Microstructural and magnetic properties of in-situ and ball mill synthesized LSMO: CoFe2O4 nanocomposites using microwave oven

Abstract

Manganite-ferrite nanocomposites are of interest due to the magnetic coupling between these two phases that affects the microstructural and magnetic properties. These composite materials are of enormous technological importance, as these materials can be used as read heads
for hard disks, magnetic storage and sensing devices. In this work, microwave assisted synthesis was carried out for the preparation of (1-x) mol % La 0.67 Sr 0.33 MnO 3 (LSMO): x mol % CoFe 2 O 4 (CF) (where x= 0, 30, 50, 70 and 100) nanopowders and nanocomposites by using microwave
oven. The main objectives of this work are: (i) study the effect of CF addition on the microstructural and magnetic properties of LSMO: CF composites. (ii) Comparative study of microstructural and magnetic properties of in-situ and ball milled synthesized LSMO: cobalt ferrite nanocomposites using microwave oven. Different characterization techniques such as DSC-TG, XRD, particle size analysis, SEM, density and M-H loop have been performed to study the properties of these composites. Minimum calcinations temperature for pure LSMO and CF powders is 800 °C as observed from thermal analysis. X-ray diffraction analysis confirms the presence of two phases with either LSMO or CF, without any impurities. The most intense peak of LSMO in ball-milled
synthesized LSMO: CF composites show more strain due to its high density microstructure and small size with nearly spherical in shape as compared to in-situ LSMO: CF composites. The particle size of LSMO is smaller as compared to CF in these composites. Back-scattered SEM
with EDAX confirms the two phase system of all LSMO: CF composites except for 70 mol% LSMO: 30 mol% CF ball-milled composites (thin layer of CF is well surrounded on LSMO particles). All composites show higher coercivity and lower saturation magnetization as compared with standard CF samples. Composites having composition of 70 mol% LSMO: 30 mol% CF ball-milled samples show higher coercivity of 1080 Oe among all composites due to its different microstructure, where LSMO is acts as pinning center. This composite is showing
better magnetic properties as compared to other composites and could be most applicable for
practical application.