Питома площа поверхні, кристалітний розмір та термокінетика формування нанопорошків оксиду γ → α-Al2O3 при 570 -1470 К
Powders where the γ≈α-Al2O3-nano phases are the priority precursors for catalysts for heterogeneous catalysis with the maximum content of surface 5-coordinated Al centers for Pt attachment. Hydrogenated nano powders (~8 nm) of γ-, γ '-, θ-, κ-Al2O3 soluble in hydrochloric acid were obtained fro...
Saved in:
| Date: | 2020 |
|---|---|
| Main Authors: | , , , , , , , , , , |
| Format: | Article |
| Language: | English |
| Published: |
Chuiko Institute of Surface Chemistry National Academy of Sciences of Ukraine
2020
|
| Subjects: | |
| Online Access: | https://surfacezbir.com.ua/index.php/surface/article/view/704 |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| Journal Title: | Surface |
| Download file: |  |
Institution
Surface| _version_ | 1869291865311805440 |
|---|---|
| author | Гарбуз, В. В. Петрова, В. А. Сілінська, Т. А. Лобунець, Т. Ф. Биков, О. І. Муратов, В. Б. Терентьєва, Т. М. Кузьменко, Л. М. Васільєв, О. О. Оліфан, О. І. Хомко, Т. В. |
| author_facet | Гарбуз, В. В. Петрова, В. А. Сілінська, Т. А. Лобунець, Т. Ф. Биков, О. І. Муратов, В. Б. Терентьєва, Т. М. Кузьменко, Л. М. Васільєв, О. О. Оліфан, О. І. Хомко, Т. В. |
| author_institution_txt_mv | [
{
"author": "В. В. Гарбуз",
"institution": "Інститут проблем матеріалознавства ім. І. М. Францевича НАН України"
},
{
"author": "В. А. Петрова",
"institution": "Інститут проблем матеріалознавства ім. І. М. Францевича НАН України"
},
{
"author": "Т. А. Сілінська",
"institution": "Інститут проблем матеріалознавства ім. І. М. Францевича НАН України"
},
{
"author": "Т. Ф. Лобунець",
"institution": "Інститут проблем матеріалознавства ім. І. М. Францевича НАН України"
},
{
"author": "О. І. Биков",
"institution": "Інститут проблем матеріалознавства ім. І. М. Францевича НАН України"
},
{
"author": "В. Б. Муратов",
"institution": "Інститут проблем матеріалознавства ім. І. М. Францевича НАН України"
},
{
"author": "Т. М. Терентьєва",
"institution": "Інститут проблем матеріалознавства ім. І. М. Францевича НАН України"
},
{
"author": "Л. М. Кузьменко",
"institution": "Інститут проблем матеріалознавства ім. І. М. Францевича НАН України"
},
{
"author": "О. О. Васільєв",
"institution": "Інститут проблем матеріалознавства ім. І. М. Францевича НАН України"
},
{
"author": "О. І. Оліфан",
"institution": "Інститут проблем матеріалознавства ім. І. М. Францевича НАН України"
},
{
"author": "Т. В. Хомко",
"institution": "Інститут проблем матеріалознавства ім. І. М. Францевича НАН України"
}
] |
| author_sort | Гарбуз, В. В. |
| baseUrl_str | |
| collection | OJS |
| datestamp_date | 2021-03-01T11:03:55Z |
| description | Powders where the γ≈α-Al2O3-nano phases are the priority precursors for catalysts for heterogeneous catalysis with the maximum content of surface 5-coordinated Al centers for Pt attachment. Hydrogenated nano powders (~8 nm) of γ-, γ '-, θ-, κ-Al2O3 soluble in hydrochloric acid were obtained from the processing of aluminum boride powders with an icosahedral structure. Samples, which underwent a step-by-step and single heating of 50-100K heat treatment for 2 hours at temperatures of 570-1470K, were received in quantity of 34. The specific surface area of SВET, m2g-1 was measured by the thermal nitrogen desorption  express method of gas chromatography through the GC-1 device. X-ray (phase and coherent), fluorescence and phase chemical-analytical evaluation of the samples were performed. The thermokinetic characteristics of the processes are calculated using the exponential Arrhenius law. Dimensional characteristics of crystallites (10.4-48 nm); specific surface area of powders (213-8.6 m2g-1, SВET); thermokinetic parameters of α-Al2O3 crystallite growth process (V α-Al2O3 - 1.44 10-3 - 6.67 10-3 nm s-1; E α-Al2O3 = 38.7±2.1kJ mol-1; A0 = 0.16±0.0 s-1 along the temperature line 1220-1470K were determined and calculated. The process of dehydration of two OH-groups occurs in the region 570-720K Ea H2O ↑ = 30.5 ± 0.5 kJ mol-1 A0 = 1.33±0.3 s-1. The last group of OH at temperatures of 820 -1070К and a rate of 2.13 10-4 - 4.93 10-4 mol s-1 Ea H2O ↑ = 13.2 ± 0.8 kJ mol-1 A0 = 16.9 ± 0.9 s-1. The activation energy of the phase transition is Ea., γ → α-Al2O3 = 23.9 ± 1.0 kJ mol-1 A0 = 2.01 ± 0.72 s-1 (770-970K) and Ea., γ → α-Al2O3 = 83.5 ± 0.8 kJ mol-1 A0 =(2,05±0,95) 103 s-1 (1070-1170K). It agrees well with the known heat of conversion Eа, γ→α-Al2O3 = 85 kJ mol-1. The TK of γ≈α-Al2O3-nano phases is at 1170K. |
| doi_str_mv | 10.15407/Surface.2020.12.146 |
| first_indexed | 2025-07-22T19:35:10Z |
| format | Article |
| fulltext |
Поверхность. 2020. Вып. 12(27). С. 146–152 146
UDC 541.1 + 620.22 + 546.171.1 / 27 + 620.18 doi: 10.15407/Surface.2020.12.146
SPECIFIC SURFACE AREA, CRYSTALLITE SIZE AND
THERMOKINETIC OF OXIDE FORMATION γ → α-Al2O3
NANO POWDERS AT 570 – 1470 K
V.V. Garbuz, V.A. Petrova, T.A. Silinskaya, T.F. Lobunets, O.I. Bykov, V.B. Muratov,
T.M. Terentyeva, L.M. Kuzmenko, O.O. Vasiliev, O.I. Olifan, T.V. Homko
Institute for Problems of Materials Science. I. Frantsevich National Academy of Sciences of
Ukraine, Krzhizhanovsky str., 3 Kyiv, 03680, Ukraine, e-mail: wpetrowa@ukr.net;
Garbuz.v1950@Gmail.com
Powders where the γ≈α-Al2O3-nano phases are the priority precursors for catalysts for
heterogeneous catalysis with the maximum content of surface 5-coordinated Al centers for Pt
attachment. Hydrogenated nano powders (~8 nm) of γ-, γ '-, θ-, κ-Al2O3 soluble in hydrochloric
acid were obtained from the processing of aluminum boride powders with an icosahedral
structure. Samples, which underwent a step-by-step and single heating of 50-100K heat
treatment for 2 hours at temperatures of 570-1470K, were received in quantity of 34. The
specific surface area of SВET, m2g-1 was measured by the thermal nitrogen desorption express
method of gas chromatography through the GC-1 device. X-ray (phase and coherent),
fluorescence and phase chemical-analytical evaluation of the samples were performed. The
thermokinetic characteristics of the processes are calculated using the exponential Arrhenius
law. Dimensional characteristics of crystallites (10.4-48 nm); specific surface area of powders
(213-8.6 m2g-1, SВET); thermokinetic parameters of α-Al2O3 crystallite growth process (V α-Al2O3 -
1.44 10-3 - 6.67 10-3 nm s-1; E α-Al2O3 = 38.7±2.1kJ mol-1; A0 = 0.16±0.0 s-1 along the temperature
line 1220-1470K were determined and calculated. The process of dehydration of two OH-groups
occurs in the region 570-720K Ea H2O ↑ = 30.5 ± 0.5 kJ mol-1 A0 = 1.33±0.3 s-1. The last group of
OH at temperatures of 820 -1070К and a rate of 2.13 10-4 - 4.93 10-4 mol s-1 Ea H2O ↑ = 13.2 ±
0.8 kJ mol-1 A0 = 16.9 ± 0.9 s-1. The activation energy of the phase transition is Ea., γ → α-Al2O3 =
23.9 ± 1.0 kJ mol-1 A0 = 2.01 ± 0.72 s-1 (770-970K) and Ea., γ → α-Al2O3 = 83.5 ± 0.8 kJ mol-1 A0
=(2,05±0,95) 103 s-1 (1070-1170K). It agrees well with the known heat of conversion Eа, γ→α-Al2O3
= 85 kJ mol-1. The TK of γ≈α-Al2O3-nano phases is at 1170K.
Keywords: specific surface area, crystallite size, thermal kinetics, phase transition, powders,
γ→α-Al2O3-nano, dehydration, crystallite growth
Introduction
The search for ceramic and composite materials resistant to shocking physical impact is
relevant. These include related icosahedral compounds such as boron carbide, including reaction
products in the system: "Al - B15-x Cx [1] and BN" [2-9].
Powder γ-Al2O3-nano, in contrast to α-Al2O3 - easily soluble in hydrochloric acid, active
sintering material. A solution of sodium tetrahydroxy-aluminate, from waste refining powders
AlB12, AlB12C2, Al8B4C7 [10, 11] became a precursor to produce γ-Al2O3. In the process of
γ→α-Al2O3 phase transition, extended in temperature and time, the state of the powder is special,
where the content of γ, octahedrally coordinated aluminum (3+) is proportional to the α-phase of
Al2O3 with tetrahedral Al (3+). Under these conditions, the surface of the oxide particles
according to 27Al MAS-NMR spectroscopy at a magnetic field of 17.6 Tesla [12-14] has up to
20% of intermediate unsaturated 5-coordinated 27Al ionic polyhedral. They act as mounting
points for catalytically active materials, such as Pt. The degree of phase transition and the
147
content of 5-coordinated aluminum atoms depends on: the thermokinetic characteristics of the
processes of dehydration; phase transformations and growth of α-phase crystallites. The study of
the formation of oxides (subject of research) γ→α-Al2O3 in the temperature range of these
processes is relevant. Thermokinetic measurements are inherent in the chemical features of the
components of the research object α-Al2O3-nano using delicate methods of chemical phase
analysis, X-ray diffraction, coherent scattering and methods of nitrogen desorption in the region
of heat treatment
570-1470 K. The results of measurements are calculated using Svante Arrhenius equation.
Methodologically, such experiments were performed for the first time.
Materials and research methods
Powder 5.0-10.0 nm preferably γ; γ’-Al2O3-nano (RFA) was obtained during the
processing of technological waste products of interaction in the system: “BN – Al” [10].
Hydroxyl derivatives of aluminum (3+) were precipitated from alkaline solutions with nitric acid
to pH 4.0-5.0. The coagulated product is purified 5 times according to rural cheese production
technologies. The difference of osmotic pressure of aqueous solutions and pure aqua at a ratio of
1:10, respectively, was used. According to the known version, the powder is partially dehydrated
at 420 and 570 K according to the data [16].1 Diffractograms of γ-Al2O3 samples calcined at
1170 K had reflections of crystalline phases, including α-Al2O3. Samples of Al2O3 powder are
calcined in steps (2 hours) to a temperature of 1470 K sequentially or once. The phases γ-
Al(OH)3, γ-AlO(OH), γ-Al2O3 and γ’-Al2O3, in contrast to α-Al2O3, are soluble in hydrochloric
acid. [16]. All modifications of alumina are soluble in NaOH melt. Aluminum (3+) was
determined by complex-metric direct and inverse titration with fluoride masking [17]. OH-
groups after substitution with fluoride (KF) – acid-metrically with phenol-phthalein according to
Tananaev [17]. Hydrogen, nitrogen (and oxygen) - pulsed reductive extraction with carbon and
gas chromatography [12]. Carbon was measured by oxidative extraction and coulomb-metrically
(AN 7529m) [17]. Diffractograms were performed on an X-ray diffractometer DRON-3,0 Cu kα-
radiation, monochromator. The specific surface area SBET, m2g-1 was determined by express
method of thermal nitrogen desorption using the GC-1 device. The X-ray fluorescence analyzer
EXPERT 3L W207U" (Ukraine) was used, the Al2O3 content was 99.69% (wt.), SiO2 -
0.31%. γ→α-Al2O3 and growth of α-Al2O3-nano crystallites according to Arrhenius exponential
law.
Obtained results and discussions
Phase composition. The obtained results do not coincide with the data [16], apparently due
to the lack of heat treatment time. The original γ-Al2O3 is a mixture of 65.3% of the mass. γ-
AlO(OH) and 34.7.7% γ-Al(OH)3. The γ-Al(OH)3 phase decomposes in the region of 770-870K.
Phase γ-AlO (OH) - at 1030K. The samples annealed sequentially or once at 1170K had a phase
composition of: soluble phases2 45.0% γ-Al2O3 and 55.0% of other Al2O3 phases3 (1); 58.0% γ-
Al2O3 and 42.0% α-Al2O3 (2), respectively. Al2O3 powders without soluble γ-Al2O3 were
obtained at 1230-1470K heat treatment.
Dehydration. Data from the thermokinetic process of dehydration of Al2O3 powders are
presented in the table. The total content of bound water in the OH-groups was ≈ 20% of the
mass. Dehydration of the 1st (accumulative) and 2nd (single) heating modes in the region 570-
870K have a hysteresis of discrepancy. As the temperature increases from 870K to 1470K, the
1 In the future, the time of each heat treatment was two hours, respectively.
2 - conventionally referred to below as γ-Al2O3.
3 - conventionally referred to below as α-Al2O3.
148
dehydration curves merge into one line. The dehydration rate increases from 1.87 10-5 to 4.93 10-4
mol s-1 (Table). The activation energy of dehydration of the two OH-groups (equation 1) in the region
570-730K is Ea H2O ↑ = 30.5 ± 0.5 kJ mol-1. The last group of OH (equations 2, 3) at temperatures of 830-
1070K and a velocity of 2.13 10-4 - 4.93 10-4 mol s-1 dissociates with the activation energy within Ea H2O
↑ = 13.2 ± 0.8 kJ mol-1. Above 1070K, Al2O3-nano powder becomes virtually anhydrous.
Al(OH)3solid → 770-870K → AlO(OH)solid + H2O ↑ gas (1)
AlO(OH)solid → 1030K → 0.5 Al2O3hard + 0.5 H2O ↑ gas (2)
OH-solid → 770-1030K → 0,5O2-
solid + 0,5 H2O ↑ gas (3)
The dehydration reaction constant is: kH2O ↑ = [H2O] 0.5. Dehydration rate V H2O ↑ = [H2O]
exposure time-1 (s-1). The rate constant kv = (V H2O ↑) 0.5.
Phase transition. The reaction (4; 5) phase transition (Table) can be represented as:
γ-Al2O3 → 670-1230K → α-Al2O3 (cumulative heating) (4) or
γ-Al2O3 → 1130-1230K → α-Al2O3 (single-stage heating) (5).
Table 1. Thermokinetic characteristics of hydrated powders γ → α-Al2O3-nano (9.7-48.0 nm;
SBET = 213.0-8.6 m2g-1) in the field of 570-1470K
N T, K Velocity, V, mol s-1,
(nm s-1)
Activation
energy Ea
kJ mol-1
Frequency
factor,
A0 s
-1
1 620-670 H2O↑106= 0.58-5.24 H2O↑ = 29.7±1.0 H2O↑ = 0.78±0,04
2 820-1070 H2O↑106= 6.56-15.2 H2O↑ =13.2±1.0 H2O↑102 = 5.8±0.2
3 670-970 γ→α-Al2O3106= 3.47-
12.5
γ→α-Al2O3= 23.9±1.0 γ→α-Al2O3= 2,0±0,7
4 1070-
1200
γ→α-Al2O3105= 2.78-
14.2
γ→α-Al2O3= 83.3±1.0 γ→α-Al2O3= (2,05±0,95) 103
5 700-1120 crystallite growth
α-Al2O3 103nm s-1
=1.44-2.79
not an exponential
area-
not an exponential area
6 1120-
1420
crystallite growth
α-Al2O3, 103nm s-1
= 3.36-6.47
crystallite growth
=38.7±2.1
crystallite growth =0.16±0.02
Where k = [α-Al2O3] (mol) reaction constant. V γ → α = [α-Al2O3] exposure time-1 (s-1)
formation rate α-Al2O3 and kv γ → α = (V γ → α)
1 - rate constant γ → α-Al2O3. The activation
energy Ea γ → α Al2O3 phase transition, in the mode of stepwise cumulative heating, is equal to 23.9 ± 0.8
kJ mol-1 in the region 670-970K at a process speed of 3.47 10-6 - 1.25 10-5 mole s-1. Increasing
the temperature to 1070-1170K, increases the rate of phase transition γ → α-Al2O3 to 2.78 10-5 -
1.42 10-4 mol s-1. The activation energy of the Ea γ → α-Al2O3 phase transition under these conditions is
149
83.5 ± 0.8 kJ mol-1. The obtained value of Ea γ → α-Al2O3 correlates with the known - 85 kJ mol-1
[16]. In the mode of single heating, the low-temperature branch γ → α-Al2O3 is absent. The
frequency coefficient of the process A0 phase transition throughout the temperature line remains
constant (2.05±0.95)103 s-1. Thermokinetic phase transition γ → dehydration → (η-, θ-, γ’-, δ-, χ-
, κ-) → α-Al2O3 is a complex multistage process of formation of alumina crystallites. The
product of the transition is α-modification.
Specific surface area and size of crystallites. The specific surface area (SBET, m2g-1) was
measured experimentally in the range of 213.0 - 8.6 m2g-1 in samples maintained at temperatures
of 570; 870; 1070; 1220; 1270; 1470K respectively. The temperature dependence of SBET has the
form of an inverse Ƨ-shaped dependence with a noticeable inflection at 1170-1220K. The curve,
in fact, has the nature of the first derivative of the power function of the specific volume (V, m3g-
1). The ratio S/V in the spherical4 and cubic approximation is equal to "6a-1", where "a" is the
average integral length of the diameter or face of geometric figures. As the heat treatment
temperature increases, the specific surface area and the parameter a decrease. The S/V ratio
increases continuously (in the absence of a jump in the parameters of the martensitic phase
transition). The process of agglomeration of crystallites at a segment of high temperatures causes
the curve to bend towards the abscissa. The curve acquires an S-shape. The value of the average
size of α-Al2O3 crystallites in the region of coherent scattering of the diagonal plane hkl012 (≈48
nm) at a temperature of 1470K was established. The temperature dependence of S/V allowed to
calculate the average size of α-phase crystallites along the temperature line 570-1470K. The
increasing region of the α-Al2O3 crystallite size curve is similar to the exponent and can be
calculated from the Arrhenius equation. The determined thermokinetic parameters of α-Al2O3-
nano crystallite growth are presented in the table. As can be seen from the table, the specific area
of powders decreases from 213.1 to 8.6 m2g-1 in the temperature range 570-1470K. The size of
α-Al2O3-nano crystallites increases in the form of an S-shaped curve from 9.7 to 48.0 nm from
570 to 1470K at a rate of 2.89 10-3 to 1.33 10-2 nm s-1. At temperatures of 1220-1370 K, the
activation energy is 38.7 ± 2.1 kJ mol-1. Further increase in temperature leads to agglomeration
of α-Al2O3 crystallites. The frequency growth rate of crystallites A0 did not exceed 1.83 ± 0.07 s-
1.
Conclusions
Considering the obtained data, there is a proportional relationship between the degree of
solubility of the phases of aluminum (3+) in hydrochloric acid and dehydration of powders. The
higher content of hydroxyl groups correlates with a higher mass fraction of dissolved Al (3+).
Reducing the content of OH groups increases the resistance of the powder to dissolution in
hydrochloric acid. Dissolution of γ- and γ’-Al2O3 was confirmed by X-ray phase analysis. The
monograph [16] states that γ’-Al2O3 is converted to γ-Al2O3 at 1170K. Above 1270 γ-Al2O3 is
converted to α-Al2O3 (heat of conversion 85.9 kJ mol-1). The activation energy of the phase
transition γ → α-Al2O3 is equal to Ea = 83.5 ± 0.8 kJ mol-1, respectively. The difference in
values is ˂ 3.0% relative. For the first time, a low-temperature (670 - 970K) branch of the γ → α-
Al2O3 phase transition was established under cumulative step heating, with the activation energy
of the process being approximately four times lower in comparison with the high-temperature
section. Ea = 23.9 ± 0.8 kJ mol-1. The specific surface area of the samples at 570 and 1470K is
213 and 33 m2g-1, the size of the crystallites is 10.4 and 48.0 nm, respectively. The activation
energy of crystallite growth at 1220-1370 K is 38.7 ± 2.1 kJ mol-1, the frequency coefficient of
the process A0 = 0.80 ± 0.02 s-1.
4 The sorption properties of the surface of the samples γ≈α-Al2O3 (1270K) indicate that the crystallites have a
spherical shape.
150
References
1. Domnich V., Reynaud S., Haber R. A., Chhowalla M. Boron Carbide: structure;
properties; and stability under stress. J. Am. Ceram. Soc. 2011. 94(11): 3605.
2. Stachin J. D., Pyzik A., Carrol D., Prunier A., Allen T. Boron Carbide Aluminum Cermet
is for Pressure Housing Applications. Naval Command, Control and Ocean Surveillance
Center. RDT&E Division, San Diego, California 92152-5000, Technical Report 1574,
September 1992: 192.
3. Yijun Du’, Shuyou Li, K. Zhang’, K. Lu’ BN/Al composite formation by high-energy ball
milling. Scrypta Materialia. 1997. 36(1): 7.
4. Ehsan Ghasali, Masoud Alizadeh, Touradj Ebadzadeh, Amir hossein Pakseresht, Ali
Ranbari. Investigation on microstructural and mechanical properties of B4C–aluminum
matrix composites prepared by microwave sintering. J. Mater. Res. Technol. 2015. 4(4):
411.
5. S. Wu, G. Xiao, L. Xue, L. Xue, M. Zhai, W. Zhu. Solid reaction between Al and B4C.
Canadian Metallurgical Quarterly. 2015. 54(2): 247.
6. Firestein K. L., Steinman F. E., Golovin I. S., Joan Cifre, Obraztsova E. A. , Matveev A.
T., Kovalskii A. M., Lebedev O. I. Fabrication, characterization and mechanical properties
of spark plasma sintered Al – BN nanoparticle composites. Materials Science &
Engineering. 2015. 642: 104.
7. Agus Pramono, Lembit Kommel, Lauri Kollo, Renno Veinthal. The Aluminum Based
Composite Produced by Self-Propagating High Temperature Synthesis. Materials Science
(Medziagotira). 2016. 22 (1): 1392.
8. Qian Zhao, Yunhong Liang, Zhihui Zhang, Xiujuan Li, Luguan Ren. Microstructure and
Dry-Sliding Wear Behavior of B4C Ceramic Particulate Reinforced Al 5083 Matrix
Composite. Metals. 2016. 6(227). 1; doi: 10.3390/met6090227
9. Patent US 8,030,234 B2. Aleksander J. Pyzik, Robert A. Newman, Mark A. Chartier, Amy
M. Wetzel, Christopher N. Haney. Aluminum boron carbide composite and method to
form said composite / Int - Classification C043 35/563 (2006-01), C04B 35/58 (2006-01).
Filed: Oct. 7, 2009; filed on Oct. 27, 2008; Published Oct. 4, 2011.
10. Patent US 5,039,633. Aleksander J. Pyzik, Robert T. Nilsson. B4C/Al cermets and method
for making same: Int. Cl.5 /; C22C 29/04. US - Cl. 501/93; 75/ 244; Filed Sep. 14. 1989.
Date of Patent: Aug. 13. 1991.
11. Patent UA, IPC (2016.01), С01В 35/04 (2016.01). Mazur, VB Muratov, VV Garbuz, EV
Kartuzov, OO Vasiliev. Method for obtaining AlB12 aluminum dodecaboride powder. PV
- Patent for utility model №UA107193U; filed 11/26/2015; published 25.05.2016, Bull. №
10.
12. Patent UA IPC (2016.01), С01В 35/04 (2016.01). Mazur, VB Muratov, VV Garbuz, EV
Kartuzov, OO Vasiliev. Impact-resistant ceramics based on aluminum dodecaboride. PV -
№UA107259U; filed 15.12.2015; published 25.05.2016, Bull. № 10.
13. A. Düvel, E. Romanova, M. Sharifi, D. Freude M., Wark P., Heitjans M., Wilkening.
Mechanically Induced Phase Transformation of γ-Al2O3 into α-Al2O3. Access to
Structurally Disordered γ-Al2O3with a Controllable Amount of Pentacoordinated Al Sites.
The Journal of Physical Chemistry. 2011. 115(46): P. 22770.
https://pubs.acs.org/doi/abs/10.1021/jp206077r
14. Mironenko R. M., Belskaya O. B., Maevskaya O. V., Gulayeva T.I., Kazakov M.O.,
Lavernov A.V., Likholov V.A. Effect of Surface Modification of γ-Al2O3 Using Oxalate
Complexes of Aluminium on the Formation and Properties of Platinum Centres of
Pt/Al2O3. Catalysts Chemistry for Sustainable Development. 2013. 21: P. 241.
151
15. Ja Hun Kwak, Jian Zhi Hu, Adrienne C. Lukaski, Do Heui Kim. The Role of Penta
Coordinated Al3+ Ions in the High Temperature Phase Transformation of Al2O3. The
Journal of Physical Chemistry. 2008. 112(25): P.9486. DOI: 10.1021/jp802631u
16. Remy H. Course of inorganic chemistry. (Moscow: Mir, 1972).[in Russian]
17. VA Dubok, VI Kornilova, LE Pechentkovskaya. Improvement of methods of chemical
analysis of refractory compounds and metal alloys. ( Kiev: Naukova Dumka, 1988) [in Russian].
ПИТОМА ПЛОЩА ПОВЕРХНІ, КРИСТАЛІТНИЙ РОЗМІР
ТА ТЕРМОКІНЕТИКА ФОРМУВАННЯ НАНОПОРОШКІВ
ОКСИДУ γ → α-Al2O3 ПРИ 570 -1470 К
В.В. Гарбуз, В.А. Петрова, Т.А. Сілінська, Т.Ф. Лобунець, О.І. Биков, В.Б. Муратов,
Т.М. Терентьєва, Л.М. Кузьменко, О.О. Васільєв, О.І. Оліфан,
Т.В. Хомко
Інститут проблем матеріалознавства ім. І. М. Францевича НАН України, вул.
Кржижанівського, 3 Київ,
03680, Украина, e-mail: wpetrowa@ukr.net, Garbuz.v1950@Gmail.com
Проведено рентгенівське (фазове та когерентне), флуоресцентне та фазове
хіміко-аналітичне оцінювання γ≈α-Al2O3-нано порошків. Термокінетичні характеристики
процесів обчислюються за допомогою експоненціального закону Арреніуса. Визначено та
розраховано розмірні характеристики кристалітів (10,4-48 нм); питома поверхня
порошків (213-8,6 м2г-1, SВET); термокінетичні параметри процесу росту кристалітів α-
Al2O3 (Vα-Al2O3 - 1,44 10-3 - 6,67 10-3 нм с-1; Eα-Al2O3 = 38,7 ± 2,1 кДж моль-1; A0 = 0,16 ± 0,0 с-
1 по лінії температур 1220-1470K). Процес зневоднення двох ОН-груп в області 570-720K
Ea H2O ↑ = 30,5 ± 0,5 кДж моль-1; A0 = 1,33 ± 0,3 с-1. Остання група ОН при температурі
820 -1070К і швидкості 2,13 10-4 - 4,93 10-4 моль с-1; Ea H2O ↑ = 13,2 ± 0,8 кДж моль-1; A0 =
16,9 ± 0,9 с-1. Енергія активації фазового переходу - Ea, γ → α-Al2O3 = 23,9 ± 1,0 кДж моль-1;
A0 = 2,01 ± 0,72 с-1 (770-970K) та Ea, γ → α-Al2O3 = 83,5 ± 0,8 кДж моль-1; A0 = (2,05 ± 0,95)
103 с-1 (1070-1170K). Це добре узгоджується з відомим теплом перетворення Eа, γ → α-Al2O3
= 85 кДж моль-1. ТК γ≈α -Al2O3-нанофази знаходиться на рівні 1170K.
Ключові слова: питома площа поверхні, розмір кристаліту, термічна кінетика, фазовий
перехід, порошки, γ→α-Al2O3-нано, дегідратація, ріст кристалітів
152
УДЕЛЬНАЯ ПЛОЩАДЬ ПОВЕРХНОСТИ,
КРИСТАЛЛИТНЫЙ РАЗМЕР И ТЕРМОКИНЕТИКА
ОБРАЗОВАНИЯ НАНОПОРОШКОВ ОКСИДА γ → α-Al2O3
ПРИ 570 -1470 К
В.В. Гарбуз, В.А. Петрова, Т.А. Силинская, Т.Ф. Лобунец, А.И. Биков, В.Б. Муратов,
Т.М. Терентьева, Л.Н. Кузьменко, А.А. Васильев, Е.И. Олифан,
Т.В. Хомко
Институт проблем материаловедения им. И.Н.Францевича НАН Украины ул.
Кржижановского, 3 Киев, 03680, Украина, e-mail: wpetrowa@ukr.net,
Garbuz.v1950@Gmail.com
Проведено рентгеновское (фазовое и когерентное), флуоресцентное и фазовое
химико-аналитическое оценивание γ≈α-Al2O3-нано порошков. Термокинетические
характеристики процессов вычисляются с помощью экспоненциального закона
Аррениуса. Определены и рассчитаны размерные характеристики кристаллитов (10,4-48
нм); удельная поверхность порошков (213-8,6 м2г-1, SВET); термокинетические параметры
процесса роста кристаллитов α-Al2O3 (Vα-Al2O3 - 1,44 10-3 - 6,67 10-3 нм с-1; Eα-Al2O3 = 38,7 ±
2,1 кДж моль-1; A0 = 0,16 ± 0,0 с-1 по линии температур 1220-1470K). Процесс
обезвоживания двух ОН-групп в области 570-720K Ea H2O ↑ = 30,5 ± 0,5 кДж моль-1; A0 =
1,33 ± 0,3 с-1. Последняя группа ОН при температуре 820 -1070К и скорости 2,13 10-4 -
4,93 10-4 моль с-1; Ea H2O ↑ = 13,2 ± 0,8 кДж моль-1; A0 = 16,9 ± 0,9 с-1. Энергия активации
фазового перехода - Ea, γ → α-Al2O3 = 23,9 ± 1,0 кДж моль-1; A0 = 2,01 ± 0,72 с-1 (770-970K)
та Ea, γ → α-Al2O3 = 83,5 ± 0,8 кДж моль-1; A0 = (2,05 ± 0,95) 103 с-1 (1070-1170K). Это
хорошо согласуется с известным теплом преобразования Eа, γ → α-Al2O3 = 85 кДж моль-1.
ТК γ≈α -Al2O3-нанофази находятся на уровне 1170K.
Ключевые слова: удельная площадь поверхности, размер кристаллита, термическая
кинетика, фазовый переход, порошки, γ→α-Al2O3-нано, дегидратация, рост
кристаллитов
|
| id | oai:ojs.pkp.sfu.ca:article-704 |
| institution | Surface |
| keywords_txt_mv | keywords |
| language | English |
| last_indexed | 2026-03-12T17:17:47Z |
| publishDate | 2020 |
| publisher | Chuiko Institute of Surface Chemistry National Academy of Sciences of Ukraine |
| record_format | ojs |
| resource_txt_mv | surfacezbircomua/9d/00628b9939fab9d77bfea23893eda99d.pdf |
| spelling | oai:ojs.pkp.sfu.ca:article-7042021-03-01T11:03:55Z Specific surface area, crystallite size and thermokinetic of oxide formation γ → α-Al2O3 nano powders at 570 – 1470 K Удельная площадь поверхности, кристаллитный размер и термокинетика образования нанопорошков оксида γ → α-Al2O3 при 570 -1470 К Питома площа поверхні, кристалітний розмір та термокінетика формування нанопорошків оксиду γ → α-Al2O3 при 570 -1470 К Гарбуз, В. В. Петрова, В. А. Сілінська, Т. А. Лобунець, Т. Ф. Биков, О. І. Муратов, В. Б. Терентьєва, Т. М. Кузьменко, Л. М. Васільєв, О. О. Оліфан, О. І. Хомко, Т. В. specific surface area crystallite size thermal kinetics phase transition powders γ→α-Al2O3-nano dehydration crystallite growth удельная площадь поверхности размер кристаллита термическая кинетика фазовый переход порошки, γ→α-Al2O3-нано дегидратация рост кристаллитов питома площа поверхні розмір кристаліту термічна кінетика фазовий перехід порошки, γ→α-Al2O3-нано дегідратація ріст кристалітів Powders where the γ≈α-Al2O3-nano phases are the priority precursors for catalysts for heterogeneous catalysis with the maximum content of surface 5-coordinated Al centers for Pt attachment. Hydrogenated nano powders (~8 nm) of γ-, γ '-, θ-, κ-Al2O3 soluble in hydrochloric acid were obtained from the processing of aluminum boride powders with an icosahedral structure. Samples, which underwent a step-by-step and single heating of 50-100K heat treatment for 2 hours at temperatures of 570-1470K, were received in quantity of 34. The specific surface area of SВET, m2g-1 was measured by the thermal nitrogen desorption  express method of gas chromatography through the GC-1 device. X-ray (phase and coherent), fluorescence and phase chemical-analytical evaluation of the samples were performed. The thermokinetic characteristics of the processes are calculated using the exponential Arrhenius law. Dimensional characteristics of crystallites (10.4-48 nm); specific surface area of powders (213-8.6 m2g-1, SВET); thermokinetic parameters of α-Al2O3 crystallite growth process (V α-Al2O3 - 1.44 10-3 - 6.67 10-3 nm s-1; E α-Al2O3 = 38.7±2.1kJ mol-1; A0 = 0.16±0.0 s-1 along the temperature line 1220-1470K were determined and calculated. The process of dehydration of two OH-groups occurs in the region 570-720K Ea H2O ↑ = 30.5 ± 0.5 kJ mol-1 A0 = 1.33±0.3 s-1. The last group of OH at temperatures of 820 -1070К and a rate of 2.13 10-4 - 4.93 10-4 mol s-1 Ea H2O ↑ = 13.2 ± 0.8 kJ mol-1 A0 = 16.9 ± 0.9 s-1. The activation energy of the phase transition is Ea., γ → α-Al2O3 = 23.9 ± 1.0 kJ mol-1 A0 = 2.01 ± 0.72 s-1 (770-970K) and Ea., γ → α-Al2O3 = 83.5 ± 0.8 kJ mol-1 A0 =(2,05±0,95) 103 s-1 (1070-1170K). It agrees well with the known heat of conversion Eа, γ→α-Al2O3 = 85 kJ mol-1. The TK of γ≈α-Al2O3-nano phases is at 1170K. Проведено рентгеновское (фазовое и когерентное), флуоресцентное и фазовое химико-аналитическое оценивание γ≈α-Al2O3-нано порошков. Термокинетические характеристики процессов вычисляются с помощью экспоненциального закона Аррениуса. Определены и рассчитаны размерные характеристики кристаллитов (10,4-48 нм); удельная поверхность порошков (213-8,6 м2г-1, SВET); термокинетические параметры процесса роста кристаллитов α-Al2O3 (Vα-Al2O3 - 1,44 10-3 - 6,67 10-3 нм с-1; Eα-Al2O3 = 38,7 ± 2,1 кДж моль-1; A0 = 0,16 ± 0,0 с-1 по линии температур 1220-1470K). Процесс обезвоживания двух ОН-групп в области 570-720K Ea H2O ↑ = 30,5 ± 0,5 кДж моль-1; A0 = 1,33 ± 0,3 с-1. Последняя группа ОН при температуре 820 -1070К и скорости 2,13 10-4 - 4,93 10-4 моль с-1; Ea H2O ↑ = 13,2 ± 0,8 кДж моль-1; A0 = 16,9 ± 0,9 с-1. Энергия активации фазового перехода - Ea, γ → α-Al2O3 = 23,9 ± 1,0 кДж моль-1; A0 = 2,01 ± 0,72 с-1 (770-970K) та Ea, γ → α-Al2O3 = 83,5 ± 0,8 кДж моль-1; A0 = (2,05 ± 0,95) 103 с-1 (1070-1170K). Это хорошо согласуется с известным теплом преобразования Eа, γ → α-Al2O3 = 85 кДж моль-1. ТК γ≈α -Al2O3-нанофази находятся на уровне 1170K. Проведено рентгенівське (фазове та когерентне), флуоресцентне та фазове хіміко-аналітичне оцінювання γ≈α-Al2O3-нано порошків. Термокінетичні характеристики процесів обчислюються за допомогою експоненціального закону Арреніуса. Визначено та розраховано розмірні характеристики кристалітів (10,4-48 нм); питома поверхня порошків (213-8,6 м2г-1, SВET); термокінетичні параметри процесу росту кристалітів α-Al2O3 (Vα-Al2O3 - 1,44 10-3 - 6,67 10-3 нм с-1; Eα-Al2O3 = 38,7 ± 2,1 кДж моль-1; A0 = 0,16 ± 0,0 с-1 по лінії температур 1220-1470K). Процес зневоднення двох ОН-груп в області 570-720K Ea H2O ↑ = 30,5 ± 0,5 кДж моль-1; A0 = 1,33 ± 0,3 с-1. Остання група ОН при температурі 820 -1070К і швидкості 2,13 10-4 - 4,93 10-4 моль с-1; Ea H2O ↑ = 13,2 ± 0,8 кДж моль-1; A0 = 16,9 ± 0,9 с-1. Енергія активації фазового переходу - Ea, γ → α-Al2O3 = 23,9 ± 1,0 кДж моль-1; A0 = 2,01 ± 0,72 с-1 (770-970K) та Ea, γ → α-Al2O3 = 83,5 ± 0,8 кДж моль-1; A0 = (2,05 ± 0,95) 103 с-1 (1070-1170K). Це добре узгоджується з відомим теплом перетворення Eа, γ → α-Al2O3 = 85 кДж моль-1. ТК γ≈α -Al2O3-нанофази знаходиться на рівні 1170K. Chuiko Institute of Surface Chemistry National Academy of Sciences of Ukraine 2020-12-03 Article Article application/pdf https://surfacezbir.com.ua/index.php/surface/article/view/704 10.15407/Surface.2020.12.146 Surface; No. 12(27) (2020): Surface; 146-152 Поверхность; № 12(27) (2020): Поверхность; 146-152 Поверхня; № 12(27) (2020): Поверхня; 146-152 3154-8091 3154-8083 10.15407/Surface.2020.12 en https://surfacezbir.com.ua/index.php/surface/article/view/704/702 Авторське право (c) 2020 В. В. Гарбуз, В.А. Петрова, Т.А. Сілінська, Т. Ф. Лобунець, О. І. Биков, В. Б. Муратов, Т. М. Терентьєва, Л. М. Кузьменко, О. О. Васільєв, О. І. Оліфан, Т. В. Хомко |
| spellingShingle | питома площа поверхні розмір кристаліту термічна кінетика фазовий перехід порошки γ→α-Al2O3-нано дегідратація ріст кристалітів Гарбуз, В. В. Петрова, В. А. Сілінська, Т. А. Лобунець, Т. Ф. Биков, О. І. Муратов, В. Б. Терентьєва, Т. М. Кузьменко, Л. М. Васільєв, О. О. Оліфан, О. І. Хомко, Т. В. Питома площа поверхні, кристалітний розмір та термокінетика формування нанопорошків оксиду γ → α-Al2O3 при 570 -1470 К |
| title | Питома площа поверхні, кристалітний розмір та термокінетика формування нанопорошків оксиду γ → α-Al2O3 при 570 -1470 К |
| title_alt | Specific surface area, crystallite size and thermokinetic of oxide formation γ → α-Al2O3 nano powders at 570 – 1470 K Удельная площадь поверхности, кристаллитный размер и термокинетика образования нанопорошков оксида γ → α-Al2O3 при 570 -1470 К |
| title_full | Питома площа поверхні, кристалітний розмір та термокінетика формування нанопорошків оксиду γ → α-Al2O3 при 570 -1470 К |
| title_fullStr | Питома площа поверхні, кристалітний розмір та термокінетика формування нанопорошків оксиду γ → α-Al2O3 при 570 -1470 К |
| title_full_unstemmed | Питома площа поверхні, кристалітний розмір та термокінетика формування нанопорошків оксиду γ → α-Al2O3 при 570 -1470 К |
| title_short | Питома площа поверхні, кристалітний розмір та термокінетика формування нанопорошків оксиду γ → α-Al2O3 при 570 -1470 К |
| title_sort | питома площа поверхні, кристалітний розмір та термокінетика формування нанопорошків оксиду γ → α-al2o3 при 570 -1470 к |
| topic | питома площа поверхні розмір кристаліту термічна кінетика фазовий перехід порошки γ→α-Al2O3-нано дегідратація ріст кристалітів |
| topic_facet | specific surface area crystallite size thermal kinetics phase transition powders γ→α-Al2O3-nano dehydration crystallite growth удельная площадь поверхности размер кристаллита термическая кинетика фазовый переход порошки γ→α-Al2O3-нано дегидратация рост кристаллитов питома площа поверхні розмір кристаліту термічна кінетика фазовий перехід порошки γ→α-Al2O3-нано дегідратація ріст кристалітів |
| url | https://surfacezbir.com.ua/index.php/surface/article/view/704 |
| work_keys_str_mv | AT garbuzvv specificsurfaceareacrystallitesizeandthermokineticofoxideformationgaal2o3nanopowdersat5701470k AT petrovava specificsurfaceareacrystallitesizeandthermokineticofoxideformationgaal2o3nanopowdersat5701470k AT sílínsʹkata specificsurfaceareacrystallitesizeandthermokineticofoxideformationgaal2o3nanopowdersat5701470k AT lobunecʹtf specificsurfaceareacrystallitesizeandthermokineticofoxideformationgaal2o3nanopowdersat5701470k AT bikovoí specificsurfaceareacrystallitesizeandthermokineticofoxideformationgaal2o3nanopowdersat5701470k AT muratovvb specificsurfaceareacrystallitesizeandthermokineticofoxideformationgaal2o3nanopowdersat5701470k AT terentʹêvatm specificsurfaceareacrystallitesizeandthermokineticofoxideformationgaal2o3nanopowdersat5701470k AT kuzʹmenkolm specificsurfaceareacrystallitesizeandthermokineticofoxideformationgaal2o3nanopowdersat5701470k AT vasílʹêvoo specificsurfaceareacrystallitesizeandthermokineticofoxideformationgaal2o3nanopowdersat5701470k AT olífanoí specificsurfaceareacrystallitesizeandthermokineticofoxideformationgaal2o3nanopowdersat5701470k AT homkotv specificsurfaceareacrystallitesizeandthermokineticofoxideformationgaal2o3nanopowdersat5701470k AT garbuzvv udelʹnaâploŝadʹpoverhnostikristallitnyjrazmeritermokinetikaobrazovaniânanoporoškovoksidagaal2o3pri5701470k AT petrovava udelʹnaâploŝadʹpoverhnostikristallitnyjrazmeritermokinetikaobrazovaniânanoporoškovoksidagaal2o3pri5701470k AT sílínsʹkata udelʹnaâploŝadʹpoverhnostikristallitnyjrazmeritermokinetikaobrazovaniânanoporoškovoksidagaal2o3pri5701470k AT lobunecʹtf udelʹnaâploŝadʹpoverhnostikristallitnyjrazmeritermokinetikaobrazovaniânanoporoškovoksidagaal2o3pri5701470k AT bikovoí udelʹnaâploŝadʹpoverhnostikristallitnyjrazmeritermokinetikaobrazovaniânanoporoškovoksidagaal2o3pri5701470k AT muratovvb udelʹnaâploŝadʹpoverhnostikristallitnyjrazmeritermokinetikaobrazovaniânanoporoškovoksidagaal2o3pri5701470k AT terentʹêvatm udelʹnaâploŝadʹpoverhnostikristallitnyjrazmeritermokinetikaobrazovaniânanoporoškovoksidagaal2o3pri5701470k AT kuzʹmenkolm udelʹnaâploŝadʹpoverhnostikristallitnyjrazmeritermokinetikaobrazovaniânanoporoškovoksidagaal2o3pri5701470k AT vasílʹêvoo udelʹnaâploŝadʹpoverhnostikristallitnyjrazmeritermokinetikaobrazovaniânanoporoškovoksidagaal2o3pri5701470k AT olífanoí udelʹnaâploŝadʹpoverhnostikristallitnyjrazmeritermokinetikaobrazovaniânanoporoškovoksidagaal2o3pri5701470k AT homkotv udelʹnaâploŝadʹpoverhnostikristallitnyjrazmeritermokinetikaobrazovaniânanoporoškovoksidagaal2o3pri5701470k AT garbuzvv pitomaploŝapoverhníkristalítnijrozmírtatermokínetikaformuvannânanoporoškívoksidugaal2o3pri5701470k AT petrovava pitomaploŝapoverhníkristalítnijrozmírtatermokínetikaformuvannânanoporoškívoksidugaal2o3pri5701470k AT sílínsʹkata pitomaploŝapoverhníkristalítnijrozmírtatermokínetikaformuvannânanoporoškívoksidugaal2o3pri5701470k AT lobunecʹtf pitomaploŝapoverhníkristalítnijrozmírtatermokínetikaformuvannânanoporoškívoksidugaal2o3pri5701470k AT bikovoí pitomaploŝapoverhníkristalítnijrozmírtatermokínetikaformuvannânanoporoškívoksidugaal2o3pri5701470k AT muratovvb pitomaploŝapoverhníkristalítnijrozmírtatermokínetikaformuvannânanoporoškívoksidugaal2o3pri5701470k AT terentʹêvatm pitomaploŝapoverhníkristalítnijrozmírtatermokínetikaformuvannânanoporoškívoksidugaal2o3pri5701470k AT kuzʹmenkolm pitomaploŝapoverhníkristalítnijrozmírtatermokínetikaformuvannânanoporoškívoksidugaal2o3pri5701470k AT vasílʹêvoo pitomaploŝapoverhníkristalítnijrozmírtatermokínetikaformuvannânanoporoškívoksidugaal2o3pri5701470k AT olífanoí pitomaploŝapoverhníkristalítnijrozmírtatermokínetikaformuvannânanoporoškívoksidugaal2o3pri5701470k AT homkotv pitomaploŝapoverhníkristalítnijrozmírtatermokínetikaformuvannânanoporoškívoksidugaal2o3pri5701470k |