Electrical and magnetic properties of La_0.7Ca_0.3MnO₃ nanoparticle prepared by reactive milling method

Abstract

La0.7Ca0.3MnO3 nanoparticle in an orthorhombic structure with space group of Pnma was prepared by a combination of the reactive milling method and annealing at 900 °C for 1 h in air. The mean crystal size determined through the powder x-ray diffraction data is 18 ± 2 nm. Based on the dependences of the resistivity and the magnetisation on temperature and applied magnetic field, the electrical-magnetic properties, the magnetoresistance and the magnetocaloric effects have been investigated. It shows La0.7Ca0.3MnO3 nanoparticle undergoes a metal-insulator and a ferromagnetic-paramagnetic phase transitions at T MI = 252 K and T C = 253 K, respectively. The temperature dependences of resistivity of material in the absence and presence of 4 kOe in a range of 30–300 K were fitted to the phase segregation model. The magnetoresistance and the magnetocaloric effects related to the double-exchange interactions taking place around T MI and T C were observed, corresponding to the values of the magnetoresistance MR = 9.29% and the maximum magnetic entropy change ∣ΔS max∣ = 0.18 J/kg.K under an applied magnetic field of 4 kOe. Besides, the low field magnetoresistance value at low temperature region and the change of the specific heat of La0.7Ca0.3MnO3 nanoparticle have also been concerned.

Structural and critical properties of Pr0.5Sr0.5MnO3 nanoparticle

“…Herein, the full width at half maximum of (111) line of Si powder was used as a standard to eliminate the instrumental broadening. A detailed description can be found somewhere in [21,22]. Accordingly, the average crystalline size of PSMO particles is found to be <D> = 58 ± 2 nm.…”

“…A PSMO-NP sample was fabricated by a combination of reactive milling and heat treatment [21]. High-purity powders (upper 99.9%) of Pr 6 O 11 , SrO, and Mn were used as the initial ingredients.…”

“…Vial and balls grinding are made of high hardened steel of Spex SamplePrep. The ball/powder mass ratio was chosen to be 24/5 [21]. The heat treatment process was carried out in air with a temperature change rate of 50 °C min −1 .…”

Multiferroic characteristics and microwave absorption properties of La1.5Sr0.5NiO4/BaTiO3 nanocomposites

“…Besides, their XRD peaks are relatively broad, suggesting the finite crystalline size in these samples. The average crystalline sizes (D) for BTO and LSNO phases were determined using the Williamson-Hall method [29,30]:…”

“…where β and ε are the full width at half maximum (FWHM) of the XRD peak and the lattice strain, respectively; θ is the Bragg diffraction angle; k=0.9 is the shape factor. Due to the nanosized effect, the value of β was corrected using the following expression [29,31]: The analysis of the BTO sample confirmed its cubic crystal structure, which belonged to the Pm−3m space group with a lattice parameter of a≈4.013 Å and volume of V≈64.63 Å 3 . Meanwhile, the LSNO sample had a tetragonal crystal structure belonging to the I4/mmm space group with lattice parameters of a=b≈3.834 Å, c≈12.752 Å, and V≈187.45 Å 3 .…”