The nanopowders of the transition metal ZrO2 and HfO2 oxides were obtained by the hydrothermal autoclave synthesis. The nanoparticles possess a rounded shape and a size range of 40 to 80 nm (ZrO2), of 10 to 40 nm (HfO2). X-ray diffraction analysis and electron microscopy show that the structure of the nanoparticles is monoclinic

Dobromyslov, M.B.

Karpovich, N.F.

Kuzmenko, A.P.

Panfilov, V.I.

Pugachevsky, M.A.

SocioEconomic Challenges Journal (Sumy State University)

JOURNAL OF NANO- AND ELECTRONIC PHYSICS ЖУРНАЛ НАНО- ТА ЕЛЕКТРОННОЇ ФІЗИКИ 
Vol. 7 No 4, 04076(2pp) (2015) Том 7 № 4, 04076(2cc) (2015) 
 
 
2077-6772/2015/7(4)04076(2) 04076-1  2015 Sumy State University 
Short Communication 
 
The Hydrothermal Autoclave Synthesis of the Nanopowders of the Refractory  
ZrO2 and HfO2 Oxides 
 
N.F. Karpovich1, M.A. Pugachevsky1, V.I. Panfilov2, A.P. Kuzmenko3, M.B. Dobromyslov4 
 
1 Institute of Materials Science of the Khabarovsk Scientific Center FEB RAS, Khabarovsk 
2  Far Eastern State Transport University, Khabarovsk 
3 Department of Nanotechnology&Engeneering Physics, SWSU, Kursk, 
4 Pacific National University, Khabarovsk, Russia 
 
(Received 01 October 2015; published online 24 December 2015) 
 
The nanopowders of the transition metal ZrO2 and HfO2 oxides were obtained by the hydrothermal au-
toclave synthesis. The nanoparticles possess a rounded shape and a size range of 40 to 80 nm (ZrO2), of 10 
to 40 nm (HfO2). X-ray diffraction analysis and electron microscopy show that the structure of the nano-
particles is monoclinic. 
 
Keywords: Hydrothermal synthesis, Nanoparticles, Refractory oxides, Zirconium, Hafnium. 
 
 PACS numbers: 81.07.Wx, 78.67.Bf 
 
In the last years, problems of producing nanopowders 
of refractory transition metal oxides of transit metals such 
as zirconium dioxide and hafnium dioxide [1] have become 
intensively studied. Great attention to them is dictated by 
a number of distinctive properties. In addition to the high 
melting temperature ( ZrO2 –2700 С, HfO2 – 2800 С), 
strength, corrosive resistance they have a record low, 
among oxides, heat conductivity they keep in the wide 
temperature range, which dictates their relevance in 
powder metallurgy when heat isolators are manufactured 
[2] Distinctive optical properties due to a stable reflection 
coefficient in the UV range (up to 220 nm), in the visible 
and the IR ranges determine their application also in re-
flecting coatings of space vehicles that work under tough 
temperature conditions [3]. Nanopowders of ZrO2 and 
HfO2 of high chemical purity are used in atomic technolo-
gy where zirconium and hafnium have found various ap-
plications. On the basis of zirconium, one can made ther-
mal insulation coatings of nuclear reactor walls. Na-
nopowders of hafnium can be used for control rods of nu-
clear reactors since it is well known that hafnium features 
big cross-section of neutron capture In this connection, the 
production of chemically pure nanopowders of hafnium 
and zirconium is an urgent task. Hydrothermal synthesis 
[4, 5] can be one of the means for production of oxide ce-
ramics nanopowders. The present work deals with the 
results on synthesizing nanopowders of ZrO2 and HfO2 
with the autoclave method. Morphological and structural 
features of particles obtained are also provided. 
Synthesis of ZrO2 and HfO2 nanopowders was con-
ducted by the hydrothermal method in a steel auto-
clave with a 50-ml volume Teflon liner. As precursors, 
zirconium propoxide (IV) in propanol (70 %, ACROS, 
USA) and hafnium isopropoxide (IV) in (OOCH-
(CH3)2)4HOCH(CH3)2 (99 %, Alfa Aesar, Germany) 
were used. At first, the precursors were solvated in a 
relevant spirit and hydrolyzed in 10 ml of distilled wa-
ter with further aging for one day. After that, diethyl-
amine and oleic acid in the ratio 1 : 1 : 1 and distilled 
water were added. The autoclave was kept at a tem-
perature of 160 С for 24 hours. From the obtained so-
lution, solvent was removed and the particles were 
dried at a dynamic heating of up to 400 С for one day 
and further at an isothermal additionally 24 hours at a 
temperature of 400 С. 
The structure and phase composition of synthesized 
nanopowders were studied in transmission electron 
microscope ZEISS Libra-120 (accelerating voltage 
120 kV) which featured a HAADF detector and an en-
ergy Ω- filter. Calibration of electronograms in the mi-
crodiffraction mode was done with a test sample for the 
transmission electron microscopy (TEM) on the basis of 
a polycrystalline Au film. Qualitative and quantitative 
phase composition were also determined with X-ray 
diffractometer DRON-7M. The chemical structure was 
examined by the Raman light scattering with micro-
spectrometer OmegaScopetm (AIST NT, Zelenograd, 
Russia) that was integrated with scanning probe and 
confocal microscopes. Morphology and the particle sizes 
of HfO2 were studied with atomic-force microscope 
NTEGRA Prima and AIST-NT Smart. Granulometric 
investigations were conducted both in a hand mode and 
with the help of a program packet Gwyddion to atomic-
force microscope Aist-NT Smart. 
Investigations by atomic-force microscopy and elec-
tron microscopy have revealed that the nanopowders of 
both ZrO2 and HfO2 were synthesized as particles of a 
round shape. Fig. 1 shows TEM images of synthesized 
nanoparticles of zirconium dioxide (a) and hafnium 
dioxide (b). According to granulometric study, the par-
ticle sizes were within the limits from 40 to 80 nm for 
ZrO2 and from 10 to 40 nm for HfO2 (Fig. 2).The aver-
age particle size was 54 nm for ZrO2 and 23 nm for 
HfO2. 
By using diffraction of electrons from synthesized 
nanopowders, phase analysis was conducted. Inter-
planar distances derived from diffraction maxima on 
electronograms (inserts in Fig. 1) for samples of ZrO2 
and HfO2 are given in Table 1. Comparison of these 
values with crystallographic database shows that the 
synthesized nanoparticles of both ZrO2 [6] and HfO2 [7] 
were in a monoclinic modification. 
b) 
 N.F. KARPOVICH, M.A. PUGACHEVSKY, ET AL. J. NANO- ELECTRON. PHYS. 7, 04076 (2015) 
 
 
04076-2 
 
 
 
 
Fig. 1 – TEM images of nanopowders of ZrO2 (a) and HfO2 
(b) synthesized by the hydrothermal method 
 
 
 
 
 
Fig. 2 – Granulometric composition of the nanopowders 
obtained: a) ZrO2 (a); b) HfO2 
 
Electron microscopy data are corroborated by X-ray 
phase analysis. In Fig. 3 depicted are X-ray diffracto-
grams of ZrO2 and HfO2 nanopowders. The interplanar 
spacings determined by the maxima on the X-ray pic-
tures are also given in Table 1. X-ray phase data also 
indicate that nanoparticles of zirconium and hafnium 
oxides obtained by the hydrothermal method were in a 
monoclinic phase. 
 
 
Fig. 3 – X-raydiffractograms of synthesized nanopowders: 
a) ZrO2  and (b) HfO2 
 
Table 1 – Comparison of phase analysis of TEM and X-ray 
phase analysis with crystallographic database. The values are 
given in angstroms 
 
Card  
3-515 
Monocli-
nic ZrO2 
,,,,,,,,, 
X
-R
P
A
 Card  
6-318 
Monocli-
nic HfO2 
ПЭМ 
X
-R
P
A
  
3,70 3,67 3,72 3,68 3,73 3,71 
3,64 3,62 3,66 3,61 3,62 3,62 
3,17 3,18 3,18 3,15 3,17 3,16 
2,84 2,83 2,84 2,82 2,85 2,83 
2,63 2,63 2,65 2,59 2,59 2,60 
2,56 2,58 2,57 2,52 2,55 2,54 
 2,51 2,53 2,48 2,50 2,50 
2,34 2,37 2,37 2,32 2,34 2,36 
2,22 2,21 2,24 2,196 2,19 2,18 
2,02 2,02 2,04 1,981 1,99 2,00 
1,85 1,84 1,86 1,838 1,83 1,85 
1,82 1,81 1,83 1,807 1,81 1,82 
1,69 1,68 1,70 1,684 1,68 1,68 
1,65 1,65 1,66 1,653 1,64 1,65 
 
It is known that a dimension effect, when a critical 
size is achieved, can stabilize high-temperature phases 
of polymorphic materials such as ZrO2 and HfO2. In 
work [8], experimentally and theoretically was shown 
that the critical size for ZrO2 is less than 2 nm. As was 
earlier demonstrated, the particles synthesized in the 
present work were of significantly greater than the 
critical size. Therefore, the monoclinic structure is en-
ergetically favorable in them. In our papers [9-11] it 
was shown that with laser ablation one can stabilize 
high-temperature tetragonal and cubic phases of both 
ZrO2 and HfO2 in nanoparticles with the size of up to 
50 nm. This stabilization is achieved owing to the for-
mation of structural defects in surface layers of nano-
particles. 
а 
а 
b 
б) 
b 
а 
b 


The Hydrothermal Autoclave Synthesis of the Nanopowders of the Refractory ZrO2 and HfO2 Oxides

Electronic Sumy State University Institutional Repository

JOURNAL OF NANO- AND ELECTRONIC PHYSICS ЖУРНАЛ НАНО- ТА ЕЛЕКТРОННОЇ ФІЗИКИ Vol. 7 No 4, 04076(2pp) (2015) Том 7 № 4, 04076(2cc) (2015)   2077-6772/2015/7(4)04076(2) 04076-1  2015 Sumy State University Short Communication  The Hydrothermal Autoclave Synthesis of the Nanopowders of the Refractory  ZrO2 and HfO2 Oxides  N.F. Karpovich1, M.A. Pugachevsky1, V.I. Panfilov2, A.P. Kuzmenko3, M.B. Dobromyslov4  1 Institute of Materials Science of the Khabarovsk Scientific Center FEB RAS, Khabarovsk 2  Far Eastern State Transport University, Khabarovsk 3 Department of Nanotechnology&Engeneering Physics, SWSU, Kursk, 4 Pacific National University, Khabarovsk, Russia  (Received 01 October 2015; published online 24 December 2015)  The nanopowders of the transition metal ZrO2 and HfO2 oxides were obtained by the hydrothermal au-toclave synthesis. The nanoparticles possess a rounded shape and a size range of 40 to 80 nm (ZrO2), of 10 to 40 nm (HfO2). X-ray diffraction analysis and electron microscopy show that the structure of the nano-particles is monoclinic.  Keywords: Hydrothermal synthesis, Nanoparticles, Refractory oxides, Zirconium, Hafnium.   PACS numbers: 81.07.Wx, 78.67.Bf  In the last years, problems of producing nanopowders of refractory transition metal oxides of transit metals such as zirconium dioxide and hafnium dioxide [1] have become intensively studied. Great attention to them is dictated by a number of distinctive properties. In addition to the high melting temperature ( ZrO2 –2700 С, HfO2 – 2800 С), strength, corrosive resistance they have a record low, among oxides, heat conductivity they keep in the wide temperature range, which dictates their relevance in powder metallurgy when heat isolators are manufactured [2] Distinctive optical properties due to a stable reflection coefficient in the UV range (up to 220 nm), in the visible and the IR ranges determine their application also in re-flecting coatings of space vehicles that work under tough temperature conditions [3]. Nanopowders of ZrO2 and HfO2 of high chemical purity are used in atomic technolo-gy where zirconium and hafnium have found various ap-plications. On the basis of zirconium, one can made ther-mal insulation coatings of nuclear reactor walls. Na-nopowders of hafnium can be used for control rods of nu-clear reactors since it is well known that hafnium features big cross-section of neutron capture In this connection, the production of chemically pure nanopowders of hafnium and zirconium is an urgent task. Hydrothermal synthesis [4, 5] can be one of the means for production of oxide ce-ramics nanopowders. The present work deals with the results on synthesizing nanopowders of ZrO2 and HfO2 with the autoclave method. Morphological and structural features of particles obtained are also provided. Synthesis of ZrO2 and HfO2 nanopowders was con-ducted by the hydrothermal method in a steel auto-clave with a 50-ml volume Teflon liner. As precursors, zirconium propoxide (IV) in propanol (70 %, ACROS, USA) and hafnium isopropoxide (IV) in (OOCH-(CH3)2)4HOCH(CH3)2 (99 %, Alfa Aesar, Germany) were used. At first, the precursors were solvated in a relevant spirit and hydrolyzed in 10 ml of distilled wa-ter with further aging for one day. After that, diethyl-amine and oleic acid in the ratio 1 : 1 : 1 and distilled water were added. The autoclave was kept at a tem-perature of 160 С for 24 hours. From the obtained so-lution, solvent was removed and the particles were dried at a dynamic heating of up to 400 С for one day and further at an isothermal additionally 24 hours at a temperature of 400 С. The structure and phase composition of synthesized nanopowders were studied in transmission electron microscope ZEISS Libra-120 (accelerating voltage 120 kV) which featured a HAADF detector and an en-ergy Ω- filter. Calibration of electronograms in the mi-crodiffraction mode was done with a test sample for the transmission electron microscopy (TEM) on the basis of a polycrystalline Au film. Qualitative and quantitative phase composition were also determined with X-ray diffractometer DRON-7M. The chemical structure was examined by the Raman light scattering with micro-spectrometer OmegaScopetm (AIST NT, Zelenograd, Russia) that was integrated with scanning probe and confocal microscopes. Morphology and the particle sizes of HfO2 were studied with atomic-force microscope NTEGRA Prima and AIST-NT Smart. Granulometric investigations were conducted both in a hand mode and with the help of a program packet Gwyddion to atomic-force microscope Aist-NT Smart. Investigations by atomic-force microscopy and elec-tron microscopy have revealed that the nanopowders of both ZrO2 and HfO2 were synthesized as particles of a round shape. Fig. 1 shows TEM images of synthesized nanoparticles of zirconium dioxide (a) and hafnium dioxide (b). According to granulometric study, the par-ticle sizes were within the limits from 40 to 80 nm for ZrO2 and from 10 to 40 nm for HfO2 (Fig. 2).The aver-age particle size was 54 nm for ZrO2 and 23 nm for HfO2. By using diffraction of electrons from synthesized nanopowders, phase analysis was conducted. Inter-planar distances derived from diffraction maxima on electronograms (inserts in Fig. 1) for samples of ZrO2 and HfO2 are given in Table 1. Comparison of these values with crystallographic database shows that the synthesized nanoparticles of both ZrO2 [6] and HfO2 [7] were in a monoclinic modification. b)  N.F. KARPOVICH, M.A. PUGACHEVSKY, ET AL. J. NANO- ELECTRON. PHYS. 7, 04076 (2015)   04076-2     Fig. 1 – TEM images of nanopowders of ZrO2 (a) and HfO2 (b) synthesized by the hydrothermal method      Fig. 2 – Granulometric composition of the nanopowders obtained: a) ZrO2 (a); b) HfO2  Electron microscopy data are corroborated by X-ray phase analysis. In Fig. 3 depicted are X-ray diffracto-grams of ZrO2 and HfO2 nanopowders. The interplanar spacings determined by the maxima on the X-ray pic-tures are also given in Table 1. X-ray phase data also indicate that nanoparticles of zirconium and hafnium oxides obtained by the hydrothermal method were in a monoclinic phase.   Fig. 3 – X-raydiffractograms of synthesized nanopowders: a) ZrO2  and (b) HfO2  Table 1 – Comparison of phase analysis of TEM and X-ray phase analysis with crystallographic database. The values are given in angstroms  Card  3-515 Monocli-nic ZrO2 ,,,,,,,,, X-RPA Card  6-318 Monocli-nic HfO2 ПЭМ X-RPA  3,70 3,67 3,72 3,68 3,73 3,71 3,64 3,62 3,66 3,61 3,62 3,62 3,17 3,18 3,18 3,15 3,17 3,16 2,84 2,83 2,84 2,82 2,85 2,83 2,63 2,63 2,65 2,59 2,59 2,60 2,56 2,58 2,57 2,52 2,55 2,54  2,51 2,53 2,48 2,50 2,50 2,34 2,37 2,37 2,32 2,34 2,36 2,22 2,21 2,24 2,196 2,19 2,18 2,02 2,02 2,04 1,981 1,99 2,00 1,85 1,84 1,86 1,838 1,83 1,85 1,82 1,81 1,83 1,807 1,81 1,82 1,69 1,68 1,70 1,684 1,68 1,68 1,65 1,65 1,66 1,653 1,64 1,65  It is known that a dimension effect, when a critical size is achieved, can stabilize high-temperature phases of polymorphic materials such as ZrO2 and HfO2. In work [8], experimentally and theoretically was shown that the critical size for ZrO2 is less than 2 nm. As was earlier demonstrated, the particles synthesized in the present work were of significantly greater than the critical size. Therefore, the monoclinic structure is en-ergetically favorable in them. In our papers [9-11] it was shown that with laser ablation one can stabilize high-temperature tetragonal and cubic phases of both ZrO2 and HfO2 in nanoparticles with the size of up to 50 nm. This stabilization is achieved owing to the for-mation of structural defects in surface layers of nano-particles. а а b б) b а b 

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The Hydrothermal Autoclave Synthesis of the Nanopowders of the Refractory ZrO2 and HfO2 Oxides

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