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La2NiMnO6 is prepared for two different sintering time durations: 4 hour (4H) and 24 hour (24H). The magnetization data suggest a double ferromagnetic (FM) transition for 24H, whereas a single FM transition for 4H sample. The 4H sample was found to possess several microscopic pores compared with the 24H sample, and thus, these pores are vacuum impregnated with polyvinylidene fluoride (PVDF). The PVDF in the impregnated sample is found to crystallize in beta phase. The first and second order magnetoelectric coefficients are extracted from the measured data and plotted as a function of temperature. The room temperature region is found to be dominated by the magnetoconductivity/magnetoloss and thus resulting low ME voltage. With lowering of temperature, the situation improves, and for T < 200 K, the loss component becomes negligible so that the true magnetoelectricity is observed. A comparative study on all the three samples (4H, 24H, and 4H + PVDF) shows a significant enhancement in the magnetoelectricity in the 4H + PVDF sample. The highlight of this report is the unique way to arrest the porosity by PVDF impregnation into the pores of La2NiMnO6 so that leakage is minimized.

Multiferroic polymer composites of La2NiMnO6 and poly(vinylidene fluoride) (PVDF) in the form of disks and thick films were made via a two-step method and a solution casting method, respectively. These composite samples are studied via powder x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and field emission scanning electron microscopy (FESEM). The XRD data revealed the biphasic (P21/n + R-3c) crystal symmetry of La2NiMnO6 nanoparticles in the disk samples but monophasic (R-3c) crystal symmetry in the film sample. The formation of an electroactive β-phase of PVDF is observed in the FTIR spectra of a composite film sample. Estimation (via FTIR data) revealed the maximum β-phase fraction of PVDF (∼37%) and zero porosity (in FESEM images) for the film sample. The magnetoelectric (ME) voltage measurement on these composite samples show significant ME voltage for temperatures as high as 400 K, which otherwise is zero for T > 277 K in La2NiMnO6. Among the three composites, the film sample exhibited the maximum value of a first-order ME coefficient of 9.6 mV/cm Oe, and this value is at least two orders higher than that of the La2NiMnO6 pellet. Such a high value of ME coefficient favors this sample for its utilization in device applications and thus makes it technologically viable for ME based applications.