Sains Malaysiana 38(2): 209-213(2009)

 

Electrical and Microstructural Properties of (La1-xPrx)1/2Ba1/2MnO3 Compounds

(Kajian Elektrik dan Mikrostruktur dalam Sebatian-sebatian

 (La1-xPrx)1/2Ba1/2MnO3)

 

Huda Abdullah

Faculty of Engineering, Universiti Kebangsaan Malaysia

43600 Bangi, Malaysia

 

S.A. Halim

Physics Department, Faculty of Sciences, Universiti Putra Malaysia

43400 UPM Serdang, Selangor, Malaysia 

 

Received:   26 April 2008 / Accepted:  14 July 2008

 

 

ABSTRACT

 

The electrical and microstructural properties of (La1-xPrx)1/2Ba1/2MnO3 (x = 0.000, 0.167, 0.333, 0.500, 0.677, 0.833 and 1.000) compounds, prepared by the solid state reaction, have been investigated. The electrical property has been determined by using standard the four-point probe resistivity measurement with a temperature range of 30 K to 300 K. By increasing the Pr doping, the metal-insulator transition temperature (Tp) shifted to lower temperatures, which are 254, 248, 228, 220, 196, 180 and 158K for x = 0.000, 0.167, 0.333, 0.500, 0.677, 0.833 and 1.000, respectively. Using several theoretical models, it has been concluded that the metallic (ferromagnetic) part of the resistivity (ρ) (below TP) fits well with the equation ρ = ρ0 + ρ2.5T2.5, indicating that ρ0 is due to the importance of grain and domain boundary effects, a second term ~ ρ2.5T2.5 appears that might be attributed to electron-electron scattering. The scanning electron microscope (SEM) micrographs show the grains size decreases as the level of porosity increases, which contributes to the increase resistivity.

 

Keywords: Metal-insulator transition; transition temperature;  resistivity

 

 

ABSTRAK

 

Sifat elektrik dan mikrostruktur bagi sebatian (La1-xPrx)1/2Ba1/2MnO3 (x = 0.000, 0.167, 0.333, 0.500, 0.677, 0.833 and 1.000), yang disediakan dengan tindakbalas keadaan pepejal, telah dikaji. Pencirian elektrik ditentukan dengan menggunakan pengukuran kerintangan penduga empat titik piawai dalam lingkungan suhu daripada 30K hingga 300K. Dengan peningkatan Pr, suhu peralihan (Tp) beranjak ke suhu yang lebih rendah, iaitu 254, 248, 228, 220, 196, 180 dan 158K masing-masing untuk x = 0.000, 0.167, 0.333, 0.500, 0.677, 0.833 dan 1.000. Dengan menggunakan beberapa model  disimpulkan bahawa kerintangan (ρ) di kawasan logam (ferromagnet) di bawah Tp sesuai dipadankan dengan persamaan ρ = ρ0 + ρ2.5T2.5.  Ini menunjukkan ρ0 disebabkan oleh kesan penting butiran dan sempadan domain. Sebutan kedua ~ ρ2.5T2.5 berkemungkinan penyeraka elektron-elektron. Mikrograf  bagi mikroskop elektron imbasan (SEM) menunjukkan saiz butiran menurun dengan peningkatan keporosan, yang menyumbang kepada peningkatan kerintangan.

 

Kata kunci: Kerintangan; peralihan logam-penebat; suhu peralihan

 

 

REFERENCES  

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Venkataiah, G., Krishna, D.C., Vithal, M., Rao, S.S., Bhat, S.V., Prasad, V., Subramanyam, S.V. & Venugopal Reddy, P. 2005. Effect Of Sintering Temperature On Electrical Transport Properties Of La0.67Ca0.33mno3 Physica B 357: 370–379.

Zener, C. 1951. Interaction Between The d-Shells in the Transition Metals II Ferromagnetic Compounds Of Manganese With Perovskite Structure. Phys. Rev. 82: 403-405.

 

 

 

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