Effects of pH and sintering temperature on the synthesis and electrical properties of the bilayered LaSr2Mn2O7 manganite prepared by the sol–gel process

Abstract

The bilayered LaSr 2 Mn 2 O 7 manganite was synthesized by the sol-gel process at different pH values (3.5, 7, and 9.5) and different sintering temperatures (1553, 1623, and 1723 K) to investigate the effects of growth conditions upon the structural and electrical properties of the samples under investigation. X-Ray diffraction and FT-IR spectroscopy techniques confirm the phase formation for all samples. However, samples sintered at 1553, 1623, and 1723 K, and formed at pH = 7 are single phased having a tetragonal structure. Study of these single-phased samples indicates that with increase in the sintering temperature from 1553 to 1723 K, the average grain size increases from *200 to *1000 nm. To investigate the influence of grain size on the conduction mechanism, resistivity of the samples was measured as a function of temperature. The data obtained was analyzed by the adiabatic small polaron hopping model. These analyses show the influence of grain size on the parameters obtained by fitting the data by the above models.

Structure–Activity Relationship in Manganese Perovskite Oxide Nanocrystals from Molten Salts for Efficient Oxygen Reduction Reaction Electrocatalysis

“…The l-LSMO Scherrer crystal size of 67 nm is smaller than reported values for RP manganite particles. [24][25][26][27][28] SEM and TEM (Figure 1c-g, respectively) show that the l-LSMO sample is made of cube-like particles with a broad size distribution between 50-200 nm in agreement with the crystallite size. Selected area electron diffraction (SAED, Figure 1e inset) and the Fast Fourier Transform-analyzed HRTEM (Figure 1h) show spot-like patterns indicating well-oriented crystallites within the same particle.…”

DC magnetization studies of nano- and micro-particles of bilayered manganite LaSr2Mn2O7

“…It is possible that there is a mixture of first order and second order phase transition in the SB-1280 and SB-1350 samples. 12 13 In order to further investigation the nature of the phase transition involved, we performed the susceptibility measurement at the ZFC (cooling and heating) modes. The thermal hysteresis (TH) can give us information about the existence of a first order phase transition [30] or even TH phenomenon is observed more pronounced around transition in phase-separate manganites [31].…”

“…These studies suggest that the bi-layered manganites La 2-2x Sr 1+2x Mn 2 O 7 similar to other manganites, offer unique opportunity to investigate the influence of particle size on magnetic properties. In our previous study, in order to investigate the effect of particle size, we prepared a number of LaSr 2 Mn 2 O 7 ceramic samples using sol-gel method, and the effects of the particle size 3 on the electrical properties of this compound were reported [12]. In this work, we report the DC magnetization (DCM) studies of the samples with nano-and micro-sized particles.…”

“…2 were weighted in appropriate proportions. The details of the sol-gel process and powder preparation have been reported in references [12,13]. The samples were synthesized at pH=7 and calcinations temperatures 1000 °C.…”

Preparation of La0.7Ca0.3−xSrxMnO3 Manganites by Four Synthesis Methods and Their Influence on the Magnetic Properties and Relative Cooling Power

“…The obtained gel was heated at a rate of 10 °C/min up to 250 °C, and maintained at this temperature for 14 h. After that, two thermal treatments, one at 550 °C for 3 h and another at 1000 °C for 10 h, were carried out. The obtained powders were pressed and sintered at 1200 °C for 6 h [22,23]. Also, powders obtained by this method were sintered in a Fuji Dr. Sinter Lab Jr.…”