State diagram of the Zn3As2-MnAs system

Article abstract of DOI:10.1134/S0036023615120189

The Zn₃As₂-MnAs system was studied by X-ray powder diffraction, differential thermal, and microstructural analyses. This system is of the eutectic type with the eutectic coordinates (30 wt % (50 mol %) Zn₃As₂, 70 wt % (50 mol %) MnAs, T _melt = 815°C). The MnAs solubility boundary on the side of Zn₃As₂ is 10 wt %. Zn₃As₂ alloys containing more than 10 wt % MnAs are ferromagnetic with T _c ~ 320 K. Their magnetization increases with increasing MnAs content.

Full text of DOI:10.1134/S0036023615120189

ISSN 0036ꢀ0236, Russian Journal of Inorganic Chemistry, 2015, Vol. 60, No. 12, pp. 1578–1582. © Pleiades Publishing, Ltd., 2015.
Original Russian Text © S.F. Marenkin, I.V. Fedorchenko, V.M. Trukhan, S.V. Trukhanov, T.V. Shoukavaya, P.N. Vasil’ev, A.L. Zhaludkevich, 2015, published in Zhurnal Neorganꢀ
icheskoi Khimii, 2015, Vol. 60, No. 12, pp. 1723–1727.
PHYSICOCHEMICAL ANALYSIS
OF INORGANIC SYSTEMS
State Diagram of the Zn3As2–MnAs System
S. F. Marenkina, b, I. V. Fedorchenkoa, b, V. M. Trukhanc, S. V. Trukhanovc,
T. V. Shoukavayac, P. N. Vasil’eva, b, and A. L. Zhaludkevichc
a MISiS National Research Technological University, Leninskii pr. 4, Moscow, 119991 Russia
b Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences,
Leninskii pr. 31, Moscow, 119991 Russia
c SSPA “Scientific and Practical Material Research Centre of NAS of Belarus”,
National Academy of Sciences of Belarus, ul. P. Brovki 19, Minsk, 22072 Belarus
eꢀmail: marenkin@rambler.ru
Received March 23, 2015
Abstract—The Zn3As2–MnAs system was studied by Xꢀray powder diffraction, differential thermal, and
microstructural analyses. This system is of the eutectic type with the eutectic coordinates (30 wt % (50 mol %)
Zn3As2, 70 wt % (50 mol %) MnAs, Tmelt = 815°C). The MnAs solubility boundary on the side of Zn3As2 is
10 wt %. Zn3As2 alloys containing more than 10 wt % MnAs are ferromagnetic with Tc ~ 320 K. Their magꢀ
netization increases with increasing MnAs content.
DOI: 10.1134/S0036023615120189
Alloys of zinc and manganese arsenides are considꢀ components were Zn3As2 and MnAs, which were synꢀ
ered promising materials for granulated structures thesized in a vacuum in doubleꢀwall quartz ampoules
with giant magnetoresistance [1]. Granulated strucꢀ from highꢀpurity elemental substances Zn, As, and
tures are of interest owing to their possible use in spinꢀ Mn taken in stoichiometric ratios [10]. The reactants
tronics [2].
were placed in the inner ampoule, the inner walls of
which were lined with pyrolytic carbon for preventing
quartz from interacting with melts of components.
The processes were carried out in a furnace with autoꢀ
Alloys of zinc and manganese arsenides were studꢀ
ied as magnetic materials [3–5], and in those studies
they were regarded as solid solutions (Zn1 – xMnx)3As2
within the concentration range
lished [4] temperature dependences of the magnetizaꢀ
tion of these alloys are characteristic of superparamagꢀ
nets [6]. From the curves, paramagnetic and ferroꢀ
magnetic components can be separated. It is well
matic temperature control with an accuracy of
1°С.
0
≤
х 0.13. The pubꢀ
≤
To avoid escape of highly volatile components from
the evaporation zone because of their evaporation, the
ampoules were positioned in the isothermal part of the
furnace. The temperature–time conditions of the synꢀ
thesis were the following: heating at a rate of 50 deg/h
known that introduction of atoms of dꢀelements, in
to 600
heating to 1015
°
С
and treatment at this temperature for 2 h,
for Zn3As2 and to 950 for MnAs
particular, manganese, to a semiconductor leads to
a transition of the semiconductor from the diamagꢀ
netic to the paramagnetic state. The ferromagꢀ
netism of (Cd1 – xMnx)3As2, which is isostructural to
(Zn1 – xMnx)3As2, was attributed [7] to manganese
clusters. In our opinion, the samples studied in the disꢀ
cussed works [3–6] were inhomogeneous and conꢀ
tained not only the solid solution (Zn1 – xMnx)3As2 but
also MnAs nanoinclusions. We believe that the presꢀ
ence of such nanoinclusions accounts for the ferroꢀ
magnetic properties of manganeseꢀcontaining zinc
arsenide alloys [8, 9]. In this context, it was of interest
to continue to study alloys of zinc and manganese arsꢀ
enides, in particular, to determine the nature of the
interaction between Zn3As2 and MnAs.
°С
°С
and treatment of melts for better homogenization for
no less than 3 h, and cooling of ampoules in switchedꢀ
off furnace mode. The samples of intermediate comꢀ
positions were obtained under the temperature–time
conditions similar to those of the Zn3As2 synthesis.
The samples were investigated by Xꢀray powder difꢀ
fraction, differential thermal, and microstructural
analyses.
The Xꢀray powder diffraction analysis was perꢀ
formed with a Bruker D8 ADVANCE diffractometer
(
Cu
K
radiation, = 0.1540 nm, graphite monochroꢀ
λ
α
mator). Phases were identified based on the ICDD
PDFꢀ2 powder diffraction file database using the Difꢀ
frac.Suite EVA and Topaz software at the Research
Equipment Sharing Center for Physical Methods for
Studying Substances and Materials, Kurnakov Instiꢀ
EXPERIMENTAL
Samples for studying the phase diagram were preꢀ tute of General and Inorganic Chemistry, Russian
pared at an interval of 10 mol % MnAs. The initial Academy of Sciences, Moscow, Russia. The Xꢀray
1578

STATE DIAGRAM OF THE Zn3As2–MnAs SYSTEM
1579
I
MnAs reference
(f)
MnAs initial
0/100
(e)
Zn3As2ꢀMnAs
50/50
(d)
Zn3As2ꢀMnAs
90ꢀ10
(c)
Zn3As2 initial
100/0
(b)
(а)
Zn3As2 reference
25
30 35
40 45
50 55
60 65
70
75 80
85
2θ
, deg
Fig. 1. Xꢀray powder diffraction patterns of the reference Zn As sample [11], the initial Zn As sample, the sample of the comꢀ
3
2
3
2
position (90 wt % Zn As , 10 wt % MnAs), the sample of the composition (50 wt % Zn As , 50 wt % MnAs), the initial MnAs
3
2
3
2
sample, and the reference Zn As sample [12].
3
2
powder diffraction patterns of the initial phases Zn3As2
and MnAs agreed well with those of the reference samꢀ
ples [11, 12]. The Xꢀray powder diffraction patterns of
intermediate samples contained peaks corresponding
to both Zn3As2 and MnAs; the only exception was the
sample of the composition (90 wt % Zn3As2, 10 wt %
MnAs), the Xꢀray powder diffraction patterns of
which showed only Zn3As2 peaks (Fig. 1). Figure 1
presents the Xꢀray powder diffraction patterns of the
reference Zn3As2 sample [11] and the Zn3As2 sample
that was synthesized in this work and used as a precurꢀ
sor. Figure 1 also shows the Xꢀray powder diffraction
patterns of the reference MnAs sample [12] and the
MnAs sample obtained in this work. The Xꢀray powder
diffraction patterns of intermediate samples were preꢀ
sented by the example of the sample of the composiꢀ
tion (50 wt % Zn3As2, 50 wt % MnAs), which is charꢀ
acterized by peaks assigned both to Zn3As2 and MnAs.
This coincides with the results of the microstructural
studies and is indicative of the formation of solid soluꢀ
tions, which was confirmed by the shift of the Zn3As2
peaks in the Xꢀray powder diffraction patterns of interꢀ
mediate samples in comparison with that of the referꢀ
ence sample [11] (Fig. 2).
I
b
a
77.0
77.5
78.0
78.5
79.0
79.5
80.0
, deg
2
θ
Fig. 2. Fragments of the Xꢀray powder diffraction patterns
of (a) the sample of the composition (50 wt % Zn As ,
50 wt % MnAs) and (b) the reference Zn As sample [11].
3
2
3
2
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 60 No. 12 2015

1580
MARENKIN et al.
100 μm
100 μm
(а)
(b)
100 μm
(c)
Fig. 3. Microstructures of the samples of the compositions (a) (30 wt % Zn As , 70 wt % MnAs), (b) (40 wt % Zn As , 60 wt %
3
2
3
2
MnAs), and (c) (10 wt % Zn As , 90 wt % MnAs).
3
2
Figure 3 shows the microstructures of the samples seen from Figs. 3a and 3b that the samples containing
of the compositions (30 wt % Zn3As2, 70 wt % MnAs) more than 10 wt % MnAs are twoꢀphase. The microꢀ
(Fig. 3a), (40 wt % Zn3As2, 60 wt % MnAs) (Fig. 3b), structure of the sample containing 70 wt % MnAs corꢀ
and (90 wt % Zn3As2, 10 wt % MnAs) (Fig. 3c). It is responds to the structure of a eutectic.
Data of differential thermal analysis on the Zn3As2–MnAs system
Composition
Temperatures at events, C
°
wt %
mol %
Zn3As2
MnAs
Zn3As2
MnAs
α
ꢀ
→ βꢀZn3As2
teut
tliq
100
90
80
70
60
50
40
30
20
10
4
0
10
20
30
40
50
60
70
80
90
96
100
100
96
92
86
80
72
63
53
40
24
10
0
0
4
651
635
594
590
590
585
580
580
575
580
590
–
–
1015
1000
–
–
8
815
812
816
814
810
810
812
820
820
–
14
20
28
37
47
60
76
90
100
980
950
930
920
–
830
925
923
935
0
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 60 No. 12 2015

STATE DIAGRAM OF THE Zn3As2–MnAs SYSTEM
0.065
1581
FC
0.060
0.055
ZFC
0
50
100 150 200
, K
250 300
350
T
Fig. 4. Temperature dependence of the magnetization of the sample of the composition (80 wt % Zn As , 20 wt % MnAs) in a
3
2
magnetic field at
H = 100 Oe.
wt % MnAs
70
T, °C
0 10 20 30 40 50 60
80
90
100
1100
1100
1000
900
800
700
600
500
400
1000
900
800
700
600
L
L + Zn3As2
L + MnAs
β
β
ꢀZn3As2 + MnAs
α
α
ꢀZn3As2 + MnAs
500
400
0
Zn3As2
10
20
30
40
50
mol % MnAs
60
70
80
90
100
MnAs
Fig. 5. State diagram of the Zn As –MnAs system.
3
2
The results of the differential thermal analysis the temperature at this event decreased to 590
°С. The
event at 815°С was attributed to the melting of the
eutectic. The higherꢀtemperature events determined
the liquidus line.
(table) confirmed the data of the Xꢀray powder diffracꢀ
tion and microstructural analyses on the eutectic
nature of the interaction in the Zn3As2–MnAs system.
In the thermal curves, thermal events were determined
The magnetic properties of the samples were meaꢀ
sured with a Cryogenic vibration magnetometer. Studꢀ
ies showed that alloys in the Zn3As2–MnAs system,
with an accuracy of
event at 651 in the sample containing 100 wt %
Zn3As2 characterizes the polymorphic transformation
of ꢀZn3As2 to ꢀZn3As2. In the twoꢀphase samples, 10 wt % MnAs), are ferromagnets with a Curie temꢀ
5°С and assigned as follows: the
°С
except the sample of the composition (90 wt % Zn3As2
,
α
β
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 60 No. 12 2015

1582
MARENKIN et al.
perature of ~320 K. The magnetization increased with
This work was supported by the Russian Scientific
increasing MnAs content of alloys. As an example, Foundation (project no. 13ꢀ03ꢀ00125).
Figure 4 presents the temperature dependence of the
magnetization of the sample of the composition (70 wt %
Zn3As2, 30 wt % MnAs).
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nates (30 wt % (50 mol %) Zn3As2, 70 wt % (50 mol %)
MnAs, tmelt = 815°C). The microstructure of the
eutectic is lamellar; the MnAs solubility in Zn3As2 was
approximately estimated at ~10 wt %.
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The authors gratefully acknowledge the financial
support of the Ministry of Education and Science of
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Translated by V. Glyanchenko
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 60 No. 12 2015