ACerS Richard M. Fulrath Award Session: ACerS Richard M. Fulrath Award Session
Program Organizers: Jonathan Salem, NASA Glenn Research Center
Monday 2:00 PM
September 30, 2019
Room: Portland Ballroom 253
Location: Oregon Convention Center
Session Chair: Jonathan Salem, NASA Glenn Research Center
2:00 PM Invited
Engineering Cellular Ceramics with Modulated Pore Configurations: Manabu Fukushima1; 1National Institute of Advanced Industrial Science and Technology
This presentation reviews our advanced methodology for engineering macroporous ceramic components, that can create wide range of porosity from 50 to 98 vol% and various pore configurations such as unidirectional, bridging, bamboo-like, spherical and gradient porosities, by employing carefully selected gelation-freezing, blowing and sintering conditions. Three main technological features have beendiscussed in terms of (1) partial sintering with a suitable amount of sintering additive, to control nano-sized porosity during sintering, (2) the use of ice crystals, as sacrificial pore formers, formed by freezing raw particle dispersed gel bodies, leading to ultrahighly porous ceramic components after sublimating ice crystals by vacuum drying and subsequently sintering, and (3) various blowing techniques for molten preceramic polymers or powder compacts to provide spherical porosities. This presentation intends to give an overview of their distinctive characteristics such as fluid permeability, mechanical strength, machinability, electrochemical performance, piezoelectric property and thermal conductivity of the produced ceramic components with varied morphology and compositions. In addition, the relationship between the microstructure and mechanical/thermal properties has been discussed using a multiscale modeling technique, in which a homogenization method has been conducted with microscopic models created from three dimensional images, collected by X-ray computed tomography (CT) and stress or temperature distributions in macroscopic samples by finite element method. The simulation results have been well consistent with the experimental results, suggesting that this modeling technique can be thus confirmed to become a strong tool for the prediction of the mechanical or thermal properties of porous ceramics. The simple, ecofriendly, and versatile approaches proposed tailor porous architectures with engineered porosity and yields macro-cellular component with distinctive characteristics suitable for a variety of industrial applications.
2:40 PM Invited
Fabrication and Characterization of Nanoscale Dielectrics for the Design of Advanced Ceramic Capacitors: Keigo Suzuki1; 1Murata Manufacturing Co., Ltd.
Recently, dielectric layer thickness of multi-layer ceramic capacitors (MLCCs) reaches 1 mm. The starting materials for dielectric ceramics in MLCCs should have their particle size less than several ten nanometers. Hence, fabricating nanopowder with particle sizes less than 10 nm as well as understanding their properties are crucial for the design of future MLCCs. Barium titanate (BaTiO3) nanoparticles with sizes below 10 nm were fabricated by the novel processing methods such as plasma CVD. These methods allowed us to clarify the size dependent behavior of dielectric properties of BaTiO3 nanocrystals. Nanoscale characterization of dielectrics by using scanning probe microscope (SPM) is powerful approach for the design of advanced MLCCs. Morphology dependent properties for BaTiO3 films were investigated by piezoresponse force microscopy under ultrahigh vacuum (UHV) and concomitant Kelvin probe force microscopy (KFM), demonstrating that the hysteresis and surface charging behavior are strongly sensitive to microstructure and defects of the films. Further, UHV-KFM measurement for degraded MLCCs demonstrated that electric field concentrations emerged near the Ni/dielectric interface in MLCC with the evolution of insulation degradation. These findings in BaTiO3 films and MLCCs are revealed only through UHV measurements where screening charges from the ambient can be minimized, demonstrating that UHV-SPM is vital technique not only for understanding the behavior in ferroelectric nanostructures but also for the design of reliable MLCCs.
3:00 PM Invited
Piezoelectric Thin Film Processing, PiezoMEMS Devices, and an Overview of PRIGM, SHRIMP, & AMEBA Programs: Ronald Polcawich1; 1Defense Advanced Research Projects Agency (DARPA)
This presentation will provide a brief overview of previous and current research activities in piezoelectric thin films followed by a discussion of several application areas taking advantage of these materials. Within the realm of piezoelectric thin films, the two dominant materials are aluminum nitride, AlN, and lead zirconate titanate, PZT. AlN has been integral to the development of filter technologies instrumental in enabling hand-held smartphones capable of operating over a diverse set of frequency bands across the globe. PZT with its higher piezoelectric coefficient has been critical for enabling advanced inkjet print heads and is starting to make additional in roads in inertial sensors as well as acoustic and pressure sensor markets. For each of these materials, sputtering has been the dominate deposition method, especially recently. Continued advancements in deposition approaches are critical to enabling the next generation of devices especially as continued device scaling becomes important for the internet of thing devices. This presentation will touch base on a few new results for PZT thin film processes and highlight a few of the interesting challenges that exist moving the technology forward. Additionally, this presentation will provide a snapshot of the current research portfolio in the area of miniature inertial sensors, small scale robotics, and hand-held VLF transmitters with an emphasis on piezoelectric actuation to enabling these technologies. Finally, a few topics will be presented on the improvements in additive manufacturing of functional materials, such as shape memory alloys or piezoelectrics and how this could vastly improve rapid prototyping capabilities and unlock novel MEMS applications through previously inaccessible device geometries.
3:20 PM Break
3:40 PM Invited
Dielectric Material Design and Lifetime Prediction for Highly Reliable MLCCs: Koichiro Morita1; 1Taiyo Yuden Co., Ltd.
Multilayer ceramic capacitors (MLCCs) are widely used for consumer electronics, network servers, industrial machines, and automotive, owing to large capacitance per volume and high reliability. State-of-the-art MLCCs have extremely thin dielectric layers as less than 0.5 ?m at present, which requires highly reliable ceramics materials to endure a high electric field for a long time period. We have consistently worked on improving the reliability of dielectric materials for MLCC resulting in the MLCC capacity density which has been expanded more than 100 times in the past ten years. Oxygen vacancy migration under dc electric field is widely believed to be one of the main causes of the resistance degradation of MLCCs with Ni internal electrodes (Ni-MLCCs). We, therefore, researched the degradation behavior of MLCC over time and its suppression method. Our research clearly showed the influence of various additive elements on reliability from both the structure and the electric characteristics. We employed electrochemical impedance analysis along with thermally stimulated depolarization current (TSDC) analysis to design the grain boundary composition for MLCCs, which led to the development of new understanding concerning the roles of grain boundary for the suppression of oxygen vacancy migration. For example, we revealed that a high concentration of Mn segregation at the grain boundary had a dominant influence on the device lifetime and insulating properties for the Ni internal electrode MLCCs.It is also extremely important to make a correct prediction of reliability in the actual usage environment of MLCCs. We recently proposed a novel physical model that takes into consideration the overpotential factor that can solve the underlying problems in highly accelerated lifetime test (HALT) as well as a new life prediction formula theoretically modified based on the model.
4:00 PM Invited
Engineered Ceramic Materials for Energy Storage: Vilas Pol1; 1Purdue University
ViPER (Vilas Pol’s Energy Research) laboratory at Purdue University focuses its research activities on the development of high capacity ceramic based electrode materials, their engineering for longer cycle life and improved battery safety. Considering the advantages and limitations of known synthesis techniques, a solvent-less, single step ‘Autogenic Chemical Reactions (ACR)' processing technology has been developed to fabricate a variety of unique anode and cathode materials for Li-ion, Na-ion, K-ion and Li-S batteries. Mechanistic elucidation of the formation of representative ceramic materials (TiO2-C, VOx-C) under auto-generated pressure at elevated temperature will be discussed. ACR is distinct from existing solvothermal, hydrothermal, and solid-state processes, becoming a revolutionary versatile synthesis route. ViPER’s recent efforts on structural, morphological, compositional and electrochemical properties of various fascinating electro-chemistries with transformative technological aspects will be discussed.