April 2019 - Msepostdoc-list

Seminar Notice for Kyungjean Min's Ph.D. Final Exam. Seminar, Wednesday, April 17, at 1:30 p.m., in ARMS 1021. Exam same day at 2:30 p.m., in ARMS 2009. "Impurity Control and Analysis of Ultra-Pure Gallium for Increasing Mobility in Gallium Arsenide Grown
by Son, Rosemary E 10 Apr '19

10 Apr '19

Please consider attending the following: MATERIALS ENGINEERING SEMINAR "Impurity Control and Analysis of Ultra-Pure Gallium for Increasing Mobility in Gallium Arsenide Grown by Molecular Beam Epitaxy" By Kyungjean Min Purdue MSE Ph.D. Final Exam Advisor: Professor Kevin P. Trumble and David R. Johnson ABSTRACT High mobility 2DEG (two-dimensional electron gas) confined in GaAs is a good platform to understand correlated electron systems and a promising candidate for qubit devices. For example, the non-Abelian feature of Fractional Quantum Hall state enabling topological quantum computation is only found in GaAs with high mobility. Theoretical calculations have shown that the mobility is inversely proportional to impurities in GaAs/AlGaAs heterstructures grown by Molecular Beam Epitaxy (MBE). In recent MBE experiments, the source Ga was found to be more important in the limitation of mobility than Al and As. A high mobility of 35 million cm2/Vs was recently observed when an 8N Ga (total nominal impurity concentration of ~10 ppb) source was used compared to 25 million cm2/Vs for a 7N Ga source. In addition, significant mobility increase was observed after in-situ distillation of the source Ga before growth. In order to clarify the mechanism of how the distillation contributed to the Ga purification, thus resulting the mobility increase, the MBE in-situ distillation was analyzed by molecular distillation theory. Evaporation behavior of solvent Ga was analyzed including effects of evaporation from a crucible with receding liquid depth. Then impurity removal through molecular distillation was analyzed with molecular evaporation kinetics. The remaining 7N and 8N Ga after in-situ MBE distillation and growth were elementally analyzed by ICP-MS (Inductively Coupled Plasma Mass Spectrometry) and compared with analyses of the starting 7N and 8N Ga from same lots. Due to the increased detection limit of ICP-MS in metal analysis, the concentrations of most impurity elements reached the detection limit of ~1-10 ppb. However, unusual high concentration of 690 ppb Ge was found in the 7N Ga, exceeding the nominal concentration of 7N (100 ppb). Significant decrease in Ge concentration was found in the comparison of initial ultra-pure Ga and remaining Ga for both grades of 7N and 8N. The significant Ge losses cannot be explained by atomic Ge evaporation due to the low vapor pressure of Ge. However, a hypothesis Ge evaporation as GeO(g) by Ge active oxidation was proposed. In order to test the active oxidation of very dilute Ge in Ga in the MBE conditions with very low P(O2), the equilibrium P(GeO)-P(O2) vapor species diagram was calculated from thermodynamics. The analysis shows that even very dilute Ge in Ga of ~ 1 ppm concentration can be actively oxidized in the extremely low P(O2) of MBE. In order to prove active oxidation of Ge, molecular distillation of 7N Ga was performed in a specially constructed high vacuum chamber. The 7N Ga with unusual high Ge concentration of 440 ppb (by GDMS analysis) was distilled for 16 h at 1360 K under the starting P(O2) of 3 x 10-6 atm and the total pressure of ~ 10-5 torr. The chamber vacuum was monitored by Residual Gas Analyzer (RGA) and the residual Ga after 16 h distillation was analyzed by GDMS. In the GDMS analysis, significant Ge loss was found from 440 ppb to below the detection limit of 10 ppb, confirming Ge active oxidation hypothesis. The oxygen-assisted impurity removal in distillation also may be applicable to other impurities with high vapor pressure gaseous oxide, but low vapor pressure itself such as Al, Si and Sn. Date: Wednesday, April 17, 2019 Time: 1:30 P.M. Place: ARMS 1021

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Seminar Notice for Eduard Caicedo-Casso's Ph.D. Final Exam. Wednesday, April 17, in HAMP 2113, at 3:00 p.m. Exam same day, in ARMS 2237, at 4:00 p.m. " Shear Rheometry Protocols to Advance the Development of Microstructured Fluids"
by Son, Rosemary E 10 Apr '19

10 Apr '19

Please consider attending the following: MATERIALS ENGINEERING SEMINAR "Shear Rheometry Protocols to Advance the Development of Microstructured Fluids" By Eduard A. Caicedo-Casso Purdue MSE Ph.D. Final Exam Advisor: Professor Kendra A. Erk ABSTRACT The successful transformation of microstructured (complex) fluids into commercial products often relies on the ability to understand and control their rheological behavior. However, the implementation of rheological frameworks to drive business decisions is challenging. Majority of these fluids contain a wide variety of mesoscopic phases that contribute to a convoluted and distinct rheological response. Therefore, it is essential to combine flow characterization techniques with proper physical measurements to fully elucidate the root causes of the rheological behavior of microstructured fluids. In this order of ideas, this doctoral dissertation shows the development of three protocols of applied shear rheology. These protocols aim to advance the transformation of novel self-assembly block copolymers, concentrated surfactant solutions, and water-soluble polymers into real products. A robust set of experimental evidence is used to bridge the mesoscopic signatures of each microstructured fluid to their flow behavior. This talk focuses on the demonstration of the critical factors (chemical, physical, or thermodynamical) that could potentially drive the rheological behavior thus the successful transformation of the studied microstructured fluids. The novelty of this work lies in the integration of simple rheological measurements, scattering characterization techniques, mass transfer measurements, and advanced rheo-flow velocimetry to draw meaningful conclusions relevant to current industrial demands Date: Wednesday, April 17, 2019 Time: 3:00 P.M. Place: HAMP 2113

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Seminar Notice for Reaz Chowdhury's Ph.D. Final Exam Seminar. Monday, April 15, at 1:00 p.m., in HAMP 2102. Exam same day at 2:00 p.m., in ARMS B197. "Roll-to-Roll Fabrication of Cellulose Nanocrystal Nanocomposite for Gas Barrier and Thermal Management A
by Son, Rosemary E 08 Apr '19

08 Apr '19

Please consider attending the following: MATERIALS ENGINEERING SEMINAR "Roll-to-Roll Fabrication of Cellulose Nanocrystal Nanocomposite for Gas Barrier and Thermal Management Applications" By Reaz A. Chowdhury Purdue MSE Ph.D. Final Exam Advisor: Professor Jeffery P. Youngblood ABSTRACT Cellulose nanocrystals (CNCs) and its composite coatings may impart many benefits in packaging, electronic, optical, etc. applications; however, large-scale coating production is a major engineering challenge. To fill this knowledge gap, a potential large-scale manufacturing technique, roll-to-roll reverse gravure processing, has been described in this work for the manufacture of CNC and CNC-poly(vinyl alcohol) (PVA) coatings on a flexible polymer substrate. Various processing parameters which control the coating structure and properties were examined. The most important parameters in controlling liquid transfers were gravure roll, gravure speed, substrate speed, and ink viscosity. After successful fabrication, coating adhesion was investigated with a crosshatch adhesion test. The surface roughness and morphology of the coating samples were characterized by atomic force microscopy and optical profilometer. The Hermans order parameter (S) and coating transparency were measured by UV-Vis spectroscopy. The effect of viscosity on CNC alignment was explained by the variation of shear rate, which was controlled by the micro-gravure rotation. Finally, the CNC alignment effect was investigated for gas barrier and thermal management applications. In packaging applications, cellulose nanomaterials may impart enhanced gas barrier performance due to their high crystallinity and polarity. In this work, low to superior gas barrier pristine nanocellulose films were produced using a shear-coating technique to obtain a range of anisotropic films. Induction of anisotropy in a nanocellulose film can control the overall free volume of the system which effectively controls the gas diffusion path and hence, controlled anisotropy results in tunable barrier properties. The highest anisotropy materials showed a maximum of 900-fold oxygen barrier improvement compared to the isotropic arrangement of nanocellulose film. The Bharadwaj model of nanocomposite permeability was modified for pure nanoparticles, and the CNC data were fitted with good agreement. Overall, the oxygen barrier performance of anisotropic nanocellulose films was 97 and 27 times better than traditional barrier materials such as biaxially oriented poly(ethylene terephthalate) (BoPET) and ethylene vinyl alcohol copolymer (EVOH), respectively, and thus could be utilized for oxygen-sensitive packaging applications. The in-plane thermal conductivity of CNC - PVA composite films containing different PVA molecular weights, CNC loadings and varying order parameters (S) were investigated for potential application in thermal management of flexible electronics. Isotropic CNC - PVA bulk films with 10-50 wt% PVA solid loading showed significant improvement in thermal conductivity compared to either one component system (PVA or CNC). Furthermore, anisotropic composite films exhibited in-plane thermal conductivity as high as ~ 3.45 W m-1 K-1 in the chain direction, which is higher than most polymeric materials used as substrates for flexible electronics. Such an improvement can be attributed to the inclusion of PVA as well as to a high degree of CNC orientation. The theoretical model was used to study the effect of CNC arrangement (both isotropic and anisotropic configurations) and interfacial thermal resistance on the in-plane thermal conductivity of the CNC-PVA composite films. To demonstrate an application for flexible electronics, thermal images of a concentrated heat source on both neat PVA and CNC-PVA composite films were taken that showed the temperature of the resulting hot spot was lower for the composite films at the same power dissipation. Date: Monday, April 15, 2019 Time: 1:00 P.M. Place: HAMP 2102

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HC Brown Lectures - Registration Deadline Friday, April 12
by Coar, Stacey L 08 Apr '19

08 Apr '19

36th Herbert C. Brown Lectures in Organic Chemistry Date: Thursday, April 18, 2019 Time: 8:55 AM - 6:30 PM (EDT) Location: Purdue University, Stewart Center (STEW) Room 214 Friday, April 12 is the last day to register for the HC Brown Lectures! Registration is free and includes lunch for all participants who register by Friday, April 12, 2019. Don't forget to sign up to present a poster. The poster submission deadline is Wednesday, April 10 at 5pm. Registration and poster submissions must be submitted electronically through the online registration form. Please contact Donna Bertram (dbertram(a)purdue.edu<mailto:dbertram@purdue.edu>) if you have any questions. For the detailed program and the online registration form, please visit our website: https://www.chem.purdue.edu/hcbrownlectures/. Thank you, Jean Chmielewski, Chair chml(a)purdue.edu<mailto:chml@purdue.edu> Chris Uyeda, Chair-elect cuyeda(a)purdue.edu<mailto:cuyeda@purdue.edu>

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Seminar Notice for Shikha Shrestha's Ph.D. Final Exam, Friday, April 12, at 2:00 p.m., in ARMS 1028. " Effect of Nanocellulose Reinforcement on the Properties of Polymer Composites
by Son, Rosemary E 05 Apr '19

05 Apr '19

Please consider attending the following: MATERIALS ENGINEERING SEMINAR "Effect of Nanocellulose Reinforcement on the Properties of Polymer Composites" By Shikha Shrestha Purdue MSE Ph.D. Final Exam Advisor: Professor Jeffrey P. Youngblood ABSTRACT Polymer nanocomposites are envisioned for use in many advanced applications, such as structural industries, aerospace, automotive and electronic materials, due to the improved properties like mechanical strengthening, thermal and chemical stability, easy bulk processing, and/or light-weight instigated by the filler-matrix combination compared to the neat matrix. In recent years, due to increasing environmental concerns, many industries are inclining towards developing sustainable and renewable polymer nanocomposites. Cellulose nanomaterials (CNs), including cellulose nanocrystals (CNCs) and cellulose nanofibrils (CNFs), have gained popularity due to their excellent mechanical properties and eco-friendliness (extracted from trees, algae, plants etc.). However, to develop CN-reinforced nanocomposites it is necessary to understand impact of hygroscopic swelling, aspect ratio, and content of CNs on the overall performance of nanocomposites; and overcome the low dispersibility of CNs and improve their compatibility with hydrophobic matrix. In this work, we attempt to understand the influence of single nanocrystals in the hygroscopic response exhibited by nanostructured films; effect of CNCs on the properties of CNC-reinforced fibers; and hydrophobized CNFs using a facile, aqueous surface modification to improve interfacial compatibility with epoxy. To evaluate the effect of CNC alignment in the bulk response to hygroscopic expansion, self-organized and shear-oriented CNC films were prepared under two different mechanisms. The coefficient of hygroscopic swelling (CHS) of these films was determined by using a contact-free method of Contrast Enhanced Microscopy Digital Image Correlation (CEMDIC) that enabled the characterization of dimensional changes induced by hygroscopic swelling of the films. By calculating the CHS values of CNC, it was determined that hygroscopic swelling is highly dependent on the alignment of nanocrystals within the films, with aligned CNC films showing dramatically reduced hygroscopic expansion than randomly oriented films. Next, to study the effects of different aspect ratios of CNCs on intrinsic properties of polyvinyl alcohol (PVA) fibers, CNCs extracted from wood and cotton were reinforced into PVA to produce fibers by dry-jet-wet spinning. The elastic modulus and tensile strength of the fibers improved with increasing CNC content (5 - 15 wt. %) at the expense of their strain-to-failure. The mechanical properties of fibers with cotton CNC were higher than the fibers with wood CNC when the same amount of CNCs were added due to their higher aspect ratio. The degree of orientation along the spun fiber axis was quantified by 2D X-ray diffraction. Micromechanical models were used to predict the fiber performance and compare with experimental results. Finally, to improve the dispersibility and compatibility of CNFs with epoxy, CNFs were modified by a water-based method where tannic acid (TA) acts as a primer with CNF and reacts with hexadecylamine (HDA). The modified (-m) and unmodified (-um) CNFs were filled into hydrophobic epoxy resin. Better dispersion and stronger adhesion between fillers and epoxy were obtained for m-CNF than the um-CNF, resulting in better mechanical properties of nanocomposites at the same loading. Thermal stability and the degradation temperature of m-CNF/epoxy improved when compared to neat epoxy. Date: Friday, April 12, 2019 Time: 2:00 P.M. Place: ARMS 1028

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Seminar Notice for Anneliese Brenner's Ph.D. Final Exam Friday, April 12, at 8:30 a.m., in HAMP 2118. "Microstructural Investigations of Sm-Doped ZrB2 for Hypersonic Applications"
by Son, Rosemary E 05 Apr '19

05 Apr '19

Please consider attending the following: MATERIALS ENGINEERING SEMINAR "Microstructural Investigations of Sm-Doped ZrB2 for Hypersonic Applications" By Anneliese E. Brenner Purdue MSE Ph.D. Final Exam Advisor: Professor Rodney W. Trice ABSTRACT Sharp leading edges required for hypersonic vehicles improve the maneuverability as well as reduce aerodynamic drag. However, due to the sharp design, increased surface temperatures require materials that can withstand these extreme conditions. Ultra-high temperature ceramics are a material group being considered for the leading-edge material, specifically ZrB2/SiC (ZBS) which has a high thermal shock resistance, melting temperature, and thermal conductivity. Studies done by Tan et. al. has shown that adding samarium (Sm) as a dopant to ZBS has an emittance of 0.9 at 1600oC and develop oxide scales that have excellent ablation performance. However, it remained unknown how the Sm doped oxide scale formed as well as how the emittance and ablation performance are affected by the microstructure. This study investigates the oxide scale development of 3 mol% doped Sm-ZBS billets as well as how differences in microstructure affect the emittance and ablation performance. Samples were prepared via chemical infiltration of samarium nitrate into spray-dried powders of 80 vol.% ZrB2/20 vol.% SiC; powders were then pressed into billets and pressureless sintered. Samples cut and polished from these billets were then oxidized for 10, 60, or 300 s, respectively, using an oxyacetylene torch. X-ray diffraction was used to determine the sequence of oxidation of Sm-ZBS, beginning with the formation of ZrO2 and Sm2O3. The final oxide scale was determined to be c1-Sm0.2Zr0.8O1.9, with a melting temperature exceeding 2500oC. SEM and EDS were also used to investigate the microstructural formation that occurs from the bursting of convection cells. Samples with different microstructures revealed similar topographical microstructures post-ablation due to the sequence of the oxide formation. However, samples with rougher surfaces and higher porosities had a higher concentration of trapped glass in the cross-sectional oxide scale. It was also found that due to differences in heating the sample during emittance testing, the oxide developed was the same for all the samples. It was also found that differences in microstructure had no effect on the spectral emittance of Sm-ZBS at ultra-high temperatures. The fabrication of c1-Sm0.2Zr0.8O1.9 (SZO) as a bulk billet was also investigated to use as a thermal barrier coating (TBC) in replacement of Sm-ZBS. Date: Friday, April 12, 2019 Time: 8:30 A.M. Place: HAMP 2118

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Seminar Reminder for Angel Pena's Ph.D. Final. Thursday, April 4, at 9:00 a.m., in ARMS 3115. "Evaluation of Rare-Earth Element Dopants (Sm and Er) Effect on the Ablation Resistance and Emittance Tailoring of ZrB2/SiC Sintered Billets"
by Son, Rosemary E 03 Apr '19

03 Apr '19

Please consider attending the following: MATERIALS ENGINEERING SEMINAR "Evaluation of Rare-Earth Element Dopants (Sm and Er) Effect on the Ablation Resistance and Emittance Tailoring of ZrB2/SiC Sintered Billets" By Angel Antonio Pena Purdue MSE Ph.D. Final Exam Advisor: Professor Rodney W. Trice ABSTRACT Hypersonic flight causes ultra-high surface temperatures which are most intense on sharp leading edges. One way of reducing the surface temperature is to apply a high emittance ceramic on the leading edge, increasing the radiation component of heat transfer. An ideal HEC must have a high emittance, while also possess a strong ablation resistance. From a scientific standpoint, it would be helpful if emittance could be tailored at different wavelengths. The approach used to create a ceramic with tailorable emittance was the use two different rare-earth elements, adding them to a ultra-high temperature ceramic (UHTC) in small quantities. The samarium element was added to increase the emittance of the UHTC over a large wavelength range, and the erbium element was added to decrease the emittance at specific wavelength ranges. The goal of this study was to create an UHTC with tailorable emittance while maintaining the required ablation resistance. Therefore, ZBS billets with five different Sm to Er ratios and with a nominal total amount of 3 mol.% dopant incorporated were prepared by sintering in vacuum to 2000 °C. The ablation resistance was evaluated by using an oxyacetylene torch and observing at exposure times of 60s and 300s, whereas the emittance was evaluated at the Air Force Research Lab facilities via a laser heating testing. The results for the ablation testing showed that ZBS billets co-doped with Sm and Er formed a beneficial c1-(Sm/Er)0.2Zr0.8O1.9 oxide scale as the majority phase, which is more thermally stable than the m-ZrO2 oxide scale typically formed in oxidized ZBS systems. The crystalline and the amorphous phases were formed by a convection cell mechanism. Differences in surface temperatures between ZBS samples with different dopant ratios suggest differences in spectral absorptance/emittance between each of the five compositions evaluated. Despite the emittance profiles by varying the Sm:Er molar ratios were similar because m-ZrO2 was formed as the major oxide phase, the emittance study showed that the erbium oxide influences the emittance profile, as can be noted by the maximum and minimum emittance peaks. Results showed that the emittance changes as a function of the Sm:Er molar ratios and temperature at shorter wavelength ranges. These changes in the emittance are caused by the different Sm and Er concentrations on the surface. Future work should be focused on producing the beneficial c1-(Sm/Er)0.2Zr0.9O1.8 phase directly from the manufacturing process, and therefore, maximize the effect of varying the Sm:Er molar ratios to tailor the emittance. This study represents the first generation and reported emittance data of UHTC doping ZBS systems with both Sm and Er elements. Date: Thursday, April 4, 2019 Time: 9:00 A.M. Place: ARMS 3115

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MSE Seminars on 4/26/19
by Coar, Stacey L 03 Apr '19

03 Apr '19

Good morning, We have two seminars coming up on April 26th. I just want to give everyone a heads up since it is going to be a busy month. Please put these on your calendar. [cid:image003.png@01D4EA06.51DD54B0][cid:image004.jpg@01D4EA06.51DD54B0] Stacey Stacey Coar Secretary/Development Assistant School of Materials Engineering Purdue University Neil Armstrong Hall of Engineering 701 West Stadium Ave. Room 2300 West Lafayette, IN 47907 765-494-4100 scoar(a)purdue.edu<mailto:scoar@purdue.edu>

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MSE Student Night April 25, 2019, Please Respond
by Coar, Stacey L 02 Apr '19

02 Apr '19

Good afternoon, There is still plenty of time to sign up for this year’s MSE Student Night on April 25th from 6:30 – 8pm. This event is a great opportunity to network with your peers, industry professionals, faculty and staff, and food will be provided. This is also a great opportunity to see this year’s senior design posters and the press boxes at Ross-Ade! RSVP at MSE student night 2019 survey<https://purdue.ca1.qualtrics.com/jfe/form/SV_bHkvgdmw35UcSI5> by April 11th if you have not taken the survey. Important Info: · RSVPS are required (even for seniors) · Business attire, photos will be taken with Sponsors · Student and Faculty award presentations will be presented during the program [cid:image001.jpg@01D4D8B0.7F452A70] Stacey Stacey Coar Secretary/Development Assistant School of Materials Engineering Purdue University Neil Armstrong Hall of Engineering 701 West Stadium Ave. Room 2300 West Lafayette, IN 47907 765-494-4100 scoar(a)purdue.edu<mailto:scoar@purdue.edu>

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FW: CCO professional development offerings
by Son, Rosemary E 01 Apr '19

01 Apr '19

(A) AAUW StartSmart Salary Negotiation Workshop for graduate women Scheduled on April 2, 2019 from 5 - 7 PM in KRAN G013. Read details and register here<https://gspd.gosignmeup.com/public/Course/browse?courseid=2716>. (B) CCO Job Search Series for Grad Students This 4-part "Job Search Series" will walk you through most of the job or internship search process: personal branding, document development, networking & interviewing. You can stay back after the 45-min. small-group workshops for one-on-one feedback.* Apr. 3: Personal brand: what are you known for? For an effective job search, candidates should have a coherent personal brand. Learn key components of a successful brand, how to develop your own, & learn how to manage & communicate it in different contexts (in person, online). Apr. 10: Resumes & cover letters Learn what makes a resume compelling, & how to write impactful cover letters. Bring a resume & job posting to work on. Apr. 17: Networking (online & in person) Learn effective strategies, including informational interviews, social media usage, & follow-up. Apr. 24: Interviewing Learn how to accomplish both goals of an interview: marketing yourself effectively, & learning as much as you can about the company. We will also discuss how to answer visa-related, salary-related, & inappropriate/illegal questions. All 'Job Search Series' workshops: RAWLS 2097 from 4:15 to 5 PM NO RSVP needed; arrive early to get a seat! Room seats 30. Questions? askCCO(a)purdue.edu<mailto:askCCO@purdue.edu> * 5 to 6 PM: CCO drop-in hour. You can stay back for one-on-one feedback after the workshop is completed. Sign up when you arrive; limited spots available. If requesting a document review (CV, resume, cover letter), please bring a print out. Only one document per student. Please direct all questions about these events to me. Thank you for your help in advertising these opportunities. Amruta Amruta Inamdar, Ph.D. Career Services Consultant - Graduate Students Purdue University Center for Career Opportunities; YONG 245 amruta(a)purdue.edu<mailto:amruta@purdue.edu>; 765-494-1409 LinkedIn<https://www.linkedin.com/in/amruta-inamdar/>, Twitter<https://twitter.com/GradProfCareers> & Facebook<https://www.facebook.com/PurdueGradCareers/> My Office is a Safe Space [PU150CO_YRS_H_BG_RGB]<https://takegiantleaps.com/>

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