Abstract
Herein, rare-earth manganite, La0.67Sr0.33MnO3, has been prepared by a citric acid-assisted sol–gel auto-combustion method at a maintained pH value of 11. Room-temperature X-ray diffraction (RT-XRD) data analysis revealed a rhombohedral structure for the sample with the space group R3c, which was further confirmed by synchrotron radiation X-ray diffraction (SR-XRD). Rietveld refinement was carried out for both spectra, which confirmed the SR-XRD and RT-XRD results and the various structural parameters. To determine any of the phase transitions in the sample, temperature-dependent X-ray diffraction corresponding to the temperatures of 100 K, 200 K, 250 K, and 325 K was carried out, and no new phase was found. Temperature-dependent Raman characterization confirmed the metallic phase of the sample with the reduced Jahn–Teller distortion. Scanning electron microscopy confirmed the growth in the grain size as a result of a high sintering temperature. Compositional verification was conducted using energy-dispersive analysis of X-ray diffraction (EDAX). Low-temperature dc resistivity measurement showed a metal-insulator transition temperature (TMI) of ≈178 K. The DSC-specific heat measurement shows the ferromagnetic metallic nature where heat capacity increases with an increase in temperature.
Highlights
Rare-earth manganites of perovskite structure with the general chemical formula Ln1ÀxAxMnO3 (Ln3+ is a lanthanide ion and A2+ is an alkaline-earth ion) have attracted the core concentration of scientists for more than two decades
The single-phase and crystalline nanopowder of La0.67Sr0.33MnO3 was successfully prepared by the sol–gel auto-combustion method by maintaining the pH at 11 using ammonia
Ethylene glycol (EG) addition effectively helped in controlling the particle size, and citric acid played the role of a chelating agent as well as an organic fuel in the combustion and calcination process
Summary
Rare-earth manganites of perovskite structure with the general chemical formula Ln1ÀxAxMnO3 (Ln3+ is a lanthanide ion and A2+ is an alkaline-earth ion) have attracted the core concentration of scientists for more than two decades. The sol–gel auto-combustion method is a versatile solution technique used to obtain ultra ne, homogenous powders of a variety of glass and ceramic materials at low temperatures in a short span of time This method is widely and successfully used for the synthesis of metal oxides at relatively low processing temperatures, free from foreign ions with precise control of the doping level and the particles in the nano-size range. Keeping in mind the abovementioned features of the sol–gel auto-combustion technique, the present study has been carried out to investigate the structure of the LSMO for phase purity using different structure probing techniques; in addition, the best advantage of the present study is the preparation with the maintenance of pH by the addition of ammonia to enhance cation binding to citrate as well as the homogeneity and stability of metal citrate solutions. Citric acid, and glycol on the various physical properties of the material has been studied
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