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Fuel cells, particularly solid oxide fuel cells (SOFC), are important for the future of greener and more efficient energy sources. Although SOFCs have been in existence for over fifty years, they have not been deployed extensively because they need to be operated at a high temperature (∼1000 °C), are expensive,

Fuel cells, particularly solid oxide fuel cells (SOFC), are important for the future of greener and more efficient energy sources. Although SOFCs have been in existence for over fifty years, they have not been deployed extensively because they need to be operated at a high temperature (∼1000 °C), are expensive, and have slow response to changes in energy demands. One important need for commercialization of SOFCs is a lowering of their operating temperature, which requires an electrolyte that can operate at lower temperatures. Doped ceria is one such candidate. For this dissertation work I have studied different types of doped ceria to understand the mechanism of oxygen vacancy diffusion through the bulk. Doped ceria is important because they have high ionic conductivities thus making them attractive candidates for the electrolytes of solid oxide fuel cells. In particular, I have studied how the ionic conductivities are improved in these doped materials by studying the oxygen-vacancy formations and migrations. In this dissertation I describe the application of density functional theory (DFT) and Kinetic Lattice Monte Carlo (KLMC) simulations to calculate the vacancy diffusion and ionic conductivities in doped ceria. The dopants used are praseodymium (Pr), gadolinium (Gd), and neodymium (Nd), all belonging to the lanthanide series. The activation energies for vacancy migration between different nearest neighbor (relative to the dopant) positions were calculated using the commercial DFT code VASP (Vienna Ab-initio Simulation Package). These activation energies were then used as inputs to the KLMC code that I co-developed. The KLMC code was run for different temperatures (673 K to 1073 K) and for different dopant concentrations (0 to 40%). These simulations have resulted in the prediction of dopant concentrations for maximum ionic conductivity at a given temperature.
ContributorsAnwar, Shahriar (Author) / Adams, James B (Thesis advisor) / Crozier, Peter (Committee member) / Krause, Stephen (Committee member) / Arizona State University (Publisher)
Created2011
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Description
There is an inexorable link between structure and stress, both of which require study in order to truly understand the physics of thin films. To further our knowledge of thin films, the relationship between structure and stress development was examined in three separate systems in vacuum. The first was continued

There is an inexorable link between structure and stress, both of which require study in order to truly understand the physics of thin films. To further our knowledge of thin films, the relationship between structure and stress development was examined in three separate systems in vacuum. The first was continued copper thin film growth in ultra-high vacuum after adsorption of a sub-monolayer quantity of oxygen. Results showed an increase in compressive stress generation, and theory was proposed to explain the additional compressive stress within the films. The second system explored was the adsorption of carbon monoxide on the platinum {111} surface in vacuum. The experiments displayed a correlation between known structural developments in the adsorbed carbon monoxide adlayer and the surface stress state of the system. The third system consisted of the growth and annealing stresses of ice thin films at cryogenic temperatures in vacuum. It was shown that the growth stresses are clearly linked to known morphology development from literature, with crystalline ice developing compressive and amorphous ice developing tensile stresses respectively, and that amorphous ice films develop additional tensile stresses upon annealing.
ContributorsKennedy, Jordan (Author) / Friesen, Cody (Thesis advisor) / Sieradzki, Karl (Committee member) / Crozier, Peter (Committee member) / Arizona State University (Publisher)
Created2011
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Description

"No civil discourse, no cooperation; misinformation, mistruth." These were the words of former Facebook Vice President Chamath Palihapitiya who publicly expressed his regret in a 2017 interview over his role in co-creating Facebook. Palihapitiya shared that social media is ripping apart the social fabric of society and he also sounded

"No civil discourse, no cooperation; misinformation, mistruth." These were the words of former Facebook Vice President Chamath Palihapitiya who publicly expressed his regret in a 2017 interview over his role in co-creating Facebook. Palihapitiya shared that social media is ripping apart the social fabric of society and he also sounded the alarm regarding social media’s unavoidable global impact. He is only one of social media’s countless critics. The more disturbing issue resides in the empirical evidence supporting such notions. At least 95% of adolescents own a smartphone and spend an average time of two to four hours a day on social media. Moreover, 91% of 16-24-year-olds use social media, yet youth rate Instagram, Facebook, and Twitter as the worst social media platforms. However, the social, clinical, and neurodevelopment ramifications of using social media regularly are only beginning to emerge in research. Early research findings show that social media platforms trigger anxiety, depression, low self-esteem, and other negative mental health effects. These negative mental health symptoms are commonly reported by individuals from of 18-25-years old, a unique period of human development known as emerging adulthood. Although emerging adulthood is characterized by identity exploration, unbounded optimism, and freedom from most responsibilities, it also serves as a high-risk period for the onset of most psychological disorders. Despite social media’s adverse impacts, it retains its utility as it facilitates identity exploration and virtual socialization for emerging adults. Investigating the “user-centered” design and neuroscience underlying social media platforms can help reveal, and potentially mitigate, the onset of negative mental health consequences among emerging adults. Effectively deconstructing the Facebook, Twitter, and Instagram (i.e., hereafter referred to as “The Big Three”) will require an extensive analysis into common features across platforms. A few examples of these design features include: like and reaction counters, perpetual news feeds, and omnipresent banners and notifications surrounding the user’s viewport. Such social media features are inherently designed to stimulate specific neurotransmitters and hormones such as dopamine, serotonin, and cortisol. Identifying such predacious social media features that unknowingly manipulate and highjack emerging adults’ brain chemistry will serve as a first step in mitigating the negative mental health effects of today’s social media platforms. A second concrete step will involve altering or eliminating said features by creating a social media platform that supports and even enhances mental well-being.

ContributorsGupta, Anay (Author) / Flores, Valerie (Thesis director) / Carrasquilla, Christina (Committee member) / Barnett, Jessica (Committee member) / The Sidney Poitier New American Film School (Contributor) / Computer Science and Engineering Program (Contributor, Contributor) / Barrett, The Honors College (Contributor)
Created2021-05
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Americans today face an age of information overload. With the evolution of Media 3.0, the internet, and the rise of Media 3.5—i.e., social media—relatively new communication technologies present pressing challenges for the First Amendment in American society. Twentieth century law defined freedom of expression, but in an information-limited world. By

Americans today face an age of information overload. With the evolution of Media 3.0, the internet, and the rise of Media 3.5—i.e., social media—relatively new communication technologies present pressing challenges for the First Amendment in American society. Twentieth century law defined freedom of expression, but in an information-limited world. By contrast, the twenty-first century is seeing the emergence of a world that is overloaded with information, largely shaped by an “unintentional press”—social media. Americans today rely on just a small concentration of private technology powerhouses exercising both economic and social influence over American society. This raises questions about censorship, access, and misinformation. While the First Amendment protects speech from government censorship only, First Amendment ideology is largely ingrained across American culture, including on social media. Technological advances arguably have made entry into the marketplace of ideas—a fundamental First Amendment doctrine—more accessible, but also more problematic for the average American, increasing his/her potential exposure to misinformation. <br/><br/>This thesis uses political and judicial frameworks to evaluate modern misinformation trends, social media platforms and current misinformation efforts, against the background of two misinformation accelerants in 2020, the COVID-19 pandemic and U.S. presidential election. Throughout history, times of hardship and intense fear have contributed to the shaping of First Amendment jurisprudence. Thus, this thesis looks at how fear can intensify the spread of misinformation and influence free speech values. Extensive research was conducted to provide the historical context behind relevant modern literature. This thesis then concludes with three solutions to misinformation that are supported by critical American free speech theory.

ContributorsCochrane, Kylie Marie (Author) / Russomanno, Joseph (Thesis director) / Roschke, Kristy (Committee member) / School of Public Affairs (Contributor) / Walter Cronkite School of Journalism and Mass Comm (Contributor, Contributor) / Watts College of Public Service & Community Solut (Contributor) / Barrett, The Honors College (Contributor)
Created2021-05
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Description

This research covers the landscape of influencer marketing and combines it with the knowledge of 11 content creators and one social media specialist, ultimately producing an actionable handbook. Participants were asked questions that were intended to discover key strategies, level of difficulty, and overall insight into the content creator world.

This research covers the landscape of influencer marketing and combines it with the knowledge of 11 content creators and one social media specialist, ultimately producing an actionable handbook. Participants were asked questions that were intended to discover key strategies, level of difficulty, and overall insight into the content creator world. Best practices and key findings are identified in the research paper, and outlined into four parts in the handbook. The handbook serves as a compilation framework derived from my primary and secondary sources designed to provide anyone interested in becoming a content creator or social media influencer on steps they may take given what their predecessors have done to successfully launch their careers in the space.

ContributorsEsparza, Alexa (Author) / Giles, Charles (Thesis director) / Schlacter, John (Committee member) / Department of Marketing (Contributor) / Barrett, The Honors College (Contributor)
Created2021-05
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This project is a case study of the how The New York Times metro desk and its journalists used Twitter throughout the duration of Hurricane Sandy. Hurricane Sandy affected the East Coast of the United States in late October and early November 2012. The study specifically focuses on a random

This project is a case study of the how The New York Times metro desk and its journalists used Twitter throughout the duration of Hurricane Sandy. Hurricane Sandy affected the East Coast of the United States in late October and early November 2012. The study specifically focuses on a random sampling of journalists' individual Twitter accounts as listed on the Times website directory and the official New York Times Metro account, which tweets breaking news in the New York City metro area of five New York City boroughs and New Jersey. This study categorizes the tweets according to types of tweet, with regard to whether individual tweets were "retweets" (reposting of another Twitter user's tweet) as well as the tweet's contents by categories relevant to the storm. This case study utilizes a qualitative approach. The categories were determined based on theme as a contextual analysis to synthesize information more broadly to be more inclusive of tweets occurring during the time frame of October 27 to November 3, 2012. The study then analyzes the tweets through the lens of the Society of Professional Journalists' Code of Ethics, a code voluntarily embraced by thousands of journalists as a guideline for ethical behavior in the profession, and the New York Times informal guidelines for its journalists' social media use. The study seeks to explore the ethical implications of Twitter's use during breaking news and how the message is delivered can be framed by as a tweet or retweet rather than shared through traditional journalism methods (via print or a news organization's website.)
ContributorsSteffan, Sara (Author) / Matera, Fran (Thesis director) / Thornton, Leslie (Committee member) / Gilpin, Dawn (Committee member) / Barrett, The Honors College (Contributor) / Walter Cronkite School of Journalism and Mass Communication (Contributor)
Created2013-05
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This thesis paper examines the challenges and opportunities that are present for nonprofit organizations seeking to engage in social media marketing. By analyzing the rise of social media as a prevalent tool for business-consumer outreach the paper proposes a dialogic approach to social media for nonprofits to effectively engage with

This thesis paper examines the challenges and opportunities that are present for nonprofit organizations seeking to engage in social media marketing. By analyzing the rise of social media as a prevalent tool for business-consumer outreach the paper proposes a dialogic approach to social media for nonprofits to effectively engage with their audiences, develop relationships with them, and mobilize them towards a common mission.

ContributorsPando, Isabella G (Author) / Moran, Stacey (Thesis director) / deLusé, Stephanie (Committee member) / Arts, Media and Engineering Sch T (Contributor) / Barrett, The Honors College (Contributor)
Created2021-05
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Description
Novel materials for Li-ion batteries is one of the principle thrust areas for current research in energy storage, more so than most, considering its widespread use in portable electronic gadgets and plug-in electric and hybrid cars. One of the major limiting factors in a Li-ion battery's energy density is the

Novel materials for Li-ion batteries is one of the principle thrust areas for current research in energy storage, more so than most, considering its widespread use in portable electronic gadgets and plug-in electric and hybrid cars. One of the major limiting factors in a Li-ion battery's energy density is the low specific capacities of the active materials in the electrodes. In the search for high-performance anode materials for Li-ion batteries, many alternatives to carbonaceous materials have been studied. Both cubic and amorphous silicon can reversibly alloy with lithium and have a theoretical capacity of 3500 mAh/g, making silicon a potential high density anode material. However, a large volume expansion of 300% occurs due to changes in the structure during lithium insertion, often leading to pulverization of the silicon. To this end, a class of silicon based cage compounds called clathrates are studied for electrochemical reactivity with lithium. Silicon-clathrates consist of silicon covalently bonded in cage structures comprised of face sharing Si20, Si24 and/or Si28 clusters with guest ions occupying the interstitial positions in the polyhedra. Prior to this, silicon clathrates have been studied primarily for their superconducting and thermoelectric properties. In this work, the synthesis and electrochemical characterization of two categories of silicon clathrates - Type-I silicon clathrate with aluminum framework substitution and barium guest ions (Ba8AlxSi46-x) and Type-II silicon clathrate with sodium guest ions (Nax Si136), are explored. The Type-I clathrate, Ba8AlxSi46-x consists of an open framework of aluminium and silicon, with barium (guest) atoms occupying the interstitial positions. X-ray diffraction studies have shown that a crystalline phase of clathrate is obtained from synthesis, which is powdered to a fine particle size to be used as the anode material in a Li-ion battery. Electrochemical measurements of these type of clathrates have shown that capacities comparable to graphite can be obtained for up to 10 cycles and lower capacities can be obtained for up to 20 cycles. Unlike bulk silicon, the clathrate structure does not undergo excessive volume change upon lithium intercalation, and therefore, the crystal structure is morphologically stable over many cycles. X-ray diffraction of the clathrate after cycling showed that crystallinity is intact, indicating that the clathrate does not collapse during reversible intercalation with lithium ions. Electrochemical potential spectroscopy obtained from the cycling data showed that there is an absence of formation of lithium-silicide, which is the product of lithium alloying with diamond cubic silicon. Type II silicon clathrate, NaxSi136, consists of silicon making up the framework structure and sodium (guest) atoms occupying the interstitial spaces. These clathrates showed very high capacities during their first intercalation cycle, in the range of 3,500 mAh/g, but then deteriorated during subsequent cycles. X-ray diffraction after one cycle showed the absence of clathrate phase and the presence of lithium-silicide, indicating the disintegration of clathrate structure. This could explain the silicon-like cycling behavior of Type II clathrates.
ContributorsRaghavan, Rahul (Author) / Chan, Candace K. (Thesis advisor) / Crozier, Peter (Committee member) / Petuskey, William T (Committee member) / Arizona State University (Publisher)
Created2013
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Description
There has been much interest in photoelectrochemical conversion of solar energy in recent years due to its potential for low-–cost, sustainable and renewable production of fuels. Despite the huge potential, there are still a number of technical barriers due to the many constraints needed in order to drive photoelectrochemical reactions

There has been much interest in photoelectrochemical conversion of solar energy in recent years due to its potential for low-–cost, sustainable and renewable production of fuels. Despite the huge potential, there are still a number of technical barriers due to the many constraints needed in order to drive photoelectrochemical reactions such as overall water splitting and the identification of efficient and effective semiconductor materials. To this end, the search for novel semiconductors that can act as light absorbers is still needed. The copper hydroxyphosphate mineral libethenite (CHP), which has a chemical formula of Cu2(OH)PO4, has been recently shown to be active for photocatalytic degradation of methylene blue under UV-–irradiation, indicating that photo-excited electrons and holes can effectively be generated and separated in this material. However, CHP has not been well studied and many of its fundamental electrochemical and photoelectrochemical properties are still unknown. In this work, the synthesis of different morphologies of CHP using hydrothermal synthesis and precipitation methods were explored. Additionally, a preliminary investigation of the relevant fundamental characteristics such as the bandgap, flatband potential, band diagram, electrochemical and photoelectrochemical properties for CHP was performed. Better understanding of the properties of this material may lead to the development of improved catalysts and photocatalysts from natural sources.
ContributorsLi, Man (Author) / Chan, Candace K. (Thesis advisor) / O'Connell, Michael (Committee member) / Crozier, Peter (Committee member) / Arizona State University (Publisher)
Created2013
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Description
This work focuses on simulation of electrical resistivity and optical behaviors of thin films, where an Ag or Au thin layer is embedded in zinc oxide. Enhanced conductivity and transparency were earlier achieved with multilayer structured transparent conducting oxide (TCO) sandwich layer with metal (TCO/metal/TCO). Sputtering pattern of metal layer

This work focuses on simulation of electrical resistivity and optical behaviors of thin films, where an Ag or Au thin layer is embedded in zinc oxide. Enhanced conductivity and transparency were earlier achieved with multilayer structured transparent conducting oxide (TCO) sandwich layer with metal (TCO/metal/TCO). Sputtering pattern of metal layer is simulated to obtain the morphology, covered area fraction, and the percolation strength. The resistivity as a function of the metal layer thickness fits the modeled trend of covered area fraction beyond the percolation threshold. This result not only presents the robustness of the simulation, but also demonstrates the influence of metal morphology in multilayer structure. Effective medium coefficients are defined from the coverage and percolation strength to obtain simulated optical transmittance which matches experimental observation. The coherence of resistivity and optical transmittance validates the simulation of the sputtered pattern and the incorporation of percolation theory in the model.
ContributorsFang, Chia-Ling (Author) / Alford, Terry L. (Thesis advisor) / Crozier, Peter (Committee member) / Theodore, David (Committee member) / Arizona State University (Publisher)
Created2012