Discipline: Nanoscience or Materials Science
Richard Harry - Tuskegee University
Co-Author(s): Shaik Zainuddin, Tuskegee University, Tuskegee, AL; Rifat Mahbub, University of Nebraska-Lincoln, Lincoln, NE; Shaik Jeelani, Tuskegee University, Tuskegee, AL.
With the rapid advancement of small-scale electronics, there is a growing need for improvement in the capacity and efficiency of their individual components. Poly(vinylidene-co-trifluoroethylene), (P(VDF-TrFE)) is an electroactive copolymer of poly(vinylidene fluoride (PVDF), which has been widely used in the electronics industry for its potent ferroelectric ordering. When coupled with a ferromagnetic filler material, such as boron nitride hexagonal nanosheets (h-BN), it is possible to achieve a magneto-electric ferroic system. This enables such devices to control and manipulate low-to-high frequency waveforms based on their coupling coefficients. In this study, we have proven the effectiveness of a modified solvent casting technique coupled with a novel hybrid mixing method for the fabrication of a magneto-electric antenna, composed of P(VDF-TrFE) and h-BN. At first, an amount of P(VDF-TrFE) was dissolved in polar solvent DMF and then combined with h-BN nanosheets at varying weight percentages of 1, 5, and 10wt% based on weight of P(VDF-TrFE) to obtain a homogeneous solution. Next, samples underwent a special hybrid mixing method, alternating between sonication and magnetic stirring to effectively disperse nanosheets. Solutions were then casted evenly onto glass substrates to synthesize thin-film magneto-electric nanocomposite antennas. Resultant antennas were then post-processed to increase their β-phase content, which is the highly polarized phase of P(VDF-TrFE). Thin-film nanocomposite antennas were then characterized in comparison to neat (0wt% h-BN) P(VDF-TrFE) variation as a control. Scanning Electron Microscopy (SEM) micrographs at magnification region of 10µm reported homogenous dispersion of h-BN nanosheets amongst P(VDF-TrFE) matrix, and displayed sites of lamellar crystal growth from the potential of nucleation. Melting and phase properties of samples were characterized using Differential Scanning Calorimetry (DSC), which showed a 2% improvement in increasing the ferroelectric to paraelectric phase transition (Curie) temperature of 120oC. X-Ray Diffraction (XRD) patterns indicated intense β-phase peaks of (200) at 21.6o and broadened peaks (002) at 26.7o indicating the strong presence of h-BN imbedded within the matrix. Antenna samples were then sputtered with Au-Pd layers for P-E Loop Tracing. P-E Hysteresis Loops were conducted to observe polarizability with respect to varying electric field, where P(VDF-TrFE) antennas loaded with 5wt% h-BN displayed an increase in polarization values up to an applied electric field of 2000 kV/cm. Saturated magnetization values were reported at room temperature via Vibrating Sample Magnetometer (VSM), where P(VDF-TrFE) antennas loaded with 10wt% exhibited highest values with excellent remnant magnetization, indicating the presence of ferromagnetic ordering. Magneto-electric coefficients were calculated using a combined field model, which implied that the higher coupling coefficient occurred with the addition of 10wt% h-BN@P(VDF-TrFE). Applications of studied nanocomposite antennas will be directed towards the fabrication of novel planar sensor devices that receive and emit high-frequency external electromagnetic fields. Such sensors can be used for a wide range of applications, including flexible displays, automotive RF switches, wearable electronics, and even artificial sensory systems for biomedical use.
Funder Acknowledgement(s): HBCU-UP GrantPartnership for the Research and Education of Materials (PREM)The National GEM Consortium
Faculty Advisor: Shaik Zainuddin, PhD, firstname.lastname@example.org
Role: Synthesis of all sample types, DSC, P-E Loops, SEM, and ME coefficient calculations.