Materials Chemistry and Physics 238 (2019) 121903
Available online 24 July 2019
0254-0584/© 2019 Elsevier B.V. All rights reserved.
Infuence of Cr on structural, spectroscopic and magnetic properties of
CoFe
2
O
4
grown by the wet chemical method
Gnana Praveena Nethala
a, *
, Ravindar Tadi
b
, Ganapathi Rao Gajula
c
, P.V. Prakash Madduri
d
, A.
V. Anupama
e
, V. Veeraiah
f
a
Department of Physics, Swarnandhra College of Engineering and Technology, Narsapur, 534280, India
b
Korea Research Institute of Standards and Science, Daejeon, 305-340, Republic of Korea
c
Department of Physics, BS&H, Sree Vidyanikethan Engineering College, Tirupati, 517102, Andhra Pradesh, India
d
School of Physical Sciences, National Institute of Science Education and Research, HBNI, Jatni, 752050, India
e
Materials Research Centre, Indian Institute of Science, Bangalore, 560012, Karnataka, India
f
Department of Physics, Andhra University, Visakhapatnam, 530003, Andhra Pradesh, India
HIGHLIGHTS
� The XRD patterns of the compounds reveal the cubic spinel structure.
� The FTIR exhibiting the vibrational bands at lower frequencies are attributed to the stretching phenomena.
� A Raman spectrum reveals that the higher frequency modes above 600 cm
1
were attributed to the vibrations from the tetrahedral site (AO
4
).
� M€ ossbauer Spectroscopy exhibits Tetrahedral sites and octahedral sites of typical inverse spinel crystal structure were assigned to six-line sub spectra confrmed to
magnetically ordered materials.
� The saturation magnetization (M
s
) decreases with an increase in the Cr concentration.
A R T I C L E INFO
Keywords:
Cation migration
Wet chemical method
M€ ossbauer spectra
Raman spectrum
Magnetization
Anisotropy
ABSTRACT
The Cr doped CoFe
2
O
4
nano crystalline ceramics are synthesized using wet chemical method. The structural,
morphological, functional, spectroscopic and magnetic properties of pure CoFe
2
O
4
and Cr doped CoFe
2
O
4
are
characterized by XRD, FESEM, FTIR, Raman, M€ ossbauer spectroscopy and M-H hysteresis loop. The X-ray
diffraction (XRD) patterns of undoped (x ¼ 0) and doped (x6¼ 0) samples reveal the formation of single phase
cubic spinel structure. The lattice parameters and cation distribution between tetrahedral (A) and octahedral (B)
sites of the samples (AB
2
O
4
) were obtained by Rietveld refnement of XRD patterns. The FESEM micrographs
exhibit dense micro structure with small voids. The energy dispersive x-ray studies confrm the presence of Cr in
CoFe
2
O
4
. The FTIR spectrum confrms that the peaks corresponding to the metal-oxygen bonds have shiftedto-
wards higher wavelength region. Raman spectrum exhibits broad peaks which confrm the existence of local
disorder due to the inter-site cation migration between tetrahedral and octahedral sites. The M€ ossbauer spec-
troscopy reveals that the magnitude of magnetic hyperfne feld of tetrahedral site (H
A
) and octahedral site (H
B
)
decreases with increase in Cr doping in CoFe
2
O
4
and that the decrease is more rapid in tetrahedral site (H
A
)
compared to that in octahedral site (H
B
). And also confrm that the magnetic hyperfne felds (B
hf
) are smaller
relative to pure cobalt ferrite representing that super exchange interaction which is decreases as the Cr con-
centration increases. The magnetization studies reveal a decrease in the saturation magnetization (M
s
) of
CoFe
2
O
4
with increase in Cr substitution. A similar and non-monotonic variation of coercivity (H
c
) and magneto
crystalline anisotropy (K) suggests that H
c
is mainly determined by K.
* Corresponding author.
E-mail addresses: praveenajoy777@gmail.com (G.P. Nethala), travindar@gmail.com (R. Tadi), ganapathi.gajula@gmail.com (G.R. Gajula).
Contents lists available at ScienceDirect
Materials Chemistry and Physics
journal homepage: www.elsevier.com/locate/matchemphys
https://doi.org/10.1016/j.matchemphys.2019.121903
Received 18 March 2019; Received in revised form 6 July 2019; Accepted 24 July 2019