Multifunctional Materials Manufacturing Facilities | Focuses
Our main research focuses include:
- High performance textured piezoelectric ceramics.
- Tunable electronic component
- Magnetoelectric composite
Colossal tunability in high frequency magnetoelectric voltage tunable inductors
Prof. Shashank Priya and Prof. Yongke Yan developed magnetoelectric VTIs that exhibit remarkable high inductance tunability of over 750% up to 10 MHz, completely covering the frequency range of state-of-the-art power electronics. The success of VTIs with large tunability and high frequency offers a new paradigm for circuit design with high energy efficiency. Their findings were published in Nature Communications, 2018, 9, 4998. [DOI: 10.1038/s41467-018-07371-y].
Abstract: The electrical modulation of magnetization through the magnetoelectric effect provides a great opportunity for developing a new generation of tunable electrical components. Magnetoelectric voltage tunable inductors (VTIs) are designed to maximize the electric field control of permeability. In order to meet the need for power electronics, VTIs operating at high frequency with large tunability and low loss are required. Here we demonstrate magnetoelectric VTIs that exhibit remarkable high inductance tunability of over 750% up to 10 MHz, completely covering the frequency range of state-of-the-art power electronics. This breakthrough is achieved based on a concept of magnetocrystalline anisotropy (MCA) cancellation, predicted in a solid solution of nickel ferrite and cobalt ferrite through first principles calculations. Phase field model simulations are employed to observe the domain level strain-mediated coupling between magnetization and polarization. The model reveals small MCA facilitates the magnetic domain rotation, resulting in larger permeability sensitivity and inductance tunability.
Giant piezoelectric voltage coefficient in grain oriented modified-PbTiO3 material
Prof. Shashank Priya and Prof. Yongke Yan reported a discovery of fundamental mechanism that can provide independent control of the highly correlated properties in terms of piezoelectric coefficient and transversal dielectric susceptibility resulting in giant piezoelectric voltage coefficient, which could be one of the best performing piezoelectric ceramic sensing material. Their findings were published in Nature Communications, 7:13089. [DOI: 10.1038/ncomms13089].
Abstract: A rapid surge in the research on piezoelectric sensors is occurring with the arrival of the Internet of Things. Single-phase oxide piezoelectric materials with giant piezoelectric voltage coefficient (g, induced voltage under applied stress) and high Curie temperature (Tc) are crucial towards providing desired performance for sensing, especially, under harsh environmental conditions. Here we report a grain-oriented (with 95% <001> texture) modified-PbTiO3 ceramic that has a high Tc (364 oC) and an extremely large g33 (115 ×10-3 V m N-1) in comparison to other known single-phase oxide materials. Our results reveal that self-polarization due to grain orientation along the spontaneous polarization direction plays an important role in achieving large piezoelectric response in a domain-motion-confined material. The phase field simulations confirm that the large piezoelectric voltage coefficient g33 originates from maximized piezoelectric strain coefficient d33 and minimized dielectric permittivity e33 in -textured PbTiO3 ceramics where domain wall motions are absent.
Giant energy density in textured piezoelectric ceramics
Prof. Shashank Priya and Prof. Yongke Yan reported the discovery of piezoelectric composition, synthesis process, and optimum microstructure that provides 359% improvement in the energy density of polycrystalline material as compared to the best-known commercial compositions. The results reported in this work will provide guidance to both academia and industry in developing high performance piezoelectrics for existing and emerging applications. Their results were published in Applied Physics Letters 102, 042903 (2013). [DOI:10.1063/1.4789854].
Abstract: Pb(Zr,Ti)O3 (PZT) based compositions have been challenging to texture or grow in a single crystal form due to the incongruent melting point of ZrO2. Here we demonstrate the method for achieving 90% textured PZT-based ceramics and further show that it can provide highest known energy density in piezoelectric materials through enhancement of piezoelectric charge and voltage coefficients (d and g). Our method provides more than 5× increase in the ratio d(textured)/d(random). A giant magnitude of d·g coefficient with value of 59 000 ×10-15m2N-1 (comparable to that of the single crystal counterpart and 359% higher than that of the best commercial compositions) was obtained.
Self-biased response in cofired magnetoelectric composites.
Self-biased response in magnetoelectric composites is fundamental towards their application in magnetic field sensors, brain interfaces, tunable transformers and filters, and storage elements. Prof. Shashank Priya and Prof. Yongke Yan demonstrated a process that is able to overcome the challenges of cofiring of heterogeneous composite and discover self-bias phenomenon in these cofired composites. Their results were published in Applied Physics Letters 102, 052907 (2013). [DOI: 10.1063/1.4791685].
Abstract: Co-fired magnetostrictive / piezoelectric / magnetostrictive laminate structure with silver inner electrode were synthesized and characterized. We demonstrate integration of textured piezoelectric microstructure with the cost-effective low-temperature co-fired layered structure to achieve strong magnetoelectric coupling. Using the co-fired composite, a strategy was developed based upon the hysteretic response of nickel-copper zinc ferrite magnetostrictive materials to achieve peak magnetoelectric response at zero DC bias, referred as self-biased magnetoelectric response. Fundamental understanding of self-bias phenomenon in composites with single phase magnetic material was investigated by quantifying the magnetization and piezomagnetic changes with applied DC field. We delineate the contribution arising from the interfacial strain and inherent magnetic hysteretic behavior of copper modified nickel zinc ferrite towards self-bias response.