brian c. davis dylan jennings

Brian C. Davis Dylan Jennings

Elizabeth Palmiotti Yewon Shin Sarah Sortedahl

Welcome to the meeting!We are very pleased to welcome all of you to the 11th Annual CCAC Student Conference.We hope you will enjoy our variety of scientific research and speakers.

We would like to begin by thanking our industry sponsors: Corning and Deltech Furnaces; aswell as the organizations affiliated with Colorado School of Mines which have sponsored thisconference: the office of the Vice President for Research and Technology Transfer (VPRTT)and the Colorado Center for Advanced Ceramics (CCAC).

We would like to thank our keynote speakers: Dr. Elango Elangovan from OxEon Energyand Dr. Candace Chan from Arizona State University. We would also like to thank our CCACFaculty presenters: Dr. Michael Sanders and Dr. David Diercks. We are grateful to all of themfor making room in their busy schedule to accept our invitation.

Last but not least, we would like to thank all of you for your hard work and active contributionto the conference.

Best Regards,

2019 CCAC Student Conference Committee*Cover Image Courtesy of George Burton

2019 CCAC Student ConferenceColorado Center for Advanced Ceramics

Program & Proceedings

August 14-15th, 2019

American Mountaineering CenterGolden, CO

Organized By

Brian C. Davis, Dylan Jennings, Elizabeth Palmiotti,Yewon Shin, and Sarah Sortedahl

Thank you to our generous sponsors!

Gold Sponsor:

Silver Sponsors:

Deltech Furnaces

VPRTT(CSM Office of the Vice President for Research and

Technology Transfer)

CCAC(Colorado Center for Advanced Ceramics)

Michael Sanders, PhD

Conference Schedule

Wednesday, August 14th

Start EndCheck-in 12:45pm 1:30pmIntroduction 1:30pm 1:50pmKeynote Speaker IDr. Elango Elangovan - OxEon Energy 1:50pm 2:40pmCoffee Break 2:40pm 3:10pmStudent Presentation Session I (4 x 20min) 3:10pm 4:30pmGroup Photo 4:30pm 4:45pmDinner (Including 15 min. walk each way)Offered by conference at El Dorado Restaurant 4:45pm 7:00pmPoster Session and Social Hour 7:00pm 8:30pmExtended Social Hour at Mountain Toad 8:30pm Close

Thursday, August 15th

Start EndBreakfastOffered by conference 7:30am 8:20amIntroduction 8:20am 8:30amKeynote Speaker IIDr. Candace Chan - Arizona State University 8:30am 9:20amCoffee Break 9:20am 9:50amStudent Presentation Session II (2 x 20min) 9:50am 10:30amFaculty Talk IDr. Michael Sanders 10:30am 10:50amFaculty Talk IIDr. David Diercks 10:50am 11:10amAwards 11:10am 11:30am

Abstracts

Nanostructured Garnets : Synthesis, Structure, and Electrochemical Propertiesas Solid Electrolytes for Solid-State Li BatteriesCandace K. Chan . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Materials, Design, and Operational Challenges of Solid Oxide ElectrolysisDevices for Space ApplicationsS. Elango Elangovan, Joseph Hartvigsen . . . . . . . . . . . . . . . . . . 2

Sharp Indentation of Silicate Glasses: Investigating Stress Field DependenciesBrian C. Davis, Ivar Reimanis, G. Scott Glaesemann . . . . . . . . . . . . . 3

Entropy Stabilized Oxides: A Thin Film StudyValerie Jacobson . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Leveraging Machine Learning to Analyze Abnormal Grain Growth in AluminaRussell Gleason, Branden Kappes, Geoff Brennecka, Aaron Stebner . . . . . 5

Investigating Metastable TiO2 Polymorph Formation via TEM in-situCrystallizationJohn S. Mangum, James E.S. Haggerty, Daniil A. Kitchaev, Okan Agirseven, Lau-ren M. Garten, John D. Perkins, Laura T. Schelhas, Michael F. Toney, David. S.Ginley, Janet Tate, and Brian P. Gorman . . . . . . . . . . . . . . . . . . 6

Atomistic Modeling of Fundamental Deformation Behaviors in MAX PhasesGabriel Plummer and Garritt Tucker . . . . . . . . . . . . . . . . . . . . 7

Conduction Mechanisms and Dielectric Properties of BaBiO3 Bulk CeramicsRachel Sehrbondy, Geoff Brennecka . . . . . . . . . . . . . . . . . . . . 8

Data-Driven Design of Triple Ionic Electronic Conducting Cathode Materials forProtonic Ceramic Fuel CellsJake Huang, Meagan Papac, Chris Borg, Andriy Zakutayev, Ryan O’Hayre . . . 9

Exsolution Studies of Nickel from BZYDylan Jennings, Sandrine Ricote, Jose Santiso, Anna Magraso, Arindom Chat-terjee, Ivar Reimanis . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Sintering additives NiO and CuO: Solid solubility in BaZr0.85Y0.15O3−δ

estimated from magnetometryMichael Knight and Ivar Reimanis . . . . . . . . . . . . . . . . . . . . . 11

Post-Deposition Recrystallization of Co-Evaporated CuInxGa(1-x)Se2 Films byMetal Halide Vapor TreatmentsElizabeth Palmiotti, Sina Soltanmohammad, Shankar Karki, Ben Belfore, SylvainMarsillac, Angus Rockett . . . . . . . . . . . . . . . . . . . . . . . . . 12

Defect study of kinetics in BCFZY0.1(Cathode) and thermodynamics in BZY20and BCZYYb (Electrolyte)Yewon Shin, Michael Sanders, Chauncheng Duan, Steve Harvey, Ryan O’Hayre 13

First Principles Study of Phase Stability in BiFeO3 and BiCrO3

Michael Walden, Cristian Ciobanu, Geoff Brennecka . . . . . . . . . . . . . 14

Investigation of the Electrical Properties of Grain Boundariesin (AgxCu1-x)(InyGa1-y)Se2

Jake Wands, Sina Soltanmohammad, William Shafarman, Angus Rockett . . . 15

Materials Characterization Facilities at MinesDavid Diercks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Accelerated Discovery of Solar Thermochemical Hydrogen ProductionMaterials via High-Throughput Computational and Experimental MethodsMichael Sanders, Anyka Bergeson-Keller, Yun Xu, Nitin Kumar, Jie Pan, DeboraR. Barcellos, Andriy Zakutayev, Vladan Stevanovic, Stephan Lany, Ryan O’Hayre 17

Nanostructured Garnets : Synthesis, Structure, and ElectrochemicalProperties as Solid Electrolytes for Solid-State Li Batteries

Candace K. Chan1

1 Materials Science and Engineering, Arizona State University, Tempe, AZ

Lithium conducting garnets such as the lithium lanthanum zirconates(LLZO) are promising solid electrolytes for future lithium batteries owing totheir beneficial confluence of high ionic conductivity, electrochemical sta-bility / compatibility with metallic lithium, thermal stability, and relative sta-bility under ambient conditions. Conventional synthesis via solid-state re-action is the most common method to obtain phase-pure crystalline LLZO,but generally results in coarse powders with wide particle size distribution,also requiring long times (often in excess of 12 h) and high processingtemperatures (often above 900 - 1000 °C).

Our group has developed several methods to prepare nanostructuredLLZO, such as LLZO nanowires using electrospinning, templating onto cel-lulosic fibers, polymer sol-gel combustion, and molten salt based methods,with a particular interest in obtaining mechanistic understanding of the for-mation processes for LLZO and the subsequent morphology changes dur-ing sintering. Using nanostructured LLZO over bulk LLZO can be ben-eficial in terms of lithium ionic conductivity, cycle life, and mechanicalstrength. Detailed structural characterization is performed to understandthe LLZO formation processes and phase transformations and correlatewith sintering properties and impedance data in LLZO-based ceramic elec-trolytes. LLZO nanomaterials can also be used as ceramic fillers in solidpolymer electrolytes. For both LLZO ceramic and composite polymer elec-trolytes, ionic conductivity exceeding 1e-4 S/cm at room temperature is ob-served, making these materials promising candidates as solid electrolytesfor next generation lithium batteries.

1

Materials, Design, and Operational Challenges of Solid OxideElectrolysis Devices for Space Applications

S. Elango Elangovan1, Joseph Hartvigsen1

1OxEon Energy, LLC, 257 River Bend Way, Suite 300 North Salt Lake, Utah 84054

There is a resurgence of interest insolid oxide electrolysis cells (SOXC) forfuel (hydrogen and syngas) production fromsteam and carbon dioxide. The high con-version efficiency of these devices is attrac-tive for renewable energy storage applica-tion. Advances in solid oxide fuel cell ma-terials are directly applicable to electroly-sis cells provided additional requirementssuch as stability of hydrogen electrode inhigh steam conditions and interface stabil-ity of oxygen electrode during operation areaddressed. The application of solid oxideelectrolysis cells extends beyond terrestrialapplications. Production of consumables from in-situ resources is critical for human explo-ration which will reduce the number and size of landers and the crew ascent vehicle.

As an initial experiment to prove feasibility, a solid oxide electrolysis stack will be testedon Mars as part of Mars2020 rover mission. The primary objective of the experiment, MOXIE(Mars OXygen ISRU Experiment) is to demonstrate production of oxygen from Mars atmo-sphere CO2 intended for life support and ascent vehicle propellant oxidant for human expedi-tion. In addition to demonstrating that the stack can electrolyze dry CO2 to produce >99.6%purity oxygen, there are several requirements specific to space mission and some specific torover mission. They include thermal cycling, rapid start up, withstanding packaging load, coldtemperature cycles, and ability to endure pyroshock and vibration experienced during launchand landing. The requirement for high purity oxygen and the ability to withstand pressuredifference (Mars ambient 7 mbar and stack internal 1 bar) necessitates the use of thermalexpansion matched components and seal. In addition, operational strategies are needed toavoid forming coke from the electrolysis or disassociation of produced CO and oxidation ofcathode material in CO2. OxEon team led the development of SOXE stacks in collaborationwith the Jet Propulsion Laboratory (JPL) and Massachusetts Institute of Technology (MIT).The work resulted in delivering a set of flight qualified stacks to JPL. A packaged stack hasbeen installed on the rover that is scheduled for launch next year for the Mars2020 mission.

The SOXE stacks can also operate on co-electrolysis mode where the Mars atmosphereCO2 along with water can be processed together to produce oxygen and fuels such asmethane for propulsion. In a follow on award, OxEon is testing scaled up stacks to produceoxygen and syngas from co-electrolysis coupled to a methanation reactor. The objectiveof the project is to demonstrate capability to produce oxygen and fuel for potential mannedmission to Mars. In addition, a redox tolerant cathode material is under evaluation.

Acknowledgement: NextSTEP ISRU work is supported under NASA Contract8-HQTR19C0006. The redox tolerant cathode work is done under a NASA Small Busi-ness Innovation Research Contract No. 80NSSC18P1940. The work related to MOXIE wasbased on support from NASA through JPL’s prime contract, under JPL subcontract number1515459.

2

Sharp Indentation of Silicate Glasses:Investigating Stress Field Dependencies

Brian C. Davis1,2, Ivar Reimanis1,2, G. Scott Glaesemann3

1Colorado School of Mines, Golden, CO2 Colorado Center for Advanced Ceramics (CCAC), Golden, CO

3 Corning Inc., Corning, NY

During sharp indentation of a silicate glass, material directly under theindenter plasticly flows and micro-crack systems develop in the adjacentlinear-elastic material. The generation of these crack systems representsa damage mechanism which significantly weakens the base material byintroducing flaws much larger than the as-manufactured population. Max-imum principal stress is the driving force for these cracks, as they grow inMode I loading. The process of indentation has numerous independentvariables (e.g. indent depth, indenter acuity); however, their effects onmaximum principal stress has not been established. This work presentsthe results of a Finite Element Analysis (FEA) sensitivity study, initiallybased upon fused silica. It also presents a semi-automated FEA toolwhich significantly reduces the labor involved for experts to create indi-vidual models, while also reducing the level of expertise necessary fornon-experts to perform basic stress analyses.

3

Entropy Stabilized Oxides: A Thin Film StudyValerie Jacobson1,2

1 Colorado School of Mines, Golden, CO2 National Renewable Energy Laboratory, Golden, CO

Cross sectional SEM image of a highly textured entropy stabilized oxide film madeusing pulsed laser deposition showing the columnar grain growth.

Conventional materials are stabilized using enthalpy, but recently en-tropy has been used instead. In 2015, this concept was applied to oxides,and a 5 cation entropy stabilized oxide composed of Mg, Co, Ni, Cu, andZn was found to stabilize into a uniform rock salt structure when quenchedfrom a high enough temperature. Here we explore further synthesis op-tions for this oxide using pulsed laser deposition (PLD) and a combinatorialdeposition chamber. In this study, laser energy of the PLD tool has beenlinked to crystal structure texturing, and the combinatorial nature of thePLD system has allowed for the exploration of the solubility limits of the 5cations. Crystal texturing has been shown to have an extremely nonlineareffect on current density measurements, and increased texturing leads to adecrease in the optical absorption onset energy of these materials. Cationgradients appear to be a means by which the rock salt structure may bedeformed, according to XRD data, and individual cations (specifically Cu)at higher concentrations reduce sheet resistance of the bulk material. Afterannealing, these samples also show Cu segregation towards the substrateand a decomposition of the single rock salt structure into at least 5 differentphases of material, which overall leads to a shift in the resistive behavior.

4

Leveraging Machine Learning to Analyze Abnormal Grain Growth inAlumina

Russell Gleason1, Branden Kappes1, Geoff Brennecka1, Aaron Stebner1

1 Colorado School of Mines, Golden, CO

Dillon, S. J., Harmer, M. P., and Rohrer, G. S. (2010), The Relative Energies ofNormally and Abnormally Growing Grain Boundaries in Alumina Displaying Dif-ferent Complexions. Journal of the American Ceramic Society, 93: 1796-1802.doi:10.1111/j.1551-2916.2010.03642.x

Alumina is one of the most widely used advanced ceramic materi-als, yet abnormal grain growth during production remains problematic.Ever since Coble’s discovery in the 1950’s that doping alumina with smallamounts of magnesium could inhibit grain growth, ceramists have soughtto understand the mechanisms behind grain growth in alumina. Thoughmany different approaches have been used to frame the problem, fromdoping, to surface energy and bulk defect chemistry, and more recentlycomplexions, a complete understanding is still elusive. This work aims totake a new approach to the subject, namely Machine Learning. This ap-proach leverages the power of data informatics to search for previouslyunrecognized phenomenological relationships among powder properties(size/purity/etc.), manufacturing processes (pressing/sintering/etc.), andthe resulting microstructural properties of alumina. Through the use of ma-chine learning algorithms, the properties of alumina samples produced bywidely varying methods can be compared to each other in order to extractrelationships, elucidate the causes of abnormal grain growth, and deter-mine methods of better controlling microstructural development in alumina.

5

Investigating Metastable TiO2 Polymorph Formation via TEM in-situCrystallization

John S. Mangum1, James E.S. Haggerty2, Okan Agirseven2, Lauren M.Garten3, John D. Perkins3, Laura T. Schelhas4, Daniil A. Kitchaev5,

Michael F. Toney4, David. S. Ginley3, Janet Tate2, and Brian P. Gorman1

1Colorado School of Mines, Golden, CO2Oregon State University, Corvallis, OR

3National Renewable Energy Laboratory, Golden, CO4SLAC National Accelerator Laboratory, Menlo Park, CA5Massachusetts Institute of Technology, Cambridge, MA

Certain structural polymorphs of titanium dioxide (TiO2) are known to exhibit photocat-alytic activity useful in applications pertaining to water splitting reactions and degradation oforganics for water treatment [1,2]. Among these polymorphs, the brookite structure has beenshown to possess the greatest photocatalytic efficiency under a variety of conditions [3,4].However, brookite is metastable and difficult to synthesize with respect to its polymorphiccounterparts, rutile and anatase.

Over the last several decades, research efforts have produced brookite TiO2 throughmany distinct synthesis procedures, ranging from hydrothermal syntheses to thin film deposi-tion [4]. Although these report the synthesis methods in detail, there is little to no evidence ofexploring the underlying mechanism that stabilizes the brookite polymorph. This work aimsto elucidate and understand that fundamental mechanism.

In our previous work, we found a range of pulsed laser deposition conditions that lead tohigh-fraction brookite films [5,6]. These films are deposited in an amorphous state and pref-erentially crystallize in the brookite structure during subsequent thermal treatment. Ramanspectroscopy and X-ray diffraction are used to differentiate the polymorphs and characterizethe overall phase fractions present in the films. Titania films were deposited under varyingoxygen partial pressures (pO2) to investigate the effect on amorphous precursor composi-tion and resulting phase formation. Both Rutherford backscattering spectrometry (RBS) andelectron energy-loss spectroscopy (EELS) reveal the as-deposited films are oxygen deficientwith respect to stoichiometric TiO2. We propose that variations in the amorphous precursors,especially composition, directly affects the resulting crystalline TiO2 phase and crystallizationkinetics via local atomic reconfiguration and strain induced by oxygen vacancies.

[1] A Fujishima, X Zhang, Comptes Rendus Chimie 9 (2006), 750.[2] A Wold, Chem. Mater. 5 (1993), 280.[3] A Paola, M Bellardita, and L Palmisano, Catalysts 3 (2013), 36.[4] R Bhave, All Theses 66 (2007).[5] J Haggerty et al., Scientific Reports 7 (2017), 15232.[6] J Mangum et al., Journal of Non-Crystalline Solids 505 (2019), 109-114.

6

Atomistic Modeling of Fundamental Deformation Behaviors in MAXPhases

Gabriel Plummer1 and Garritt Tucker1


MAX phases are a large family of layered, ternary metal carbides andnitrides, which possess a unique combination of metallic and ceramic prop-erties. While MAX phases have been recognized as remarkable materialsand are utilized in a wide variety of applications, an understanding of theirfundamental deformation mechanisms is still lacking. Atomistic modelingstudies would contribute greatly to resolving this outstanding issue, butpresently no appropriate interatomic potentials exist. Herein, utilizing anewly developed bond order potential for the Ti3AlC2 and Ti3SiC2 MAXphases, the mechanisms of MAX phase deformation are probed, with anemphasis on understanding their well-documented kinking nonlinear elas-tic (KNE) behavior and the role of their inherently layered crystalline struc-ture. The fundamental insight gained from these atomistic studies will al-low for better engineering of MAX phases to fully take advantage of theirunique properties and enable extensions to other layered materials as well.

7

Conduction Mechanisms and Dielectric Properties of BaBiO3 BulkCeramics

Rachel Sherbondy1, Geoff Brennecka1


BaBiO3 (BBO) is a semiconducting material that has increased in popu-larity in recent years due to its identification as a topological insulator and,when acceptor-doped, high-temperature superconductor. However, theconduction mechanisms and defect chemistry of BBO at and above roomtemperature are not well-understood, especially with regard to microstruc-ture. In this work, bulk BBO pellets were synthesized using solid-statetechniques, and the relationships between crystal structure and dielec-tric properties were explored. Studies of AC conductivity as a function oftemperature indicated multiple available conduction mechanisms, as de-termined by the “s parameter” from the equation σAC = Aωs where σAC isthe AC conductivity, ω is the angular frequency, A is a fitting parameter re-lated to the polarizeability, and the temperature- and frequency-dependentexponent s provides insight into the dominant mechanism of AC conduc-tion. As seen in the figure attached, the AC conductivity mechanisms weredominated by Quantum Mechanical Tunneling for high frequencies, Corre-lated Barrier Hopping for low frequencies at low temperatures, and DC-like behavior for low frequencies at high temperatures. Impedance spec-troscopy shows that the long-range resonances differ from the short-rangeresonances, which is in agreement with the chemical segregation shownin SEM images.

8

Data-Driven Design of Triple Ionic Electronic Conducting CathodeMaterials for Protonic Ceramic Fuel Cells

Jake Huang1, Meagan Papac1,2, Chris Borg3, Andriy Zakutayev2, RyanO’Hayre1


3 Citrine Informatics, Redwood City, CA

Development of high-performance triple conducting cathodes can en-able low-temperature operation of protonic ceramic fuel cells. Rapid screen-ing of cathode materials is accomplished by employing high-throughputsynthesis and characterization methods coupled with data mining and ma-chine learning techniques. We present the application of this integratedapproach to the optimization of the Ba(Co,Fe,Zr,Y)O3−δ (BCFZY) systemof perovskite oxides, which has demonstrated promising intermediate tem-perature fuel cell performance. Combinatorial pulsed laser deposition pro-duces compositionally graded thin films, from which spatially resolved mea-surements of critical performance metrics provide composition-propertycorrelations throughout the BCFZY composition space. A specialized li-brary of physical and chemical descriptors enables unique, quantitativefeaturization of compositions. The descriptor set provides the foundationfor machine learning models that are then trained on the combinatorial ex-perimental data. These models reveal underlying relationships betweenbasic descriptors and target properties, such as percolation thresholds forelectronic conductivity, and the influence of basicity and bonding on po-larization resistance. The predictive power of the models also supportsaccelerated screening of unseen composition regions with reduced exper-imental load.

9

Exsolution Studies of Nickel from BZYDylan Jennings1, Sandrine Ricote1, Jose Santiso2, Anna Magraso2,

Arindom Chatterjee2, Ivar Reimanis1

1 Colorado School of Mines, Golden, CO2 Catalan Institute of Nanoscience and Nanotechnology, Barcelona, Spain

Figure 1: Depth profile of nickel in BZY thin films as the samples become morereduced.

Exsolution has been shown to be a promising method for producingstable, highly-dispersed metallic nanoparticles. Due to this, exsolved nanopar-ticles are preferable for catalytic applications when compared to nanopar-ticles formed through typical synthesis methods. Yttrium doped bariumzirconate (BZY) can be doped with nickel metal, and nickel nanoparticlescan form through exsolution in this material system. While exsolution hasa large impact on the catalytic activity of BZY and similar materials, thekinetics of exsolution and the relationship between exsolved particles andthe BZY support is not yet well understood.

For this work, thin film samples were deposited by Professor JoseSantiso from the Catalan Institute of Nanoscience and Nanotechnologyin Barcelona, and nanopowder samples were synthesized at the ColoradoSchool of Mines. Samples with a composition of BaZr0.81Y0.15Ni0.04O3−dwere analyzed. In this work, time-of-flight secondary ion mass spectrom-etry (TOF-SIMS) is utilized to analyze the changes in nickel distribution asexsolution occurs. TOF-SIMS results indicate a large change in nickel dis-tribution as samples are reduced. Additionally, SEM and HRTEM is doneto analyze the morphology and structure of nickel nanoparticles in the sys-tem. HRTEM demonstrates that nickel particles formed through exsolutionare highly oriented with respect to the BZY support.

10

Sintering additives NiO and CuO: Solid solubility inBaZr0.85Y0.15O3−δ estimated from magnetometry

Michael Knight1 and Ivar Reimanis1


Dilute NiO or CuO additions reduce sintering temperatures and in-crease grain growth in proton conductor yttrium-doped barium zirconate(BZY). For NiO additive, formation of a liquid impurity phase BaY2NiO5

during processing has been observed and proposed to be a major con-tributor. It is believed the Ni cations play a critical role in ion exchangeand diffusion within the grains as well as at grain boundaries, but the ex-act mechanism remains controversial. The solid solubility of these sin-tering additives have been estimated by others to be around 1% on theperovskite B-site from lattice parameter changes. In this work, highly sen-sitive SQUID magnetometry is used to track effective magnetic momentsof Ni2+ and Cu2+ substituted for 0.5% - 2.0% Zr cations. Changes in mo-ment are used to estimate solid solubilities to be less than 1% and addi-tional cations may begin to form an impurity phase at lower concentrationsthat previously estimated.

11

Post-Deposition Recrystallization of Co-Evaporated CuInxGa(1-x)Se2Films by Metal Halide Vapor Treatments

Elizabeth Palmiotti1, Sina Soltanmohammad1, Shankar Karki2, BenBelfore2, Sylvain Marsillac2, Angus Rockett1

1 Colorado School of Mines, Golden, CO2 Old Dominion University, Norfolk, VA

CIGS films (a) as-deposited at 350◦C, treated with (b) InBr3, (c) CuBr with Se, and(d) InCl3 with Se at 450◦C for one hour

CuInxGa(1-x)Se2 films were co-evaporated onto molybdenum-coated soda-lime glass (SLG) substrates at a substrate temperature of 350◦C. The filmswere annelaed in InBr3, CuBr with Se, and InCl3 with Se vapors at 450◦Cfor one hour, respectively. All three vapor treatments resulted in significantimprovements to grain size. The CuBr with Se treatment resulted in themost uniform grain growth and largest grains. All treatments resulted inimproved crystallinity of the film.

12

Defect study of kinetics in BCFZY0.1(Cathode) andthermodynamics in BZY20 and BCZYYb (Electrolyte)

Yewon Shin1, Michael Sanders1, Chauncheng Duan1, Steve Harvey2,Ryan O’Hayre1


Owing to the generally lower activation energy for proton conduction compared to oxygenion conduction, protonic ceramic fuel cells (PCFCs) have demonstrated high performance atintermediate temperatures (350-600◦C). Despite their promise, however, fundamental under-standing of PCFC electrode and electrolyte materials remains limited. In this work, the de-fect transport of the new PCFC cathode material BaCo0.4Fe0.4Zr0.1Y0.1O3−δ (BCFZY0.1)developed by Duan et al. [1] and the defect thermodynamics of two of the most popularPCFC electrolyte materials,BaZr0.8Y0.2O3−δ (BZY20) and BaCe0.7Zr0.1Y0.1Y b0.1O3−δ(BCZYYb), are investigated.

O18/O16 isotope exchange depth profiling (IDEP) analysis was performed by SecondaryIon Mass Spectrometry (SIMS) to determine the oxygen tracer diffusion coefficient and sur-face exchange behavior of BCFZY0.1. In addition to conventional diamond polished SIMSsamples, we also used surface-roughened samples to simulate a porous PCFC cathode andthereby better investigate the surface reaction limited kinetics on BCFZY0.1. Improved un-derstanding of the kinetic and transport behavior of this new cathode material will enablefurther optimization for PCFC application.

A comparative study of the defect thermodynamics of BZY20 vs BCZYYb was performedusing thermogravimetric analysis (TGA) by investigating the weight changes of calcined pow-ders upon changes in pO2 between 500-900◦C in dry and wet atmospheres. The resultingthermodynamic information is used to validate the model-based defect thermodynamic andtransport properties studied by Zhu et al. [2,3]. It is our intent that a more concrete under-standing of these properties for both PCFC cathode and electrolyte materials will allow themost important thermodynamic and kinetic limitations to current PCFC performance to beidentified, thereby suggesting pathway to further advance PCFC development.

References

1. Duan, Chuancheng, et al. ”Readily processed protonic ceramic fuel cells with high performance at low temperatures.” Science 349.6254 (2015):1321-1326.2. Zhu, Huayang, et al. ”Defect Chemistry and Transport within Dense BaCe0.7Zr0.1Y0.1Y b0.1O3−δ (BCZYYb) Proton-ConductingMembranes.” Journal of The Electrochemical Society 165.10 (2018): F845-F853.3. Zhu, Huayang, et al. ”Defect Incorporation and Transport within Dense BaZr0.8Y0.2O3−δ (BZY20) Proton-Conducting Membranes.”Journal of The Electrochemical Society 165.9 (2018): F581-F588.

13

Phase Stability in BiFeO3 and BiCrO3 by First PrinciplesMichael Walden1, Cristian Ciobanu2, Geoff Brennecka1

1 Colorado School of Mines, Metallurgical and Materials Engineering, Golden, CO2 Colorado School of Mines, Mechanical Engineering, Golden, CO

A multiferroic material is onein which multiple ferroic orders arepresent. Because of the abundance ofapplications utilizing ferroelectricity orferromagnetism individually, a multifer-roic which couples these orders mayenable a wide range of more com-plex applications. A theoretical un-derstanding of how ferroic order cou-ples to structural order parameters isa prerequisite for identifying materialswhich may be multiferroic. This is es-pecially important in perovskite mul-tiferroics, which often prohibit coex-istence of ferroelectric and ferromag-netic orders due to differing criteria forthe B-site cation valence electron configuration. Bismuth-based perovskite oxides(BiXO3) avoid this dilemma by displacing the A-site cation sub-lattice to generateferroelectric polarization while maintaining anti-ferromagnetic order via un-pairedelectrons on the B-site cation sub-lattice. A critical impediment to understandingthe ferroic coupling in bismuth perovskites is poor phase stability, particularly tend-ing towards non-stoichiometry.

In order to promote stability in the stoichiometric perovskite phase, bismuth per-ovskites may be deposited as an epitaxial tetragonal phase. However, the existingliterature regarding tetragonal BiXO3 presents differing conclusions regarding thestable c/a ratio, at times suggesting a value near unity (the Pseudo-Cubic phase)and at other times suggesting a much larger value (the Super-Tetragonal phase).More comprehensive theoretical work is needed to understand the structural orderparameters of the tetragonal BiXO3 phases, particularly in the context of the sta-bility of an tetragonal phase relative to other epitaxial phases. In this work, we usedensity-functional theory to model the phase stability and structural order of tetrag-onal phases of two bismuth-based perovskites, BiFeO3 (BFO) and BiCrO3 (BCO).Our results concur with the literature regarding the stable lattice parameters andionic constants of both the 0K ground state phases of BFO and BCO (respectivelyrhombohedral and monoclinic), as well as of the 0K tetragonal phases of thesematerials. We demonstrate that while the tetragonal phases of BFO and BCO areunstable at the globally-stable lattice constants, under compressive epitaxial strainthe tetragonal phases become stable. Our energetic and structural mapping of thetetragonal phase space of BFO and BCO is used to develop a model for the cou-pling of perovskite structural order parameters to ferroic order in these materials.

14

Investigation of the Electrical Properties of Grain Boundaries in(AgxCu1-x)(InyGa1-y)Se2

Jake Wands1, Sina Soltanmohammad1, William Shafarman2, AngusRockett1

1 Colorado School of Mines, Golden, CO2 Institute of Energy Conversion, University of Delaware, Newark, DE

Alloying Cu(InGa)Se2 (CIGS) with Ag(InGa)Se2 results in thin filmsthat are more defect tolerant and can improve device performance rela-tive pure CIGS. In this study scanning microwave impedance microscopy(sMIM) and time of flight secondary ion mass spectrometry (TOF-SIMS)were used to investigate the electrical characteristics of grain boundariesin ACIGS. Two films were deposited by a three stage co-evaporation tech-nique, both of which produced complete devices over 16% efficient. sMIMmeasurements revealed Sample A to have high variation in electrical prop-erties between grains and grain boundaries while Sample B was uniformacross the surface. When analyzed with TOF-SIMS Sample A was shownto have an order of magnitude fewer oxygen counts than in Sample B. Ad-ditionally the oxygen was found to be located primarily in the grain bound-aries. It is theorized that oxygen atoms are filling and passivating VSewhich is a donor defect. The result is more uniform electronic characteris-tics throughout Sample B as seen in sMIM.

15

Materials Characterization Facilities at MinesDavid Diercks1

1Colorado School of Mines, Golden, CO

There are numerous materials characterization instruments availablefor general use on the Mines campus. The Metallurgical and Materials En-gineering (MME) Electron Microscopy Laboratory (EMLab) houses severalof these instruments, which include scanning and transmission electronmicroscopes, focused ion beam instruments, x-ray diffraction, and Ramanspectroscopy. The capabilities available in the EMLab will be highlightedand the procedures for accessing them will be presented. Information onother multi-user instruments of interest to materials researchers will alsobe discussed.

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Accelerated Discovery of Solar Thermochemical HydrogenProduction Materials via High-Throughput Computational and

Experimental MethodsMichael Sanders1, Anyka Bergeson-Keller1, Yun Xu2, Nitin Kumar1, JiePan2, Debora R. Barcellos1, Andriy Zakutayev2, Vladan Stevanovic1,

Stephan Lany2, Anthony McDaniel3, Ryan O’Hayre1

1Colorado School of Mines, Golden CO2National Renewable Research Laboratory, Golden CO

3Sandia National Laboratory, Livermore CA

Solar Thermochemical Hydrogen produc-tion (STCH) technologies employing two-stepmetal oxide water-splitting cycles are emergingas a viable approach to renewable and sus-tainable solar fuels. However, materials in-novations that overcome thermodynamic con-straints native to the current class of solar-thermal water splitting oxides are requiredto increase solar utilization and process effi-ciency. Increasingly, the search for new STCHcycle materials has turned towards perovskite-structured oxides. Perovskites have many de-sirable traits, including high structural tolerancefor non-stoichiometry, tunable point-defect thermodynamics, good chemical stabil-ity and a long history of application in related fields that require oxygen exchangefunctionality (such as solid oxide fuel cells, chemical looping, and electrochemi-cal water splitting). While research into perovskite-based STCH materials is stillin its infancy, several compounds including SrxLa1−xMnyAl1−yO3−δ (SLMA) andBaCe0.25Mn0.75O3−δ (BCM) have shown promise.

However, not only is the compositional space of these tertiary and quaternarycation perovskites vast (the number of elemental variations that will form solid-solutions of the type AxA

′1−xByB

′1−yO3−δ is thought to be in the tens of thou-

sands), but the same cation combinations can form different structures. Such is thecase for the recently reported CexSr2−xMnO4−δ (CSM) layered perovskite and therelated simple perovskite Sr1−xCexMnO3−δ (SCM). The former is a Ruddlesden-Popper phase (K2NiF4-type) where the simple perovskite layers are separated bysimple oxide rock-salt SrO layers. As such, new methodologies must be developedto adequately explore this practically limitless space.

This presentation offers an overview of the materials work being done in ourgroup through DOE’s HydroGEN consortium. It is a three-pronged exploration thatcapitalizes on the strengths and expertise of National Lab resources at NREL andSandia. Computational theory and combinatorial thin-film work are combined toaccelerate the search and testing of new potential thermochemically-active com-pounds. Bulk experiments are also performed to ultimately prove a compound’sviability, as well as feed important data back into the other two efforts to improvethe next iterations.

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brian c. davis dylan jennings

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