Nanoparticle size effect on the magnetic and transport properties of (La0.7Sr0.3)0.9Mn1.1O3 manganites

Abstract

Magnetic and transport thermal measurements of nanosize (La0.7Sr0.3)0.9Mn1.1O3 manganite are reported. The nanoparticles are synthesized with use of the co-precipitation method at different (800, 900, and 950°C) temperatures. Their crystal structure is determined to be perovskite-like with a rhombohedral distortion (the space group R3¯c). The phase composition and specific surface nanopowders are determined. The average size of synthesized nanoparticles (from 40to100nm) is estimated by both the method of low-temperature adsorption of argon and x-ray diffraction measurements. All the nanosize samples show ferromagnetic-like ordering with close phase transition temperatures. Their magnetization decreases with decreasing particle size. Comparison of experimental and calculated temperature dependences of the spontaneous magnetic moment shows that the spontaneous magnetization both in magnetic field and without field is well described in the framework of the double exchange model. The decrease of the magnetization with decreasing particle size is due to the increasing surface contribution to the magnetization. The magnetic entropy is shown to increase with increasing applied magnetic field and to be smaller for the small particles. The resistivity is found to become higher with decreasing particles size at any temperatures.

Magnetocaloric effect of monovalent K doped manganites Pr0.6Sr0.4−xKxMnO3 (x=0 to 0.2)

“…The observed gradual decay of magnetic moment from 6.58 µB for x = 0.05 down to 6.43 µB for x = 0.2 is associated with Mn 3+ (%) fraction diminishing from 0.6 to 0.4 for highest K content. One should also note that the obtained values are larger than the spinonly magnetic moments of 3.87 and 4.9 µB for Mn 4+ and Mn 3+ , respectively [30,31]. It points to the additional contribution of magnetic Pr 3+ ions bearing 3.5 µB [31,32], which may enhance magnetic moment.…”

Hydrothermal synthesis of magnetite: investigation of influence of aging time and mechanism

“…7. It is clearly seen that σ s has almost the same changing trend with the dimensional variation of crystallite, which can be explained by the research that the magnetic properties of magnetite particles strongly depend on their crystallite size and the structure [23–25].…”

Magnetic properties of La0.7Sr0.3MnO3 under the pressure and the transport property under the magnetic field

“…When the pressure increases, d decreases, so the H dip increases, making the particle magnetic moment tend to form a closed magnetic flux, and resulting in the significant decrease in magnetization. Moreover, the particle size also affects the dipolar field, 70 and hence the magnetization. The results of scanning electron microscopy of LSMO, La 0.7 Ca 0.3 MnO 3 59 and La 0.9 Ca 0.1 MnO 3 (not shown here) show that LSMO consists of tens‐of‐micrometers sized particles, whereas La 0.7 Ca 0.3 MnO 3 and La 0.9 Ca 0.1 MnO 3 contain more several micrometers particles and their aggregates with the tens‐of‐micrometers size, that is, the average particle size in LSMO is larger, resulting in the stronger interparticle dipolar interaction.…”

“…When the pressure increases, d decreases, so the H dip increases, making the particle magnetic moment tend to form a closed magnetic flux, and resulting in the significant decrease in magnetization. Moreover, the particle size also affects the dipolar field, 70 and hence the magnetization. The results of scanning electron microscopy of LSMO, La 0.7 Ca 0.3 MnO 3 59 and La 0.9 Ca 0.1 MnO 3…”