Simultaneous characterizing study of the metallic iron-organic coordination compounds by TG-DSC-MS coupling techniques

Article abstract of DOI:10.1016/S0040-6031(03)00063-7

In this work, thermogravimetry-differential scanning calorimetry-mass spectrometry (TG-DSC-MS) coupling techniques were used to make a simultaneous characterizing study for the metallic iron-organic coordination compounds formed by iron ions and organic solvent glycol during the sol-gel process of preparing the iron oxide nanometer films. The positive ion mass spectra [Fe(OCH₂CH₃)₃]⁺(mass to charge (m/z) = 191) and [Fe(OCH₂CH₂OH)₃]⁺(m/z = 239) of the organic iron coordination compounds were obtained by experimental methods for the first time. Through the comparison analysis with the results of the TG-DSC-MS for the glycol, it can be found that the thermal decomposition temperature for the metallic iron-organic coordination compounds formed with glycol is higher than that of pure glycol. The results in this research work show that the simultaneous TG-DSC-MS coupling techniques can be applied to characterize some of the metallic-organic coordination compounds appeared in the gas state at lower temperature.

Full text of DOI:10.1016/S0040-6031(03)00063-7

Thermochimica Acta 404 (2003) 63–70
Simultaneous characterizing study of the metallic iron—organic
coordination compounds by TG–DSC–MS coupling techniques
a,∗
b
a
b
Chang-Wei Lu , Qun Wang , Yun-Xian Chen , Jian-Lin Shi
a
Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Ding Xi Road, 200050 Shanghai, PR China
b
The State Key Laboratory of High Performance Ceramics and Superfine Microstructure, 1295 Ding Xi Road, 200050 Shanghai, PR China
Received 30 July 2002; received in revised form 2 January 2003; accepted 15 January 2003
Abstract
In this work, thermogravimetry–differential scanning calorimetry–mass spectrometry (TG–DSC–MS) coupling techniques
were used to make a simultaneous characterizing study for the metallic iron-organic coordination compounds formed by iron
ions and organic solvent glycol during the sol–gel process of preparing the iron oxide nanometer films. The positive ion
+
+
mass spectra [Fe(OCH2CH3)3] (mass to charge (m/z) = 191) and [Fe(OCH2CH2OH)3] (m/z = 239) of the organic iron
coordination compounds were obtained by experimental methods for the first time. Through the comparison analysis with
the results of the TG–DSC–MS for the glycol, it can be found that the thermal decomposition temperature for the metallic
iron-organic coordination compounds formed with glycol is higher than that of pure glycol. The results in this research work
show that the simultaneous TG–DSC–MS coupling techniques can be applied to characterize some of the metallic-organic
coordination compounds appeared in the gas state at lower temperature.
©
2003 Elsevier Science B.V. All rights reserved.
Keywords: Sol–gel; Iron oxide system nanometer films; TG–DSC–MS
1
. Introduction
non-crystal gel including large amount of organic
groups. After thermal treatment, a certain amount of
crystal phases were separated out from the amorphous
structure. The large amount of pores in materials
formed due to evolution of the organic groups and
the contrast surface area of materials were increased
greatly. Therefore, the catalysis performances and gas
sensitivity are optimized. However, the studies on
the mechanism and process of preparing magnetite
(Fe3O4) films by sol–gel are seldom to see in liter-
ature. Costa et al. [3] obtained several mixtures of
hematite (Fe2O3) and magnetite (Fe3O4) by means
of using the sol–gel reaction between Fe(III) ions
of Fe(NO3)3 and glycol and the thermal treatment
for the reaction products. The sol–gel reaction prod-
ucts were characterized by mössbauer spectrometry
The iron oxide system nanometer films have been
applied to produce different microwave and optical
devices and magnetic apparatus in recent years. Up
to now, many physical and chemical methods such as
liquid phase epitaxy, sputtering and plasma splay etc
can be used to prepare the magnetic Fe3O4 and other
iron oxide nanometer films [1].
Takahashi et al. [2] successfully prepared magnetite
films using sol–gel method to which many researchers
paid great attentions. In the process of preparing the
magnetite films, it was the first step to synthesize
∗
Corresponding author.
E-mail address: cwlusic@sunm.shcnc.ac.cn (C.-W. Lu).
0
040-6031/$ – see front matter © 2003 Elsevier Science B.V. All rights reserved.
doi:10.1016/S0040-6031(03)00063-7

6
4
C.-W. Lu et al. / Thermochimica Acta 404 (2003) 63–70
and X-ray diffraction (XRD) and transform electron
microscopy (TEM). The research results show the
existence of large amount of ion, but its origin is not
clear. Amelao et al. [4] synthesized ␣-Fe2O3 nanome-
ter structure films by dipping silica slides into the
alcoholic solution of Fe(OCH2CH3)3. Then the films
were studied by X-ray absorption near edge structure
to form gel. Then it was dried to obtain the sample
F(A).
According to the same procedure mentioned above
to prepare the sample F(B). The only difference be-
tween the preparation of F(A) and F(B) is that the
glycol was not used as solvent for preparing F(B).
(
XANES) and extended X-ray absorption fine struc-
2
.2. TG–DSC–MS measurement
ture (EXAFS) methods. The results show the coating
◦
films at temperature ≤ 300 C are amorphous and at
The Netzsch STA 449C TG–DSC device coupled
◦
4
00 and 500 C, nanometer hematite particles which
with Balzers Thermostar Quadrupole Mass Spectrom-
eter was used in the experiments. The quarts capillary
tube was used as the interface between thermal ana-
lyzer and the quardrupole. The mass of F(A) is 8 mg.
The mass of F(B) is 8.9 mg. Gas Ar of 5 ml/min was
used for the protective gas of TG–DSC furnace. Gas
He with a flow speed of 40 ml/min was used as the car-
rying gas. The vacuum for the system of qurdrupole
was 10 Pa. All of the procedures were controlled
according to a proposing program.
The TG–DSC program was operated first. The
temperature region was from room temperature to
possess the same stoichiometry and iron coordination
as that of the crystallized phase were dispersed in an
amorphous matrix. The results in [3] show none con-
vincible experimental data to confirm the forming of
metallic iron organic coordination compounds during
the process of preparing magnetite films by sol–gel
method.
According to the reference [5], the super fine
powders of ␥-Fe2O3 and ␥-Fe2O3 added with
Y2O3 of average diameter 10 nm were obtained
by sol–gel reaction between Fe(NO3)3·9H2O and
glycol. In this work, we used TG–DSC–MS cou-
pling technique to characterize and study the treat-
ment process of preparing the Fe3O4 magnetic
films obtained by sol–gel method. The positive ion
−4
◦
◦
1200 C. The heating rate was 10 C/min.
The MS program was operated secondly. The MID
mode was used for the measurement. In each channels,
the different m/z mass numbers were proposed one by
one (the zero channel was proposed for symbolizing
temperature; the other m/z propositions in other chan-
nels can be seen from Table 1). The mass filtering
+
mass spectra [Fe(OCH2CH3)3] (m/z = 191) and
+
[
Fe(OCH2CH2OH)3] (m/z = 239) are obtained by
experimental methods for first time in this research.
The comparative measurements for the two samples
of adding Fe(NO3)3·9H2O and alcohol and adding
Fe(NO3)3·9H2O and alcohol and glycol are also made
by TG–DSC–MS. The other positive ion mass spectra
for the decomposed products and the segments ob-
tained in the experiments are discussed preliminarily.
Table 1
Mass numbers propositionsa
m/z
Expected positive ion mass spectra
+
+
+
2
H2
C
N
1
1
1
2
4
8
+
[H2O]
+
2
. Experimental
19
[H3O]
+
2
2
3
3
6
8
0
1
[C2H2]
+
+
CO /N2
2
.1. Sample preparation
+
NO
+
[CH3O]
+
According to the certain molar proportion (the mo-
33
[CH3OH2]
+
4
4
6
4
6
2
CO2
lar ratio of glycol/Fe(NO3)3·9H2O was kept to be
+
+
NO2 /[C2H6O]
1
5:1), the Fe(NO3)3·9H2O (analytical purity) was dis-
+
C2H6O2
solved in glycol and alcohol. The concentration of
iron(III) nitrate dissolved in glycol and alcohol solu-
tion was 0.3M. Then the solution flows back at 70 C
+
191
[Fe(OCH2CH3)3]
[Fe(OCH CH OH) ]
+
3
239
2
2
◦
◦
a
The intensities of the positive ion mass spectra mentioned
above were proposed automatically.
for certain time. The obtained sol was distilled at 80 C

C.-W. Lu et al. / Thermochimica Acta 404 (2003) 63–70
65
+
time was 1 s. The mass scanning speed was 1 s. The
channel-tron was used to record the positive ion mass
spectra signals.
The calculations and data treatment were in progress
after complete the proposed programs.
and [Fe(OCH2CH3)3] (m/z = 191), respectively.
This result shows no difference with the view in liter-
ature [6] that some metallic organic compounds exist
in the state of metallic vapor at lower temperature.
The ion current intensities of m/z = 239 and 191
are so small due to the most of the metallic iron or-
ganic coordination compounds decomposed to CO,
CO2 and other fragments. Fe(OCH CH OH) and
3
. Results and discussion
2
2
3
Fe(OCH2CH3)3 decomposed to CO, CO2 or other
organic fragments, as well as H O or H .
The other eight positive ion mass spectra for the
sample F(A) are listed in Table 2.
3
.1. TG–DSC–MS results for the sample F(A)
2
2
(added with glycol)
The TG–DSC–MS results for the sample F(A)are
shown in Figs. 1 and 2. The TG curves in Fig. 1
3.2. TG–DSC–MS results for the sample (B)
(without glycol)
◦
show mass losses: 26.1% (RT-300 C); 28.96%
◦
◦
(
300–410 C); 16.8% (410–570 C). There are no
◦
mass loss appears over 600 C basically. The DSC in
Fig. 1 appear a small endothermic peaks at 169 and
43 C, a big endothermic peak at 533 C.
The TG–DSC results for the sample F(B) are
shown in Fig. 3. The TG curve shows a big step. The
DSC curve shows a small endothermic peak at
◦
◦
3
◦
The parts of MS results for the sample F(A) are
shown in Fig. 2. Corresponding to the DSC curves,
the MS curves appear the positive ion mass spectra
169 C and two small exothermic peaks at 245 and
◦
429 C. Corresponding to the DSC small endother-
◦
mic peak at 169 C, the MS spectra for sample
◦
peaks of m/z = 239 and 191 at 343 C. The ion cur-
F(B) are shown in Figs. 4 and 5. In Fig. 4, the
−
13
+
+
+
+
rent intensities are 5.8 × 10
A (m/z = 239) and
H O (m/z=18), NO (m/z = 30), CO /N (m/z =
2
2
−13
+
5
.5×10
A (m/z = 191) separately. The two peaks
28), CO (m/z = 44) peaks appear at 169 and
2
◦
are related to the vaporization of metallic iron organic
coordination compound. The formed positive ion mass
232 C. These peaks are probably related to the dis-
orption of the H O and HNO in Fe(NO ) ·6H O and
2
3
3 3
2
+
+
spectra should be [Fe(OCH2CH2OH)3] (m/z = 239)
the alcohol in sample F(B). In Fig. 5, N (m/z = 14),
Fig. 1. The TG–DSC curves for sample F(A).

6
6
C.-W. Lu et al. / Thermochimica Acta 404 (2003) 63–70
+
+
Fig. 2. The MS spectra for sample F(A): [Fe(OCH2CH3)3] (m/z = 191) and [Fe(O-CH2CH2OH)3] .
Table 2
The other eight positive ion mass spectra for the sample F(A) obtained by TG–DSC–MS
+
+
+
+
+
+
+
+
Positive ion
H2
C
H2O
H3O
C2H2
CO
CH3O
CH3OH2
33
m/z
Intensity (A)
2
10
12
10
18
19
26
10
28
10
31
−9
−10
−8
−11
−10
−9
−10
−12
10
2.1×a
10
6×a
10
10
Amplifying ratea
4×c
0.7×a
1.3×c
4.2×b
2.3×e
1.3×a
0.7×c
6×a
2
0
.5×d
2.8×c
2.3×e
3.5×b
2×c
.5×e
a
◦
The alphabetical letters imply as follows: a, 169; b, 273; c, 343; d, 379; and e, 533 C.
Fig. 3. The TG–DSC curves for sample F(B).

C.-W. Lu et al. / Thermochimica Acta 404 (2003) 63–70
67
Fig. 4. The MS spectra for sample F(B): H2O (m/z = 18), NO (m/z = 30), CO (m/z = 28) and CO2+(m/z = 44).
+
+
+
+
+
C (m/z = 12) and NO2 (m/z = 46) peaks appear
3.3. The TG–DSC–MS results for pure glycol
◦
at 169 and 232 C separately. These peaks are prob-
ably related to the decomposition of Fe(NO3)3 with
The TG–DSC cures for pure glycol are shown
in Fig. 7. The TG curve shows a big mass loss
step. The DSC curve shows a big endothermic peak
+
an exothermic effect. The N (m/z = 14) belongs
+
+
+
to the fragments of N2 or NO or NO2 . The
+
◦
◦
CH3O (m/z = 31) peaks (at 169 and 232 C) in Fig. 6
at 146.9 C and a small companying “shoulder” en-
◦
probably formed by the fragments of CH3CH2OH
dothermic peak at 165.2 C. Corresponding to the
◦
[7].
DSC peaks at 146.9 and 165.2 C, the main obtained
Fig. 5. The MS spectra for sample F(B): N (m/z = 14), C (m/z = 12) and NO2+(m/z = 46).
+
+

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8
C.-W. Lu et al. / Thermochimica Acta 404 (2003) 63–70
+
Fig. 6. The MS spectra for sample F(B): CH3O (m/z = 31).
MS spectra for pure glycol are shown in Fig. 8.
(1) The TG curve for F(A) shows obvious two big
mass loss steps. However, the TG curve For F(B)
shows one big large mass loss step.
+
+
These peaks are OH (m/z = 17), H3O (m/z = 19),
+
+
C2H OH (m/z = 46) and C2H O2 (m/z = 62).
5
6
(
2) The DSC curve for F(A) show endothermic peaks
◦
3
.4. The comparative analysis for the TG–DSC–MS
at 169,343 and 533 C separately. However, the
results of F(A) and F(B) and pure glycol
DSC curve for F(B) shows one small endother-
◦
mic peak at 169 C and two exothermic peaks at
◦
Compared with the TG–DSC–MS results of F(A)
and F(B), we can see the following differences:
245 and 429 C. Not only the quality of the ther-
mal effect is different, but also the temperature
Fig. 7. The TG–DSC curves for pure glycol.

C.-W. Lu et al. / Thermochimica Acta 404 (2003) 63–70
69
Fig. 8. The MS spectra for pure glycol.
of the peaks corresponding to the thermal effects
for F(A) is about 60–70 C higher than that of
F(B).
related to the fragments of alcohol molecule ions.
◦
+
Compared with the CH3O (m/z = 31) in the
sample F(A), the corresponding decomposition
temperature for the two samples is different. The
(
3) The 10 positive ion mass spectra measured for
+
+
+
◦
sample F(A) are: H2 (m/z = 2); C (m/z = 12);
first [CH3O] (m/z = 31) peaks appear at 169 C
+
+
+
+
[
H2O] (m/z = 18); [H3O] (m/z = 19); [C2H2]
for the both samples. The second [CH3O] (m/z =
+
+
+
◦
(
3
m/z = 26); CO (m/z = 28); [CH3O] (m/z =
31) peaks appear at 232 C for the sample F(B)
◦
1); [CH3OH2] (m/z = 33); [Fe(OCH2CH2
and at 343 C for the sample F(A). Meanwhile,
+
+
+
OH)3] (m/z = 239) and [Fe(OCH2CH2OH)3]
the ion current intensity of [CH3O] (m/z = 31)
(
m/z = 191). However, the positive ion mass
peak for F(A) is higher than for F(B). The ion
+
+
spectra measured for sample F(B) are: C (m/z =
current intensity of [CH3O] (m/z = 31) at 169
+
+
+
+
◦
−12
A and
1
2); N (m/z = 14); [H2O] (m/z = 18); CO /
and 232 C for F(B) are 6.1 × 10
+
+
−12
N2 (m/z = 28); NO (m/z = 30); [CH3O]
6.4 × 10
A respectively. But for F(A), the ion
+
+
+
−10
(
m/z = 31); CO2 (m/z = 44) and NO2 (m/z =
current intensity of [CH3O] (m/z = 31) at 169
◦
−11
A
4
6). Through the comparison, it is obvious that
and 343 C are 1.1 × 10
A and 8 × 10
+
glycol plays key role for forming the metal-
lic iron organic coordination compounds in the
respectively. It shows the [CH3O] (m/z = 31)
produced from sample F(A) is formed probably
from the fragments of alcohol and glycol. While
+
sample F(A). We found no N (m/z = 14),
+
+
+
NO (m/z = 30) and NO2 (m/z = 46) peaks in
the MS spectra for the sample F(A). It shows
the HNO3 already completely evolved out in the
process of preparing the films at the time of flow-
ing back and distillation with Fe(NO3)3 using
glycol.
the [CH3O] (m/z = 31) produced from sample
F(A) is formed probably from only the fragments
of alcohol.
(5) It is obvious that the thermal decomposition
temperature of the metallic iron organic coordi-
nation compounds [Fe(OCH2CH3)3] and Fe(O-
CH2CH2OH)3] is higher than that of pure
glycol.
+
(
4) We found the only organic group peak [CH3O]
(m/z = 31) for the sample F(B). It is probably

7
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C.-W. Lu et al. / Thermochimica Acta 404 (2003) 63–70
3
.5. The characterization for the final product films
(4) Large amount of the positive ion mass spectra of
under the different temperatures
the fragments appeared in the MS measurements.
It shows the fragmentary process of metallic iron
organic coordination could be very complicated.
Besides the expected positive ion mass spectra, the
further studies for the other fragments probably
formed in the MS system and the thermal decom-
position mechanism for the metallic iron organic
coordination compounds are necessary.
The final products films by sol–gel method using sol
of F(A) under the different temperatures were char-
acterized by X-ray diffraction analysis. The results
show that the final product films are ␣-Fe2O3, Fe3O4,
the mixtures of the Fe3O4, FeO and Fe according to
the different thermal treatment temperatures. The ob-
tained results mentioned above are very useful for the
preparation of the required nanometer magnetic films
Acknowledgements
[8].
The authors thank the foundation of shanghai sci-
ence and technology development for financial sup-
port.
4
. Conclusions
Through the TG–DSC–MS measurements and the
comparative analysis, we can get the following con-
clusions:
References
[
[
1] I. Masanoba, S. Osamu, Adv. Mater. 2 (2001) 142–145.
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Jpn. J. Appl. Phys. 28 (1989) 244.
(
1) The metallic iron organic coordination com-
pounds Fe(OCH2CH3)3 and Fe(OCH2CH2OH)3
were formed in the process of preparing nanome-
ter magnetite (Fe3O4) films for the sample F(A).
2) The thermal decomposition of the metallic iron
coordination compounds Fe(OCH2CH3)3 and
Fe(OCH2CH2OH)3 mainly completed in the two
[3] G.M. da Costa, E. De Grave, P.M. Ade Bakker, R.E.
Vandebergh, J. Sol. State Chem. 113 (1994) 405–412.
(
[4] L. Armelao, G. Granozzi, E. Tondello, P. Colombo, G. Princip,
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[
[
◦
steps. The first step was taken place at 343 C.
1
The temperature for the second thermal decom-
◦
position was at 533 C. The water and alcohol
◦
and glycol was desorbed at about 169 C.
[
7] T. Hui-Tong, Optical Identification for Organic Compounds,
Publishing House of Beijing University, Beijing, 1992,
pp. 49–53.
(
3) For the sample F(B), because without adding gly-
col, the Fe(OCH2CH2OH)3 can not be produced
from the reaction between Fe(NO3)3·6H2O and
alcohol.
[8] W. Qun, S. Jian-Lin, L. Chang-Wei, Y. Dong-Sheng, 6 January
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