The paper studies the influence the nature of the salt anion and the base of precipitant, used in the
synthesis of zirconia nanoparticles by chemical coprecipitation, on process parameters of the hydrogel drying,
xerogel dehydration and crystallization, and the occurrence of polymorphic transitions in crystalline
oxide systems are considered in this paper. The features of the structure, surface condition and properties
of zirconia nanoparticles, which were obtained by using different precursors, are examined by FTIR and
EPR spectroscopy, DSC and XRD methods.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3516

Dmitruk, A.F.

Gorban, O.A.

Gorban, S.V.

Konstantinova, T.E.

Nosolev, I.K.

Peshcherova, N.A.

Volkova, G.K.

Electronic Sumy State University Institutional Repository

PROCEEDINGS OF THE INTERNATIONAL CONFERENCE NANOMATERIALS: APPLICATIONS AND PROPERTIES Vol. 1 No 3, 03PCSI12(3pp) (2012)   2304-1862/2012/1(3)03PCSI12(3) 03PCSI12-1  2012 Sumy State University Influence of Synthesis Conditions on the Structure and the Surface State  of Zirconia Nanoparticles  N.A. Peshcherova1,2,*, A.F. Dmitruk1, O.A. Gorban’2,†, I.K. Nosolev2, G.K. Volkova2, S.V. Gorban1, T.E. Konstantinova2  1 Donetsk National University of Economics and Trade named after M. Tugan-Baranovsky, 31 Shchorsa Str., 83050, Donetsk, Ukraine 2 Donetsk Institute of Physics and Engineering NAS of Ukraine, 72, R. Luxemburg Str., 83114, Donetsk, Ukraine  (Received 20 June 2012; published online 24 August 2012)  The paper studies the influence the nature of the salt anion and the base of precipitant, used in the synthesis of zirconia nanoparticles by chemical coprecipitation, on process parameters of the hydrogel dry-ing, xerogel dehydration and crystallization, and the occurrence of polymorphic transitions in crystalline oxide systems are considered in this paper. The features of the structure, surface condition and properties of zirconia nanoparticles, which were obtained by using different precursors, are examined by FTIR and EPR spectroscopy, DSC and XRD methods.  Keywords: Zirconia nanoparticles, Xerogel, Surface area, Porosity, Aggregation, Phase composition.    PACS numbers: 61.46.Df, 61.66.Dk, 73.20. – r, 81.05.Je                                                             * pescherova@mail.ru † matscidep@aim.com 1. INTRODUCTION  Nano-sized zirconia is a popular material for use in various industries, including catalysis, ceramic indus-try, creation a solid oxide fuel cells (SOFC), prostheses, etc. Such a wide range of nano-sized zirconia is due to the possibility of varying the phase composition, parti-cle size and properties of zirconia. Note that the char-acteristics of zirconia are largely dependent on the con-ditions of synthesis of this material, since formed dur-ing its synthesis. The use of chemical coprecipitation for zirconia oxide, the most common in the industry, makes it necessary to focus not only on the mode of synthesis, namely, the modes of precipitation, drying and annealing of the material, but also on studies of the effects of nature of precursors used in synthesis. The aim of this work was to study the effect of the nature of precursors in the synthesis of the basic pro-cesses of nano-sized zirconia, namely, the processes of drying, crystallization, and as a consequence, its struc-ture, surface condition and properties.  2. SYNTHESIS AND CHARACTERIZATION OF NANOPARTICLES ZIRCONIA  Synthesis of zirconia nanoparticles has three stages — the synthesis of hydrogel, the formation of xerogel and obtaining of the crystalline oxide. The hydrogel system ZrO2 xHOn (n  1, 2) was synthesized by precipi-tation from solutions of oxychloride (ZrOCl2 8H2O) or zirconium oxynitrate (ZrO(NO3)2 6H2O) salts. Bases with different basicity (pKb) are used as precipitants: hydrazine hydrate N2H4 H2O (rK1  6.07; rK2  15.07) and ammonium hydroxide NH3 H2O (pK  4.75). The synthesis performed in the range pH 9 – 10. Deposition carried out for 1 hour with a stirring at 200 rev/min. Drying of the hydrogel performed at the microwave radiation with a frequency of 2.45 GHz and a power of 700 W with a constant diversion of water vapor from the surface of the sediment and control of the mass of the sample. Formed under these conditions xerogel was subjected to annealing in the temperature range 500 – 1300 C. At each stage of the synthesis was carried out char-acterization of the material by appropriate methods. Thus, the kinetics of drying of the hydrogel was studied by gravimetry under conditions of the microwave radia-tion, characterization of the structure of the xerogels performed by measuring the specific surface area by BET, by differential scanning calorimetry (DSC) and thermogravimetry (TG), as well as by FTIR spectrosco-py and electron paramagnetic resonance (EPR). For the characterization of oxide nanoparticles, also used the method of X-ray diffraction (XRD).  3. RESULTS AND DISCUSSION  Note, that the structure and condition of the surface of zirconia is formed as a result of sequential processes — precipitation of the hydrogel, drying of the hydrogel, the processes of dehydration and crystallization of the material. We have previously shown that the nature of the ani-on salts of zirconium determines its structure [1], which may affect the amount of structured water in the sedi-ment and the amount of occluded impurities on its sur-face. The second factor affecting the properties of the precipitating hydrogel is a pH of precipitation process, this quantity is regulated by the concentration and na-ture of the precipitant used. According to the study of electrokinetic hydrogel re-sulting sedimentation can be represented in the form of micelles:   {[mZrO2] xOH рА (х р у)R nH2O}y yR ,  where A is the anion of salt: NO3  and Cl , which are  N.A. PESHCHEROVA, A.F. DMITRUK, O.A. GORBAN’ ET AL. PROC. NAP 1, 03PCSI12 (2012)   03PCSI12-2 included in potential forming layer, and R is the precipi-tating ions: NH4  or N2H5 , which form a diffuse region of the micelle. Note, that the members of the micelle ions differently structured around a water molecule, which may significantly affect the kinetics of drying of the hy-drogel. Drying of the hydrogel is a complex process in-volving a series of transformations, namely, the phase transition of water-vapor diffusion of water molecules inside the pores and on the sediment surface, and de-sorption of water molecules from the surface sediment. To describe such a process commonly used formalism of the kinetics of Avrami–Erofeev [2]. As can be seen from the data in Table the deposition of the hydrogel in the presence of ammonia, two stepwise mechanism is implemented care of water, each of which is characterized by its kinetic parameters, whereas the dry hydrogel precipitated in the presence of hydrazine hydrate proceeds as a one-step process. Note, that the maximum drying rate is observed for the hydrogel pre-pared from nitrate salts and a basic precipitant for both stages. This leads to the formation of xerogels with large specific surface compared to other and lesser degree of aggregation. Comparison of data on the measurement of BET specific surface and the rate constants of water evaporation from the surface of the hydrogel reveals a correlation between these values ZrO2_(NO3)_NH3 (342 m2/g)  ZrO2_(Cl)_NH3 (331 m2/g)  ZrO2_(NO3)_N2H4 (294 m2/g) ZrO2_(Cl)_N2H4 (284 m2/g). According to IR spectroscopy of the surface of the xerogels has a number of features depending on the na-ture of the precursors used for synthesis. So, for xerogels derived from at least the main precipitant in the area stretching vibrations have a significant contribution to the low-frequency component at 3200 cm 1 band intensi-ty in the 3000 – 3700 cm 1. This indicates a greater con-nection with the surface water components of the sedi-ment. In the region of deformation vibrations in the transition to a lower basicity of the precipitant decreases the contribution of the band at 1500 – 1680 cm-1, which vibrations of terminal OH groups and observed its shift from 1570 cm 1 to 1514 cm 1 in the transition from xero-gels formed from ammonia to the xerogel the formation of which took place in the hydrazine hydrate solution. Thus, the number of terminal OH groups and loosely coupled with the surface of the water increases with the speed of drying of the hydrogel, which leads to the for-mation of various defects for the xerogels formed from different precursors. Thus, for the xerogel formed from nitrate raw materials in the EPR spectrum shows an anisotropic paramagnetic signal with g-factors g   1.97 and g   1.95 appropriate Zr3+. In systems based on syn-thetic raw materials of chloride, the paramagnetic center does not occur. It is interesting to note that the surface of these systems have a different activity with respect to the generation of superoxide radical (O2 ). So, on the surface of the xerogels synthesized from chloride raw material, a paramagnetic center O2 generated more in-tensively, despite the lower specific surface area of these systems. This is consistent with the data of IR spectros-copy, which show for these systems the presence of the band at 1089 cm 1, responsible for the variations of sur-face oxygen. This indicates a difference in the surface state, namely the difference in their hydration shells and surface defects, which manifests itself in the peculiari-ties of their subsequent dehydration and crystallization. As can be seen from the DSC measurements at the position of the maximum temperature of the endother-mic process of dehydration affects the nature of the ani-on of salt, and type of precipitating agent used for the synthesis of xerogel, see Fig. 1. This is consistent with the data of IR spectroscopy, the formation of xerogels with varying degrees of water connectivity and hydroxyls on the surface of various precursors. Further dehydra-tion of such systems leads to different defects in the ma-terial, which is reflected in the shift of the maximum temperature of crystallization, see Fig. 1. At the same time, a greater influence on the crystallization process has a type of precipitating agent, used in the synthesis. Thus, the transition in the synthesis of zirconia from ammonia to the hydrazine hydrate the beginning of crys-tallization of this material is delayed by 10  2.5 C. Thus, the crystallization temperature in zirconia is con-trolled by the type of precipitant, whereas the degree of order with which the system approached the crystalliza-tion depends on the nature of the anion of salt, which is chosen for synthesis. And this is what determines the parameters of the flow of polymorphic transformations from monoclinic to tetragonal modification of zirconia in the temperature range 1160 – 1180 C, and the reverse transition tetragonal-monoclinic during cooling of the material. According to the DSC temperature of the mon-oclinic-tetragonal transformation depends on the nature of anion salts, selected for synthesis. Whereas, on the temperature of the reverse transition upon cooling of the material affects the nature of the anion and the salt and the type of precipitant. This fact may also be related to differences in the size of nanoparticles, obtained from different precursors, as confirmed by X-ray diffraction data of these materials. Thus, the structure of the xerogel inherits the chang-es that occur in the hydrogels by varying the synthesis parameters, in particular the type of salt and base pre-cipitant. It is shown that this causes the rate of dehydra-tion, the state of hydration shell, the porosity, the value of specific surface area, morphology and size of nanopar-ticles of xerogel and oxide nanoparticles, obtained on its basis.   Table 1 – Parameters of the dehydration process of the hydrogel.  Precipitator NH3·H2O N2H4·H2O Anion salts Cl  NO3  Cl  NO3  n1 1.60 1.67 1.68 1.62 lnk1 3.21 2.54 3.40 3.18 n2 0.75 0.72 — — lnk2 3.68 2.39 — —   INFLUENCE OF SYNTHESIS CONDITIONS ON THE STRUCTURE … PROC. NAP 1, 03PCSI12 (2012)   03PCSI12-3   Fig. 1 – DSC curves of xerogels ZrO2 which were precipitated with different precursors: 1 – ZrOCl2(N2H4); 2 – ZrO(NO3)2(N2H4); 3 – ZrO(NO3)2(NH3); 4 – ZrOCl2(NH3)   REFERENCES  1. O.A. Gorban, Ph.S. Radchenko, N.A. Peshcherova, Proceedings of the Donetsk National Technical University. Seriya: Chemistry and Chemical Technology 15, No 163: 8 (2010). 2. Y. Masuda, J. Netsu Sokutel. 22 No4, 203 (1995). 

Influence of Synthesis Conditions on the Structure and the Surface State of Zirconia Nanoparticles

SocioEconomic Challenges Journal (Sumy State University)

PROCEEDINGS OF THE INTERNATIONAL CONFERENCE NANOMATERIALS: APPLICATIONS AND PROPERTIES 
Vol. 1 No 3, 03PCSI12(3pp) (2012) 
 
 
2304-1862/2012/1(3)03PCSI12(3) 03PCSI12-1  2012 Sumy State University 
Influence of Synthesis Conditions on the Structure and the Surface State  
of Zirconia Nanoparticles 
 
N.A. Peshcherova1,2,*, A.F. Dmitruk1, O.A. Gorban’2,†, I.K. Nosolev2, 
G.K. Volkova2, S.V. Gorban1, T.E. Konstantinova2 
 
1 Donetsk National University of Economics and Trade named after M. Tugan-Baranovsky, 
31 Shchorsa Str., 83050, Donetsk, Ukraine 
2 Donetsk Institute of Physics and Engineering NAS of Ukraine, 72, R. Luxemburg Str., 83114, Donetsk, Ukraine 
 
(Received 20 June 2012; published online 24 August 2012) 
 
The paper studies the influence the nature of the salt anion and the base of precipitant, used in the 
synthesis of zirconia nanoparticles by chemical coprecipitation, on process parameters of the hydrogel dry-
ing, xerogel dehydration and crystallization, and the occurrence of polymorphic transitions in crystalline 
oxide systems are considered in this paper. The features of the structure, surface condition and properties 
of zirconia nanoparticles, which were obtained by using different precursors, are examined by FTIR and 
EPR spectroscopy, DSC and XRD methods. 
 
Keywords: Zirconia nanoparticles, Xerogel, Surface area, Porosity, Aggregation, Phase composition. 
 
  PACS numbers: 61.46.Df, 61.66.Dk, 73.20. – r, 81.05.Je 
 
 
                                                          
* pescherova@mail.ru 
† matscidep@aim.com 
1. INTRODUCTION 
 
Nano-sized zirconia is a popular material for use in 
various industries, including catalysis, ceramic indus-
try, creation a solid oxide fuel cells (SOFC), prostheses, 
etc. Such a wide range of nano-sized zirconia is due to 
the possibility of varying the phase composition, parti-
cle size and properties of zirconia. Note that the char-
acteristics of zirconia are largely dependent on the con-
ditions of synthesis of this material, since formed dur-
ing its synthesis. The use of chemical coprecipitation 
for zirconia oxide, the most common in the industry, 
makes it necessary to focus not only on the mode of 
synthesis, namely, the modes of precipitation, drying 
and annealing of the material, but also on studies of 
the effects of nature of precursors used in synthesis. 
The aim of this work was to study the effect of the 
nature of precursors in the synthesis of the basic pro-
cesses of nano-sized zirconia, namely, the processes of 
drying, crystallization, and as a consequence, its struc-
ture, surface condition and properties. 
 
2. SYNTHESIS AND CHARACTERIZATION OF 
NANOPARTICLES ZIRCONIA 
 
Synthesis of zirconia nanoparticles has three stages 
— the synthesis of hydrogel, the formation of xerogel 
and obtaining of the crystalline oxide. The hydrogel 
system ZrO2 xHOn (n  1, 2) was synthesized by precipi-
tation from solutions of oxychloride (ZrOCl2 8H2O) or 
zirconium oxynitrate (ZrO(NO3)2 6H2O) salts. Bases 
with different basicity (pKb) are used as precipitants: 
hydrazine hydrate N2H4 H2O (rK1  6.07; rK2  15.07) 
and ammonium hydroxide NH3 H2O (pK  4.75). The 
synthesis performed in the range pH 9 – 10. Deposition 
carried out for 1 hour with a stirring at 200 rev/min. 
Drying of the hydrogel performed at the microwave 
radiation with a frequency of 2.45 GHz and a power of 
700 W with a constant diversion of water vapor from 
the surface of the sediment and control of the mass of 
the sample. Formed under these conditions xerogel was 
subjected to annealing in the temperature range 500 –
 1300 C. 
At each stage of the synthesis was carried out char-
acterization of the material by appropriate methods. 
Thus, the kinetics of drying of the hydrogel was studied 
by gravimetry under conditions of the microwave radia-
tion, characterization of the structure of the xerogels 
performed by measuring the specific surface area by 
BET, by differential scanning calorimetry (DSC) and 
thermogravimetry (TG), as well as by FTIR spectrosco-
py and electron paramagnetic resonance (EPR). For the 
characterization of oxide nanoparticles, also used the 
method of X-ray diffraction (XRD). 
 
3. RESULTS AND DISCUSSION 
 
Note, that the structure and condition of the surface 
of zirconia is formed as a result of sequential processes 
— precipitation of the hydrogel, drying of the hydrogel, 
the processes of dehydration and crystallization of the 
material. 
We have previously shown that the nature of the ani-
on salts of zirconium determines its structure [1], which 
may affect the amount of structured water in the sedi-
ment and the amount of occluded impurities on its sur-
face. The second factor affecting the properties of the 
precipitating hydrogel is a pH of precipitation process, 
this quantity is regulated by the concentration and na-
ture of the precipitant used. 
According to the study of electrokinetic hydrogel re-
sulting sedimentation can be represented in the form of 
micelles: 
 
 {[mZrO2] xOH рА (х р у)R nH2O}y yR , 
 
where A is the anion of salt: NO3  and Cl , which are 
 N.A. PESHCHEROVA, A.F. DMITRUK, O.A. GORBAN’ ET AL. PROC. NAP 1, 03PCSI12 (2012) 
 
 
03PCSI12-2 
included in potential forming layer, and R is the precipi-
tating ions: NH4  or N2H5 , which form a diffuse region of 
the micelle. Note, that the members of the micelle ions 
differently structured around a water molecule, which 
may significantly affect the kinetics of drying of the hy-
drogel. Drying of the hydrogel is a complex process in-
volving a series of transformations, namely, the phase 
transition of water-vapor diffusion of water molecules 
inside the pores and on the sediment surface, and de-
sorption of water molecules from the surface sediment. 
To describe such a process commonly used formalism of 
the kinetics of Avrami–Erofeev [2]. 
As can be seen from the data in Table the deposition 
of the hydrogel in the presence of ammonia, two stepwise 
mechanism is implemented care of water, each of which 
is characterized by its kinetic parameters, whereas the 
dry hydrogel precipitated in the presence of hydrazine 
hydrate proceeds as a one-step process. Note, that the 
maximum drying rate is observed for the hydrogel pre-
pared from nitrate salts and a basic precipitant for both 
stages. This leads to the formation of xerogels with large 
specific surface compared to other and lesser degree of 
aggregation. Comparison of data on the measurement of 
BET specific surface and the rate constants of water 
evaporation from the surface of the hydrogel reveals a 
correlation between these values ZrO2_(NO3)_NH3 (342 
m2/g)  ZrO2_(Cl)_NH3 (331 m2/g)  ZrO2_(NO3)_N2H4 
(294 m2/g) ZrO2_(Cl)_N2H4 (284 m2/g). 
According to IR spectroscopy of the surface of the 
xerogels has a number of features depending on the na-
ture of the precursors used for synthesis. So, for xerogels 
derived from at least the main precipitant in the area 
stretching vibrations have a significant contribution to 
the low-frequency component at 3200 cm 1 band intensi-
ty in the 3000 – 3700 cm 1. This indicates a greater con-
nection with the surface water components of the sedi-
ment. In the region of deformation vibrations in the 
transition to a lower basicity of the precipitant decreases 
the contribution of the band at 1500 – 1680 cm-1, which 
vibrations of terminal OH groups and observed its shift 
from 1570 cm 1 to 1514 cm 1 in the transition from xero-
gels formed from ammonia to the xerogel the formation 
of which took place in the hydrazine hydrate solution. 
Thus, the number of terminal OH groups and loosely 
coupled with the surface of the water increases with the 
speed of drying of the hydrogel, which leads to the for-
mation of various defects for the xerogels formed from 
different precursors. Thus, for the xerogel formed from 
nitrate raw materials in the EPR spectrum shows an 
anisotropic paramagnetic signal with g-factors g   1.97 
and g   1.95 appropriate Zr3+. In systems based on syn-
thetic raw materials of chloride, the paramagnetic center 
does not occur. It is interesting to note that the surface of 
these systems have a different activity with respect to 
the generation of superoxide radical (O2 ). So, on the 
surface of the xerogels synthesized from chloride raw 
material, a paramagnetic center O2 generated more in-
tensively, despite the lower specific surface area of these 
systems. This is consistent with the data of IR spectros-
copy, which show for these systems the presence of the 
band at 1089 cm 1, responsible for the variations of sur-
face oxygen. This indicates a difference in the surface 
state, namely the difference in their hydration shells and 
surface defects, which manifests itself in the peculiari-
ties of their subsequent dehydration and crystallization. 
As can be seen from the DSC measurements at the 
position of the maximum temperature of the endother-
mic process of dehydration affects the nature of the ani-
on of salt, and type of precipitating agent used for the 
synthesis of xerogel, see Fig. 1. This is consistent with 
the data of IR spectroscopy, the formation of xerogels 
with varying degrees of water connectivity and hydroxyls 
on the surface of various precursors. Further dehydra-
tion of such systems leads to different defects in the ma-
terial, which is reflected in the shift of the maximum 
temperature of crystallization, see Fig. 1. At the same 
time, a greater influence on the crystallization process 
has a type of precipitating agent, used in the synthesis. 
Thus, the transition in the synthesis of zirconia from 
ammonia to the hydrazine hydrate the beginning of crys-
tallization of this material is delayed by 10  2.5 C. 
Thus, the crystallization temperature in zirconia is con-
trolled by the type of precipitant, whereas the degree of 
order with which the system approached the crystalliza-
tion depends on the nature of the anion of salt, which is 
chosen for synthesis. And this is what determines the 
parameters of the flow of polymorphic transformations 
from monoclinic to tetragonal modification of zirconia in 
the temperature range 1160 – 1180 C, and the reverse 
transition tetragonal-monoclinic during cooling of the 
material. According to the DSC temperature of the mon-
oclinic-tetragonal transformation depends on the nature 
of anion salts, selected for synthesis. Whereas, on the 
temperature of the reverse transition upon cooling of the 
material affects the nature of the anion and the salt and 
the type of precipitant. This fact may also be related to 
differences in the size of nanoparticles, obtained from 
different precursors, as confirmed by X-ray diffraction 
data of these materials. 
Thus, the structure of the xerogel inherits the chang-
es that occur in the hydrogels by varying the synthesis 
parameters, in particular the type of salt and base pre-
cipitant. It is shown that this causes the rate of dehydra-
tion, the state of hydration shell, the porosity, the value 
of specific surface area, morphology and size of nanopar-
ticles of xerogel and oxide nanoparticles, obtained on its 
basis. 
 
 
Table 1 – Parameters of the dehydration process of the hydrogel. 
 
Precipitator NH3·H2O N2H4·H2O 
Anion salts Cl  NO3  Cl  NO3  
n1 1.60 1.67 1.68 1.62 
lnk1 3.21 2.54 3.40 3.18 
n2 0.75 0.72 — — 
lnk2 3.68 2.39 — — 
 
 INFLUENCE OF SYNTHESIS CONDITIONS ON THE STRUCTURE … PROC. NAP 1, 03PCSI12 (2012) 
 
 
03PCSI12-3 
 
 
Fig. 1 – DSC curves of xerogels ZrO2 which were precipitated with different precursors: 1 – ZrOCl2(N2H4); 2 – ZrO(NO3)2(N2H4); 
3 – ZrO(NO3)2(NH3); 4 – ZrOCl2(NH3) 
 
 
REFERENCES 
 
1. O.A. Gorban, Ph.S. Radchenko, N.A. Peshcherova, Proceedings 
of the Donetsk National Technical University. Seriya: Chemistry 
and Chemical Technology 15, No 163: 8 (2010). 
2. Y. Masuda, J. Netsu Sokutel. 22 No4, 203 (1995). 


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Influence of Synthesis Conditions on the Structure and the Surface State of Zirconia Nanoparticles

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