Sains Malaysiana 41(6)(2012): 761–768
Electrical and Magneto-Transport
Properties of Magneto-Resistive La0.70Ca0.28Sr0.02MnO3Prepared at Different Sintering
Temperature
(Sifat Elektrik dan
Magneto-Angkutan La0.70Ca0.28Sr0.02MnO3 yang disediakan pada Suhu Sinteran Berlainan)
L.S. Ewe* & R. Ramli
College of Foundation and
General Studies, Universiti Tenaga Nasional, Campus Putrajaya
Jalan Ikram-Uniten, 43000
Kajang, Selangor D.E. Malaysia
K.P. Lim
Physics
Department, Faculty of Science, Universiti Putra Malaysia, 43400 Serdang,
Selangor D.E.
Malaysia
R. Abd-Shukor
School of Applied
Physics, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor D.E. Malaysia
Diserahkan:
29 September 2011 / Diterima: 16 Januari 2012
ABSTRACT
The effects of strontium doping on
the electrical and magneto-transport properties of magneto resistive La0.70Ca0.28Sr0.02MnO3 at different sintering temperatures have been studied. The
samples were prepared by the co-precipitation technique (COP)
and sintered at 1120, 1220 and 1320 oC. XRD patterns revealed that the
samples have an orthorhombic structure and the diffraction patterns can be
indexed with the Pbnm space group. The insulator metal transition, TIM increased linearly from 261 K
to 272 K with the increase in sintering temperature. The magnetoresistance (MR) measurements were made in
magnetic fields from 0.1 to 1 T at room temperature. The percentage of MR increased with increasing of
magnetic field and sintering temperature for all samples. The electrical
resistivity data were fitted with several equations in the metallic
(ferromagnetic) and insulator (paramagnetic) regime. The density of states at
the Fermi level N(EF)
and the activation energy (Ea)
of electron hopping were estimated by using variable range hopping and small
polaron hopping model.
Keywords: Activation energy;
electrical resistivity; magnetotransport; manganites
ABSTRAK
Kesan
pengedopan strontium terhadap sifat elektrik dan magneto angkutan bahan magneto
rintangan La0.70Ca0.28Sr0.02MnO3 yang disediakan pada suhu sinteran berlainan telah dikaji. Sampel
telah disediakan dengan kaedah co-pemendakan (COP)
dan disinter pada 1120, 1220 and 1320 oC.
Corak XRD menunjukkan semua
sampel mempunyai struktur ortorombik dan corak pembelauan boleh diindeks kepada
kumpulan ruang Pbnm. Peralihan penebat logam TIM meningkat secara linear daripada 261 hingga 272 K dengan
peningkatan suhu sinteran. Pengukuran magneto rintangan (MR)
telah dijalankan dalam medan magnet daripada 0.1
hingga 1 T pada suhu bilik. Peratusan peningkatan MR meningkat dengan medan magnet dan suhu
sinteran untuk semua sampel. Data kerintangan elektrik telah
disuaikan dengan beberapa model dalam rantau logam (feromagnet) dan penebat
(paramagnet). Ketumpatan keadaan pada aras Fermi N(EF) dan tenaga pengaktifan (Ea) loncatan elektron telah
dijangkakan dengan menggunakan model loncatan julat berubah dan model polaron
kecil.
Kata
kunci: Kerintangan elektrik; magneto rintangan; manganit; tenaga pengaktifan
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*Pengarang untuk surat-menyurat; email: laysheng@uniten.edu.my
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