Synthesis and structure of quasi-one-dimensional zinc oxide doped with manganese

Article abstract of DOI:10.1134/S0036023612010111

Nanotubes of manganese-doped zinc oxide Zn_{1 - x}Mn_xO (0 ≤ x ≤ 0.2) were synthesized by heating the Zn_{1 - x}Mn _x(HCOO)(OCH₂CH₂O)1/2 precursor in air at 500°C. The precursor with extended crystals was synthesized by a solvothermal method based on heat treatment of a mixture of Zn _{1 - x}Mn_x(HCOO)₂ · 2H₂O with an ethylene glycol excess at 100-130°C. The tubular morphology of Zn _{1 - x}Mn_xO particles was identi- fied by transmission electron microscopy. Tubular quasi-one-dimensional particles were shown to have a nanodispersed polycrystalline structure, the size of separate crystallites being from 5 to 20 nm. X-ray photo- electron spectroscopy suggested that the manganese distribution on the outer surface layer of Zn_{1 - x}Mn _xO nanotubes is nonuniform. Pleiades Publishing, Ltd., 2012.

Full text of DOI:10.1134/S0036023612010111

ISSN 0036ꢀ0236, Russian Journal of Inorganic Chemistry, 2012, Vol. 57, No. 1, pp. 72–78. © Pleiades Publishing, Ltd., 2012.
Original Russian Text © O.I. Gyrdasova, V.N. Krasil’nikov, E.V. Shalaeva, M.V. Kuznetsov, A.P. Tyutyunnik, 2012, published in Zhurnal Neorganicheskoi Khimii, 2012, Vol. 57,
No. 1, pp. 78–85.
PHYSICAL METHODS
OF INVESTIGATION
Synthesis and Structure of QuasiꢀOneꢀDimensional Zinc Oxide
Doped with Manganese
O. I. Gyrdasova, V. N. Krasil’nikov, E. V. Shalaeva, M. V. Kuznetsov, and A. P. Tyutyunnik
Institute of Solid State Chemistry, Ural Branch, Russian Academy of Sciences,
ul. Pervomaiskaya 91, Yekaterinburg, 620219 Russia
Received December 10, 2010
Abstract—Nanotubes of manganeseꢀdoped zinc oxide Zn1 – xMnxO (0
the Zn1 – xMnx(HCOO)(OCH2CH2O)1/2 precursor in air at 500 . The precursor with extended crystals was
synthesized by a solvothermal method based on heat treatment of a mixture of Zn1 – xMnx(HCOO)2 2H2O
with an ethylene glycol excess at 100–130 . The tubular morphology of Zn1 – xMnxO particles was identiꢀ
≤
x
≤
0.2) were synthesized by heating
°C
·
°C
fied by transmission electron microscopy. Tubular quasiꢀoneꢀdimensional particles were shown to have a
nanodispersed polycrystalline structure, the size of separate crystallites being from 5 to 20 nm. Xꢀray photoꢀ
electron spectroscopy suggested that the manganese distribution on the outer surface layer of Zn1 – xMnxO
nanotubes is nonuniform.
DOI: 10.1134/S0036023612010111
Zinc oxide is a multifunctional semiconductor
and, therefore, is in the center of attention of
researchers in various fields of science [1–6]. In last
years, studies of this oxide have been intensified with
the aim of creating sensors, roomꢀtemperature ferroꢀ
magnents, and photocatalysts of oxidation of toxic
organic compounds and detoxification of water and air
contaminated by pathogenic bacteria, as well as sunꢀ
light water splitting cells [7–11]. The photocatalytic
properties of ZnO are dictated by its electronic strucꢀ
ture, in particular, by the existence of the band gap of
appropriate width (3.37 eV) [6]. The photocatalytic
activity of ZnO can be enhanced by tailoring its elecꢀ
tronic state energies and extending the spectral sensitivꢀ
ity range toward long wavelengths. Such an effect can be
EXPERIMENTAL
The synthesis of the Zn1 – хMnx(HCOO)
(OCH2CH2O)1/2 precursor (x = 0–0.3) was based on
the solvothermal interaction of the Zn1 – хMnx
(HCOO)2 . 2H2O formate with excess ethylene glyꢀ
col, which was thus used simultaneously as a reagent
and solvent [20]. For the reasons described below, the
synthesis temperature did not exceed 130°C. The
resulting formate glycolate crystals were separated
from the mother liquor by vacuum filtration, washed
with acetone, dried at 50
storage into weighing bottles with ground stoppers.
The Zn1 – хMnx(HCOO)2 2H2O formate used in the
°C for 1 h, and placed for
·
synthesis, was prepared by treating a mixtures of stoꢀ
ichiometric amounts of ZnO (special purity grade)
and MnCO3 (pure for analysis) with formic acid (pure
for analysis).
achieved, for example, by doping zinc oxide with d metꢀ
als [12–14]. On the other hand, the Zn1 – хMxO solid
solutions (M = Mn, Fe, Co, Ni, Cu) are roomꢀtemꢀ
perature ferromagnets, which allows one to classify
them with diluted magnetic semiconductors [15–17].
A task of prime interest is to synthesize lowꢀsize doped
zinc oxide in the quasiꢀoneꢀdimensional (1D) state
since such structures have a developed effective surface
and often exhibit anisotropy of the useful functional
properties [18, 19]
The phase analysis of the samples was performed
on a POLAM Sꢀ112 polarization microscope in the
transmission mode and by Xꢀray diffraction. The
Xꢀray powder diffraction patterns were recorded at
room temperature on a STADIꢀP automated diffracꢀ
tometer equipped with miniꢀPSD (Cu
K radiation,
α
transmission geometry, scan step
–120°). Polycrystalline silicon was used as the interꢀ
nal reference ( = 5.43075(5) Å). Possible impurity
Δ
2
θ
= 0.02
°
,
2
θ
=
2°
а
The present work was aimed at studying the formaꢀ
tion conditions lowꢀsize manganeseꢀdoped zinc oxide
phases were identified with the use of the PDF2 ICDD
database (Release 2009). Thermogravimetric analysis
was carried out on a Qꢀ1500D derivatograph on heatꢀ
ing in air at a rate of 10 K/min. The IR spectra of powꢀ
ders were recorded on a PerkinꢀElmer Spectrum One
spectrophotometer in the range 400–4000 cm–1. The
shape and size of particles in the samples were deterꢀ
mined by scanning electron microscopy (SEM) on
(
Zn1 – хMnxO) with a tubular structure of aggregates, as
well as at determining the microstructure of these aggreꢀ
gates. The doped oxide samples were synthesized by an
original precursor method in which the precursor was the
formate glycolate Zn1 – хMnx(HCOO)(OCH2CH2O)1/2
with needle or fibrous crystals [20].
72

SYNTHESIS AND STRUCTURE OF QUASIꢀONEꢀDIMENSIONAL ZINC OXIDE
73
JEMꢀ200CX and PhilipsꢀCM30 microscopes. For
2
electron microscopy studies, the powders were disꢀ
persed in isobutyl alcohol and as such were applied to
a supporting copper grid with deposited carbon coatꢀ
ing. The diffraction constant of a microscope was
determined on an aluminum film obtained by vacuum
thermal deposition onto a NaCl single crystal.
The zinc and manganese in the samples were quanꢀ
tified by atomic adsorption spectroscopy on a Perkinꢀ
Elmer instrument and by inductively coupled plasma
atomic emission spectroscopy on a JYꢀ48 spectromeꢀ
ter. The BET surface area was estimated by the lowꢀ
temperature nitrogen adsorption method on a
Micromeritics TriStar 3000 automated analyzer. The
chemical composition of the surface and the valence
state of manganese in the Zn1 – xMnxO structure were
determined by Xꢀray photoelectron spectroscopy.
Measurements were carried out on a ESCALAB MK
1
spectrometer with nonmonochromatic Mg
K radiation
α
(1253.6 eV). In the course of XPS measurements, the
residual pressure was maintained at a level of 10–8 Pa.
Sample charging due to photoelectron emission was
taken into account using the C1
s
peak of natural
s = 284.5 eV).
2000
1500
1000
, cm–1
500
hydrocarbon contaminations ( b C1
E
ν
RESULTS AND DISCUSSION
Fig.
1.
0.1
IR
spectra
of
the
(1)
Zn Mn (HCOO)(OCH CH O)
formate glycolate
0.9
2
2
1/2
The interaction of the Zn1 – хMnx(HCOO)2 2H2O
⋅
and (2) Zn Mn (OCH CH O) glycolate.
0.9 0.1 2 2
formate with ethylene glycol is temperature dependent
and occurs in three stages in the temperature range
50–180
°С:
>130
form as distorted octahedra.
The IR spectra
(OCH2CH2O)1/2 samples with
°С, Zn1 – xMnx(OCH2CH2O) glycolate crystals
Zn1−xMn HCOO ⋅ 2H O+HOCH CH OH
(
)
x
2
2
2
2
(1)
of
Zn1 – xMnx(HCOO)
= 0.0, 0.05, 0.10, 0.20,
= Zn1−xMn HCOO HOCH CH OH + 2H O ↑ ,
(
)2 (
)
x
x
2
2
2
and 0.30 are identical, which is evidence that this
compound is a substitutional solid solution with manꢀ
ganese atoms substituted for zinc atoms in the
Zn(HCOO)(OCH2CH2O)1/2 structure. Analogous
solid solutions have been obtained on the basis of
Fe2+, Co2+, Ni2+, and Cu+ cations [20]. The IR specꢀ
tra of Zn1 – xMnx(HCOO)(OCH2CH2O)1/2 can be
represented as a superposition of the HCOO– and
OCH2CH2O2– anions coordinated to a metal ion. The
asymmetric and symmetric vibrations of the carboxyl
Zn1−xMn x HCOO HOCH CH OH
(
)2 (
)
2
2
(2)
(3)
= Zn1−xMn x HCOO OCH CH O
(
)(
)
2
2
1 2
+ 1 2 HOCH2CH2OH+HCOOH ↑ ,
Zn1−xMnx HCOO OCH CH O
(
)(
)
2
2
1 2
+1 2HOCH2CH2OH
= Zn1−xMnx OCH CH O + HCOOH ↑ .
(
)
2
2
The first step at about 50
°
С
involves the formation group (COO) of the formate ion [21] are responsible
of the Zn1 – хMnx(HCOO)2(HOCH2CH2OH) solvate for two strong absorption bands at 1572 and 1360 cm–1,
as a result of substitution of one ethylene glycol respectively. The C–O bond vibrations in the
molecule for two water molecules in the formate. OCH2CH2O2– ion coordinated to zinc and manganese
The crystals of this compound have a platy habit and give rise to two strong bands at 1082 and 1041 cm–1,
low birefringence. When heated above 100°С, the analogous to those observed in the spectrum of liquid
solvate is dissolved in ethylene glycol to form a homogeꢀ ethylene glycol (1087 and 1043 cm–1) [22]. The
neous solution, and then fibrous or needleꢀshaped twisting vibrations of C–C bonds correspond to
Zn1 хMnx(HCOO)(OCH2CH2O)1/2 formate glycoꢀ strong bands at 898 and 870 cm–1 shifted toward
⎯
late crystals precipitate, which have a pronounced tenꢀ higher frequencies from the bands in the spectrum
dency for longitudinal intergrowth with an increase in of liquid ethylene glycol (883 and 862 cm–1). Figure 1
the degree of substitution of manganese for zinc. It is shows for comparison the IR spectra of the
worth noting that an indispensable condition in the Zn0.90Mn0.10(HCOO)(OCH2CH2O)1/2 formate glycoꢀ
synthesis of Zn1 – хMnx(HCOO)(OCH2CH2O)1/2 is late and Zn0.90Mn0.10(OCH2CH2O) glycolate. The
maintenance of a temperature regime since, above major difference between these IR spectra is the
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 57 No. 1 2012

74
GYRDASOVA et al.
The thermal decomposition of Zn1 – xMnx(HCOO)
(OCH2CH2O)1/2 in air occurs in two steps in the temꢀ
perature ranges ~270–340 and 340–460 (Fig. 2),
Δ
m
, mg
TG
0
°С
which corresponds to the presence of two types of
anions in the structure and to the successive decomꢀ
position of the formate and glycolate groups with
removal of the decomposition products. The experꢀ
imentally determined weight loss of the
Zn0.90Mn0.10(HCOO)(OCH2CH2O)1/2 sample on heatꢀ
2
4
DTA
ing at a rate of 2.5 K/min to 500°С is 37.94 wt %,
which is close to the theoretical weight loss 38 wt %
calculated under the assumption that the initial salt
6
8
converts to the Zn0.90Mn0.10O oxide. The powders of
the Zn1 – xMnx(HCOO)(OCH2CH2O)1/2 thermolysis
products have large BET surface areas: in particular, it
is 38–54 m2/g for the Zn1 – хMnxO series (
x
= 0–0.2).
The Xꢀray powder diffraction patterns of samples
obtained by annealing the precursor in air at 500
10
°С
points to the formation of Zn1 – хMnxO solid solutions
with a wurtzite structure (Fig. 3). The changes in the
unit cell parameters of Zn1 – хMnxO with an increase
in the degree of doping with manganese are presented
in the table. According to powder Xꢀray diffraction,
the Zn0.70Mn0.3(HCOO)(OCH2CH2O)1/2 thermolysis
product is not singleꢀphase (table) since its Xꢀray powꢀ
der diffraction pattern shows, in addition to the peaks
200
300
400
500
T,
°
C
Fig.
2.
TG
and
2
DTA
curves
of
Zn Mn (HCOO)(OCH CH O)
.
0.9
0.1
2
1/2
of the Zn1 – хMnxO solid solution (
5.241 Å, space group 63mc), peaks of an impurity
phase of the tentative composition Mn3 – yZnyO4 with
a spinel structure ( = 8.373 Å, space group Fd ).
a = 3.2556 Å, b =
P
a
3m
1
Figures 4a and 4b show typical SEM images demꢀ
onstrating the morphology and particle size of the
Zn0.9Mn0.1(HCOO)(OCH2CH2O)1/2 precursor and
the product of its thermolysis, the Zn0.9Mn0.1O oxide,
2
3
exposed to 500°С in air for 2 h. The shape of precursor
crystals is inherited by the oxide aggregates; however,
these aggregates have a loose structure since they are
composed of smaller extended particles, which easily
separate from each other upon sonication. According
to TEM, these particles are tubes with a cross section
on the order of 150 nm. The quasiꢀoneꢀdimensional
tubular structure of Zn1 – хMnxO samples obtained by
thermolysis of Zn1 – xMnx(HCOO)(OCH2CH2O)1/2 is
demonstrated by brightꢀfield TEM images (Figs. 5a
and 5b), which show a characteristic change in the difꢀ
fraction contrast along the line of projection of the
cross section of a quasiꢀoneꢀdimensional tubular
aggregate (Figs. 5b and 5d). In addition, quasiꢀoneꢀ
dimensional particles with the tube (or rod)ꢀintoꢀtube
morphology were revealed (Figs. 5c and 5d). Electron
diffraction patterns obtained for separate quasiꢀoneꢀ
dimensional particles show a system of continuous
Debye rings, which corresponds to a nanodispersed
polycrystalline structure of Zn1 – хMnxO, which have
no preferable orientation (texture) of crystallites. The
20
30
40
50
60
, deg
2
θ
Fig. 3. Xꢀray powder diffraction patterns of the Zn
solid solutions obtained in air at 450
= 0.1, and ( = 0.3.
Mn O
x
1 –
x
°С: (1) x = 0.01, (2)
x
3) x
absence of the bands corresponding to formate ion
vibrations in the spectrum of the glycolate; all
observed bands correspond to vibrations of the
OCH2CH2O2– anion and M–O bonds. The absorpꢀ
tion bands corresponding to C–O bond vibrations
(1070 and 1046 cm–1) are noticeably shifted toward
each other as compared with their positions in the
spectra of Zn1 – xMnx(HCOO)(OCH2CH2O)1/2 and
liquid ethylene glycol. The C–C vibration frequenꢀ
cies are shifted to 898 and 881 cm–1. Thus, the vibraꢀ
tional spectroscopy data are consistent with the
notion that Zn1 – xMnx(HCOO)(OCH2CH2O)1/2 and sizes of separate Zn1 – хMnxO crystallites constituting
Zn1 – xMnx(OCH2CH2O) are substitutional solid tubular quasiꢀoneꢀdimensional aggregates were estiꢀ
solutions with manganese substitution for zinc in the mated from the darkꢀfield TEM images obtained in
structures of zinc formate glycolate and zinc glycolate. the (100)/(002)/(101) diffraction reflections of the
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 57 No. 1 2012

SYNTHESIS AND STRUCTURE OF QUASIꢀONEꢀDIMENSIONAL ZINC OXIDE
75
Unit cell parameters of Zn1 – xMnxO solid solutions and the size (
d
) of their crystallites as a function of the degree of doping
with manganese
Zn1– xMnxO
Unit cell parameters
x
= 0.01
63mc
x
= 0.1
63mc
x = 0.3
P
P
P
63mc
Fd3m
a
, Å
, Å
, Å3
, nm
3.2497(3)
5.2082(5)
47.633
3.2501(3)
5.2102(5)
47.663
3.2556(9)
5.241(1)
48.107
8.373(1)
c
V
587.007
11.01
d
32.72
19.74
10.00
ZnOꢀICDD: a = 3.249 Å, c = 5.206 Å.
wurtzite phase. The size of individual crystallites varies quasiꢀoneꢀdimensional oxides are several crystallites,
from 5 to 20 nm and, hence, the walls of the tubular we can state that the high surface areas of the oxide
quasiꢀoneꢀdimensional aggregates can consist of one samples should be mainly determined by the develꢀ
to several crystallite layers.
oped surface of nanodispersed quasiꢀoneꢀdimensional
aggregates. This conclusion is consistent well with the
specific surface areas estimated using the suggested
model of the structure of nanodispersed quasiꢀoneꢀ
dimensional Zn1 – хMnxO oxides with average crystalꢀ
lite size of 15 nm. A typical TEM image of the quasiꢀ
oneꢀdimensional Zn1 – хMnxO surface is shown in Fig. 6d.
The mechanism of formation of tubular quasiꢀoneꢀ
dimensional oxides in thermolysis of quasiꢀoneꢀ
dimensional precursors is currently unknown. We may
assume that the formation and growth of oxide crystalꢀ
lites in the course of thermolysis occur in the matrix of
the precursor structure, and the tubular morphology is
either inherent in the initial precursor state or its interꢀ
mediate form in thermolysis and is inherited the oxide.
According to darkꢀfield TEM images, the polyꢀ
crystalline structure of quasiꢀoneꢀdimensional oxides
is a lowꢀporosity and highly continuous one. This is
supported by the fact that wellꢀformed intercrystallite
boundaries, including smallꢀangle ones, with offꢀoriꢀ
entation angles between crystallites of no more than 5°
are observed (Fig. 6b, inset). As a result, for most
quasiꢀoneꢀdimensional Zn1 – хMnxO oxides syntheꢀ
sized by the precursor method in this work, heating
under beam (in situ in an electron microscope) is
accompanied by recrystalization with grain coarsening
and intercrystallite boundary perfection (Fig. 6c) and,
often, by destruction of quasiꢀoneꢀdimensional aggreꢀ
gates into separate crystalline oxide particles.
The nanodispersed polycrystalline structure of
The manganese on the surface of the doped
quasiꢀoneꢀdimensional Zn1 – хMnxO oxide detected Zn1 – хMnxO oxide was quantified by means of XPS.
by TEM should account for high specific surface area The general XPS spectrum of the Zn1 – хMnxO surface
values, which is consistent with those obtained in this (not shown in this work) shows bands due to Mn, Zn,
work (S
sp ~ 38–54 m2/g). Taking into account that the O, and C electronic states, as well as the peaks of difꢀ
structure of intercrystallite boundaries in quasiꢀoneꢀ ferent Auger transitions. To estimate the metal ratio
dimensional aggregates is of low porosity and that the (Mn/Zn) on the Zn1 – хMnxO surface, it is reasonable
thickness of the walls in oneꢀdimensional tubular to use either the strongest Mn2
p
and Zn2p lines of
0.5
μ
m
10 μm
(b)
(а)
Fig. 4. SEM images of (a) Zn Mn (HCOO)(OCH CH O) and (b) the product of its thermolysis at 500°С in air.
0.9
0.1
2
2
1/2
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 57 No. 1 2012

76
GYRDASOVA et al.
(а)
(b)
110 nm
(d)
500 nm
(c)
1
2
I
I
250 nm
d, nm
150
d, nm
150
Fig. 5. (a–c) Brightꢀfield TEM images and microdiffraction patterns (insets) of quasiꢀoneꢀdimensional Zn
Mn O oxides: (a,
x
1 –
х
b) with tubular morphology, (c) with tubeꢀintoꢀtube morphology, (d) schematic calculated change in the transmitted radiation
along the cross section as a function of the quasiꢀoneꢀdimensional oxide morphology: (
1) tube and (
2) tube into tube.
201
103
110
102
101
002
100
90 nm
(b)
(а)
55 nm
170 nm
(d)
(c)
Fig. 6. (a) Electron diffraction pattern and (b, c) darkꢀfield TEM images of individual tubular quasiꢀoneꢀdimensional Zn
Mn O
x
1 –
х
structures. (a)The Debye rings were indexed to fit the wurtzite structure. (b) Polycrystalline structure with smallꢀangle intercrysꢀ
tallite boundaries (inset) of initial tubular quasiꢀoneꢀdimensional Zn Mn O oxides; (c) the recrystallized quasiꢀoneꢀdimenꢀ
1 –
х
x
sional structure after in situ irradiation in a microscope; (d) brightꢀfield TEM image of the surface of tubular quasiꢀoneꢀdimenꢀ
sional Zn Mn O oxides.
1 –
х
x
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 57 No. 1 2012

SYNTHESIS AND STRUCTURE OF QUASIꢀONEꢀDIMENSIONAL ZINC OXIDE
(а) (b)
77
641.5 eV
p3/2
Zn2p
Mn2
p
ZnO
1021.5 eV
2
2p1/2
640
650
(d)
529.6 eV
660
1010 1020 1030 1040 1050 1060
(c)
Zn3p
O1
s
Mn3
p
531.6 eV
Mn3
s
50
60
70
80
90
100
b, eV
524
528
532
536
540
E
Fig. 7. Xꢀray photoelectron spectra of core levels (a) Zn2p, (b) Mn2p, (c) Mn3p and Zn3p, and (d) O1s.
these metals or the neighboring Mn3
(Fig. 7). In the first case, the kinetic energy of Mn and zinc oxide, the O1
p
and Zn3
p
peaks Mn3 – yZnyO4 or Mn2O3 (Mn3O4). For the undoped
band position was determined at
s
Zn photoelectrons is ~600 and ~200 eV, respectively; At 530.3 0.3 eV [23, 24]. It is hardly expectable that the
such energy, the depth of analysis is limited by 2–3 nm of substitution of manganese for some zinc atoms in the
the surface layer. In the case of manganese and zinc
photoelectrons, the kinetic energy exceeds 1100 eV, charge state of oxygen and, hence, to a considerable
and the depth of analysis increases to ~5 nm. The shift of the O1 bands. Therefore, the binding energy
Mn/Zn ratio on the Zn1 – хMnxO structures estimated of the O1 level at 529.4 eV for the compound under
from the metal bands is ~3, whereas the estimates consideration is most likely due to the surface phases
made from the manganese and zinc bands give ~1.3. based on manganese oxide. The O1 band in the specꢀ
3p
ZnO lattice will lead to a significant change in the
s
s
2p
3p
s
Inasmuch as in the former case, the XPS sensitivity to tra of MnO, Mn2O3, and MnO2 oxides was reported to
the surface is higher, we can suggest that (1) the surface be at 529.6 eV for the first two oxides and at 529.9 eV
layers of the Zn1 – хMnxO structures are significantly for the last one with the scatter of 0.3 eV. The O1
s
enriched in manganese, and (2) the Mn/Zn ratio on binding energy in the Mn3 – yZnyO4 cubic spin is
the surface is close to 3. This is consistent with Xꢀray unknown; however, it is expected that it will be within
powder diffraction evidence of the existence of the 529–530 eV. An extra highꢀenergy component of the
impurity phase Mn3 – yZnyO4 and can reflect the segreꢀ OH– spectrum (at 531.7 eV) can be due to either OH
gation of spinel to the surface of the Zn1 – хMnxO groups sorbed on the oxide surface or deficient zinc
fibers. The formation of individual manganese oxide oxide structures [23]. The Mn2p spectrum can be repreꢀ
structures, most likely Mn2O3 or Mn3O4, on the surꢀ sented by a p3/2 and p1/2 doublet at 641.3 and 652.8 eV,
2
2
face also cannot be ruled out. The thickness of the respectively (Fig. 7). From the viewpoint of the energy
modified layer is a few nanometers. These surface position and multiplet spitting, the spectrum correꢀ
structures are unreliably identified by other methods sponds to the Mn2+ or Mn3+ state. The manganese
but can have a significant effect, for example, on the valence can be determined more accurately from the
photocatalytic properties of the material.
splitting of the Mn3s states [24]; however, this band is
partially overlapped by stronger Zn3p bands and canꢀ
not be interpreted correctly.
Figure 7 shows the XPS spectra of the Zn2p and
Mn2
and O1
face. The O1
p
core states, the
of the oxygen of the Zn1 – хMnxO fiber surꢀ
spectrum is composed of two bands at tubes can be synthesized by a precursor method. As a rule,
3p and 3s states of these metals,
s
Thus, our study showed that doped zinc oxide nanoꢀ
s
529.4 and 531.7 eV (Fig. 7). The major band at 529.4 eV the thermolysis of the precursor is a pseudomorphous
is due to the oxides: the host Zn1 – хMnxO structure process; i.e., the particles of the nascent oxide inherit the
and the surface layer phases, which we identify as shape of the precursor crystals. Thermal decomposition of
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 57 No. 1 2012

78
GYRDASOVA et al.
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the Zn1 – xMnx(HCOO)(OCH2CH2O)1/2 precursor
fibers of needles leads to Zn1 – xMnxO oxide as tubular
quasiꢀoneꢀdimensional aggregates with a nanodisꢀ
persed polycrystalline structure. A specific feature of
these quasiꢀoneꢀdimensional aggregates is a nonuniꢀ
form distribution of manganese in their surface layer
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