This study compares the structural and magnetic properties of bulk and nano-sized Fe2CoAl samples. X-ray diffraction showed both samples had a disordered cubic structure, with the nano-sized sample having a smaller lattice parameter and broader peaks due to a smaller grain size of 13nm. Magnetization measurements found the nano-sized sample had a 10% higher saturation magnetization and 34 times higher coercivity than the bulk sample. Additionally, the Curie temperature of the nano-sized sample was over 8000C compared to 7370C for the bulk. Mössbauer spectroscopy showed the local environments of iron atoms were similar between samples, despite increased disorder in the nano-sized sample. Overall, high-energy ball mill

1. Comparative study of the structural and magnetic properties of bulk and
nano-sized Fe2CoAl
Vishal Jain, Jagdish Nehra, V. D. Sudheesh, N. Lakshmi, and K. Venugopalan
Citation: AIP Conf. Proc. 1536, 935 (2013); doi: 10.1063/1.4810537
View online: http://dx.doi.org/10.1063/1.4810537
View Table of Contents: http://proceedings.aip.org/dbt/dbt.jsp?KEY=APCPCS&Volume=1536&Issue=1
Published by the American Institute of Physics.
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2. Comparative study of the structural and magnetic
properties of bulk and nano-sized Fe2CoAl
Vishal Jain, Jagdish Nehra, Sudheesh V.D., N. Lakshmi and K. Venugopalan
Department of Physics, Mohanlal Sukhadia University, Udaipur, Rajasthan, 313001, India
email:- vjain045@gmail.com
Abstract. The structural and magnetic properties of as-melted and high energy ball milled sample have been studied by
X-ray diffraction, 57
Fe Mössbauer spectroscopy and DC magnetization. The observed properties are compared to that of
the bulk sample. The magnetic hyperfine fields are related to structural disorder. There is a very good enhancement of
bulk magnetic properties in the nano-sized samples, the most notable one being a dramatic increase in saturation
magnetization and Curie temperature of the sample and are explained in terms of structural disordering and size effect.
Keywords: Heusler alloy, High energy ball milling, Magnetism
PACS: 81.07.Bc, 75.50.Bb
INTRODUCTION
Soft magnetic materials with high saturation
magnetization and high Curie temperature are required
in electronics as well as for recording technologies [1].
It is also one of the key requirements in many high
frequency applications, such as the planar inductors
and transformers used in integrated circuits. The
Slater–Pauling curve indicates that the addition of
cobalt increases the magnetization of iron.
High-density recording media now has a
requirement of ultra fine particles with stable magnetic
properties. In this study, structural and magnetic
properties of 13nm sized sample of Fe2CoAl
synthesized by high energy ball milling and that of the
bulk are compared.
EXPERIMENTAL
Fe2CoAl alloy was prepared by argon arc melting
using pure constituent metals in stoichiometric
proportions. The melting process was repeated to get
higher homogeneity. The as melted sample was milled
for 2 hours in a SPEX 8000M mixer/mill using
tungsten carbide vials and balls with a ball to powder
ratio of 20:1. Structural characterization has been done
by using X-ray powder diffraction (XRD) and
transmission electron microscopy (TEM).
Magnetization measurements were determined using a
Lakeshore 7304 model vibrating-sample
magnetometer (VSM). Room temperature Mössbauer
spectra were recorded using a 25mCi Co-57(Rh)
source. The calibration was done using Fe foil.
RESULTS AND DISCUSSION
FIGURE 1. X-ray diffraction pattern of the samples.
Figure.1 X-ray diffractogram of both samples show
formation of disordered, single phased, A2 type
structure (F m-3 m). No other phases were found from
the X-ray diffraction pattern. Fe2CoAl alloy having an
inverse type Heusler structure have also been reported
[2] and so only B2 ordering is obtainable at best.
Lattice parameter (a0) of as-melted sample (5.732Å) is
slightly smaller than reported value Fe2CoAl due to
atomic disordering between X, Y and Z. Inset of figure
VKRZV LQFUHDVH LQ ș YDOXH DIWHU KRXU PLOOLQJ
implying decrease in lattice parameter. The peaks
broaden after 2 hour high energy ball milling due to
decrease in grain size to 13nm as confirmed from
TEM micrographs.
Proceeding of International Conference on Recent Trends in Applied Physics and Material Science
AIP Conf. Proc. 1536, 935-936 (2013); doi: 10.1063/1.4810537
© 2013 AIP Publishing LLC 978-0-7354-1160-9/$30.00
935
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3. FIGURE 2. Room Temperature magnetization curves.
The value of coercivity and saturation
magnetization for as melt sample is 2Oe (Hc