Thermal decomposition of ammonium perchlorate activated via addition of NiO nanocrystals

Article abstract of DOI:10.1007/s10973-007-8678-3

This work reported on the thermal decomposition of ammonium perchlorate activated by addition of NiO nanocrystals with different surface areas. NiO samples were characterized by X-ray diffraction (XRD), transition electron microscope (TEM), Brunauer-Emmet

Full text of DOI:10.1007/s10973-007-8678-3

Journal of Thermal Analysis and Calorimetry, Vol. 92 (2008) 3, 765–769
THERMAL DECOMPOSITION OF AMMONIUM PERCHLORATE
ACTIVATED VIA ADDITION OF NiO NANOCRYSTALS
*
L.-J. Chen, G.-S. Li, P. Qi and L.-P. Li
State Key Lab of Structural Chemistry, Fujian Institute of Research on the Structure of Matter and Graduate School of the
Chinese Academy of Sciences, Fuzhou 350002, P.R. China
This work reported on the thermal decomposition of ammonium perchlorate activated by addition of NiO nanocrystals with differ-
ent surface areas. NiO samples were characterized by X-ray diffraction (XRD), transition electron microscope (TEM),
Brunauer–Emmett–Teller (BET) technique, Fourier transform infrared spectroscopy (FTIR), and Raman spectroscopy. With in-
creasing annealing temperature, the surface areas of NiO samples reduced from 108.6 to 0.9 m2 g–1. The catalytic activities of NiO
nanocrystals on the thermal decomposition of ammonium perchlorate were investigated by thermogravimetric analysis (TG) cou-
pled with differential thermal analysis (DTA). With addition of NiO nanocrystals, thermal decomposition temperature of AP de-
creased greatly. Larger surface areas of NiO nanocrystals promoted the thermal decomposition of AP.
Keywords: ammonium perchlorate, catalysis, NiO nanocrystals, thermal decomposition
Introduction
larger surface areas of CuO could promote the decom-
position rate of AP [12]. The catalytic activity of NiO
nanocrystals is better than the bulk [13]. Till now, there
is still lack of reports about the impact of average sizes
of oxide NiO nanocrystals on the thermal decomposi-
tion of AP. Consequently, the investigation of the effect
of the surface areas of NiO nanocrystals on the thermal
decomposition of AP is necessary to meet the high tech-
niques or defense purposes, since high burning rate
composite propellant and operational time for missiles
are highly needed in future.
Ammonium perchlorate (AP) is one of the main oxi-
dizing agents in composite solid propellants, in which
AP plays a significant role in the burning process of
the propellant [1]. The burning rate of AP is modified
by the addition of small amount of additives [2, 3].
Transition metal oxides including CuO, MgO, Fe2O3
[4–6], and their mixtures are most effective and com-
monly used burn rate additives in practical applica-
tion of composite solid propellants. These additives
can promote the thermal decomposition rate of AP
greatly. However, the underlying mechanism of addi-
tives on the thermal decomposition of AP is still un-
clear. Some thought that oxides and AP could easily
form the melting eutectics, in which the transition
from solid to liquid accelerates the thermal decompo-
sition rate of AP [7]. Others ascribed the catalytic ac-
tivities of additives to the formation of the intermedi-
ate amine compounds [8]. Survase et al. proposed an
electron based transfer mechanism, in which p-type
nanocrystals accept the electrons transferred from
perchlorate ions thus enhancing the thermal decom-
position of AP [9]. It is also concluded that addition
of catalysts can enhance the proton transfer in the
thermal decomposition process of AP [10].
In the present work, we prepared NiO nanocrys-
tals with different surface areas. The lattice vibra-
tional properties and catalytic activities of NiO nano-
crystals on the thermal decomposition of AP were in-
vestigated. NiO nanocrystals with larger surface areas
were found to be more efficient and active on the ther-
mal decomposition of AP.
Experimental
Nickel oxide nanocrystals were prepared through a
two-step process. In the first step, Ni(OH)2 was pre-
pared by a chemical precipitation method. Then NiO
nanocrystals with different surface areas were ob-
tained by annealing the precipitation at selected tem-
perature for 3 h in air. Details of the samples prepara-
tion are reported elsewhere [14].
Therefore, it is important to systematically study
the mechanism of oxide nanoparticle additives on the
thermal decomposition of AP. Luo et al. thought the av-
erage size of CuO has no influence on the thermal de-
composition of AP [11]. But recently we found that the
The structures of the samples were examined by
powder X-ray diffraction using Rigaku DMAX2500
*
Author for correspondence: lipingli@fjirsm.ac.cn
1388–6150/$20.00
© 2008 Akadémiai Kiadó, Budapest
Akadémiai Kiadó, Budapest, Hungary
Springer, Dordrecht, The Netherlands

CHEN et al.
X-ray diffractometer with monochromatized CuKa
similar except for the narrowed peaks [14]. Inset of
Fig. 1 shows the TEM image of NiO nanocrystal after
annealing at 350°C. It is seen that NiO nanocrystals
consisted of spherical particles, nanorods and some
irregular shapes.
radiation (l=0.15418 nm). The average particle size
was calculated by the Scherrer formula. The
morphologies of the samples were determined using
TEM on a JEM-2010 apparatus with an acceleration
voltage of 200 kV. The specific surface areas of NiO
nanocrystals were determined from the nitrogen ab-
sorption data at liquid nitrogen temperature using
BET technique on a Micromeritics ASAP 2000 Sur-
face Area and Porosity Analyzer. Infrared spectra of
the samples were recorded with Perkin-Elmer IR
spectrophotometer using the KBr pellet technique.
Raman spectra were recorded using a JY-HR800
spectrometer with a He–Ne laser. The excitation
wavelength is 632.8 nm and output powder is 20 mW.
The catalytic activities of NiO nanocrystals in
the thermal decomposition of AP (180 mm) were stud-
ied using the STA449C thermal analyzer at a heating
rate of 20°C min–1 in N2 atmosphere over the range of
30–500°C. TG experiments were performed using
open alumina crucible. AP and NiO nanocrystals
were mixed at a mass ratio of 98:2 to prepare the tar-
get samples for thermal decomposition analyses. A
total sample mass of 1.5 mg was used in all runs. The
exhausted gases released during the heating process
were examined by mass spectroscopy (Jupi-
ter-QMS 403C AÁolos).
Since the morphology of NiO was not single uni-
form morphology, particle sizes calculated from XRD
line or TEM are not accurate. In the following, we
will address the size effects of NiO nanocrystals using
surface areas. The surface areas of NiO nanocrystals
were measured by BET technique. NiO nanocrystal
after annealing at 350°C has a large surface area of
108.6 m2 g–1. With increasing the treatment tempera-
tures, surface areas became smaller, e.g., 87.8 m2 g–1
(380°C), 38.1 m2 g–1 (550°C), 26.3 m2 g–1 (600°C),
11.8 m2 g–1 (700°C), 6.8 m2 g–1 (800°C), and
0.9 m2 g–1 (900°C). As for nanostructured materials,
the surface area means the ability of adsorption,
which has an impact on the catalytic activation of NiO
nanocrystals in the thermal decomposition of AP.
Generally particle size reduction is followed by struc-
ture variation, such as a larger surface to volume ratio
and a high concentration of unsaturated bonds on sur-
faces. Therefore, frequencies of lattice vibration of
NiO nanocrystals should vary with particle size.
Lattice vibrations of NiO nanocrystals were stud-
ied by IR and Raman spectra. Figure 2 exhibits IR spec-
tra of NiO nanocrystals at different surface areas. An ad-
sorption band at about 435 cm–1 was observed for NiO
with surface area of 0.9 m2 g–1, which is assigned to
Ni–O stretching vibration mode [15]. With increasing
surface area, the Ni–O stretching vibration mode
showed a systematic red shift. When the surface area in-
creased to 108.6 m2 g–1, the Ni-O vibration mode shifted
to 407 cm–1. In a previous study, we have shown the par-
ticle size dependence of lattice dimension for NiO
nanocrystals [14], in which the lattice volume increased
when the particle size is smaller than 30 nm (surface
Results and discussion
Figure 1 shows the XRD pattern for NiO nanocrystal
after annealing at 350°C. All the diffraction peaks
matched well with the standard data of NiO
(JCPDS No. 47-1049). With increasing annealing
temperature, XRD patterns of NiO nanocrystals are
Fig. 1 XRD pattern for NiO nanocrystals after annealing at
350°C. Inset shows the corresponding TEM image.
Vertical bars represent the standard diffraction data
from JPCDS file for NiO (No. 47-1049)
Fig. 2 Infrared spectra of NiO nanocrystals of given surface
areas
766
J. Therm. Anal. Cal., 92, 2008

DECOMPOSITION OF AMMONIUM PERCHLORATE ACTIVATED VIA ADDITION OF NiO NANOCRYSTALS
area 20 m2 g–1). The expansion of lattice volume with in-
creasing surface areas led to the decrease of vibration
frequencies of NiO nanocrystals.
Figure 3 shows the Raman spectra of NiO nano-
crystals at different surface areas. It can be seen that
there are five Raman peaks at 400, 513, 725, 902 and
1093 cm–1, respectively. According to the reference
[16], the peaks at 400 and 513 cm–1 are assigned to
first-order transverse optical (TO) and longitudinal
optical (LO) phonon modes of NiO nanocrystals. The
peaks at 725 and 1093 cm–1 are associated with com-
bination of 2TO and 2LO. The remaining peak at
902 cm–1 is assigned to the mixed TO+LO phonon
mode. With increasing surface areas, the peaks at 725,
902 and 1093 cm–1 disappeared. The main peak at
Fig. 4 TG curves for pure AP, mixtures of AP with NiO
nanocrystals of different surface areas; a – AP, b – 0.9,
c – 6.8 and d – 108.6 m2 g–1
513 cm–1 showed a red shift to 492 cm–1 and broaden-
ing when the surface area increased to 108.6 m2 g–1.
The shift and broadening of LO phonon mode are due
to the phonon dispersion that would not be limited to
the center of the Brillouin zone with increasing sur-
face area of NiO nanocrystals. Otherwise, the lattice
expansion will lead to a red shift of Raman peak [17].
The catalytic activities of NiO nanocrystals were
investigated by thermal decomposition of AP.
Figure 4 shows the TG curves for pure AP and mix-
tures of AP and NiO nanocrystals with different sur-
face areas. The decomposition of pure AP is generally
centered at temperatures from about 329 to 434°C.
Addition of NiO nanocrystals in AP led to a signifi-
cant reduction of the beginning decomposition and
ending decomposition temperature of AP. When add-
ing NiO nanocrystals of surface area of 108.6 m2 g–1,
the beginning decomposition temperature reduced to
238.2°C and the ending decomposition temperature
reduced to 383°C. This means that the beginning de-
composition and ending decomposition temperatures
were reduced by 90.8 and 51°C, respectively. When
the surface areas of NiO nanocrystal reduced to
0.9 m2 g–1, the beginning decomposition temperature
was decreased by 66°C and the ending decomposition
temperature only by 28.5°C.
Figure 5 shows the differential thermal analysis
(DTA) curves of pure AP and mixtures of AP with
NiO nanopraticles of different surface areas. For pure
AP, an endothermic peak was observed at about
250°C, which is assigned to the crystallographic tran-
sition of AP from orthorhombic to cubic [18]. With
increasing the temperatures, AP underwent two com-
plicated decomposition stages [3], i.e., a low tempera-
Fig. 3 Raman spectra of NiO nanocrystals of given surface ar-
eas; a – 0.9, b – 26.3, c – 38.1 and d – 108.6 m2 g–1
Fig. 5 DTA curves of pure AP and mixtures of AP with NiO
nanoparticles of different surface areas
J. Therm. Anal. Cal., 92, 2008
767

CHEN et al.
Fig. 6 a – TG curve for pure AP and b – quadrupole mass
Fig. 7 a – TG curve and b – quadrupole mass spectrometry of
spectrometry of pure AP
mixture of AP with addition of NiO with surface area
of 108.6 m2 g–1
ture stage at 329.3°C and a high temperature stage at
435.5°C, which are followed by two exothermic
peaks. These two decomposition stages are consistent
with those of 80 mm AP but are apparently different
from the single step for 1.1 mm AP [3]. The presence
of these NiO nanocrystals slightly lowered the
low-temperature decomposition stage of AP (Ta as
marked in Fig. 5), while significantly lowered the
high-temperature decomposition stage of AP (Tb as
shown in Fig. 5). With reducing surface areas from
108.6 to 0.9 m2 g–1, the high-temperature decomposi-
tion peak temperature changed from 358.5 to
385.5°C. The obvious particle size dependence of cat-
alytic activity of NiO nanocrystals in AP decomposi-
tion discovered in this work is consistent with our
early work [12]. Large surface areas of NiO
nanocrystals played a key role in enhancing the cata-
lytic activities in the thermal decomposition of AP.
The catalytic activities of additives on the AP is
highly relevant to the thermal decomposition process
of AP. Boldyrev [19] proposed that the AP decompo-
sition process is followed by a proton transfer from
the cation NH+4 to the anion ClO–4 rather than the elec-
tron transfer as reported before, which results in ad-
sorption of ammonia and perchloric acid on the AP
surfaces, NH4ClO4(s)®NH3(g)+HOClO3(g) [18, 20].
The key early step is rupture of HO–ClO3 bond,
HO–ClO3®HO+ClO3. The thermogravimetric analy-
sis (TG) coupled with quadrupole mass spectroscopy
(QMS) is an effective method to measure the gases re-
leased during the thermal decomposition of AP. Fig-
ure 6 shows the TG-QMS of pure AP. The complex
thermal decomposition product were NH3, NO, HNO,
O2, HCl, N2O, NO2, ClO and NOCl. Since the thermal
decomposition product is highly dependent on the ex-
perimental condition, the products can be some differ-
ent from those reported in reference [18]. HCl is the
product of high temperature stage decomposition.
Other products exit in both thermal decomposition
stages. Figure 7 shows the TG-QMS curves of AP
with addition of NiO with surface area of
108.6 m2 g–1. The products are near the same as those
of the pure AP, except that the temperature of high-
temperature product lowered.
The TG-QMS data confirmed the formation of am-
monium and perchloric acid during the thermal decom-
position processes. The high-temperature decomposi-
tion stage of AP likely took place at the surfaces of the
NiO nanocrystals that involves the adsorption and
desorption of ammonium and perchloric acid. There-
fore, NiO nanocrystals with a largest surface area of
108.6 m2 g–1 showed the best absorption ability of am-
monia and perchloric acid on the surface of AP. While
768
J. Therm. Anal. Cal., 92, 2008

DECOMPOSITION OF AMMONIUM PERCHLORATE ACTIVATED VIA ADDITION OF NiO NANOCRYSTALS
3 J. Zhi, W. Tian-Fang, L. Shu-Fen, Z. Feng-Qi, L. Zi-Ru,
the low-temperature decomposition stage occurred ini-
Y. Cui-Mei, L. Yang, L. Shang-Wen and Z. Gang-Zhui,
tially in the pores of nuclei, NiO additives could not eas-
J. Therm. Anal. Cal., 85 (2006) 315.
ily participate in the proton transfer process. As a result,
4 N. B. Singh and A. K. Ojha, Thermochim. Acta,
NiO additives have no apparent impacts on the low tem-
390 (2002) 67.
perature decomposition process.
5 G. R. Duan, X. J. Yang, J. Chen, G. H. Huang, L. Lu and
X. Wang, Power Technol., 172 (2007) 27.
6 P. R. Patil, V. N. Krishnamurthy and S. S. Joshi, Prop.
Conclusions
Explos. Pyrotech., 31 (2006) 442.
7 F. Solymosi and L. Révész, Nature, 192 (1961) 64.
8 K. C. Patil, V. R. Verneker and S. R. Jain, Combust.
Flame, 27 (1976) 295.
This work explored the thermal decomposition of AP
at high temperatures with addition of NiO nano-
crystals. NiO nanoparticles with different surface ar-
eas were achieved by annealing the Ni(OH)2 at differ-
ent temperature. With increasing surface areas, both
IR spectra and LO Raman peak showed red shift,
which is associated with the lattice expansion. NiO
nanocrystals promoted AP decomposition, in which
the catalytic activities were found to be a function of
surface area. The high-temperature decomposition
peak temperature in the presence of NiO
nanoparticles changed from 358.5 to 385.5°C with
surface areas of NiO reduced from 108.6 to 0.9 m2 g–1.
9 D. V. Survase, M. Gupta and S. N. Asthana, Prog. Crystal
Growth Charact., 45 (2002) 161.
10 R. J. Acheson and P. W. M. Jacobs, J. Phys. Chem.,
74 (1970) 281.
11 Y. X. Luo, L. D. Lu, X. H. Liu, X. J. Yang and X. Wang,
Chin. J. Inorg. Chem., 18 (2002) 1211.
12 L. J. Chen, G. S. Li and L. P. Li, J. Therm. Anal. Cal.,
91 (2008) 581.
13 Y. P. Wang, J. W. Zhu, X. J. Yang, L. Lu and X. Wang,
Thermochim. Acta, 437 (2005) 106.
14 L. P. Li, L. J. Chen, R. M. Qihe and G. S. Li, Appl. Phys.
Lett., 89 (2006) 134102.
15 L. L. Wu, Y. S. Wu, H. Y. Wei, Y. C. Shi and C. X. Hu,
Mater. Lett., 58 (2004) 2700.
16 R. E. Dietz, G. I. Parisot and A. E. Meixner, Phys. Rev.
B., 4 (1971) 2302.
Acknowledgments
17 R. P. Wang, G. W. Zhou, Y. L. Liu, S. H. Pan,
H. Z. Zhang, D. P. Yu and Z. Zhang, Phys. Rev. B.,
61 (2000) 16827.
This work was financially supported by NSFC under the con-
tract (No. 20773132, 20771101), National Basic Research
Program of China (973 program, No. 2007CB613306), Sci-
ence and Technology Program from Fujian Province
(No. 2005L2005 and 2006HJ0178), Directional program
(KJCX2-YW-M05) and a grant from Hundreds Youth Talents
Program of CAS (Li GS).
18 M. Rajiº and M. Suºeska, J. Therm. Anal. Cal.,
63 ( 2001) 375.
19 V. V. Boldyrev, Thermochim. Acta, 443 (2006) 1.
20 P. Politzer and P. Lane, J. Mol. Struct. (Theochem),
454 (1998) 229.
Received: August 6, 2007
References
Accepted: November 27, 2007
1 L. Bereczki, K. Marthi, P. Huszthy and G. Pokol,
J. Therm. Anal. Cal., 78 (2004) 449.
DOI: 10.1007/s10973-007-8678-3
2 Y. L. Su, S. F. Li and D. H. Ding, J. Therm. Anal. Cal.,
86 (2006) 497.
J. Therm. Anal. Cal., 92, 2008
769