The paper presents the results of investigations of the phase composition and physical properties of the pure Bi, Mo and FeBiMo films, with thickness d~100-500 nm, obtained by three-electrode ion-plasma sput-tering. X-Ray analysis showed that in the as-deposited Bi films is formed a mixture of rhombohedral and cubic nanocrystalline Bi phases and traces of Bi2O3 oxide. Heat treatment at 650 K leads to the decay of the Bi non-equilibrium phase. In the Mo original films is formed a mixture of Mo cubic phase and MoO2, MoO3 oxides. As a result of heat treatment at the temperature of about 870 K phase composition and the grain size remains unchanged. FeBiMo films in the initial state is a mixture of rhombohedral and cubic Bi phases and the hexagonal Fe phase. In the Mo-doped films non-equilibrium Bi phase remains after heat treatment at 770 K. Construction of the temperature dependence of resistivity has revealed the reversible phase transition in the Bi films. A similar behavior of Bi properties is also manifested in FeBiMo films. The analysis of demagnetization curves of Bi films showed a manifestation of hysteresis properties, which is not typical for diamagnetic. This can be explained by the Bi2O3 phase presence.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3513

Bashev, V.F.

Dotsenko, F.F.

Gusevik, P.S.

Ryabtsev, S.I.

Electronic Sumy State University Institutional Repository

PROCEEDINGS OF THE INTERNATIONAL CONFERENCE  NANOMATERIALS: APPLICATIONS AND PROPERTIES Vol. 2 No 1, 01NTF08(3pp) (2013)   2304-1862/2013/2(1)01NTF08(3) 01NTF08-1  2013 Sumy State University The Physical Properties of the FeBiMo Films, Obtained by Ion-Plasma Sputtering   P.S. Gusevik*, S.I. Ryabtsev†, V.F. Bashev, F.F. Dotsenko  Dnipropetrovsk National University, 72, Gagarin Avenue, 49050 Dnipropetrovsk, Ukraine  (Received 18 May 2013; published online 30 August 2013)  The paper presents the results of investigations of the phase composition and physical properties of the pure Bi, Mo and FeBiMo films, with thickness d~100-500 nm, obtained by three-electrode ion-plasma sput-tering. X-Ray analysis showed that in the as-deposited Bi films is formed a mixture of rhombohedral and cubic nanocrystalline Bi phases and traces of Bi2O3 oxide. Heat treatment at 650 K leads to the decay of the Bi non-equilibrium phase. In the Mo original films is formed a mixture of Mo cubic phase and MoO2, MoO3 oxides. As a result of heat treatment at the temperature of about 870 K phase composition and the grain size remains unchanged.  FeBiMo films in the initial state is a mixture of rhombohedral and cubic Bi phases and the hexagonal Fe phase. In the Mo-doped films non-equilibrium Bi phase remains after heat treatment at 770 K. Construction of the temperature dependence of resistivity has revealed  the reversible phase transition in the Bi films. A similar behavior of Bi properties is also manifested in FeBiMo films. The analysis of demagnetization curves of Bi films showed a manifestation of hysteresis properties, which is not typical for diamagnetic. This can be explained by the Bi2O3 phase presence.  Keywords: FeBiMo Films, Ion-Plasma Sputtering, Non-Equilibrium Phase, Reversible Phase Transition, Ferrimagnets, Nanocrystalline Phase.   PACS numbers: 64.60.My, 64.70.dg 75.70.Cn 81.30 Bx                                                             * ft-05-1@yandex.ru † siryabts@mail.ru 1. INTRODUCTION  Currently magnetoelectric materials are widely used in sensor technology, spintronics, as well as storage devices of the information. Bismuth ferrite is a well studied magnetoelectrics with sufficiently high phase transition temperatures and has a mag-netoelectric effect at room temperature, which leads to its potential for application in spintronics.  In bulk bismuth ferrite there is a problem of charge leakage due to non-stoichiometry and defects that limit the practical application of this material as a bulk crystal. In the Bi2O3-Fe2O3 system easily generated non-equilibrium states due to the proximi-ty of phase transition temperatures. Production of thin films allows change the bismuth ferrite proper-ties in comparison with properties in a bulk form.  The aim of our work was to obtain a similar film material doped with refractory component in order to improve thermal stability of the films, obtained by three-electrode ion-plasma sputtering. In this meth-od ultra-rapid cooling rate allows to obtain such non-equilibrium structures [1].  The effective cooling rate of films depends on the relaxation time of individual atom on a substrate and its estimated value is 1012 - 1014 K/s [2]. Thus, we can speak of a “quenching from the vaporous state” (QVS).  2. MATERIALS AND METHODS  2.1 Objects of investigations  The objects of investigations were pure Bi, Mo and FeBiMo films. Film thickness are d  100-500 nm, estimated by weighing the substrates before and after sputtering. Sputtering was carried out on Na-Cl sin-gle-crystal substrates for the structural investigations by X-Ray analysis. The films obtained under identical deposition conditions on the sitall substrate were used for studying the thermal stability and physical prop-erties of non-equilibrium structures.   2.2 Methods of investigations   For the films obtaining used the method of ion-plasma sputtering in vacuum. Type-setting of targets placed directly on the sputtering surface of the com-ponent squares. An additional acceleration of Ar ions which was impinging on the target and increase in the kinetic energy of the depositing onto sitall substrates atoms was achieved by using a specially designed de-vice in the sputtering setup URM 3.279.014 [3].  The surface resistance was measured by the four point technique upon continuously films heating in the vacuum 10 mPa. The structure and compositions of the initial and annealed films were studied by the X-Ray diffraction obtained with Debye camera with CoKα radiation. The coercive force Hc was measured on a vibration magnetometer in the magnetizing field 0.3 T with parallel and perpendicular orienta-tions.  Calculation of the activation energy was carried out by Kissinger method [4]. Using the temperature dependence of the resistance at different heating rates you can construct the function ln(T2/V) from F(1000/T). This relationship satisfies the Arrhenius equation. The phase transitions activation energy was estimated by the slope of this line. The films vapor deposition conditions shown in the Table.1.   P.S. GUSEVIK , S.I. RYABTSEV, V.F. BASHEV PROC. NAP 2, 01NTF08 (2013)   01NTF08-2 Table 1 – Conditions of sputter deposited films   Bi* Bi** Mo* Mo** Fe – 18 at. %,  Bi – 18 at. %, Mo U, kV 2 2 2 2 2 IA, A 0.8 1 0.8 2 2 PAr, mPa 16 120 16 53 53 d, nm 500 500 100 160 260  Where U - target voltage; IA - anode current; PAr - pressure of orifice gas (Ar); d – film thickness  3. RESULTS AND DISCUSSION   The X-Ray analysis and estimation of the coherent-scattering regions size L (CSR) showed that in the as-deposited Bi films is formed the mixture of nanocrystal-line rhombohedral (L  6.5 nm) and cubic Bi phases and traces of Bi2O3 oxide. Heat treatment of pure Bi films in a vacuum at the temperature of about 650 K leads to non-equilibrium Bi phase disappearance and rhombohedral Bi grain growth (L  8 nm) (Fig. 1). In the original Mo films, obtained under conditions of lower anode current and working gas pressure (Mo*), is formed a mixture of nanocrystalline Mo phase (L  3.6 nm) and MoO3 oxide. When changing the depo-sition conditions ib the original Mo films (Mo**) is formed a MoO2 oxide (L  3.4 nm) as well as phase traces described above. The films structure and phase composition did not change after heat treatment at the temperature of 870 K. FeBiMo films in the initial state is a mixture of rhombohedral Bi (L  5.6 nm), cubic Bi and hexagonal Fe phases. The grain growth of rhombohedral Bi occurs after heat treatment (L  7 nm). Non-equilibrium Bi phase is observed even at high temperature treatment (  770 K) that is caused Mo addition.     Fig. 1 – X-ray diffraction patterns from pure Bi films freshly deposited (a), after heat treatment (b), * - rhombohedral Bi phase; + - cubic Bi phase; ° - Bi2O3 oxide  Investigation of the temperature dependence of re-sistivity showed that heat curves are characterized by three main sections for all films. In the first section there is a smooth decrease in resistivity with tempera-ture increasing. On the second segment there is a rapid decrease of the resistance in a relatively short tempera-ture range. This is a result of phase transitions or re-crystallization processes. The third section is character-ized by a gradual increase in resistivity (Fig. 2).     a     b  Fig. 2 – Temperature variation of resistivity of the Bi (a) and FeBiMo (b) films   Cooling of the Bi containing films leads to a specific behavior of the resistivity. In the first phase it re-mained virtually unchanged. When reaching the cer-tain temperature the resistance increases abruptly, after which continues relatively smooth growth. It should be noted that for the pure Bi films reverse phase transition temperature under cooling is about 470 K, while for the FeBiMo films this temperature is about 370 K. This temperature difference is probably related with the influence of Mo refractory. The analysis of the phase transition temperature shift with an increase in the heating rate allowed for the calculation of the phase transition activation ener-gy by Kissinger method. For pure Bi films activation energy is EA ~ 8500 K. The activation energy of the Mo films is in the range of EA ~ 6500-9500 K depending on the deposition condi-tions. FeBiMo films investigations of the temperature dependence of resistivity showed the highest value of energy EA ~ 11000 K. The analysis of the demagnetization curves of Bi films showed a manifestation of hysteresis properties. Since pure Bi is a diamagnetic, we can assume that this behavior is due to the presence of Bi2O3 and non-equilibrium Bi phases. The magnetic moment is un-compensated which is characteristic of ferrimanetic. a b  THE PHYSICAL PROPERTIES OF THE FEBIMO FILMS … PROC. NAP 2, 01NTF08 (2013)   01NTF08-3 4. CONCLUSIONS  The phase composition and physical properties of the pure Bi, Mo and FeBiMo films obtained by three-electrode ion-plasma sputtering method were studied by X-Ray analysis, measuring of relative electrical re-sistance and magnetometric measuring. As a result, it should be noted that the selection of deposition conditions allows to obtain films with differ-ent oxide groups, which is an important task in the mul-tiferroic research field. Adding to the films with non-equilibrium structures Mo refractory helps to prevent the decay of non-equilibrium phases and thus increase the thermal stabil-ity of the film material.   REFERENCES  1. P.M. Martin, Handbook of deposition technologies for films and coatings 3rd edition, (Elsevier 2010, p 912). 2. W.A. Grant, A. Ali, L.T. Chadderton, P.J. Grundy, Prepa-ration of amorphous alloys by ion implantation (London: Third international conference of rapidly quenched met-als: 1978). 3. V.F. Bashev, F.F.  Dotshenko, I.S. Miroshnichenko, V.H. Pasalsky, Phys. Met. Metallogr. 73, No 2, 152-156 (1992). 4. H.E. Kissinger, J. Res. Nat. Bur. Stand 57, No 4, 217 – 220 (1956).  

The Physical Properties of the FeBiMo Films, Obtained by Ion-Plasma Sputtering

SocioEconomic Challenges Journal (Sumy State University)

PROCEEDINGS OF THE INTERNATIONAL CONFERENCE  
NANOMATERIALS: APPLICATIONS AND PROPERTIES 
Vol. 2 No 1, 01NTF08(3pp) (2013) 
 
 
2304-1862/2013/2(1)01NTF08(3) 01NTF08-1  2013 Sumy State University 
The Physical Properties of the FeBiMo Films, Obtained by Ion-Plasma Sputtering  
 
P.S. Gusevik*, S.I. Ryabtsev†, V.F. Bashev, F.F. Dotsenko 
 
Dnipropetrovsk National University, 72, Gagarin Avenue, 49050 Dnipropetrovsk, Ukraine 
 
(Received 18 May 2013; published online 30 August 2013) 
 
The paper presents the results of investigations of the phase composition and physical properties of the 
pure Bi, Mo and FeBiMo films, with thickness d~100-500 nm, obtained by three-electrode ion-plasma sput-
tering. X-Ray analysis showed that in the as-deposited Bi films is formed a mixture of rhombohedral and 
cubic nanocrystalline Bi phases and traces of Bi2O3 oxide. Heat treatment at 650 K leads to the decay of 
the Bi non-equilibrium phase. In the Mo original films is formed a mixture of Mo cubic phase and MoO2, 
MoO3 oxides. As a result of heat treatment at the temperature of about 870 K phase composition and the 
grain size remains unchanged.  FeBiMo films in the initial state is a mixture of rhombohedral and cubic Bi 
phases and the hexagonal Fe phase. In the Mo-doped films non-equilibrium Bi phase remains after heat 
treatment at 770 K. Construction of the temperature dependence of resistivity has revealed  the reversible 
phase transition in the Bi films. A similar behavior of Bi properties is also manifested in FeBiMo films. 
The analysis of demagnetization curves of Bi films showed a manifestation of hysteresis properties, which 
is not typical for diamagnetic. This can be explained by the Bi2O3 phase presence. 
 
Keywords: FeBiMo Films, Ion-Plasma Sputtering, Non-Equilibrium Phase, Reversible Phase Transition, 
Ferrimagnets, Nanocrystalline Phase. 
 
 PACS numbers: 64.60.My, 64.70.dg 75.70.Cn 81.30 Bx 
 
 
                                                          
* ft-05-1@yandex.ru 
† siryabts@mail.ru 
1. INTRODUCTION 
 
Currently magnetoelectric materials are widely 
used in sensor technology, spintronics, as well as 
storage devices of the information. Bismuth ferrite is 
a well studied magnetoelectrics with sufficiently 
high phase transition temperatures and has a mag-
netoelectric effect at room temperature, which leads 
to its potential for application in spintronics.  
In bulk bismuth ferrite there is a problem of 
charge leakage due to non-stoichiometry and defects 
that limit the practical application of this material 
as a bulk crystal. In the Bi2O3-Fe2O3 system easily 
generated non-equilibrium states due to the proximi-
ty of phase transition temperatures. Production of 
thin films allows change the bismuth ferrite proper-
ties in comparison with properties in a bulk form.  
The aim of our work was to obtain a similar film 
material doped with refractory component in order to 
improve thermal stability of the films, obtained by 
three-electrode ion-plasma sputtering. In this meth-
od ultra-rapid cooling rate allows to obtain such non-
equilibrium structures [1].  
The effective cooling rate of films depends on the 
relaxation time of individual atom on a substrate 
and its estimated value is 1012 - 1014 K/s [2]. Thus, 
we can speak of a “quenching from the vaporous 
state” (QVS). 
 
2. MATERIALS AND METHODS 
 
2.1 Objects of investigations 
 
The objects of investigations were pure Bi, Mo and 
FeBiMo films. Film thickness are d  100-500 nm, 
estimated by weighing the substrates before and after 
sputtering. Sputtering was carried out on Na-Cl sin-
gle-crystal substrates for the structural investigations 
by X-Ray analysis. The films obtained under identical 
deposition conditions on the sitall substrate were used 
for studying the thermal stability and physical prop-
erties of non-equilibrium structures.  
 
2.2 Methods of investigations  
 
For the films obtaining used the method of ion-
plasma sputtering in vacuum. Type-setting of targets 
placed directly on the sputtering surface of the com-
ponent squares. An additional acceleration of Ar ions 
which was impinging on the target and increase in the 
kinetic energy of the depositing onto sitall substrates 
atoms was achieved by using a specially designed de-
vice in the sputtering setup URM 3.279.014 [3].  
The surface resistance was measured by the four 
point technique upon continuously films heating in 
the vacuum 10 mPa. The structure and compositions 
of the initial and annealed films were studied by the 
X-Ray diffraction obtained with Debye camera with 
CoKα radiation. The coercive force Hc was measured 
on a vibration magnetometer in the magnetizing 
field 0.3 T with parallel and perpendicular orienta-
tions.  
Calculation of the activation energy was carried 
out by Kissinger method [4]. Using the temperature 
dependence of the resistance at different heating rates 
you can construct the function ln(T2/V) from 
F(1000/T). This relationship satisfies the Arrhenius 
equation. The phase transitions activation energy was 
estimated by the slope of this line. 
The films vapor deposition conditions shown in the 
Table.1. 
 
 P.S. GUSEVIK , S.I. RYABTSEV, V.F. BASHEV PROC. NAP 2, 01NTF08 (2013) 
 
 
01NTF08-2 
Table 1 – Conditions of sputter deposited films 
 
 Bi* Bi** Mo* Mo** 
Fe – 18 at. %,  
Bi – 18 at. %, Mo 
U, kV 2 2 2 2 2 
IA, A 0.8 1 0.8 2 2 
PAr, mPa 16 120 16 53 53 
d, nm 500 500 100 160 260 
 
Where U - target voltage; IA - anode current; PAr - pressure of 
orifice gas (Ar); d – film thickness 
 
3. RESULTS AND DISCUSSION  
 
The X-Ray analysis and estimation of the coherent-
scattering regions size L (CSR) showed that in the as-
deposited Bi films is formed the mixture of nanocrystal-
line rhombohedral (L  6.5 nm) and cubic Bi phases 
and traces of Bi2O3 oxide. Heat treatment of pure Bi 
films in a vacuum at the temperature of about 650 K 
leads to non-equilibrium Bi phase disappearance and 
rhombohedral Bi grain growth (L  8 nm) (Fig. 1). 
In the original Mo films, obtained under conditions 
of lower anode current and working gas pressure (Mo*), 
is formed a mixture of nanocrystalline Mo phase 
(L  3.6 nm) and MoO3 oxide. When changing the depo-
sition conditions ib the original Mo films (Mo**) is 
formed a MoO2 oxide (L  3.4 nm) as well as phase 
traces described above. The films structure and phase 
composition did not change after heat treatment at the 
temperature of 870 K. 
FeBiMo films in the initial state is a mixture of 
rhombohedral Bi (L  5.6 nm), cubic Bi and hexagonal 
Fe phases. The grain growth of rhombohedral Bi occurs 
after heat treatment (L  7 nm). Non-equilibrium Bi 
phase is observed even at high temperature treatment 
(  770 K) that is caused Mo addition. 
 
 
 
 
Fig. 1 – X-ray diffraction patterns from pure Bi films freshly 
deposited (a), after heat treatment (b), * - rhombohedral Bi 
phase; + - cubic Bi phase; ° - Bi2O3 oxide 
 
Investigation of the temperature dependence of re-
sistivity showed that heat curves are characterized by 
three main sections for all films. In the first section 
there is a smooth decrease in resistivity with tempera-
ture increasing. On the second segment there is a rapid 
decrease of the resistance in a relatively short tempera-
ture range. This is a result of phase transitions or re-
crystallization processes. The third section is character-
ized by a gradual increase in resistivity (Fig. 2). 
 
 
 
 a 
 
 
 
 b 
 
Fig. 2 – Temperature variation of resistivity of the Bi (a) and 
FeBiMo (b) films  
 
Cooling of the Bi containing films leads to a specific 
behavior of the resistivity. In the first phase it re-
mained virtually unchanged. When reaching the cer-
tain temperature the resistance increases abruptly, 
after which continues relatively smooth growth. 
It should be noted that for the pure Bi films reverse 
phase transition temperature under cooling is about 
470 K, while for the FeBiMo films this temperature is 
about 370 K. This temperature difference is probably 
related with the influence of Mo refractory. 
The analysis of the phase transition temperature 
shift with an increase in the heating rate allowed for 
the calculation of the phase transition activation ener-
gy by Kissinger method. 
For pure Bi films activation energy is EA ~ 8500 K. 
The activation energy of the Mo films is in the range of 
EA ~ 6500-9500 K depending on the deposition condi-
tions. FeBiMo films investigations of the temperature 
dependence of resistivity showed the highest value of 
energy EA ~ 11000 K. 
The analysis of the demagnetization curves of Bi 
films showed a manifestation of hysteresis properties. 
Since pure Bi is a diamagnetic, we can assume that 
this behavior is due to the presence of Bi2O3 and non-
equilibrium Bi phases. The magnetic moment is un-
compensated which is characteristic of ferrimanetic. 
a 
b 
 THE PHYSICAL PROPERTIES OF THE FEBIMO FILMS … PROC. NAP 2, 01NTF08 (2013) 
 
 
01NTF08-3 
4. CONCLUSIONS 
 
The phase composition and physical properties of the 
pure Bi, Mo and FeBiMo films obtained by three-
electrode ion-plasma sputtering method were studied by 
X-Ray analysis, measuring of relative electrical re-
sistance and magnetometric measuring. 
As a result, it should be noted that the selection of 
deposition conditions allows to obtain films with differ-
ent oxide groups, which is an important task in the mul-
tiferroic research field. 
Adding to the films with non-equilibrium structures 
Mo refractory helps to prevent the decay of non-
equilibrium phases and thus increase the thermal stabil-
ity of the film material. 
 
 
REFERENCES 
 
1. P.M. Martin, Handbook of deposition technologies for films 
and coatings 3rd edition, (Elsevier 2010, p 912). 
2. W.A. Grant, A. Ali, L.T. Chadderton, P.J. Grundy, Prepa-
ration of amorphous alloys by ion implantation (London: 
Third international conference of rapidly quenched met-
als: 1978). 
3. V.F. Bashev, F.F.  Dotshenko, I.S. Miroshnichenko, 
V.H. Pasalsky, Phys. Met. Metallogr. 73, No 2, 152-156 
(1992). 
4. H.E. Kissinger, J. Res. Nat. Bur. Stand 57, No 4, 217 – 
220 (1956). 
 


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The Physical Properties of the FeBiMo Films, Obtained by Ion-Plasma Sputtering

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