Disentangling the power transfer process by non-contact optical measurement in nickel-zinc ferrite/piezoelectric magnetoelectric gyrators

•Non-contact optical measurement method was employed to disentangle power transfer.•Mechanical loss in interlayers still restricts further improvement of efficiency.•Higher efficiency with lower mechanical loss was found in tri-layer gyrators. To precisely position the main energy dissipation sources in ferrite/piezoelectric ME-coil gyrators, the dynamic magneto-mechanical-electric conversion process was disentangled quantitatively by employing a non-contact optical measurement methodology. For the sample fabrication, successful crystallization as well as desired magnetic properties for sintered spinel ferrites was confirmed by XRD and SQUIDs measurements. Trapped magnetic energies in ferrites will convert into kinetic energies accompanying indispensable dissipations in this dynamic process, and the converted kinetic energies can be measured quantitatively in the form of vibrating velocity by focused laser beam. As a result, only ~71% of mechanical energies can be transferred successfully to next layer due to the influence of adhesive in tri-layer sample while the value is 57% for bi-layer one. Finally, comparative studies of low-frequency/resonance ME interactions and power conversion efficiency in tri-layer and bi-layer samples were measured, and an eventual maximum PE of 80.3% under optimum load of 3.5 kΩ was achieved. We infer from the results that the mechanical loss between layers is still a bottleneck to block the efficient energy transfer. These findings provide a deep analysis to reveal the dynamic energy transfer in ME-coil gyrators as well as a flexible pathway for ME gyrators design.