March 6-11, 2016
All-oxide composites are increasingly investigated in the field of microelectronics and telecommunications because of their multi-functionalities. Dielectric properties can be tuned in ferroelectric-based composites performed by Spark plasma sintering (SPS) through a control of composition, grain size, architecture and charged defects at interfaces. Using SPS on ceramic bilayers made of ferroelectric Ba0.65Sr0.35TiO3 (BST65/35) and TiO2 dielectric phases, we show that the reactivity at their interfaces is dependent on the direction of the current and/or on the sintering temperature. The electric current promotes an interphase growth whose thickness depends on the bilayer stacking and on the current direction. The influences of the current density and direction on the rate of growth of interphases were mainly studied for intermetallic multilayers. We show here that this can be extended to dielectric oxides and that properties can be tuned by adjusting the nature of the composite (BST/TiO2, BST/ZrO2) and the architecture (bilayer, multilayer or random 3D mixing). The specific SPS conditions enable the control of both the interface between the two components and the reduction level leading to interface-driven dielectric properties. We suggest that such approach can be extended to other interphases between oxides of different reduction ability.
Catherine Elissalde, "Electric current as a driving force for interphase growth in spark plasma sintered dielectric composites" in "Electric Field Assisted Sintering and Related Phenomena Far From Equilibrium", Rishi Raj (University of Colorado at Boulder, USA) Thomas Tsakalakos (Rutgers University, USA) Eds, ECI Symposium Series, (2016). http://dc.engconfintl.org/efa_sintering/29