Large scale synthesis of tellurium nanoribbons in tetraethylene pentamine aqueous solution and the stability of tellurium nanoribbons in ethanol and water

Article abstract of DOI:10.1021/jp0544484

Superlong single crystal tellurium nanoribbons with a width of 200-300 nm and length up to several-hundred micrometers have been synthesized in tetraethylene pentamine aqueous solution at 80°C. The stability of as prepared tellurium nanoribbons in solvents such as pure ethanol and deionized water has been studied. The poor crytallinity of the initial single crystalline Te nanoribbons with prolonged storing time demonstrated that the initial single crystalline nanobelts tend to be destroyed and to dissolve in the solvent. In meantime, the supersaturation of the solvable Te species in such solvents will result in the formation of amorphous Te, and the formation of amorphous TeO ₂ due to partial oxidation of the Te nanostructures and the newly formed amorphous Te. The detailed corrosion process, crystallinity, and shape evolution process have been carefully examined by the XRD, TEM, HRTEM, and XPS techniques. This erosion phenomenon attacked by solvents has been not identified previously, suggesting that tellurium nanoribbons synthesized by other chemical methods could be also not stable in solution system and their storage after laboratory synthesis requires special attention.

Full text of DOI:10.1021/jp0544484

22740
J. Phys. Chem. B 2005, 109, 22740-22745
Large Scale Synthesis of Tellurium Nanoribbons in Tetraethylene Pentamine Aqueous
Solution and the Stability of Tellurium Nanoribbons in Ethanol and Water
Zhubing He and Shu-Hong Yu*
DiVision of Nanomaterials & Chemistry, Hefei National Laboratory for Physical Sciences at Microscale,
Structural Research Laboratory of CAS, School of Chemistry & Materials, UniVersity of Science and
Technology of China, Hefei 230026, P. R. China
ReceiVed: August 9, 2005; In Final Form: September 30, 2005
Superlong single crystal tellurium nanoribbons with a width of 200-300 nm and length up to several hundred
micrometers have been synthesized in tetraethylene pentamine aqueous solution at 80 °C. The stability of as
prepared tellurium nanoribbons in solvents such as pure ethanol and deionized water has been studied. The
poor crytallinity of the initial single crystalline Te nanoribbons with prolonged storing time demonstrated
that the initial single crystalline nanobelts tend to be destroyed and to dissolve in the solvent. In meantime,
the supersaturation of the solvable Te species in such solvents will result in the formation of amorphous Te,
2
and the formation of amorphous TeO due to partial oxidation of the Te nanostructures and the newly formed
amorphous Te. The detailed corrosion process, crystallinity, and shape evolution process have been carefully
examined by the XRD, TEM, HRTEM, and XPS techniques. This erosion phenomenon attacked by solvents
has been not identified previously, suggesting that tellurium nanoribbons synthesized by other chemical methods
could be also not stable in solution system and their storage after laboratory synthesis requires special attention.
Introduction
Other bioorganic molecules have also been utilized to shape
the growth of one-dimensional tellurium nanowires.13 Recently,
One-dimensional nanostructures of functional materials have
attracted more and more attention from scientists and engineers,
as they can be used in the fabrication of nanodevices. As a
narrow band gap semiconductor, tellurium exhibits many
potential properties, such as photoconductivity, nonlinear optical
response, thermoelectric reactivity, and an effect of superfast
electronic excitation on the A1 phonon frequency, resulting in
their applications in electronic and optical electronic devices.
Many methodologies have been developed for the syntheses of
elemental tellurium nanostructures, for example, electrochemical
and electrophoretic deposition and physical evaporation. A
self-seeding growth regime was utilized to illustrate the synthesis
of tellurium nanorods, nanowires, and nanotubes. Helical
nanobelts and nanotubes based on belt-roll-growth mecha-
nisms were made. Under high alkaline and acidic conditions,
our group has used biomolecules as additives to produce scrolled
1
4
nanotubes and nanowires with sharp ends.
These methods offered flexible routes to prepare one-
dimensional structures with different shapes and structural
features. Nevertheless, low cost and easy controlling synthetic
routes are still needed. Additionally, it is critical to examine
whether these tellurium nanostructures in various forms are
stable or not in solutions from the viewpoint of applications;
however, there has been no investigation performed on this issue.
In this paper, we report a facile route to prepare uniform
superlong tellurium nanoribbons at low temperature and the
stability of the nanoribbons in solvents. Tetraethylene pentamine
aqueous solution can reduce telluride to elemental tellurium
under mild conditions. The shape evolution process of single
crystalline nanoribbons has been investigated. The stability of
as-prepared nanoribbons in different solvents has been studied
for the first time.
1
2
3
4
5
nanowires and nanotubes were also fabricated by solvothermal
6
method, in which surfactants played an important role in
morphology shaping. Under high alkaline solution, rigid tel-
lurium nanotubes were synthesized in hydrazine by a solvo-
thermal method. Gautam et al. reported a hydrothermal route
7
Experimental Section
to prepare Y-junction nanowires in the presence of a strong
reducing reagent NaBH4. Surfactant trioctylphosphine oxide
8
Synthesis of Superlong Tellurium Nanoribbons. All chemi-
cals are used as received without further purification. In a typical
synthesis procedure, 0.025 mmol of sodium telluride was
dissolved into 12.5 mL of distilled water, and then the solution
mixed with 12.5 mL of tetraethylene pentamine (AC) was
vigorously stirred in a wide mouthed reagent bottle for half an
hour. Finally, the bottle was sealed with PARAFILM and placed
into a bake oven at 80 °C for different times. After 1.5 h, the
solution turned dark blue. Subsequently, an obvious floccule
floated throughout the whole solution after 8 h and a cloudy
flocculent came into being finally with a transparent yellow
solution when left alone. The product was washed with ethanol
several times and preserved in sample takers.
(
TOPO) was also utilized as a good surfactant to form uniform
9
nanowires in polydecene at 203 °C. Microwave-assisted
synthesis of tellurium reduced the necessary temperature in
glycol solvents to 80 °C.10 Ionic liquid was taken as template
for preparing tellurium nanowires and nanorods, in which
N-butylpyridinium tetrafluoroborate and PVP were applied in
1
1
the synthesis. Chemical decomposition of stabilizer-depleted
CdTe nanoparticles in the presence of a strong complexing agent
1
2
results in the formation of highly crystalline Te nanowires.
*
Correspondence should be addressed to S. H. Yu, Fax: + 86 551
3
603040, Email: shyu@ustc.edu.cn.
1
0.1021/jp0544484 CCC: $30.25 © 2005 American Chemical Society
Published on Web 11/12/2005

Synthesis of Tellurium Nanoribbons
J. Phys. Chem. B, Vol. 109, No. 48, 2005 22741
Figure 1. XRD pattern of the product synthesized using 0.02 mmol
NaTeO in 25 mL aqueous tetraethylene pentamine solution at 80 °C.
3
The volume ratio of distilled water and tetraethylene pentamine is 1:1.
The Stability and Corrosion of Nanoribbons in Different
Solvents. For stability study, a certain amount of fresh prepared
tellurium nanoribbons was put into two 50 mL weighing bottles,
respectively, one for pure ethanol and the other for deionized
water. They are kept for different times and the intermediates
after different storing times were sampled for characterization.
Characterization. The structure of these obtained samples
were characterized by the X-ray diffraction pattern (XRD),
which was recorded on a MAC Science Co. Ltd. MXP 18 AHF
X-ray diffractometer with monochromatized Cu KR radiation
Figure 2. SEM and TEM images of the sample synthesized with 0.02
mmol NaTeO in 25 mL aqueous tetraethylene pentamine (the volume
3
ratio of distilled water and tetraethylene pentamine is 1:1) at 80 °C for
different time. (a, b) low and high magnification of FESEM images of
the sample for 4 days. (c) electron diffraction pattern taken on a single
nanoribbon. (d, e) TEM images of the samples obtained after reaction
for 4 h and 24 h, respectively. (f) TEM image of the sample obtained
after reaction for 4 days.
(λ ) 1.54056 Å). Transmission electron microscopy (TEM) and
high-resolution transmission electron microscopy (HRTEM),
were performed on a Hitachi (Tokyo, Japan) H-800 transmission
electron microscope (TEM) at an accelerating voltage of 200
kV, and a JEOL-2010 high-resolution transmission electron
microscopy (HRTEM), also at 200 kV, respectively. Scanning
electron microscope (SEM) measurements were carried out with
a field-emission microscope (JEOL, 7500B) operated at an
acceleration voltage of 10 kV. The IR spectra were measured
on a Bruker Vector-22 FT-IR spectrometer at room temperature.
The ingredients of the sample were detected by X-ray photo-
electron spectroscopy (XPS) technique, which was operated on
VG ESCALAB MKII with monochromatized Mg KR radiation.
composed of ultralong nanoribbons of tellurium with lengths
of several micrometers and widths of 200-300 nm as clearly
observed in the high magnification SEM image (Figure 2b).
The selected area diffraction pattern in Figure 2c was taken on
a typical individual nanobelt, showing that the nanobelt is singe
crystalline with growth direction along [001]. The IR spectrum
of the freshly prepared sample does not show the presence of
any tetraethylene pentamine.
Time dependent growth process of nanobelts was investigated.
Amorphous particles formed after 4 h (Figure 2d). Because of
their own high thermodynamic level, these amorphous particles
tend to grow into nanowires of trigonal tellurium owing to its
31 helical-chain in structure. The formation of amorphous
nanoparticles formed rapidly by reducing sodium telluride with
tetraethylene pentamine is consistent with that previous report.4
With time prolonged, the nanoparticles tend to form wirelike
nanostructures on which a lot of nanoparticles adsorbed after
reaction for 24 h (Figure 2e). In the end, the beads-stringlike
nanostructures ripened into nanobelts at consumption of these
adsorbed nanoparticles as shown in Figure 2f.
The concentration of sodium telluride has significant effects
on the formation of nanostructures. A low concentration of
sodium telluride favors the formation of nanobelts rather than
nanowires. The influence of the concentration on the nano-
structures was illustrated in Figure 3. When the concentration
decreased to 0.05 mmol, nanobelts turned out in the final product
(Figure 3c). Moreover, the diameter of nanowires declined with
the concentration decreasing as Figure 3b,c shows.
Results and Discussion
Synthesis of Single Crystalline Te Nanoribbons. Hydrazine
was used as the reducing agent to reduce positive valence of
4
6
tellurium under flux and solvothermal conditions. Aqueous
ammonia was also taken as solvent to synthesize tellurium
5
nanotubes and nanobelts, where it acts as not only a solvent,
but also a reactant, which plays a crucial role in reducing
tellurate into elemental tellurium. In the present case, tellurium
colloids turned out after only 1.5 h in aqueous tetraethylene
pentamine solvent at 80 °C. Obvious floccule can be obtained
after reaction for 8 h. It has to be pointed out that not all the
amines can reduce tellurate to elemental tellurium, and only
amines with multiamino groups are able to yield elemental
tellurium. In present work, using either tetraethylene pentamine
or diethanol triamine can produce tellurium.
Figure 1 shows that the product is well crystallized elemental
tellurium. All the diffraction peaks can be indexed as trigonal
tellurium phase (JCPDS 36-1452). The enhanced relative
intensities of 100 and 110 diffraction peaks compared with those
for the standard indicated the possible preferential orientation.
The SEM image in Figure 2a shows that the floccule is
Stability of Te Nanoribbons in Different Solvents. The
nanoribbons were not stable when they are stored in solvents

22742 J. Phys. Chem. B, Vol. 109, No. 48, 2005
He and Yu
Figure 3. TEM images of the samples obtained at 80 °C using different concentration of sodium telluride. (a-c) The concentration of sodium
telluride is 0.5, 0.1, and 0.05 mmol sodium telluride, respectively. The reaction was done in 25 mL aqueous tetraethylene pentamine solution with
the volume ratio of 1:1(distilled water and tetraethylene pentamine).
(
in 1, 2, 3 order marked as three white panes). At the tip of the
damaged nanoribbon, no crystal lattice fringes can be observed
Figure 5b). However, the lattice fringes with a spacing of 5.90
(
Å can be observed on the trunk of the ribbon, corresponding to
the growth direction along [001] (Figure 5c). The lattice fringes
with a spacing of 2.23 Å, which are perpendicular to those of
(001) plane, are corresponding to that of (110) plane. However,
the lattice fringes with a spacing of 3.24 Å are frequently
observed, corresponding to that of (101) plane. Additionally,
an amorphous layer of a thickness of about 25 nm coexisted
with the destroyed backbone was observed. Furthermore, a lot
of jags were observed and they already extended along the whole
backbone of the ribbon, which can be confirmed by the contrast
difference of the TEM image.
However, this observation is different from what the erosion
event took place in water. Although an amorphous layer also
yielded around the ribbon, but the eroded notches are observed
along the backbone and they turned along it, the key difference
between them is that bone structure eroded in water keep intact
as a fresh one with conspicuous lattice fringes of spacing 5.90
Å for (001) plane (Figure 6b,c). Also an amorphous layer was
observed (Figure 6b). The result suggested that polar water
molecules could only attack from surface along the backbone
of the nanoribbons gradually rather than that ethanol molecules
can penetrate into the backbone.
Figure 4. TEM images of rotten tellurium nanoribbons in pure ethanol
and deionized water for 35 days, respectively. (a, b) Typical morphology
of structures which were penetrated by pure ethanol is shown. The
inserted ED taken on the structures, showing that the structures are
amorphous. (c, d) Typical TEM images of the gnawed structures by
water are shown. The inserted ED pattern shows that the remaining
part of the nanoribbons is still single crystalline.
such as pure ethanol or deionized water. This observation is
not consistent with a previous report that tellurium nanotubes
4
remained unchanged in water or ethanol for several months.
The morphology of the rotten nanoribbons in ethanol and
water after storing in these two solvents for 35 days is shown
in Figure 4. Higher magnification TEM images show that the
smooth surface of the initial intact nanoribbons becomes rough
and there are a lot of holes within the nanoribbon body (Figure
The erosion process and the crytallinity of the intermediates
in the two solvents were respectively examined by time
dependent XRD measurement (Figure 7). The intermediate
samples after storing for different time were also examined by
HRTEM. The XRD pattern for the initial nanoribbons shows
that there are three intensive diffraction peaks (100), (101), (110)
are observed and the (100) peak is the strongest and (101) plane
is weakest (Figure 7a). Compared with the XRD pattern for
the initial single crystalline tellurium (Figure 7a), the intensities
of the diffraction peaks for the product after storing in ethanol
for 15 days become weaker. Two distinguished features are
observed based on the XRD patterns. First, the (100), (110)
peaks became weaker and (101) and became more intensified.
As we discussed above, the nanoribbons were attacked by
ethanol molecules both from surface and inside. And the
backbones of the nanoribbons are destroyed more than those in
water since a lot of holes are observed (Figure 4a,b) in the
intermediate sample obtained after aging for 35 days. The (100)
and (110) planes are perpendicular to the (001) plane, while
the (101) plane is not, the fact that the more frequently observed
the lattice fringes of (101) by the HRTEM images in Figure
5c,d are well consistent with the presence of intensified (101)
peak appeared in the XRD patterns (Figure 7b,c). The results
suggested that the ethanol molecules attacked the (001) and the
4a,b). The ethanol molecules could invade into the backbone
of the nanoribbon (Figure 4b). The selected area diffraction
pattern taken on the wires shows an amorphous feature (inset
in Figure 5a). In contrast, the sample obtained after eroding in
water for the same period shows different features as that above
observed in ethanol (Figure 4c,d). The long nanoribbons become
shorter and the obvious eroding event happened in a way that
is different from in ethanol. In addition, the electron diffraction
pattern taken on the backbone of the eroded nanoribbon shows
that it is still single crystalline (inset in Figure 4d).
To further understand the initial stages of the eroding process,
the samples after eroding for 15 days were obtained for TEM,
HRTEM, and XRD analysis. High-resolution TEM images in
Figure 5 reveal the detailed structural features during the eroding
process, which were taken on the samples after eroding for 15
days in ethanol. Figure 5a shows the initial stage of erosion
happened on the nanoribbons. Figure 5b,c,d shows the HRTEM
images selected on a eroded nanoribbon (shown in Figure 5a)
which were taken on the different positions of the nanoribbon

Synthesis of Tellurium Nanoribbons
J. Phys. Chem. B, Vol. 109, No. 48, 2005 22743
Figure 5. HRTEM images of the samples after erosion for 15 days in absolute ethanol: (a) typical morphologies of rotting nanoribbons; (b-d)
HRTEM images taken in three areas along the backbone of the nanoribbon marked in part a, corresponding to the areas 1, 2, and 3, respectively.
Figure 6. TEM and HRTEM images of the sample obtained after erosion for 15 days in deionized water, respectively: (a) typical morphology of
rotten structures in water; (b) HRTEM image taken in the area marked in white rectangle in part a; (c) a magnified one selected in the area marked
in part b.
Figure 7. XRD patterns of time dependent samples during erosion of
the intact nanoribbons in pure ethanol: (a) as-prepared tellurium
nanoribbons; (b) nanoribbons after storing for 15 days; (c) nanoribbons
after storing for 30 days.
Figure 8. XRD patterns of time dependent samples during erosion of
the intact nanoribbons in deionized water: (a) as-prepared tellurium
nanoribbons; (b) nanoribbons after storing for 15 days; (c) nanoribbons
after storing for 30 days.
planes which are perpendicular to it more severely than those
planes which are not perpendicular to the (001), resulting in
the much enhanced (101) peak appeared in the XRD pattern
shown in Figure 7b,c. Second, with storing time prolonged, the
crystallinity of the products becomes poor, implying the
formation of an amorphous phase. The obvious poor crytallinity
of the samples after storing for a period demonstrated that the
initial single crystalline nanobelts tend to be destroyed and to
dissolve gradually in the solvent. In the mean time, the
supersaturation of the solvable Te species in the solution will
result in the formation of amorphous Te. The 2θ value around

22744 J. Phys. Chem. B, Vol. 109, No. 48, 2005
He and Yu
Figure 9. XPS spectra for the fresh sample (a, black) and the sample (b, red) after eroding for 4 months in ethanol: (a) surveys of the two samples;
b) survey of the Te 3d region in the two samples; (c) survey of the oxygen O 1s region in the two samples.
(
5
5° corresponds to the initial amorphous Te phase (Figure 7c),
tellurium (575.95 eV), accompanying the presence of O 1s peak
(529.85 eV) in both spectra (Figure 9c), are consistent with that
like that we observed in the intermediate product using amino
acid controlled synthesis of highly crystallined Te nanostruc-
tures.
1
6
for TeO2 reported by Garbassi et al. In addition, other two
stripped peaks of the spectrum (curve a, black) in Figure 9c
located at 531.85 and 533.35 eV, which denote -OH groups
1
4
In contrast, the intensity of each peak declined for the eroded
nanoribbons in water, showing the same trend as that for the
product obtained in ethanol. However, the relative intensities
of three main peaks (100), (101), (110) (Figure 8b,c) for the
eroded intermediates obtained in water remained the same as
those for the initial intact nanoribbons (Figure 8a). The highly
resolved lattice (intact (001) plane) image in Figure 6c clearly
showed the continuous lattice fringes with a spacing of 5.90 Å.
Even though the backbone of the nanoribbon was destroyed,
however, the core part is still continuous single crystalline,
resulting in that the XRD pattern is still kept as the same feature
as that of initial nanoribbons (Figure 6a,b). An amorphous layer
on the nanoribbon core was observed also (Figure 6b).
17
18
contained in metal hydroxides and H2O, respectively. These
results confirmed that the freshly prepared Te nanostructures
tend to be oxidized in air to some extent, however, the Te
nanostructures were seriously eroded and oxidized after long
time storing in ethanol and amorphous TeO2 will form.
In conclusion, we have demonstrated a facile route to prepare
ultralong single crystal nanoribbons of tellurium in aqueous
tetraethylene pentamine at low temperature. Tetraethylene
pentamine acts not only as solvents and reducing reactants, but
also as a soft template to shape one-dimensional structure. The
shape evolution process of single crystalline nanoribbons has
been investigated, in which the nanoribbons evolved from
amorphous nanoparticles and nanowires finally to nanoribbons.
On the basis of the detailed corrosion experiments, it has been
confirmed that the as prepared Te nanoribbons are not stable if
stored in solvents such as ethanol and water. The structure
erosion in solvents is undertaking gradually attacked by solvent
molecules with storing time prolonging. The poor crytallinity
of the samples with prolonged storing time demonstrated that
the initial single crystalline nanobelts tend to be destroyed and
to dissolve in the solvent. In the mean time, the supersaturation
of the solvable Te species in the solution will result in the
The XPS data measured on as prepared sample and the sample
after eroding 4 months in ethanol is shown in Figure 9. The
XPS quantitative analysis for the sample after eroding for 4
months indicated that the molar percentages of tellurium and
oxygen are 27.5 at. % and 43.9 at. %, respectively. The obvious
Te 3d peak shift shown in Figure 9b indicated that the different
valence state of Te in the freshly prepared Te nanostructures
and the eroded nanostructures. The spectrum (line a, black) in
Figure 9b demonstrates the presence of both elemental tellurium
3
d5/2 peak (572.70 eV)15 and a small amount of oxidized

Synthesis of Tellurium Nanoribbons
J. Phys. Chem. B, Vol. 109, No. 48, 2005 22745
formation of amorphous Te in the solvents. In addition, the
oxidization of the Te nanostructures and the newly formed
amorphous tellurium will result in the formation of amorphous
TeO2 as a possible byproduct. The results demonstrated that
the tellurium nanostructures synthesized by other methods could
be also not stable in solution system and their storage after
laboratory synthesis needs special attention. The stability of
tellurium nanostructures synthesized by other routes in other
solvents is being further examined and will be reported in due
course.
(4) (a) Mayers, B.; Xia, Y. AdV. Mater. 2002, 14, 279. (b) Mayers, B.;
Xia, Y. J. Mater. Chem. 2002, 12, 1875.
(
5) Mo, M. S.; Zeng, J.; Liu, X. M.; Yu, W.; Zhang, S. Y.; Qian, Y.
T. AdV. Mater. 2002, 14, 1658.
6) (a) Liu, Z. P.; Hu, Z. K.; Xie, Q.; Yang, B. J.; Wu, J.; Qian, Y. T.
(
J. Mater. Chem. 2003, 13, 159. (b) Liu, Z. P.; Li, S.; Yang, Y.; Hu, Z. K.;
Peng, S.; Liang, J. B.; Qian, Y. T. New J. Chem. 2003, 27, 1748. (c) Liu,
Z. P.; Hu, Z. K.; Liang, J. B.; Li, S.; Yang, Y.; Peng, S.; Qian, Y. T.
Langmuir 2004, 20, 214.
(7) Liu, Z. P.; Li, S.; Yang, Y.; Hu, Z. K.; Peng, S.; Liang, J. B.; Qian,
Y. T. New J. Chem. 2003, 27, 1748.
(
8) Gautam, U. K.; Rao, C. N. R. J. Mater. Chem. 2004, 14, 2530.
9) Yu, H.; Gibbons, P. C.; Buhro, W. E. J. Mater. Chem. 2004, 14,
(
Acknowledgment. S.-H.Y. expresses thanks for the funding
support from the Centurial Program of the Chinese Academy
of Sciences, the National Science Foundation of China (Nos.
595.
(10) Zhu, Y. J.; Hu, X. L. Chem. Lett. 2003, 32, 732.
(11) Zhu, Y. J.; Wang, W. W.; Qi, R. J.; Hu, X. L. Angew. Chem., Int.
Ed. 2004, 43, 1410.
2
0325104, 20321101, and 50372065), and the Scientific Re-
search Foundation for the Returned Overseas Chinese Scholars,
State Education Ministry.
(12) Tang, Z. Y.; Wang, Y.; Sun, K.; Kotov, N. A. AdV. Mater. 2005,
7, 358.
1
(
(
(
13) Lu, Q. Y.; Gao, F.; Komarneni, S. AdV. Mater. 2005, 16, 1629.
14) He, Z. B.; Yu, S. H.; Zhu, J. P. Chem. Mater. 2005, 17, 2785.
References and Notes
15) Mandale, A. B.; Badrinarayanan, S. J. Electron Spectrosc. Relat.
(1) (a) Kudryavstev, A. A. The Chemistry and Technology of Selenium
Phemon. 1990, 53, 87.
16) Garbassi, F.; Bart, J. C. J.; Petrini, G. J. Electron Spectrosc. Relat.
Phenom. 1981, 22, 95.
17) Kishi, K.; Ikeda, S. Bull. Chem. Soc. Jpn. 1973, 46, 341.
and Tellurium; Collet’s Ltd.: London, 1974. (b) Tangney, P.; Fahy, S. Phys.
ReV. B 2002, 14, 279.
(
(2) Zhao, A. W.; Ye, C. H.; Meng, G. W.; Zhang, L. D.; Ajayan, P.
(
M. J. Mater. Res. 2003, 18, 2318.
3) Li, X. L.; Cao, G. H.; Feng, C. M.; Li, Y. D. J. Mater. Chem.
004, 14, 244.
(
(18) Nefedov, V. I.; Gati, D.; Dzhurinskii, B. F.; Sergushin, N. P.; Salyn,
Y. V. Zh. Neorg. Khim. 1975, 20, 2307.
2