Hyperfine Interactions 156/157: 229–234, 2004.
© 2004 Kluwer Academic Publishers. Printed in the Netherlands.
229
Effect of Mg
2+
on the Magnetic Compensation of
Lithium–Chromium Ferrite
A. RAIS
∗
, A. A. YOUSIF, A. GISMELSEED, M. E. ELZAIN, A. AL RAWAS
and I. A. AL-OMARI
Department of Physics, Sultan Qaboos University, P.O. Box 36, Muscat 123, Sultanate of Oman;
e-mail: amrais@yahoo.com
Abstract. Mg-substituted ferrite Li
0.5
Mg
x
Fe
1.25−(2/3)x
Cr
1.25
O
4
(0 x 0.3) was studied
using X-ray diffraction, Mössbauer spectroscopy and magnetic measurements. X-ray diffraction
patterns show that all samples have cubic spinel structure. The temperature-dependent magnetic
measurements revealed that the compensation point T
K
of Li
0.5
Fe
1.25
Cr
1.25
O
4
starts to approach
the Neel temperature T
N
as Mg
2+
substitution of Fe
3+
increases, until the compensation disappears
at x = 0.3. This effect is investigated in relation to the cation distribution established using the
Mössbauer study of this system.
Key words: magnetic compensation, X-ray diffraction, Mössbauer spectroscopy.
1. Introduction
The ferrite Li
0.5
Fe
2.5
O
4
has been the subject of extensive technical and fundamental
studies both in its pure form as well as its substituted form [1–3]. Various re-
searchers have reported the effect of additions of divalent, trivalent and tetravalent
ions in lithium ferrites and the different parameters have been measured depending
on the desired application [4–6].
The phenomenon of magnetic compensation is the disappearance of the mag-
netization at a temperature other than the Neel temperature and Gorter et al. [7]
were the first to observe this phenomenon in Li
0.5
Fe
1.25
Cr
1.25
O
4
. The chromium-
doped lithium ferrite Li
0.5
Fe
2.5−x
Cr
x
O
4
is among the few systems exhibiting this
phenomenon. In this work, we report the effect of Mg
2+
substitution for Fe
3+
on
the magnetic compensation of lithium–chromium ferrite. Moreover, using a Möss-
bauer study of this system, we propose a cation distribution for Li
0.5
Mg
x
Cr
1.25
Fe
1.25−(2/3)x
O
4
and investigate its relationship with the magnetization measure-
ments.
*
Author for correspondence.