band wavenumber(υ) observed for the V-doped pigment using RHA(750/5 h), SiO 2 (800/3 h) and single crystal (Wall et
al.[11]) compared with those observed for commercial zircon powder, together with assignments from pure zircon by Syme et al.[22]
Assignment
852 851 867 -
788 798 815 -
615 621 -
571
499 V-O a
498
181 181 -
/cm −1 ) of synthesized pigments are compared with other compounds in which
Table 4. Raman Internal vibrations and wavenumber(
ṽ
vanadium has tetrahedral coordination.
group 11) Factor group 11) ZrSiO 4 :V Powder 11) ZrSiO 4 : V Powder (RHA) NaVO 3 synthsized V 2 O 5 commercial
Site
d D 2d D 4h /cm −1 /cm −1 /cm −1 /cm −1
T
ṽ ṽ ṽ ṽ
A 1 A 1g 950 950 953 991
A 1 A 1g 378 - 342 301
with a tetrahedral coordination (the α-NaVO 3
compounds
in the present research as well as commercial
synthesized
by the presence of the vanadium located at the silicon site
in the tetravalent state.

process of V-Zircon pigments
Formation
pigment was synthesized in an alumina crucible
When
synthesized pigment formed 2-3 layers as shown in
the
11. The result of the XRD analysis on the individual
Fig.
is shown in Table 5 and the results of the Raman
layers
in Fig. 12. As shown in Table 5, 2 layers of brown
analysis
yellow were observed in the pigments synthesized
and o colors o
C and 650 C whereas 3 layers of yellow, brown
600 at
blue were observed in the pigment synthesized
and o colors
C. According to the result of the XRD analysis on
700 at
o o at 600 C and 650 C, in all the
the pigments synthesized
was a detection of unreacted M-ZrO 2,
there formed layers
cristobalite and NaVO 3
with a similar intensity. In
quartz,
Raman spectra however, there was a distinct difference
the
the intensity. This is because the Raman frequency allows
in
detection as peaks of the vibration modes for inter-
the
interactions, if the degree of crystallization
molecular o even
In the case of the pigment synthesized at 600 C
low. is
3 hours, the yellow layer which was formed above
for
brown layer, showed a higher Raman intensity of the
the
Fig. 11. Layers of pigment synthesized at 700 o C for 3 h.
5. XRD phase study according to each layers of V-doped
Table
pigments using RHA at different temperature and holding time.
zircon
o C) 600 (3 h) 650 (3 h)
Temp.(
h) 700(10
Yellow
layer
Brown
layer
M(vs),
C(m),
Q(w)
N(t)
M(vs),
C(m),
Q(w)
N(t)
M(vs),
C(m),
Q(w)
N(t)
M(vs),
C(m),
Q(w)
N(t)
Blue
layer
Brown
layer
Yellow
layer
Z(vs)
M(w)
M(vs)
C(m)
Q(w)
Z(w)
M(vs)
C(m)
Q(w)
N(t)
Z(vs)
M(t)
M(vs)
C(m)
Q(w)
Z(w)
M(vs)
C(m)
Q(w)
N(t)
Z(vs)
M(t)
M(vs)
C(m)
Q(w)
Z(w)
: Zircon, M : m-zro2, Q : quartz, C : cristobalite, N : NaVO 3
*Z
: very strong, m : medium, w : weak, t : trace
*vs
12. Raman spectra of vanadium 0.2 mol% doped zircon blue
Fig.
using RHA at different temperatures and times. Z : Zircon,
pigments
showed a remarkable increase in the Raman intensity
also
NaVO 3
compared to the brown layer.
of
o calcination temperature was 700 C, the result
Where the
XRD analysis showed the detection of almost the
the of
phase regardless of the holding time. In this case,
same
main phase of the blue layer was zircon while a trace
the
zircon was detected in the brown layer. In the yellow
of
there was an observation of M-ZrO 2
, quartz, cristo-
layer,
and NaVO 3
which were undergoing a reaction.
balite
to the result of the Raman analysis in Fig. 12,
According
o layer of the pigment synthesized at 700 C
the yellow
remarkable decrease in the Raman intensity of
a shows
3
to the yellow layer of the pigment synthesized
NaVO o compared
600 C. This is due to the movement of vanadium
at
into the zircon lattice as zircon begins to be formed.
ions
the case of the pigment synthesized under the calcination
In
o 700 C for 7 hours, the yellow layer at the
conditions of
as the blue layer broadened thus
disappeared bottom
2 layers but there was no big change in the
forming
phase formed. This means that the synthetic
crystalline
of the pigment has a tendency of spreading
reaction
that is, in the vertical direction. The pigment
downwards
o the calcination condition of 700 C for
synthesized under
formed only one layer of a V-ZrSiO 4
blue pigment
hours 10
was found to be the single phase of zircon.
which
formation process of V-ZrSiO 4
blue pigment using
The
husk ash was determined by XRD and Raman analyses.
rice
based on the results, a schematic model of the reaction
And
o mineralizer NaF at 600 C to produce the intermediate
with the
NaVO 3
which is a eutectic and that in this
phase
a of SiF 4
into the M-ZrO 2
lattice to synthesize
as o form
the temperature reaches 750 C at which point
until zircon
286 Kyu-Ri Pyon, Kyong-Sop Han and Byung-Ha Lee
M : Monoclinic ZrO 2 , N : NaVO 3 .
main phase M-ZrO 2
as shown in Fig. 12. The yellow layer
Powder color of layers / Phase present
700 (3 h) 700 (5 h) 700 (7 h)
Z(vs)
is shown in Fig. 13. It was confirmed that V 2
O 5
process
is responsible for the pigment coloring, first reacts
which
N(t)
N(t)
N(t)
5+ exists in the state of V . In this case, SiO 2
way vanadium
to the vapor phase of SiF 4
[8]. SiO 2
diffuses
converted is
the reaction is completed. It was determined that vanadium

Fig. 13. Schematic model for formation of the vanadium zircon ceramic pigment.
are included into the zircon structure in the state of
ions +
resulting in the blue coloring.
4
o C
*500-700
2 +4NaF→ SiF 4(g) +2Na 2 O [24]
SiO
2 +4NaF→ SiF 4(g) +Na 2 SiO 3 [24]
2SiO
2 O 5 +4NaF+O 2 → 4NaVO 3 +2F 2
2V
2 +2F 2 → SiF 4(g) +O 2
SiO
o C
*700-800
4 +ZrO 2 +O 2 → ZrSiO 4 +2F 2 [24]
SiF
3 +ZrO 2 +SiO 2 → ZrSiO 4 +2Na 2 O
4NaVO
2 → ZrSiO 4 M-ZrO
Conclusions
In the case where rice husk ash was used to
(1)
a V-ZrSiO 4 pigment, the best coloring was
synthesize
o synthesis was carried out at 750 C for 5
obtained when
the addition of O.2 mol% of V 2 O 5 and 0.5 mol%
with hours
NaF; the resulting color values were L* 58.38, a* −12.87
of
b* −10.63.
and
The process the pigment synthesis is
(2) o formation o of
500 C to 700 C, the temperature for
From follows: as
active reaction there is the initial step reaction caused
an
the phase transition of α-quartz →β-cristobalite involving
by
reaction of V 2 O 5 with NaF to produce the intermediate
the
NaVO 3 and SiF 4 . At the final step in the temperature
phase
o o C to 800 C, zircon is synthesized as
range from 700
into the M-ZrO 2 lattice. As soon as it is
diffuses 4 SiF
4+ is incorporated into the mother crystal
produced, V
a turquoise blue coloring of the pigment.
in resulting
As for the valence of the vanadium ions in the
(3)
pigment, the result of UV-Vis analysis showed
synthesized
4+ absorption bands of V at 290 nm
the characteristic
→ 2A 1 ) and 640 nm (2B 1 → 2 E ).
1 (2B
Based on the result of the Raman spectral analysis
(4)
the synthesized pigment, new assignments were made
of
the internal modes at 1003, 971, 950, 625, 434, 389,
of −1 zircon
201 and 181 cm as well as the V-O vibration
219, 353,
Formation and color properties of vanadium doped ZrSiO 4 ceramic pigments 287
α-quartz →β-cristobalite
internal modes at 950, 912, 882, 498 and 473 cm −1 .
Acknowledgments
This work was supported by Korea Science and

(KOSEF) grant funded by Korean Government
Engineering
(No. ROA-2006-000-10442-0).
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