Effect of Al and Ti substitution on the structural and magnetotransport properties of Lanthanum-Strontium manganite

Manganite systems have been of considerable interest in the recent past due to their potential to operate in wide property range and also to serve as effective magnetic sensing and storing devices. We report a novel hybrid method, by which La0.7Sr0.3Mn1-xAxO3 (A = Al and Ti, x = 0.00 and 0.06) samples were synthesized at temperature 1100 °C. La0.7Sr0.3MnO3 was selected as a parent material because it has metal to insulator transition near to room temperature. The XRD confirms that all the samples were in single phase (with no detectable secondary phases) having a rhombohedral structure in hexagonal lattice having a space group R3̄c. Unit cell volume is affected by Al+3 and Ti+4 ions and this structural variation slows down the electron transfer through the Mn+3-O−2-Mn+4 network seriously. EDAX analysis shows that the weight percentage of prepared samples matches with the calculated weight percentage of all the samples. Scanning electron microscopy shows that each sample has fine and clear grain boundaries (GBs). Metal-insulator transition (TMI) was increased from 230 K to 275 K in Ti+4 doped sample while TMI remain unchanged in Al+3 substituted sample under the 8 T applied magnetic field. As a positive effect, enhancement in MR % was observed at room temperature. These results prove that Al and Ti substitution at Mn site enhances the various properties of this manganite system. These properties are important for application point of view.