Controlled Synthesis, Processing, and Applications of Structural and Functional Nanomaterials: Nanostructure Synthesis & Mechanisms
Sponsored by: ACerS Basic Science Division, ACerS Electronics Division, ACerS Engineering Ceramics Division
Program Organizers: Haitao Zhang, University of North Carolina at Charlotte; Gurpreet Singh, Kansas State University; Kathy Lu, University of Alabama Birmingham; Edward Gorzkowski, Naval Research Laboratory; Jian Shi, Rensselear Polytechnich University; Michael Naguib, Tulane University; Sanjay Mathur, University of Cologne
Monday 2:00 PM
October 10, 2022
Room: 320
Location: David L. Lawrence Convention Center
Session Chair: Haitao Zhang, University of North Carolina at Charlotte; Sanjay Mathur, University of Cologne
2:00 PM Invited
Manipulating Material Synthesis Using Electromagnetic Fields: B. Reeja Jayan1; 1Carnegie Mellon University
This talk will describe our efforts to merge exploratory experiments and computation with data-driven methods to define new thermodynamic foundations that better explain the behavior of groups of atoms under externally applied electromagnetic fields. We used high-resolution synchrotron x-ray studies to demonstrate the first experimental evidence that 2.45 GHz microwave fields stabilize a different atomic structural arrangements or phase(s) in ceramics like TiO2, and ZrO2, compared to conventional, high temperature furnace based synthesis. Through a combination of in-situ and ex-situ characterization, as well as molecular dynamics simulations, we show that externally applied fields can induce far-from-equilibrium phases in ceramics via a defect-mediated, field-driven, nonthermal effect. Our work thus lays the theoretical foundations for deploying EM fields as a new processing tool to access high temperature ceramic phases with minimal thermal input; allowing us to explore regions of phase space, microstructures, and properties not accessible via conventional synthesis.
2:30 PM Invited
Out-of-oven Rapid Fabrication of Entropy Stabilized Oxides Patterned on Carbonaceous Nanomaterials Using Radio Frequency Heating: Jared Rapp1; Lalith Kumar Bhaskar2; Ravi Kumar2; Aniruddh Vashisth1; 1University of Washington; 2Indian Institute of Technology-Madras
High entropy oxides (HEOs) are a new class of stable hybrids of different metal oxides, with material properties somewhere between the constituent oxides, or occasionally entirely new properties. One unique quality of HEOs is that their chemical compositions can be adjusted, either by manipulating the element type and ratios, allowing for the fine-tuning of material properties. Currently, the largest limitation of HEOs are their energy intensive fabrication processes that require 1500℃ multiple-hour sintering process. As a result, the development and scale-up of new HEOs has been slow. In this talk, we will present a new HEO fabrication method that couples solution combustion synthesis and radio frequency (RF) rapid heating for energy efficient HEO synthesis. This method reduces the formation temperature of HEOs down in the range of 200℃, allowing for much more efficient fabrication; RF heating allows for out-of-oven synthesis of HEOs in a matter of seconds rather than hours.
3:00 PM
Synthesis and Growth Mechanism Study of Metalloid Nanostructures: Ahmed Abdelazeez1; Shifat Us Sami1; Tom Schmedake1; Yong Zhang1; Haitao Zhang1; 1University of North Carolina at Charlotte
Metalloids are a group of elemental materials with properties in between those of metals and nonmetals, including B, Si, Ge, As, Te, and At, etc. While various nanostructures of B, Si, and Ge have been intensively studied with synthesis, property measurement and device testing, the nanostructures of other metalloids have not been thoroughly investigated. We are interested in the nanostructures of Te (tellurium). Te is a p-type semiconductor with a narrow band gap, which can be tuned with dimension control. It has special electrical and optical properties, such as photoconductivity, non-linear optical property, high carrier mobility, thermoelectricity, and piezoelectricity, etc. This talk is focused on the development of low-dimensional structures of Te, from microrods, nanowires, to nanoplates using a vapor-based synthesis method. Growth mechanism study is performed to explore the parameter effects on the growth control of dimensions and morphologies. Structure characterization and property measurement are also performed.
3:20 PM Break
3:40 PM
Molten Salt Synthesis of Inorganic Nanomaterials: Yuanbing Mao1; 1Illinois Institute of Technology
Nanomaterials often possess novel properties and provide model systems to understand nanoscience phenomena. Given the intimacy between the structural features and functions of nanomaterials, the development of facile synthetic methods is still an urgent necessity. Molten-salt synthesis (MSS) method is one of those approaches with simplicity, versatility, and cost-effectiveness. While bulk materials have long been prepared using flux method, uniform nanomaterials prepared by the similar MSS technique has only arisen relatively recently, that is, within the current century. Over the years, our laboratory has applied this method to make various nanomaterials, especially those of transition-metal oxides. In this presentation, various examples will be demonstrated, including materials with perovskite, fluorite, pyrochlore and spinel structures, along with relevant growth mechanism studies and the property measurements of these synthesized nanomaterials. Therefore, the MSS method will continue becoming widely disseminated and broadly adopted as a facile, reliable, and scalable synthetic approach for nanomaterials.
4:00 PM
Enhancing the Low-temperature Consolidation of Nanosilver Materials: Henry Young1; Jared McCoppin2; 1Wright State University; 2University of Dayton
Nanosilver materials represent a potential alternative to polymer-filled epoxies in high-temperature electronics die attach applications. Silver nanoparticles, with diameters typically in the 10-30nm range, can be consolidated to solid silver structures at temperatures significantly under the bulk sintering temperature range, at low pressure and temperatures. Surface diffusion acts as the primary sintering/consolidation mechanism, and sufficient mass transport can occur to allow nanoparticle consolidation at pressure in the 1-10 MPa range and at 100-300C. Such “cold sintering” processes allow die attach with a controlled zero-stress point, which has significant advantages in power electronics packages. We have studied the effect of a range of nanosilver sintering aids, such as AgNO3 and other additives that can provide enhanced diffusion during consolidation, and their effect on microstructural development during consolidation.
4:20 PM
Thermo-Chemical Reduction Controlled Exsolution of Metal Nanoparticles (NPs) From Perovskite Lattice: Synthesis to Application: Aman Bhardwaj1; Shital Kale2; Benedict Witulski1; Anna Verma1; Sanjay Mathur1; 1University of Cologne; 2Chonnam National University
Transition-metal nanoparticle (NP) catalysts supported on solid materials represent potentially competitive candidates for heterogeneous catalysis. However, the high surface free energy and high redox ability possess a huge threat to their microstructural and chemical stability. Therefore, methodologically and conceptually novel immobilization methods are critically required. In this work, we employ the exsolution approach for the development of metal NPs decorated metal oxide catalysts. Ni metal and Fe-Ni alloy NPs were exsolved from Ce, Ni co-doped LaTiO3 and Sr, Ni co-doped LaFeO3 perovskite oxide backbones by a controlled thermochemical reduction treatment. The materials synthesized thus were evaluated as electrocatalyst for hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR) and found to deliver superior electrochemical properties over bare metal oxide. This validates the great potential of the exsolution technique for the development of highly active and stable metal/metal oxide heterostructure catalysts.
4:40 PM
Mechanistic Investigation of the Formation of Transition Metal Nanocrystallites Embedded in Amorphous Silicon Nitride Nanocomposites: Norifumi Asakuma1; Shotaro Tada1; Erika Kawaguchi1; Motoharu Terashima1; Sawao Honda1; Samuel Bernard2; Yuji Iwamoto1; 1Nagoya Institute of Technology; 2University of Limoges, CNRS, IRCER, UMR 7315
We report the mechanistic investigation of the formation of transition metal (Tm) nanocrystallites during the formation of amorphous silicon nitride at a temperature as low as 400 ℃, using perhydropolysilazane (PHPS) as a preformed precursor and further coordinated by transition chloride (TmCl2, Tm = Co, Ni); thus, forming the non-noble Tm as a potential catalyst and the support in an one-step process. It was demonstrated that TmCl2 catalyzed dehydrocoupling reactions between Si-H and N-H bonds in PHPS to afford ternary silylamino groups, which resulted in the formation of a nanocomposite precursor via complex formation: Tm (II) cation of TmCl2 coordinated the ternary silylamino ligands formed in situ. It was revealed that the Tm-N bond formed by a nucleophilic attack of the N atom on the Tm(II) cation center, followed by Tm nucleation below 300 ℃, which was promoted by the decomposition of the transition metal nitride species (TmxNy).