Hydrothermal synthesis of pure-phase copper silicate Na2Cu 2Si4O11·2H2O with ammonia as complexing agent

Article abstract of DOI:10.1002/ejic.201001002

Pure-phase copper silicate, Na₂Cu₂Si ₄O₁₁·2H₂O (AV-23), was synthesized hydrothermally by starting with a molar ratio of CuO:3.2SiO₂:3. 02Na₂O:4.57NH₃:146H₂O. To avoid the formation of polycrystalline CuO, aqueous ammonia was used as complexing agent. The inductively coupled plasma atomic emission spectroscopy ICP-AES, XRD, and SEM measurements of the precursors indicated that the sequence in which the starting materials are added can effectively adjust the competition between precipitation and complexation, and consequently the alkali balance in the solution, as copper is present in the form of both Cu(OH)₂ and [Cu(NH₃)₄]²⁺. This adjustment optimizes the distribution of the precursor, which influences the morphology of Cu(OH) ₂. The kinetics of the crystallization is thus affected in such a way that prevents the formation of impure phases.

Full text of DOI:10.1002/ejic.201001002

FULL PAPER
DOI: 10.1002/ejic.201001002
Hydrothermal Synthesis of Pure-Phase Copper Silicate Na Cu Si O ·2H O
2
2
4
11
2
with Ammonia as Complexing Agent
[a]
[a]
[a]
[a]
[a]
Qizhou Jiang, Qi Shi, Hong Xu,* Jinping Li, and Jinxiang Dong*
Keywords: Hydrothermal synthesis / Silicates / Copper / Pure phases / Competitive balance
Pure-phase copper silicate, Na
synthesized hydrothermally by starting with a molar ratio of
CuO:3.2SiO :3.02Na O:4.57NH :146H O. To avoid the for-
mation of polycrystalline CuO, aqueous ammonia was used
as complexing agent. The inductively coupled plasma atomic
emission spectroscopy ICP-AES, XRD, and SEM measure-
ments of the precursors indicated that the sequence in which
the starting materials are added can effectively adjust the
2
Cu
2
Si
4
O
11·2H
2
O (AV-23), was
competition between precipitation and complexation, and
consequently the alkali balance in the solution, as copper is
2
+
2
2
3
2
present in the form of both Cu(OH)
adjustment optimizes the distribution of the precursor, which
influences the morphology of Cu(OH) . The kinetics of the
2 3 4
and [Cu(NH ) ] . This
2
crystallization is thus affected in such a way that prevents
the formation of impure phases.
Introduction
pared by treatment of a mixture of Na
O, CuSO , SiO ,
2 4 2
[18]
and H O for 10 d at 230 °C, by Rocha et al. in 2004.
2
Microporous materials containing metal cations have
been extensively studied recently due to their novel topolog-
ies, interesting chemical properties, and potential applica-
tions in optoelectronics, batteries, magnetic materials, and
sensors. Such properties are introduced by metal centers not
present in classical zeolites.[1,2] Representative examples of
these porous transition-metal silicates include the titanium
Soon after that, AV-23 and its dehydrated form were exam-
ined in detail as new magnetic chain compounds. These
compounds are characterized by a strong alternation of the
exchange interaction, which follows from the topology of
the isolated chains of the edge-sharing octahedra (or square
[15]
pyramids). In later reports, Jacobson and co-workers did
not gain pure-phase AV-23 by treating a mixture of NaOH,
[
3–4]
silicates ETS-4 and ETS-10, discovered in the late 1980s.
[16]
Cu(OH) , SiO , and H O for 2 d at 240 °C. In our earlier
2
2
2
In the meanwhile, many microporous materials containing
other metals such as Nb, V, Sn, Cu, and Ca, have been
investigation, using our previously reported procedures and
[18]
molar ratio,
CuSH-1Na by treating a mixture of Na O, Cu(NO ) , SiO ,
we always obtained AV-23 mixed with
[
5–12]
reported.
2
3 2
2
Recently, some copper silicates with mixed octahedral/
tetrahedral microporous siliceous frameworks have been
studied for their novel framework topologies and interesting
magnetic properties.[13–15] Using hydrothermal techniques
under conditions comparable to those used in classical zeo-
lite synthesis, a series of copper silicates were synthe-
and H O for 4 d at 220 °C. Only by increasing the molar
2
ratio of Na O/CuO could we avoid the formation of CuSH-
2
1Na; however, the products were always mixed with some
polycrystalline CuO and amorphous phases. Certainly, the
copper source and the conditions of crystallization have in-
fluenced the experimental result.
[
16]
sized. These were the first examples of this class of com-
In this paper, an alternative synthesis method of AV-23
using aqueous ammonia as a complexing agent of Cu2 is
proposed. Here, copper is present in the forms of both
2
+
pounds containing the Cu linking group and a novel
framework structure; the copper silicate system has a gene-
+
ral formula and
a
designated system: CuSH-1A
2+
Cu(OH) and [Cu(NH ) ] in the precursors, which is good
2
3 4
{
Na [Cu Si O (OH) ][(AOH) (NaOH) (H O) ] (A = Na,
4
2
12 27
2
x
y
17]
2
z
for the dispersion of precursors and influences the mor-
[
K, Rb, Cs, x ≈ 1, y ≈ 1, z ≈ 6)}.
Na Cu Si O ·2H O (AV-23, CuSH-2Na ), with a ther-
Copper silicate
phology of Cu(OH) , consequently avoiding the formation
[18]
[16]
2
2
2
4
11
2
of impure phases during crystallization. Pure-phase copper
mally stable three-dimensional microporous open frame-
work and properties enabling reversible zeolitic water re-
moval without destruction of the framework, was first pre-
silicate Na Cu Si O ·2H O (AV-23) was obtained success-
2
2
4
11
2
fully by using this procedure. This method may also be used
to prepare other pure-phase porous transition metal sili-
cates. Attention is focused on the Na O–Cu(NO ) –SiO –
2
3 2
2
[
a] Research Institute of Special Chemicals, Taiyuan University of
Technology,
NH ·H O–H O system: the effect of different synthesis con-
3 2 2
Taiyuan 030024, Shanxi, P.R. China
Fax: +86-351-6111178
E-mail: dongjinxiangwork@hotmail.com
xuhongwork@126.com
ditions and the competitive balance of chemical reactions
in solution are discussed in detail. The samples were charac-
terized by using X-ray diffraction (XRD), optical micro-
2112
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2011, 2112–2117

Hydrothermal Synthesis of Pure-Phase Copper Silicate
scopy, scanning electron microscopy (SEM), energy disper- Cu = 1.9229), whereas sample 1 is quite pure: the molar
sive spectroscopy (EDS), and inductively coupled plasma ratio of Si/Cu is 2.008, which is in agreement with the re-
atomic emission spectroscopy (ICP-AES).
ported molecular formula (Si/Cu = 2).
Results and Discussion
The powder XRD method was employed to identify the
framework structures of the obtained samples. As shown in
Figure 1, the positions and relative intensities of the diffrac-
tion peaks of the synthesized pure-phase samples AV-23
were found to be in agreement with those of a previously
reported copper silicate (154123-ICSD).[
19]
Figure 2. Effect of different synthesis procedures on copper silicate
AV-23 synthesis.
Figure 1. Reported and typical experimental powder XRD patterns
of AV-23.
Synthesis
A systematic synthesis study of AV-23 in the Na O–
2
Cu(NO ) –SiO –NH ·H O–H O system was carried out.
3
2
2
3
2
2
The different synthesis procedures and molar ratio of the
reagents in the precursor were studied first and then
crystallization time was investigated.
Effect of Ammonia
After fixing the starting molar ratio at CuO:3.2-
SiO :3.02Na O:4.57NH :146H O, which was aimed to in-
sure the role of ammonia in the synthesis of pure-phase
AV-23, two referential synthesis procedures were examined
Figure 3. Crystal morphology and EDS results of elemental com-
position at certain positions of the samples obtained with different
synthesis procedures: (a) sample 1, (b) sample 2, and (c) sample 3.
2
2
3
2
(
Figure 2). As seen in the SEM (Figure 3) and optical mi-
Different amounts of ammonia were added into the sys-
croscopy (Figure 4) photographs, sample 1, obtained by tem as the Cu2 complexing agent when using procedure 1
+
2
+
procedure 1 with aqueous ammonia as the Cu complex- (Figure 2). XRD analysis revealed no different phase peaks
ing agent, was pure-phase AV-23; it was isolated as large when the molar ratio of NH /CuO was changed from 0 to
3
spherical aggregates of long green needles (Figures 3a and 9.14. However, when the ratio was increased to 22.85, an
4c) with no impurity. However, the samples obtained in dif- impure-phase peak was found mixed with AV-23 (Figure 5),
ferent procedures, such as sample 2 (Figures 3b and 4a), and we consider this as an unknown phase after XRD
obtained without using any aqueous ammonia, and sample analysis. The optical microscopy photographs show that
3
(Figure 3c and 4f), obtained by adding sodium hydroxide when the molar ratio of NH /CuO was 4.57, only the green
3
first, were always found to be mixed with some impure AV-23 phase was obtained (Figure 4c); with a decrease in
black phases. The EDS analysis results of elemental compo- the NH /CuO ratio, some black phases attributed to poly-
3
sition at certain positions and chemical analysis indicate crystalline CuO and amorphous phases appeared (Fig-
that sample 2 (Figure 3e) is mixed with some polycrystalline ures 4a,b). With an increase in the NH /CuO ratio, the pre-
3
CuO (Si/Cu = 2.142), and sample 3 (Figure 3f) is either viously mentioned unknown phase, which was described as
mixed with polycrystalline CuO or amorphous phases (Si/ small deep-blue spheres, appeared (Figures 4d,e).
Eur. J. Inorg. Chem. 2011, 2112–2117
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
2113

Q. Z. Jiang, Q. Shi, H. Xu, J. P. Li, J. X. Dong
FULL PAPER
the Na O/CuO ratio to 4.0, an unknown phase mixed with
2
some dark polycrystalline CuO and amorphous phases was
produced, which had the same XRD pattern as the pre-
viously mentioned unknown phase found during the study
of the molar ratio of NH /CuO, so we consider this as the
3
unknown phase, too. We did not obtain the CuSH-3Na
[
16]
phase, as previously reported.
Figure 4. Optical microscopy photographs of typical samples at dif-
ferent synthesis conditions: (a) NH
CuO = 2.28; (c) NH /CuO = 4.57 (sample 1); (d) NH
e) NH /CuO = 22.85; and (f) sample 3.
3
/CuO = 0 (sample 2); (b) NH
3
/
Figure 6. Effect of the starting Na
silicate AV-23 synthesis.
2
O/CuO molar ratio on copper
3
3
/CuO = 9.14;
(
3
Effect of the Molar Ratios of SiO /CuO and H O/CuO
2
2
The effects of the molar ratios SiO /CuO and H O/CuO
2
2
on the synthesis of AV-23 products is shown in Table 1.
Experiments were carried out at 220 °C for 96 h. After
fixing the starting molar ratio at CuO:3.02Na O:4.57NH :
2
3
1
46H O, the SiO /CuO molar ratios were varied from 1.6
2 2
to 9.6 in the synthesis mixture for AV-23. A pure AV-23
product was obtained when the SiO /CuO molar ratio was
2
[
16]
3
.2. In agreement with the previous reports, the products
contained a mixture of AV-23, polycrystalline CuO, and an
amorphous phase when the SiO /CuO molar ratio was de-
2
creased. With an increase in the SiO /CuO molar ratio,
2
CuSH-1Na was found mixed in the products; pure-phase
Figure 5. Effect of the starting NH
silicate AV-23 synthesis.
3
/CuO molar ratio on copper CuSH-1Na was obtained when the SiO /CuO molar ratio
2
reached 4.8. A further increase in the SiO /CuO molar ratio
2
afforded quartz phases.
Effect of the Na O/CuO Molar Ratio
2
The Na O/CuO molar ratio plays a very important role
2
Table 1. Effect of the starting SiO
on copper silicate AV-23 synthesis.
2
/[Ca]uO and H
2
O/CuO molar ratio
in the synthesis of copper silicate AV-23. Experiments were
carried out at 220 °C for 96 h. After fixing the starting mo-
lar ratio at CuO:3.2SiO :4.57NH :146H O, the starting
Run SiO /CuO
2
2
H O/CuO Products
2
3
2
1
1.6
146
AV-23+polycrystalline CuO+
amorphous
Na O/CuO molar ratio was varied from 2.0 to 4.0. This
2
variation in the Na O/CuO ratio in the precursor led to the
2
2
3
4
5
6
3.2
4.8
6.4
9.6
3.2
146
146
146
146
85
AV-23
AV-23 + CuSH-1Na
CuSH-1Na
CuSH-1Na + quartz
AV-23 + polycrystalline CuO +
amorphous
formation of different types of products as shown in Fig-
ure 6. Pure-phase AV-23 samples were obtained when the
Na O/CuO ratio was 3.02. As the concentration of sodium
2
hydroxide decreased, the crystallinity of the AV-23 phase
became poor, and a CuSH-1Na impurity phase crystallized
with AV-23; pure CuSH-1Na was obtained when the ratio
7
8
9
1
3.2
3.2
3.2
3.2
146
195
243
316
AV-23
AV-23 + CuSH-1Na
CuSH-1Na
was 2.2. In contrast, an increase in the Na O/CuO ratio
2
0
CuSH-1Na + amorphous
produced dark polycrystalline CuO and some unidentified
amorphous phases mixed with AV-23. With an increase in [a] CuO:3.02Na
2
3
O:4.57NH , 96 h, 220 °C.
2114
www.eurjic.org
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2011, 2112–2117

Hydrothermal Synthesis of Pure-Phase Copper Silicate
After fixing the starting molar ratio at CuO:3.2-
SiO :4.57NH :146H O, and when the H O/CuO ratio is
2
3
2
2
1
46, pure AV-23 product can be formed. A lower H O con-
2
tent in the gel usually results in the formation of impure
phases of polycrystalline CuO and amorphous phases. At a
higher H O content in the reaction mixture, CuSH-1Na was
2
found in the products, and pure-phase CuSH-Na was ob-
tained when the H O/CuO molar ratio reached 243. How-
2
ever, a further increase in the H O content leads to the for-
2
mation of amorphous phases.
Effect of Crystallization Time
Figure 8. Effect of crystallization time on copper silicate AV-23 syn-
thesis.
To study the effect of crystallization time, after fixing the
starting molar ratio of the components at CuO:3.2-
SiO :3.02Na O:4.57NH :146H O, experiments were carried
2
2
3
2
out at 220 °C (Figure 7). The XRD patterns of the products Competitive Balance between Precipitation and
that crystallized after 6 h were attributed to CuSH-1Na Complexation in Solution
(
Figure 7). However, highly crystallized CuSH-1Na was not
In order to investigate the reasons for the formation of
impurity phases, we characterized the copper species in the
precursors of different procedures by ICP-AES, XRD, and
SEM analyses. As the adding sequence of silica sol is not so
critical to the synthesis of pure-phase AV-23, the following
experiments were carried out with the samples obtained
from the precursors to which we had not added silica sol.
The copper content in the solutions from which all the
precipitate had been filtered out was measured by ICP-
AES. In the designed experiment (procedure 1), when am-
monia solution is added first and then sodium hydroxide,
the copper content is 670.6 mg/L; however, in procedure 2,
without ammonia solution, and procedure 3, in which so-
dium hydroxide is added first and then ammonia solution,
the copper contents are 1.9 and 153.6 mg/L, respectively.
This indicates that the copper in the precursor of procedure
obtained with any change in the crystallization time at the
current molar ratio of the components. Figure 8 shows that
the AV-23 phase appeared upon crystallization after 12 h.
Well-crystallized, pure-phase AV-23 was obtained after a
crystallization time of 96 h (Figure 8). In the framework of
CuSH-1Na, the molar ratio of Cu/Si is 1:4, and copper is
present in the form of [(CuO )·2H O] single chains, which
are sandwiched by silicate double layers containing one-di-
mensional 12-ring channels. However, in the framework of
AV-23, the Cu/Si molar ratio is 1:2, and copper is present
in [(Cu Si O )·2H O] chains that are interconnected along
4
2
2
4
11
2
the b direction to form layers. The adjacent layers are con-
nected via corner-sharing tetrahedral SiO , which leads to
4
a three-dimensional microporous framework with major
channels running along the a direction. This indicates that
the long crystallization times preferably lead to a higher
ratio of Cu/Si and a three-dimensional framework in this
system, and the formation of AV-23 may be due to the
recrystallization of CuSH-1Na.
1
shows a greater tendency to dissolve in the solution than
the copper in the precursors of the other two procedures.
As we know, if more copper dissolves in the solution, the
conditions will be more suitable for the dispersion of the
precursors than for the precipitation of Cu(OH) . This indi-
2
cates that the precursor of procedure 1 will be obviously
better distributed than the other two precursors and will
thus be better at the synthesis of pure-phase AV-23.
The difference in the precursors can be explained by the
balance of competing chemical reactions in the solutions
[
19–23]
2+
+
(
Table 2).
For the precursor of procedure 1, if Cu
reacts with aqueous ammonia firstly, then a lot of NH4
will be contained in the solution. When sodium hydroxide
is added, precipitation and complexation reactions compete
with each other, which leads to an acid/alkali balance in the
[
23]
solution.
Equation (3)] is relatively large; copper is present in the
forms of both precipitated Cu(OH) and soluble [Cu(NH )
The equilibrium constant, K, of this reaction
[
2
3
2+
4]
. However, in procedure 2, the equilibrium constant is
even larger [Equation (1)]; the precipitation of Cu(OH) oc-
2
curs completely. There will even be an equilibrium between
Figure 7. X-ray powder diffraction patterns of the sample with
fixed starting molar ratio crystallized for 6 h and typical CuSH-
2+
Cu(OH) and [Cu(OH) ] , as the pH is not high enough
2
4
1Na.
to make Cu(OH) dissolve [Equation (2)]. And in procedure
2
Eur. J. Inorg. Chem. 2011, 2112–2117
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
2115

Q. Z. Jiang, Q. Shi, H. Xu, J. P. Li, J. X. Dong
FULL PAPER
Table 2. Values of K under different reaction conditions.[19–23]
Run
Equation
K
–
18
Equation (1)
Equation (2)
Equation (3)
Equation (4)
Cu2++2OH = Cu(OH)
2
(s)
3.85ϫ 10
–
2–
–3
Cu(OH)
Cu(OH)
Cu(OH)
2
2
2
(s) + 2OH = Cu(OH)
(s) + 4NH
(s) + 4NH
4
3.38ϫ 103
+
]2++2NH
3
+ 2NH
= [Cu(NH
4
= [Cu(NH
3
)
4
3
·H
2
O
3.21ϫ 10
1.04ϫ 10
2
+
–
–6
3
3
)
4
]
+2OH
3
, where sodium hydroxide was added first instead of aque-
2
+
ous ammonia, Cu first reacts with sodium hydroxide, and
Cu(OH)2 precipitates completely. After the addition of
aqueous ammonia, even the Cu(OH) precipitate can react
2
with free NH in the solution; however, the equilibrium
3
constant of Equation (4) is relatively small, and the effect
of Equation (3) is also very small as there is not much
+
NH , so the precipitates are difficult to dissolve in ammo-
4
nia solution.
The XRD and SEM analysis indicate that the competi-
tion balance can also influence the morphology and the pu-
rity of precipitated Cu(OH) . The SEM photograph of the
2
Cu(OH) samples prepared by procedure 1 (Figure 9) shows
2
very uniform aggregates of long needles. However, the SEM
photograph of the Cu(OH) samples obtained by the pro-
2
2
Figure 10. The XRD analysis of Cu(OH) samples obtained by dif-
cedures 2 and 3 do not have a uniform morphology. The ferent procedures. (a) procedure 1, (b) procedure 2, (c) procedure
3
.
XRD patterns indicate that the samples are always mixed
with some CuO (Figure 10). This may influence the kinetics
of the crystallization of the products, and consequently the
formation of polycrystalline CuO and amorphous phases
during crystallization.
Conclusions
It has been shown that the adding sequence of reagents
in the synthesis of AV-23 using ammonia as complexing
agent can obviously influence the dispersion of the precur-
sors, the morphology and the purity of Cu(OH) , which can
2
consequently influence the kinetics of crystallization and
the purity of the products. The best adding sequence is dis-
tilled water, copper nitrate trihydrate, ammonia solution,
sodium hydroxide, and silica sol. The molar ratio is
CuO:(2.8–3.4)SiO :(2.9–3.1)Na O:(4.57–6.86)
2
2
NH :146H O. The competition between precipitation and
3
2
complexation and alkali balance in the precursor mixture
obviously imply that the synthesis procedure is a key factor
in producing pure-phase AV-23. In the crystallization time
study, there was a phase transition process, and an interme-
diate phase CuSH-1Na was produced.
2
Figure 9. Crystal morphology of the Cu(OH) samples obtained by
different synthesis procedures. (a) procedure 1 (ϫ5000), (b) pro-
cedure 1 (ϫ20000), (c) procedure 2 (ϫ5000), (d) procedure 3
Experimental Section
(ϫ5000).
The reagents used in the experiments were copper nitrate trihydrate
[
Cu(NO
sodium hydroxide (NaOH, Sinopharm Chemical Reagent, China,
6%), and ammonia solution (NH , Sinopharm Chemical Reagent,
3 2 2
) ·3H O, Sinopharm Chemical Reagent, China, 99.5%],
Obviously, the key to the preparation of pure-phase cop-
per silicate AV-23 is controlling the precipitation of Cu-
OH) in the precursor. The order in which the reagents are
9
3
China, 25%), which were all analytical-grade reagents. Silica sol
(
2
(Qingdao Haiyang Chemical, China, SiO , 30 wt.-%) is an indus-
2
mixed obviously influences the dispersion of the precursors
trial chemical. All chemicals were purchased from commercial
and the morphology and purity of Cu(OH) , consequently sources and used without further purification. Distilled water was
2
the kinetics of crystallization and the purity of products.
prepared in the laboratory. A typical synthesis for the crystalli-
2116
www.eurjic.org
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2011, 2112–2117

Hydrothermal Synthesis of Pure-Phase Copper Silicate
zation of pure-phase AV-23 was prepared from a gel as follows.
Copper nitrate trihydrate, ammonia solution, and distilled water
were thoroughly mixed in a beaker by stirring at room temperature
for 5 min. Sodium hydroxide and silica sol were then added. After
further stirring for about 10 min, the mixture with a molar ratio
[1] J. Rocha, M. W. Anderson, Eur. J. Inorg. Chem. 2000, 801–818.
[2] S. C. Colin, A. C. Paul, Chem. Rev. 2003, 103, 663–702.
[
[
[
[
3] S. M. Kuznicki (Engelhard Corp.), US Patent 4 853 202, 1989.
4] S. M. Kuznicki (Engelhard Corp.), US Patent 4 938 939, 1990.
5] J. Rocha, Z. Lin, Rev. Mineral. Geochem. 2005, 57, 173–201.
6] R. F. Howe, Y. K. Krisnandi, Chem. Commun. 2001, 1588–
of CuO:3.2SiO
3
2
2
:3.02Na
0 mL Teflon-lined steel autoclave and kept without stirring at
20 °C in an oven for 96 h. The solid product was collected by
2 3 2
O:4.57NH :146H O was transferred into a
1
589.
7] P. Calza, C. Paze, E. Pelizzetti, A. Zecchina, Chem. Commun.
001, 2130–2131.
[
cooling the mixture to room temperature, filtered, washed with dis-
tilled water, and dried at 100 °C overnight. The crystallinity and
phase purity of the product was characterized by XRD patterns
2
[8] L. Al-Attar, A. Dyer, R. Harjula, J. Mater. Chem. 2003, 13,
2963–2968.
collected with a Rigaku Mini Flex II diffractometer with Cu-K
α
[9] C.-Y. Li, C.-Y. Hsieh, H.-M. Lin, H.-M. Kao, K.-H. Lii, Inorg.
Chem. 2002, 41, 4206–4210.
radiation operated at 30 kV and 15 mA. The scanning range was
from 5 to 40° (2θ) at 4°/min. SEM images were observed with
JEOL JSM-6700F equipment at 10 kV. The samples were coated
with gold to increase their conductivity before scanning. EDS (Ox-
ford 7421) was used to detect the constituent elements in the sam-
ples using the characteristic X-rays generated from a sample bom-
barded with electrons. An optical microscope camera (DCM300
MICROSCOPE CAMERA #5880) was used for purity and micro-
scopic analysis. The precursors of the three different procedures
that were conducted without adding silica sol were filtered, and the
precipitates were dried at room temperature overnight. They were
characterized by XRD from 32 to 41°(2θ) at 0.25°/min and by SEM
with JEOL JSM-6700F equipment at 10 kV. The copper content in
the filtered solutions was measured by inductively coupled plasma
atomic emission spectroscopy (ICP-AES) with a Plasam-Spec-I
spectrometer.
[
10] Z. Lin, J. Rocha, A. Valente, Chem. Commun. 1999, 2489–2490.
11] J. Huang, X. Q. Wang, A. J. Jacobson, J. Mater. Chem. 2003,
[
13, 191–196.
[
[
12] J. Huang, X. Q. Wang, L. M. Liu, A. J. Jacobson, Inorg. Chem.
2003, 42, 4057–4061.
13] A. M. dos Santos, P. Brandao, A. Fitch, M. S. Reis, V. S. Ama-
ral, J. Rocha, J. Solid State Chem. 2007, 180,16–21.
[14] P. Brandao, J. Rocha, M. S. Reis, A. M. dos Santos, R. Jin, J.
Solid State Chem. 2009, 182, 253–258.
[
15] A. M. dos Santos, V. S. Amaral, P. Brandao, F. A. A. Paz, J.
Rocha, L. P. Ferreira, M. Godinho, O. Volkova, A. Vasiliev,
Phys. Rev. B 2005, 72, 0924031–0924034.
[
16] X. Q. Wang, L. M. Liu, A. J. Jacobson, Solid State Sci. 2005,
7, 1415–1422.
[
17] X. Q. Wang, L. M. Liu, A. J. Jacobson, Angew. Chem. Int. Ed.
003, 42, 2044–2047.
[18] P. Brandao, F. A. A. Paz, J. Rocha, Chem. Commun. 2005, 171–
73.
2
1
[
[
[
[
[
19] Das Kupferoxyd-Ammoniak, ein Auflösungsmittel für die Pflan-
zenfaser: E. Schweizer, J. Prakt. Chem. 1857, 72, 109–111.
20] J. A. Dean, Lange’s Handbook of Chemistry, McGraw-Hill,
New York, 1973, vol. 1, pp. 357–360.
21] J. Inczedy, P. H Andrea, T. Julian, Analytical Applications of
Complex Equilibria, Wiley, New York, 1976, pp. 22–31.
22] Q. Wang, Chemical Reaction Competitive Balance in Solution,
Beijing Agriculture Univ. Press, Beijing, 1988, pp. 8–18.
23] X. Deng, Z. Chen, Mater. Lett. 2004, 58, 276–280.
Received: September 20, 2010
Acknowledgments
The authors thank the China National Funds for Distinguished
Young Scientists (20825623), the Chinese National Natural Science
Foundation (50972098), the Program for the Top Young and Mid-
dle-Aged Innovative Talents of Higher Learning Institutions of
Shanxi, and the Program for the Top Science and Technology Inno-
vation Teams of Higher Learning Institutions of Shanxi for finan-
cial support.
Published Online: March 18, 2011
Eur. J. Inorg. Chem. 2011, 2112–2117
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
2117