Mapping solution loss-tangent dependent deposition rate of MnZn-ferrite via microwave-assisted solvothermal processing

Abstract

Microwave-assisted solvothermal (MAS) process is still in its infancy, wherein the effect of various process parameters are not thoroughly studied and yet to be established. This lack of understanding renders less than satisfactory reproducibility of the physical and electromagnetic characteristics of the deposited film. This work explores the effect of precursor solution preparation protocol on the microwave-heating mechanism, which in turn, impacts the rate of film deposition of Manganese Zinc Ferrite. A key pre-deposition step, sonication time - required to dissolve the solute precursors into the polar solvent or solvent mixture - was found to have significant impact on the quality and the reproducibility of the deposited film. Thus, keeping the deposition parameters constant (deposition time and microwave power) for all experiments, the sonication time was systematically varied to investigate its effect on the deposited film. It was evidenced that the pre-deposition sonication time of the solution affects the quantity of the volatile solvent in the solution which subsequently changes solution's effective loss tangent value, thereby affecting the film quality due to changes in heating rate while microwave irradiation assisted deposition. Furthermore, to affirm the impact of solution loss-tangent, solvents with different loss-tangent were mixed at different proportion before MAS deposition process. The deposition rate found to be varied from 10 nm/min to 120 nm/min by increasing the sonication time from 30 min to 75 min. Moreover, it was evinced that the high rate of deposition yielded a relatively rough and porous film that has a tendency of delamination.