Effect Of Co3+ Substitution on Electro-Magnetic Properties of Pr¬0.75¬Na¬0.25¬mno¬3 ¬and Nd¬0.75¬Na¬0.25¬mno¬3¬ Manganites

Nurhabibah Nabilah Ab Mannan,Zakiah Mohamed,Mohamad Zaky Noh,Suhadir Shamsuddin,Sufia Aqilah Razali

doi:10.14419/ijet.v7i4.30.22331

Nurhabibah Nabilah Ab Mannan, Zakiah Mohamed + Show 3 more

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https://doi.org/10.14419/ijet.v7i4.30.22331

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Abstract

This paper reports influences of cobalt (Co) substituted at Mn-site of Pr0.75Na0.25Mn1-xCoxO3 and Nd0.75Na0.25Mn1-yCoyO3 on structure, electrical transport and magnetic properties. All of the samples were prepared via standard solid state reaction method. X-ray diffraction measurement indicates that all samples were crystallized in an orthorhombic structure (space group Pnma). Resistivity measurement displays the x = 0 sample manifests an insulator behavior while metal-insulator transition was found at 108 K and 84 K for x = 0.02 and 0.05 respectively for Pr0.75Na0.25Mn1-xCoxO3. On the other hand, all of the samples for Nd0.75Na0.25Mn1-yCoyO3 showed insulator behavior down to low temperature and analysis of the resistivity change with respect to temperature, dlnρ/dT-1 versus T reveals a slope changes of resistivity have been recorded. Two obvious peaks were recorded from the analysis for y = 0.02 and 0.05 which can be suggested to the existence of charge order transition at the vicinity. For magnetic properties, x = 0 sample showed a paramagnetic-antiferromagnetic transition and further substitution of Co, x = 0.02 and 0.05, induce the paramagnetic-ferromagnetic transition and antiferromagnetic arrangement respectively. Meanwhile, further substitution of Co, y = 0.02 and 0.05 indicate antiferromagnetic transition with increasing TN as Co increased.

Highlights

Rare-earth perovskite manganite with the compositional formula of R1-xAxMnO3 where R is trivalent rare earth and A is divalent alkaline earth ions have caught much interest due to their interesting electrical transport and magnetic properties such as colossal magnetoresistance, charge ordering and metal to insulator behavior [1,2,3,4,5]
The existence of charge ordering (CO) is always found in the half-doped manganites in which the ratio of Mn3+ to Mn4+ is 1:1 where the ions arranged themselves in an ordered arrangement reported in several divalent doped manganites such as La0.5Ca0.5MnO3 [11,12], Pr0.5Ca0.5MnO3 [13] and Nd0.5Ca0.5MnO3 [7]
The phase of the samples was characterized by Xray diffraction (XRD) technique employing a Bruker D8 Advance at room temperature with Cu-Kα radiation which were operated at 40 kV and 40 mA

Summary

Introduction

Rare-earth perovskite manganite with the compositional formula of R1-xAxMnO3 where R is trivalent rare earth and A is divalent alkaline earth ions have caught much interest due to their interesting electrical transport and magnetic properties such as colossal magnetoresistance, charge ordering and metal to insulator behavior [1,2,3,4,5]. The coexistence of ferromagnetic to paramagnetic transition at Curie temperature (TC) and metal to insulator transition temperature at metal-insulator temperature (TMI) are usually interpreted by Zener’s double-exchange (DE) mechanism due to the mixed valency of the manganites. This mechanism involves simultaneous hopping of an electron (eg) from Mn3+ to O2- and from O2- to Mn4+if the manganese core spins in parallel alignment are ferromagnetically coupled [6]. It is well known that cobalt shoes different spin states resulting from the competition between values of crystal field splitting and

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