Effect of microwave instant heating on magnetic, electric and microwave absorption properties of La0.7Na0.3MnO3

The emerging method of microwave (MW) heating was adopted to synthesize a phase pure La0.7Na0.3MnO3 from their oxide precursors. The MW power (P) used for heating the sample was varied from P = 1000 W to 1600 W to examine the effect of MW power on its physical properties. A well-crystalline single phase La0.7Na0.3MnO3 was achieved in 20 min of MW irradiation with P = 1600 W. The obtained grain sizes at P = 1000 W have grown bigger and densified while increasing the P = 1600 W. Growth in the grains was reflected in the resistivity of La0.7Na0.3MnO3 prepared at high P. As the P increases from 1000 W to 1600 W, the resistivity decreases drastically and the metal–insulator transition also becomes sharp at a temperature very close to TC whereas the ferromagnetic Curie temperature (TC) is least affected. The sample prepared at low P showed larger microwave absorption than the sample prepared under high P. These findings were correlated and discussed with the structural and morphological features acquired by microwave irradiation with different powers.