Journal of Superconductivity and Novel Magnetism
https://doi.org/10.1007/s10948-018-4776-7
ORIGINAL PAPER
Study of the Effect of Pr Doping on Structural, Morphological
and Magnetic Properties of Nickel Ferrite
Mukesh Kumari
1
· Mukesh Chander Bhatnagar
1
Received: 19 May 2018 / Accepted: 13 June 2018
© Springer Science+Business Media, LLC, part of Springer Nature 2018
Abstract
Praseodymium rare earth ion (Pr
3+
) doped nickel ferrite (NiFe
2−x
Pr
x
O
4
,0 <x< 0.1) nanocrystals (NFPO) were
synthesized by hydrothermal method. The structural, morphological and magnetic properties of the prepared samples have
been studied. The x-ray diffraction (XRD) and fourier transform infrared (FTIR) techniques confirmed the phase formation
of the NFPO nanocrystals. The average crystallite size of NFPO nanoparticles found to be in the range 39 to 44 nm. The
presence of Pr ions in NFPO was confirmed by energy-dispersive x-ray (EDX) analysis. It has been observed that after
a certain amount of Pr doping, the morphology of the nanocrystals starts changing from nano-octahedrons to nanorods
shape, as confirmed by transmission electron microscopy (TEM). Also, the magnetic properties of the prepared nanocrystals
were measured using physical properties measurement system (PPMS) at 10 K and 300 K. The saturation magnetization
(Ms) first decreases with the increasing loading amount of Pr ions up to (x = 0.025) and later it increases at both the
temperatures. However, the value of coercivity shows an increasing trend with the increasing amount of Pr ions in NFPO at
room temperature.
Keywords Ferrites · Hydrothermal · Rare earth-doped nanoparticles · Nano-octahedrons
1 Introduction
Recently, the spinel ferrites with general formula AB
2
O
4
,
belonging to the cubic spinel structure, have drawn huge
attention due to their remarkable properties to meet
the necessities of various applications. Nickel ferrite, a
centrosymmetric ferrite which is a soft magnetic material
with an inverse spinel structure, have a broad range
of applications in many fields such as gas sensors [1],
photocatalytic [2] and microwave absorber [3].
The inverse spinel structure of nickel ferrite (NFO) has
16 octahedral (B site) and 8 tetrahedral (A site) filled sites
out of total 32 B sites and 64 A sites created by oxygen ions.
In a unit cell of the spinel structure, there are 16 Fe
3+
,8
Ni
2+
and 32 O
2−
ions. In case of inverse spinel structure, 16
Fe
3+
ions are equally conveyed between A and B sites. The
Mukesh Kumari
mukeshdhillon20@gmail.com
1
Indian Institute of Technology Delhi, New Delhi, 110016,
India
remaining eight B sites are occupied by Ni
2+
ions. Physical
properties of the ferrites depend on cation distribution
among these sites, which is very much sensitive to the
method of preparation [4], particle size [5] and doping [6].
The specific nature of the dopant (semiconductor, metal)
into spinel structure can also influence the final magnetic
and electrical characteristics [7, 8]. The amount of this
modification is decided by the ionic radius, the valency of
the substituting ion and its site of preference [9–11].
Many scientific groups are working on the doping of
these rare earth (RE) ions in the spinel structure because of
their strong spin-orbit coupling of the angular momentum
and unpaired 4f electrons. Addition of RE metal ions into
the spinel structure creates strain due to distortion that can
affect the structure and/or morphology [12]. In this way, the
electrical and magnetic behaviour of these nano ferrites can
be modified according to the application [13]. Zhiqing et al.
studied the effect of Sm ions substitution on dielectric and
magnetic properties of Ni–Zn ferrite [14]. Pratibha Rao et
al. studied the effect of Pd incorporation on the gas sensing
behaviour of NFO and reported the reduction in operating
temperature and also observed faster response and recovery
characteristic [15]. Xiaofei Wu et al. found the change