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<p>This study focuses on the calcination temperature, between 600 and 1050&#xa0;°C, used to prepare La<sub>0.67</sub>Sr<sub>0.33</sub>MnO<sub>3</sub> (LSMO) nanoparticles via a non-aqueous sol–gel method, with respect to their structure, magnetism, and magnetotransport properties. The X-ray diffraction and Rietveld refinement indicate phase-pure nanoparticles in a rhombohedral (<i>R</i>-3<i>c</i>) structure. Moreover, they evidence the rise of the average size of crystallites from 31.9 to 111.4&#xa0;nm with the lowest microstrain at about 900&#xa0;°C. Magnetic measurements demonstrate that reduced surface disorder at increased temperatures enhances the saturation magnetization (<i>M</i>ₛ) sixfold, increasing from 6.86 to 38.14&#xa0;emu/g with the calcination temperature increase. However, the data indicate the transition in magnetic behavior: coercivity and remanence increase up to a maximum at 900&#xa0;°C and then decline, marking the transition between single-domain and multi-domain behavior. Room-temperature magnetoresistance measurements identify an inverse dependence of the particle size on the magnitude of low-field magnetoresistance (LFMR)—larger particles have lower LFMR. The sample calcined at 600&#xa0;°C, where intergranular spin-polarized tunneling occurs across many grain boundaries, has a very large LFMR of more than 95%. In contrast, for the 1050&#xa0;°C sample, larger grain size allows better magnetic coherence and fewer boundary regions and, hence, it has a much weaker MR of about 40%. The findings show that calcination temperature is the main tuning knob for LSMO nanoparticles; it allows a predetermined balance between hard magnetic characteristics for magnetic components with high sensitivity in magnetoresistive devices for sensor applications.</p>

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Tuning the structure, magnetization, and magnetoresistance of LSMO nanoparticles via sol–gel calcination

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年3月6日

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  • M. A. Salim,
  • Ahmed F. Mabied,
  • A. M. Moustafa,
  • Ayat E. Hassanien,
  • H. M. Hashem,
  • Mohamed R. Balboul

摘要

This study focuses on the calcination temperature, between 600 and 1050 °C, used to prepare La0.67Sr0.33MnO3 (LSMO) nanoparticles via a non-aqueous sol–gel method, with respect to their structure, magnetism, and magnetotransport properties. The X-ray diffraction and Rietveld refinement indicate phase-pure nanoparticles in a rhombohedral (R-3c) structure. Moreover, they evidence the rise of the average size of crystallites from 31.9 to 111.4 nm with the lowest microstrain at about 900 °C. Magnetic measurements demonstrate that reduced surface disorder at increased temperatures enhances the saturation magnetization (Mₛ) sixfold, increasing from 6.86 to 38.14 emu/g with the calcination temperature increase. However, the data indicate the transition in magnetic behavior: coercivity and remanence increase up to a maximum at 900 °C and then decline, marking the transition between single-domain and multi-domain behavior. Room-temperature magnetoresistance measurements identify an inverse dependence of the particle size on the magnitude of low-field magnetoresistance (LFMR)—larger particles have lower LFMR. The sample calcined at 600 °C, where intergranular spin-polarized tunneling occurs across many grain boundaries, has a very large LFMR of more than 95%. In contrast, for the 1050 °C sample, larger grain size allows better magnetic coherence and fewer boundary regions and, hence, it has a much weaker MR of about 40%. The findings show that calcination temperature is the main tuning knob for LSMO nanoparticles; it allows a predetermined balance between hard magnetic characteristics for magnetic components with high sensitivity in magnetoresistive devices for sensor applications.