The purpose of this work is to determine the optimal parameters of synthesis of nano-tubular crystals Co-chrysotile. The optimal temperature ranges and pressure for the synthesis of nano-tubular crystals Co-chrysotile 573 – 673 K, 19.6 – 98.1 MPa at the time of isothermal exposure from 15 to 24 h.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3525

Beresnev, V.M.

Pavlenko, V.I.

Smolikov, A.A.

Sokolenco, I.V.

Solokha, A.S.

Vezentsev, A.I.

Electronic Sumy State University Institutional Repository

PROCEEDINGS OF THE INTERNATIONAL CONFERENCE  NANOMATERIALS: APPLICATIONS AND PROPERTIES Vol. 2 No 3, 03NCNN14(3pp) (2013)   2304-1862/2013/2(3)03NCNN14(3) 03NCNN14-1  2013 Sumy State University Nanotubular Crystals of Co-chrysotile (Co-hydro Silicate)  A.A. Smolikov1,*, A.I. Vezentsev2, V.M. Beresnev3, V.I. Pavlenko1, A.S. Solokha1, I.V. Sokolenco1  1 Belgorod Shukhov State Technological University, 308 012 Belgorod, Russia 2 National-Research University – Belgorod State University, 308 015 Belgorod, Russia 3 Kharkov Karazin State University, 61 077 Kharkov, Ukraine  (Received 19 May 2013; published online 30 August 2013)  The purpose of this work is to determine the optimal parameters of synthesis of nano-tubular crystals Co-chrysotile. The optimal temperature ranges and pressure for the synthesis of nano-tubular crystals Co-chrysotile 573 – 673 K, 19.6 – 98.1 MPa at the time of isothermal exposure from 15 to 24 h.  Keywords: Co-chrysotile nano-tubes, Synthesis, Optimal parameters.    PACS numbers: 61.46.Fg                                                           * smolikov@bsu.edu.ru 1. INTRODUCTION  The first attempt to synthesize the cobalt chrysotile (Co6 [(OH)8 | Si4O10]) stoichiometric 3CoO 2SiO2 2H2O, was made in the early 40-ies of the 20-th century [1]. Theoretical premise of was that the divalent cobalt’s cation has ionic radius (rCo+2  8.2 ∙10–11 m) close to the radius of the magnesium cation (rMg+2  7.8 ∙ 10–11 m), therefore, must there cobalt structural analogue of chrysotile. The structure of these fibrous hydro silicates is the same: the first (inner) tetrahedral layers of nano-tubes consist from silicon-oxygen network and the sec-ond (external) octahedral layer – net of hydroxide bru-cite type. According to Pauling's theory twisting of these (serpentine) layers in the form of tubes due to the fact that the parameters of the silicon-oxygen cell grid is slightly smaller than the cell parameters brucite layer. The next attempt to synthesize nanotubes Co-chrysotile, undertaken in 12 years [2], was not suc-cessful, but later in the synthesis in a reducing envi-ronment [3–7] obtained cobalt chrysotile fibers. Co-chrysotile forms easily, under the same conditions as that for chrysotile and its crystals as for chrysotile fiber characteristic habit. Tubing wall cobalt chryso-tile consist of 4 layers thinner than that of Mg-and Ni-chrysotile (garnierite): 11 layers in chrysotile and 9 in garnierite. The outer diameter of the cobalt chrysotile fibers is less than its analogs – magnesium chrysotile and garnierite, due much greater disparity between the tetrahedral and octahedral layers of the crystal lattice.  2. EXPERIMENTAL  The purpose of this work is to determine the opti-mum temperature and pressure for the synthesis of nano-tubular crystals Co-chrysotile. We syntheses of Co-chrysotile from the precipitation of stoichiometric composition (ratio of CoO: SiO2  3:2 as the chrysotile) obtained from solutions CoSO4, H2SiO3 nH2O (or Na2SiO3) and NaOH as we used charges from Co(OH)2 and H2SiO3 nH2O. Study of precipitation [6], obtained from solutions of salts, showed that these sediments are composed of nano-sized X-ray amorphous particles strongly hydrated phase with a layered structure, which at hydrothermal recrystallization transformed into hydro-silicates certain chemical composition and morphology. The precipitate was washed from Na2SO4, and 5 g was placed in an autoclave, filled calculated amount of distilled water with hydrazine (to creation reducing conditions). The resulting slurry was autoclaved at 473 – 673 K, 9.81 – 245  MPa and isothermal expo-sure time from 2 to 240 h. We controlled the formation and growth of fibrils Co-chrysotile by x-ray phase and electron microscopic analyzes.  3. RESULTS AND DISCUSSION  Investigation of the products of hydrothermal crystallization at 473 K, 9.81 – 245 MPa precipita-tion ratio CoO: SiO2 = 3:2 obtained from solutions CoSO4, Na2SiO3 and NaOH, showed that after 2 h of autoclaving products are formed predominantly squamous morphology (as films) with few layers, begins to twist as rolls in the tube (Fig. 1). As the temperature increases to 673 K this pattern is ob-served in 2 h, i. e., the temperature affects the kinet-ics of the process. Pressure has almost no effect on the rate of crystallization. On the basis of these con-clusions, the following experiments were carried out by recrystallization of precipitation at 673 K and 98.1 MPa. Kind of product recrystallized precipitate for 10 hours and micro-electron diffraction from curled the layers shown in Fig. 2a. Draws attention to the fact of incomplete stage of structure (edges of nano-plate particles are too thin, and in many cases do not have sharp edges). Embryos of cobalt chryso-tile fibrils observed in a small number in the gel-like mass. Fig. 2b presents form of products recrystalliza-tion sediment and micro-electron diffraction pattern of the nanotubes after the 24 h exposure. Products of recrystallization after 240 h autoclaving have almost the same form.   A. SMOLIKOV, A.I. VEZENTSEV, V.M. BERESNEV ET AL. PROC. NAP 2, 03NCNN14 (2013)   03NCNN14-2   Fig. 1 – Embryonic layers of cobalt chrysotile observed in the products of hydrothermal treatment sludge (slurry) at 473 – 673 K, 9.81 – 245 MPa    a    b  Fig. 2 – The transformation of embryonic layers, shown in Fig. 1, into tubular fibers and micro-electron-diffraction-patterns of recrystallization products. Autoclaving time: Fig. 2a – 10 h, Fig. 2b – 24 h.  It can be argued that these photographs illustrate the initial stage of the formation of tubular fibrils and the resulting fibrils to grow in length, apparently, due to dissolution of small embryos fibrils during recrystal-lization, based on the theory of Pauling's a mismatch between brucite and silicon oxide layers, as the cause of the twisting of the layers in the tube. Original film, apparently bent differently, therefore, can twist in the form of tubes with cylindrical coaxial layers, and with the layers arranged conically. Micro-electron-diffraction patterns obtained by micro-diffraction from thin edges of lamellar particles indicate the presence of diffuse background or circular picture of Debye-Scherer, indicating incomplete primary level of struc-ture of embryonic layers. Not getting enough of the fiber fraction and after washing of sodium nitrate, it was decided to try to synthesize cobalt chrysotile from the charge, consisting of cobalt hydroxide, crystals which have, as in brucite, hexagonal shape with negligible thickness, and silicic acid in the molecular ratio corresponding to the mag-nesium chrysotile. The rate of full interaction between the components of the charge from (of) Co(OH)2 and silica acid (SiO2 nH2O) at 473 K is small – for their interaction will need  40-hours, increasing the temperature up to a certain limit accelerates the formation and growth of fibrils. For full interaction components is about 15 h at 673 K. X-ray amorphous product was after a hydro-thermal treatment. The interaction between cobalt hydroxide and silicic acid leads to the formation of fibers, which are electron micrographs were observed in the form of separate tubular empty fibrils or they aggregates (Fig. 3). The study of these fibrils by electron micro-diffraction showed that they electron-amorphous. Synthesis prod-uct contains 100  of the tubular fibers.    Fig. 3 – Micro-electron-diffraction pattern of cobalt chrysotile fibrils, synthesized for 40 hours from cobalt hydroxide and silicic acid  E.N. Korytkova et al. [8] have recently been synthe-sized in the system MgO–CoO–SiO2–H2O isomorphic substituted in the octahedral sites of the Mg-Co-chrysotile composition (Mg, Co)6 [(OH)8 | Si4O10] in accordance with the theory of isomorph’s miscibility [9].  4. CONCLUSIONS  From the above results it is clear that the tempera-ture of the hydrothermal process is the main factor that affects the speed of the phase formation in the system. Temperature hydrothermal treatment is the domi-nant factor in the process of hydrothermal crystalliza-tion. The processing time to a lesser extent, affects the  NANOTUBULAR CRYSTALS OF CO-CHRYSOTILE (CO-HYDRO SILICATE) PROC. NAP 2, 03NCNN14 (2013)   03NCNN14-3 synthesis Co6 [(OH)8 | Si4O10]. The pressure in the range studied (9.81 – 245 MPa) has no appreciable effect on the rate of reaction compo-nents. The optimal temperature ranges and pressure for the synthesis of nano-tubular crystals Co-chrysotile 573 – 673 K, 19.6 – 98.1 MPa at the time of isothermal holding from 15 to 24 h. Found that in all the experiments beyond a certain length,  up to 1 mkm, the growth of fibrils stops, long-er hydrothermal treatment does not increase the length.   REFERENCES  1. W. Feitknecht, A. Berger, Helv. Chim. Acta 25 №7–8 1543 (1942). 2. D.M. Roy, R. Roy, Amer. Miner. 39, 957 (1954). 3. W. Noll, H. Kircher, H. Sybertz, Kobaltchrysotile, Natur-wiss 45, №20, (1958). 4. W. Noll, H. Kircher, W. Sybertz, Beitr. Min. Petr. Н. 7, №4, 232 (1960). 5. C.W.F.T. Pistorius, News Jahrb. Mineral., Monatshefte, №2–3, 30 (1963). 6. A.A. Smolikov, Development of technology for the synthesis and study of the structural analogues of chrysotile asbes-tos: Dissertation, 196 (1982). 7. A.A. Smolikov, A.I. Vezentsev, Proceedings of the Interna-tional scientific conference: 2007, 60 (Kharkov, Ukraine, MESYSU and NASU, 2007). 8. E.N. Korytkova, L.N. Pivovarova, I. Drozdov, V.V. Gusarov, J. of Gener. Chem. 77, №10, 1600 (2007). 9. V.S. Urusov, Isomorphs miscibility theory (Moscow: Nau-ka: 1977).  

Nanotubular Crystals of Co-chrysotile (Co-hydro Silicate)

SocioEconomic Challenges Journal (Sumy State University)

PROCEEDINGS OF THE INTERNATIONAL CONFERENCE  
NANOMATERIALS: APPLICATIONS AND PROPERTIES 
Vol. 2 No 3, 03NCNN14(3pp) (2013) 
 
 
2304-1862/2013/2(3)03NCNN14(3) 03NCNN14-1  2013 Sumy State University 
Nanotubular Crystals of Co-chrysotile (Co-hydro Silicate) 
 
A.A. Smolikov1,*, A.I. Vezentsev2, V.M. Beresnev3, V.I. Pavlenko1, A.S. Solokha1, I.V. Sokolenco1 
 
1 Belgorod Shukhov State Technological University, 308 012 Belgorod, Russia 
2 National-Research University – Belgorod State University, 308 015 Belgorod, Russia 
3 Kharkov Karazin State University, 61 077 Kharkov, Ukraine 
 
(Received 19 May 2013; published online 30 August 2013) 
 
The purpose of this work is to determine the optimal parameters of synthesis of nano-tubular crystals 
Co-chrysotile. The optimal temperature ranges and pressure for the synthesis of nano-tubular crystals Co-
chrysotile 573 – 673 K, 19.6 – 98.1 MPa at the time of isothermal exposure from 15 to 24 h. 
 
Keywords: Co-chrysotile nano-tubes, Synthesis, Optimal parameters. 
 
  PACS numbers: 61.46.Fg 
 
 
                                                        
*
 smolikov@bsu.edu.ru 
1. INTRODUCTION 
 
The first attempt to synthesize the cobalt chrysotile 
(Co6 [(OH)8 | Si4O10]) stoichiometric 3CoO 2SiO2 2H2O, 
was made in the early 40-ies of the 20-th century [1]. 
Theoretical premise of was that the divalent cobalt’s 
cation has ionic radius (rCo+2  8.2 ∙10–11 m) close to the 
radius of the magnesium cation (rMg+2  7.8 ∙ 10–11 m), 
therefore, must there cobalt structural analogue of 
chrysotile. The structure of these fibrous hydro silicates 
is the same: the first (inner) tetrahedral layers of nano-
tubes consist from silicon-oxygen network and the sec-
ond (external) octahedral layer – net of hydroxide bru-
cite type. According to Pauling's theory twisting of 
these (serpentine) layers in the form of tubes due to the 
fact that the parameters of the silicon-oxygen cell grid 
is slightly smaller than the cell parameters brucite 
layer. 
The next attempt to synthesize nanotubes Co-
chrysotile, undertaken in 12 years [2], was not suc-
cessful, but later in the synthesis in a reducing envi-
ronment [3–7] obtained cobalt chrysotile fibers. Co-
chrysotile forms easily, under the same conditions as 
that for chrysotile and its crystals as for chrysotile 
fiber characteristic habit. Tubing wall cobalt chryso-
tile consist of 4 layers thinner than that of Mg-and Ni-
chrysotile (garnierite): 11 layers in chrysotile and 9 in 
garnierite. The outer diameter of the cobalt chrysotile 
fibers is less than its analogs – magnesium chrysotile 
and garnierite, due much greater disparity between 
the tetrahedral and octahedral layers of the crystal 
lattice. 
 
2. EXPERIMENTAL 
 
The purpose of this work is to determine the opti-
mum temperature and pressure for the synthesis of 
nano-tubular crystals Co-chrysotile. We syntheses of 
Co-chrysotile from the precipitation of stoichiometric 
composition (ratio of CoO: SiO2  3:2 as the chrysotile) 
obtained from solutions CoSO4, H2SiO3 nH2O (or 
Na2SiO3) and NaOH as we used charges from Co(OH)2 
and H2SiO3 nH2O. Study of precipitation [6], obtained 
from solutions of salts, showed that these sediments 
are composed of nano-sized X-ray amorphous particles 
strongly hydrated phase with a layered structure, 
which at hydrothermal recrystallization transformed 
into hydro-silicates certain chemical composition and 
morphology. 
The precipitate was washed from Na2SO4, and 5 g 
was placed in an autoclave, filled calculated amount 
of distilled water with hydrazine (to creation reducing 
conditions). The resulting slurry was autoclaved at 
473 – 673 K, 9.81 – 245  MPa and isothermal expo-
sure time from 2 to 240 h. 
We controlled the formation and growth of fibrils 
Co-chrysotile by x-ray phase and electron microscopic 
analyzes. 
 
3. RESULTS AND DISCUSSION 
 
Investigation of the products of hydrothermal 
crystallization at 473 K, 9.81 – 245 MPa precipita-
tion ratio CoO: SiO2 = 3:2 obtained from solutions 
CoSO4, Na2SiO3 and NaOH, showed that after 2 h of 
autoclaving products are formed predominantly 
squamous morphology (as films) with few layers, 
begins to twist as rolls in the tube (Fig. 1). As the 
temperature increases to 673 K this pattern is ob-
served in 2 h, i. e., the temperature affects the kinet-
ics of the process. Pressure has almost no effect on 
the rate of crystallization. On the basis of these con-
clusions, the following experiments were carried out 
by recrystallization of precipitation at 673 K and 
98.1 MPa. Kind of product recrystallized precipitate 
for 10 hours and micro-electron diffraction from 
curled the layers shown in Fig. 2a. Draws attention 
to the fact of incomplete stage of structure (edges of 
nano-plate particles are too thin, and in many cases 
do not have sharp edges). Embryos of cobalt chryso-
tile fibrils observed in a small number in the gel-like 
mass. 
Fig. 2b presents form of products recrystalliza-
tion sediment and micro-electron diffraction pattern 
of the nanotubes after the 24 h exposure. Products of 
recrystallization after 240 h autoclaving have almost 
the same form. 
 
 A. SMOLIKOV, A.I. VEZENTSEV, V.M. BERESNEV ET AL. PROC. NAP 2, 03NCNN14 (2013) 
 
 
03NCNN14-2 
 
 
Fig. 1 – Embryonic layers of cobalt chrysotile observed in the 
products of hydrothermal treatment sludge (slurry) at 473 –
 673 K, 9.81 – 245 MPa 
 
 
 
a 
 
 
 
b 
 
Fig. 2 – The transformation of embryonic layers, shown in 
Fig. 1, into tubular fibers and micro-electron-diffraction-
patterns of recrystallization products. Autoclaving time: 
Fig. 2a – 10 h, Fig. 2b – 24 h. 
 
It can be argued that these photographs illustrate 
the initial stage of the formation of tubular fibrils and 
the resulting fibrils to grow in length, apparently, due 
to dissolution of small embryos fibrils during recrystal-
lization, based on the theory of Pauling's a mismatch 
between brucite and silicon oxide layers, as the cause of 
the twisting of the layers in the tube. Original film, 
apparently bent differently, therefore, can twist in the 
form of tubes with cylindrical coaxial layers, and with 
the layers arranged conically. Micro-electron-
diffraction patterns obtained by micro-diffraction from 
thin edges of lamellar particles indicate the presence of 
diffuse background or circular picture of Debye-
Scherer, indicating incomplete primary level of struc-
ture of embryonic layers. 
Not getting enough of the fiber fraction and after 
washing of sodium nitrate, it was decided to try to 
synthesize cobalt chrysotile from the charge, consisting 
of cobalt hydroxide, crystals which have, as in brucite, 
hexagonal shape with negligible thickness, and silicic 
acid in the molecular ratio corresponding to the mag-
nesium chrysotile. 
The rate of full interaction between the components 
of the charge from (of) Co(OH)2 and silica acid 
(SiO2 nH2O) at 473 K is small – for their interaction 
will need  40-hours, increasing the temperature up to 
a certain limit accelerates the formation and growth of 
fibrils. For full interaction components is about 15 h at 
673 K. X-ray amorphous product was after a hydro-
thermal treatment. 
The interaction between cobalt hydroxide and silicic 
acid leads to the formation of fibers, which are electron 
micrographs were observed in the form of separate 
tubular empty fibrils or they aggregates (Fig. 3). The 
study of these fibrils by electron micro-diffraction 
showed that they electron-amorphous. Synthesis prod-
uct contains 100  of the tubular fibers. 
 
 
 
Fig. 3 – Micro-electron-diffraction pattern of cobalt chrysotile 
fibrils, synthesized for 40 hours from cobalt hydroxide and 
silicic acid 
 
E.N. Korytkova et al. [8] have recently been synthe-
sized in the system MgO–CoO–SiO2–H2O isomorphic 
substituted in the octahedral sites of the Mg-Co-
chrysotile composition (Mg, Co)6 [(OH)8 | Si4O10] in 
accordance with the theory of isomorph’s miscibility [9]. 
 
4. CONCLUSIONS 
 
From the above results it is clear that the tempera-
ture of the hydrothermal process is the main factor 
that affects the speed of the phase formation in the 
system. 
Temperature hydrothermal treatment is the domi-
nant factor in the process of hydrothermal crystalliza-
tion. 
The processing time to a lesser extent, affects the 
 NANOTUBULAR CRYSTALS OF CO-CHRYSOTILE (CO-HYDRO SILICATE) PROC. NAP 2, 03NCNN14 (2013) 
 
 
03NCNN14-3 
synthesis Co6 [(OH)8 | Si4O10]. 
The pressure in the range studied (9.81 – 245 MPa) 
has no appreciable effect on the rate of reaction compo-
nents. 
The optimal temperature ranges and pressure for 
the synthesis of nano-tubular crystals Co-chrysotile 
573 – 673 K, 19.6 – 98.1 MPa at the time of isothermal 
holding from 15 to 24 h. 
Found that in all the experiments beyond a certain 
length,  up to 1 mkm, the growth of fibrils stops, long-
er hydrothermal treatment does not increase the 
length. 
 
 
REFERENCES 
 
1. W. Feitknecht, A. Berger, Helv. Chim. Acta 25 №7–8 1543 
(1942). 
2. D.M. Roy, R. Roy, Amer. Miner. 39, 957 (1954). 
3. W. Noll, H. Kircher, H. Sybertz, Kobaltchrysotile, Natur-
wiss 45, №20, (1958). 
4. W. Noll, H. Kircher, W. Sybertz, Beitr. Min. Petr. Н. 7, 
№4, 232 (1960). 
5. C.W.F.T. Pistorius, News Jahrb. Mineral., Monatshefte, 
№2–3, 30 (1963). 
6. A.A. Smolikov, Development of technology for the synthesis 
and study of the structural analogues of chrysotile asbes-
tos: Dissertation, 196 (1982). 
7. A.A. Smolikov, A.I. Vezentsev, Proceedings of the Interna-
tional scientific conference: 2007, 60 (Kharkov, Ukraine, 
MESYSU and NASU, 2007). 
8. E.N. Korytkova, L.N. Pivovarova, I. Drozdov, 
V.V. Gusarov, J. of Gener. Chem. 77, №10, 1600 (2007). 
9. V.S. Urusov, Isomorphs miscibility theory (Moscow: Nau-
ka: 1977). 
 


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Nanotubular Crystals of Co-chrysotile (Co-hydro Silicate)

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