J Supercond Nov Magn (2013) 26:251–260
DOI 10.1007/s10948-012-1756-1
REVIEW ARTICLE
Effects of Transition-Metal V-Doping on the Structural, Magnetic
and Transport Properties in La
0.67
Sr
0.33
MnO
3
Manganite Oxide
Safa Mnefgui · Abdessalem Dhahri · Jemai Dhahri ·
El-Kebir Hlil
Received: 12 May 2012 / Accepted: 17 August 2012 / Published online: 9 September 2012
© Springer Science+Business Media, LLC 2012
Abstract We have investigated the structural, magnetic,
and electrical transport properties of a series of ABO
3
-type
perovskite compounds, La
0.67
Sr
0.33
Mn
1−x
V
x
O
3
(0 ≤ x ≤
0.15). The samples were characterized by X-ray diffrac-
tion and data were analyzed using Rietveld refinement tech-
nique, it has been concluded that these materials have the
rhombohedral structure with R 3C space group. The mag-
netization and resistivity measurements versus temperature
proved that all our samples exhibit a ferromagnetic to para-
magnetic transition and a metallic to semiconductor one
when the temperature increases. Both the Curie tempera-
ture T
C
and the resistivity transition temperature T
P
of the
composites decrease, while the resistance increases as the V
content increases. It has been concluded that the electrical
conduction mechanism in the metallic regime at low tem-
peratures (T < T
P
) can be explained on the basis of grain
boundary effects and the single electron-magnon scattering
process. Resistivity data were well fitted with the relation
ρ = ρ
0
+ ρ
2
T
2
+ ρ
4.5
T
4.5
, whereas the adiabatic Small Po-
laron Hopping (SPH) and Variable Range Hopping (VRH)
models are found to fit well in the paramagnetic semicon-
ducting regime at the high temperature (T > T
P
).
Keywords Manganite · Vanadium · Rietveld refinement ·
Conduction mechanism · Variable range hopping
S. Mnefgui ( ) · A. Dhahri · J. Dhahri
Laboratoire de Physique des Solides, Département de Physique,
Faculté des Sciences de Monastir, 5019 Monastir, Tunisia
e-mail: mnefguisafa@yahoo.fr
E.-K. Hlil
Institut Néel, CNRS-Université J. Fourier, B.P. 166,
38042 Grenoble, France
1 Introduction:
For nearly the last decade, there has been extensive re-
search on ABO
3
-type manganites of the general formula
R
1−x
A
x
MnO
3
(R = La, Nd, Pr, Y, etc. and A = Ca, Sr, Ba,
Pb, etc.). These compounds have attracted much attention
due to their extraordinary magnetic and electronic proper-
ties as well as their promise for the potential technological
applications [1–3]. The manganite system offers a high de-
gree of chemical flexibility. This leads, together with a com-
plex interplay between structures, electronic and magnetic
properties, to a very rich phase diagram involving various
metallic, insulating and magnetic phases [4]. These proper-
ties are sensitive to the doping concentration x , which de-
termine the Mn
3+
/Mn
4+
ratio to maintain charge neutral-
ity, the average cationic radii 〈r
A
〉 and the ionic size mis-
match between the various A-site ions, and it is represented
by the variance σ
2
=
∑
i
y
i
r
2
i
−〈r
A
〉
2
, where r
i
corresponds
to the radii of the various A-sites cations and y
i
to their frac-
tional occupancies (
∑
i
y
i
= 1) [5, 6]. When the antiferro-
magnetic insulator, LaMnO
3
, is doped with the divalent ions
(A
2+
), it can be driven into a metallic ferromagnetic state
due to conversion of proportional number of Mn
3+
to Mn
4+
through the so-called “double exchange (DE)” of the Mn
3+
–
O
2−
–Mn
4+
mechanism by Zener [7]. Because of the strong
Hund’s coupling, the electronic configurations are Mn
3+
(t
3
2g
e
1
g
) and Mn
4+
(t
3
2g
e
0
g
). The mobile e
g
electrons produced
due to the hole doping via DE mediate ferromagnetism and
conduction. Previously, only these theories have used to ex-
plain the transport and magnetic properties of the mangan-
ites by suggesting that the mixed valence of Mn
3+
/Mn
4+
is a key component for understanding the ferromagnetic–
paramagnetic (FM–PM) phase transition associated with an
insulator–metal (IM) transition in these manganites and the
CMR effect [8, 9]. But recent detailed research has shown