December 2018 - Msepostdoc-list

Seminar Notice for Zara Molaeinia's Preliminary Exam Thursday, Dec. 20, 2018, at 9:00 a.m., in ARMS 1103
by Son, Rosemary E 19 Dec '18

19 Dec '18

Please consider attending the following: MATERIALS ENGINEERING SEMINAR "3D Multi-Scale Crystal Plasticity Finite Element Modeling of Nano-Metallic Multilayers" By Zara Molaeinia Purdue MSE Ph.D. Preliminary Exam Advisor: Professor David F. Bahr ABSTRACT Nanometallic multilayers (NMMs) are two-dimensional nanosystems made of alternating metallic nanolayers as unique multifunctional materials with novel properties such as high strength and ductility. The essential concepts differentiating NMMs from their bulk counterparts are the primary role of the layer thickness and the detailed structure of interfaces as the controlling parameters to modify and regulate laminate composites multifunctionality. Design and behavioral prediction of NMMs necessitate an exhaustive study and a profound understanding of anisotropic plastic response in single and polycrystalline NMMs as well as strengthening mechanisms ascribed to layers and interfaces morphology and composition, crystallographic orientations demarcated by grain boundaries, precipitates, and dislocation mechanisms in different segments. Multiscale modeling of NMMs using 3D crystal plasticity in a nonlinear finite element (CPFE) framework is being developed to investigate the mechanical behavior of these nanolaminate systems. The model is governed by features at three dominant scales, viz. (i) sub-layer scale characterized by the morphology and size of the precipitates, (ii) layer scale of single crystals portrayed by layers and interfaces characteristics, and (iii) super-layer scale corresponding to representative polycrystalline aggregates. In the multiscale spectrum, the length scale variation is considered to stride from nano- to micro- and millimeter. Physics-based non-local crystal plasticity constitutive models are considered at different scales to capture dislocation mechanisms and size effects due to the presence of precipitates, interfaces and grain boundaries. In order to bridge the multiscale segments, methods of parametric homogenization are availed. Date: Thursday, December 20, 2018 Time: 9:00 A.M. Place: ARMS 1103

1 1

Seminar Notice for Aiga Yermembetova's Preliminary Exam. Seminar, Tuesday, Dec. 18, at 8:00 a.m., in ARMS 1028. Review: same day, at 9:00 - 9:30 a.m., in ARMS 2222; Exam: same day at 9:30 in ARMS 2222
by Son, Rosemary E 17 Dec '18

17 Dec '18

Please consider attending the following: MATERIALS ENGINEERING SEMINAR "Nanocomposite Films on Flexible Substrates for Conductometric Sensing of Gas Analytes." By Aiganym Yermembetova Purdue MSE Ph.D. Preliminary Exam Advisors: Professor Alexander Wei and Professor David F. Bahr ABSTRACT In recent years a lot of attention has been invested on 2D transition metal dichalcogenides (TMDC), their synthesis, structural, electrical and optical properties. Due to the interesting chemical, electrical properties, such as tunable bandgap, TMDCs have been considered as promising candidates for the manufacturing of low-cost devices on flexible substrates. The following work describes progress toward conductometric sensors based on exfoliated MoS2 for the detection of specific volatile organic compounds (VOCs). Date: Tuesday, December 18, 2018 Time: 8:00 A.M. Place: ARMS 1028

1 1

Seminar Reminder for Jiaqi Yang's Preliminary Exam Seminar, Thursday, Dec. 13, at 11:30, in ARMS 1021. "First Principle Study of Transition Metal Based Electrocatalysts"
by Son, Rosemary E 12 Dec '18

12 Dec '18

Please consider attending the following: MATERIALS ENGINEERING SEMINAR "First Principle Study of Transition Metal Based Electrocatalysts" By Jiaqi Yang Purdue MSE Ph.D. Preliminary Exam Advisor: Professor Peilin Liao ABSTRACT Electrocatalysts for the water splitting reaction and fuel cell reactions attract lots of efforts. The hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR) are of great importance among these reactions. Noble metal based electrocatalysts are reported as the state-of-art in electrocatalysts of HER and ORR. However, the high price of noble metals is the key limit to use in large scale application. Transition metal and its nitrides are considered as promising candidates to replace noble metal based electrocatalysts. In order to find the ideal replacement, the screening on transition metal based electrocatalysts is of critical importance. This study is planning to focus on transition metal based electrocatalysts, especially the interfacial structure and transition metal nitride as Pt cluster substrate. The goal is to find favorable candidates for HER and ORR reactions, reveal the pattern of their electrocatalytical performance and eventually explain the mechanism of their enhancement. Date: Thursday, December 13, 2018 Time: 11:30 A.M. Place: ARMS 1021

1 0

Seminar Reminder for Jarrod Lund's Preliminary Exam, Tuesday, Dec. 11, at 5:00 p.m., in ARMS 1021
by Son, Rosemary E 10 Dec '18

10 Dec '18

Please consider attending the following: MATERIALS ENGINEERING SEMINAR “Modeling Charged Grain Boundaries in Lithium-ion Cathode Materials” By Jarrod M. Lund Purdue MSE Ph.D. Preliminary Exam Advisor: Professor R. Edwin García ABSTRACT Modern and future technologies such as cell phones, laptops, electric vehicles, and renewable energies are increasingly dependent on the availability of eﬃcient, long lasting batteries. To achieve these desired properties, batteries must be designed at every length scale, from atomistic chemistry to the macroscopic interactions between components. This paper reviews models which analyze the impact of grain boundaries on conductivity. In particular, the Debye-H¨uckel model deﬁned the length of the space charge layer, the Mott-Schottky model showed how immobile dopants increased the space charge layer’s width. The Gouy-Chapman model used two defects of opposite charge polarity to minimize the space charge layer. Recently, the Mebane-DeSouza model included non-dilute eﬀects for the ﬁrst time, while the Vikrant-Chueh-Garcíamodel showed how mechanical eﬀects inﬂuence electrochemical properties. By expanding the Vikrant-Chueh-García model to incorporate non-idealities in other materials, a new phase ﬁeld model of the grain boundary is developed to help in the optimization of the space charge layer in high power applications. Date: Tuesday, December 11, 2018 Time: 5:00 P.M. Place: ARMS 1021

1 0

Seminar Reminder for Pengyu Xu's Preliminary Exam, Tuesday, Dec. 11, at 8:30 a.m., in ARMS 3115
by Son, Rosemary E 10 Dec '18

10 Dec '18

Please consider attending the following: MATERIALS ENGINEERING SEMINAR "Cathode-Electrolyte Interfacial Properties in Solid State Li-Ion Batteries" By Pengyu Xu Purdue MSE Ph.D. Preliminary Exam Advisor: Professor Lia A. Stanciu ABSTRACT Lithium ion batteries (LIBs) have been applied to portable electronics as power source for the past decades. However, the conventional lithium ion batteries suffer greatly from safety issues since the organic electrolytes are flammable. Therefore, replacing organic electrolytes with solid electrolytes (SEs) has been considered as a solution to the safety problem. Solid state electrolytes usually provide boarder electrochemical windows which allow the use of electrode materials with higher capacity and larger potential difference, therefore increase the energy density of batteries. Meanwhile, there are still great challenges encountered when trying to apply SEs to all-solid-state batteries. Poor ionic conductivities of SSEs and high interfacial resistances between SSEs and electrodes are drawbacks that can result in low power densities and inferior cycling performances of the batteries. There is evidence that the formation of inter-electrode films (IEF) at the interface of ceramic compounds could heavily influence the charge transfer kinetics and cost great capacity loss. However, the chemical and thermodynamic properties of the IEFs as well as the phase formation dynamics are still lack of understanding. Our goal is to study the formation of charged IEF, and engineer structurally stable 2D interfacial phases that maximize the interfacial conductivity and mechanical integrity. This is very important to solid state batteries. Date: Tuesday, December 11, 2018 Time: 8:30 A.M. Place: ARMS 3115

1 0

Seminar Notice for Jiaqi Yang's Preliminary Exam Seminar, Thursday, Dec. 13, at 11:30, in ARMS 1021. "First Principle Study of Transition Metal Based Electrocatalysts"
by Son, Rosemary E 07 Dec '18

07 Dec '18

Please consider attending the following: MATERIALS ENGINEERING SEMINAR "First Principle Study of Transition Metal Based Electrocatalysts" By Jiaqi Yang Purdue MSE Ph.D. Preliminary Exam Advisor: Professor Peilin Liao ABSTRACT Electrocatalysts for the water splitting reaction and fuel cell reactions attract lots of efforts. The hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR) are of great importance among these reactions. Noble metal based electrocatalysts are reported as the state-of-art in electrocatalysts of HER and ORR. However, the high price of noble metals is the key limit to use in large scale application. Transition metal and its nitrides are considered as promising candidates to replace noble metal based electrocatalysts. In order to find the ideal replacement, the screening on transition metal based electrocatalysts is of critical importance. This study is planning to focus on transition metal based electrocatalysts, especially the interfacial structure and transition metal nitride as Pt cluster substrate. The goal is to find favorable candidates for HER and ORR reactions, reveal the pattern of their electrocatalytical performance and eventually explain the mechanism of their enhancement. Date: Thursday, December 13, 2018 Time: 11:30 A.M. Place: ARMS 1021

1 0

Seminar Reminder for Jessica Sargent's Preliminary exam. Monday, Dec. 10, at 10:30 a.m., in ARMS 1028
by Son, Rosemary E 07 Dec '18

07 Dec '18

Please consider attending the following: MATERIALS ENGINEERING SEMINAR "Investigation of pH-Sensitive Hydrogel Nanocomposite Behavior in Ionic Media" By Jessica Sargent Purdue MSE Ph.D. Preliminary Exam Advisors: Professor John A. Howarter and Professor Kendra A. Erk ABSTRACT pH-sensitive hydrogels and hydrogel nanocomposites have found applications across many fields, from medicine to infrastructure. In these applications, the hydrogel performance is strongly dictated by the character of the aqueous environment in which it is employed. While the complexity of and uses for these materials has grown significantly, the fundamental understanding of interactions between the hydrogels and their environments remains poorly understood. The vast majority of characterization currently performed on hydrogels in situ measures only bulk properties, while molecular scale properties are only observable in dry gel materials. In particular, the macroscale effect of salt ions on pH-sensitive hydrogels can be observed readily, but the character of the interactions causing the changes in hydrogel properties remain largely only theorized. This work proposes methods by which to characterize the ionic interactions occurring between polymer, nanoparticle, and counterion as well as the spatial arrangement of these species within the hydrogel nanocomposite matrix. In so doing, this work aims to develop fundamental structure-property relationships between the chemistry and structure of a hydrogel and interactions with its environment that will contribute to the informed design of pH-sensitive hydrogel materials for optimal performance in distinct target environments. Date: Monday, December 10, 2018 Time: 10:30 A.M. PURDUE MSE [cid:image003.png@01D48E09.2BFA2290] Place: ARMS 1028

1 0

Seminar Notice for Zachary McClure's Preliminary Exam. Monday, Dec. 10, at 1:30, in ARMS 1028. Review Dec. 10, 2:30 - 3:00 in ARMS 2326; Exam Dec. 10, at 3:00, in ARMS 2326
by Son, Rosemary E 07 Dec '18

07 Dec '18

Please consider attending the following: MATERIALS ENGINEERING SEMINAR “Thermal Transport Properties in Complex Nanostructured Metals: A Methodology Case Study” By Zachary D. McClure Purdue MSE Ph.D. Preliminary Exam Advisor: Professor Alejandro Strachan ABSTRACT Research attention towards reactive metal multilayers (RMM) has grown rapidly in the last 30 years. This class of energetic materials boast a well-controlled gas less exothermic reaction when primed that can be used for ignition mechanisms, lead-free soldering, and welding applications. The reaction mechanism of these multilayers involve an initial stimulus followed by a mixing of the alternating metallic layers. This mixing gives oﬀ heat and cascades into a self-propagating reaction front. The characteristics of this reaction front are determined by the exothermicity of the heat of mixing between metallic layers, and the thermal transport from the reaction site to unreacted material. Many multilayers have abrupt, sharp interfaces between layers, and thermal transport across the interface can be modeled using simple electron model approximations. However, in more recent years researchers have been ﬁnding classes of multilayers that pre-blend their interface prior to any thermal or mechanical stimulus. The amorphous regions between bulk crystalline layers can be beneﬁcial or detrimental to thermal transport depending on the application. This review takes a computational approach for calculating the thermal transport characteristics of the amorphous alloy region. We will compare two diﬀerent methods for calculating thermal conductivity in metallic glasses using the length dependent MD-Landauer approach, and variations of the Mott s-d model. The former boasts robust DFT calculations coupled with non-equilibrium Green’s functions to model transport across a device, and the latter considers the contributions between s and d-states of a glass for thermal transport. The two methods will be explored in detail, calculations will be done with each, and their results will be compared with initial experimental results from collaboration with Sandia National Laboratory (SNL) Date: Monday, December 10, 2018 Time: 1:30 P.M. Place: ARMS 1028

1 1

Seminar Notice for Jarrod Lund's Preliminary Exam, Tuesday, Dec. 11, at 5:00 p.m., in ARMS 1021
by Son, Rosemary E 05 Dec '18

05 Dec '18

Please consider attending the following: MATERIALS ENGINEERING SEMINAR “Modeling Charged Grain Boundaries in Lithium-ion Cathode Materials” By Jarrod M. Lund Purdue MSE Ph.D. Preliminary Exam Advisor: Professor R. Edwin García ABSTRACT Modern and future technologies such as cell phones, laptops, electric vehicles, and renewable energies are increasingly dependent on the availability of eﬃcient, long lasting batteries. To achieve these desired properties, batteries must be designed at every length scale, from atomistic chemistry to the macroscopic interactions between components. This paper reviews models which analyze the impact of grain boundaries on conductivity. In particular, the Debye-H¨uckel model deﬁned the length of the space charge layer, the Mott-Schottky model showed how immobile dopants increased the space charge layer’s width. The Gouy-Chapman model used two defects of opposite charge polarity to minimize the space charge layer. Recently, the Mebane-DeSouza model included non-dilute eﬀects for the ﬁrst time, while the Vikrant-Chueh-Garcíamodel showed how mechanical eﬀects inﬂuence electrochemical properties. By expanding the Vikrant-Chueh-García model to incorporate non-idealities in other materials, a new phase ﬁeld model of the grain boundary is developed to help in the optimization of the space charge layer in high power applications. Date: Tuesday, December 11, 2018 Time: 5:00 P.M. Place: ARMS 1021

1 0

Seminar Notice for Pengyu Xu's Preliminary Exam, Tuesday, Dec. 11, at 8:30 a.m., in ARMS 3115
by Son, Rosemary E 05 Dec '18

05 Dec '18

Please consider attending the following: MATERIALS ENGINEERING SEMINAR "Cathode-Electrolyte Interfacial Properties in Solid State Li-Ion Batteries" By Pengyu Xu Purdue MSE Ph.D. Preliminary Exam Advisor: Professor Lia A. Stanciu ABSTRACT Lithium ion batteries (LIBs) have been applied to portable electronics as power source for the past decades. However, the conventional lithium ion batteries suffer greatly from safety issues since the organic electrolytes are flammable. Therefore, replacing organic electrolytes with solid electrolytes (SEs) has been considered as a solution to the safety problem. Solid state electrolytes usually provide boarder electrochemical windows which allow the use of electrode materials with higher capacity and larger potential difference, therefore increase the energy density of batteries. Meanwhile, there are still great challenges encountered when trying to apply SEs to all-solid-state batteries. Poor ionic conductivities of SSEs and high interfacial resistances between SSEs and electrodes are drawbacks that can result in low power densities and inferior cycling performances of the batteries. There is evidence that the formation of inter-electrode films (IEF) at the interface of ceramic compounds could heavily influence the charge transfer kinetics and cost great capacity loss. However, the chemical and thermodynamic properties of the IEFs as well as the phase formation dynamics are still lack of understanding. Our goal is to study the formation of charged IEF, and engineer structurally stable 2D interfacial phases that maximize the interfacial conductivity and mechanical integrity. This is very important to solid state batteries. Date: Tuesday, December 11, 2018 Time: 8:30 A.M. Place: ARMS 3115

1 0