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

RUJUKAN

Chang, Y.L. & Ong, C. K. 2004. Temperature sintering effects on the magnetic, electrical and transport properties of La0.67Sr0.33MnO3/Nd0.67Sr0.33MnO3 composites. J. Phys Condens. Matter 16: 3711-3718.

Chattopadhyay, S., Sarkar, A., Pal, S., Kulkarni, S.D., Joy, P.A. & Chaudhari, B. K. 2007. Studies of quenched disorder in La0.7Ca0.3MnO-type CMR manganite system from magnetic, transport and positron annihilation spectroscopic measurements. Physica B 398: 23-27.

Dagotto, E., Hotta, T. & Moreo, A. 2001. Colossal magnetoresistant materials: The key role of phase separation. Physics Report 344: 1-153.

Ewe, L.S., Hamadneh, I., Hazar, A.S. & Abd-Shukor, R. 2008. Sound velocity in perovskite manganites La0.67Ca0.33MnO3 with different grain sizes. Physica B 403: 2394-2398.

Ewe, L.S., Hamadneh, I., Salama, H., Nasri, N.A., Halim, S.A. & Abd-Shukor, R. 2009. Magnetotransport properties of La0.67Ca0.33MnO3 with different grain sizes. Appl. Phys. A 95: 457-463.

Fontcuberta, J., Martinez, B., Seffar, A., Pinol, S., Garcia-Mu-noz, J.L. & Obradors, X. 1996. Colossal magnetoresistance of ferromagnetic manganites: Structural tuning and mechanisms. Phys. Rev. Lett. 76: 1122-1125.

Grossin, G. & Noudem, J.G. 2004. Synthesis of fine La0.8Sr0.2MnO3 powder by different ways. Solid State Science 6: 939-944.

Jeong, Y.H., Park, S.H., Koo, T.Y. & Lee, K.B. 1998. Fisher-Langer relation and scaling in the specific heat and resistivity of La0.7Ca0.3MnO3. Solid State Ionics 108: 249-254.

Jin, S. Tiefel, T. H. Mccormack, M. Fastnacht, R. A, Ramesh, R. Chen, H. 1994. Thousand fold change in resistivity in magnetoresistive La-Ca-Mn-O. Science 264: 413

Kalyana Lakshmi, Y., Venkataiah, G., Vithal, M. & Venugopal Reddy, P. 2008. Magnetic and electrical behavior of La1-xAxMn)3 (A= Li, Na, K and Rb) manganites. Physica B 403: 3059-3066.

Kameli, P., Salamati, H. & Aezami, A. 2008. Influence of grain size on magnetic and transport properties of polycrystalline La0.8Sr0.2MnO3 manganites. Journal of Alloys and Compounds 450: 7-11.

Karmakar, S., Taran, S., Chaudhuri, B.K., Sakata, H., Sun, C.P., Huang, C.L. & Yang, H.D. 2005. Study of grain boundary contribution and enhancement of magnetoreisistance in La0.67Ca0.33MnO3/V2O5 composites. J. Phys. D: Appl. Phys. 38: 3757-3763.

Rao, C.N. & Raychaudhuri, A.K. 1998. Colossal Magnetoresistance, Charge Ordering and Other Novel Properties of Manganates and Related Materials. Singapore: World Scientific.

Ravi, V., Kulkarni, S.D., Samuel, V., Kale, S.N., Mona, J., Rajgopal, R., Daundkar, A., Lahoti, P. S. & Joshee, R. S. 2007. Synthesis of La0.7Sr0.3MnO3 at 800oC using citrate gel method. Ceramics International 33: 1129-1132.

Roul, B.K., Sahu, D.R., Mohanty, S. & Pradhan, A.K. 2001. Effect of high temperature sintering schedule for enhanced CMR properties of La0.67Ca0.33MnO3 close to room temperature. Materials Chemistry and Physics 67: 267-271.

Siwach, P.K., Prasad, R., Gaur, A., Singh, H.K., Varma, G.D. & Srivastava, O.N. 2007. Microstrcture-magnetotransport correlation in La0.7Ca0.3MnO3. Journal of Alloys and Compounds 443: 26-31.

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.

Venkataiah, G. & Venugopal Reddy, P. 2005. Structural, magnetic and magnetotransport behavior of some Nd-based perovskite manganites. Solid State Communications 136: 114-119.

Venkataiah, G., Prasad, V. & Venugopal Reddy, P. 2007. Influence of A-site cation mismatch on structural, magnetic and electrical properties of lanthanum manganites. Journal of Alloys and Compounds 429: 1-9.

Xiong, C., Hu, H., Xiong, Y., Zhang, Z., Pi, H., Wu, X., Li, L., Wei, F. & Zheng, C. 2009. Electrical properties and enhanced room temperature magnetoresistance in (La0.7Ca0.2Sr0.1MnO3)1-x/Pdx composites. Journal of Alloys and Compounds 479: 357-362.

Zainullina, Z. I., Bebenin, N. G., Ustinov, V. V. & Mukovskii, Ya. M. 2004. Elastic properties of La1-xSrxMnO3 single crystal. J. Magn. Mag. Mater. 272-276: 473-474.

Zhang, Y. B., Li, S., Sun, C. Q., Widjaja, S. & Hing, P. 2006. Transition dependence of La2/3Ca1/3MnO3 oxide on microstructure. Journal of Materials Processing Technology 122: 266-271.

 

 

*Pengarang untuk  surat-menyurat; email: laysheng@uniten.edu.my

 

 

sebelumnya