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Metal hydride materials have been intensively studied for hydrogen storage applications. In addition to potential hydrogen economy applications, metal hydrides offer a wide variety of other interesting properties. For example, hydrogen-dominant materials, which are hydrides with the highest hydrogen content for a particular metal/semimetal composition, are predicted to display high-temperature

Metal hydride materials have been intensively studied for hydrogen storage applications. In addition to potential hydrogen economy applications, metal hydrides offer a wide variety of other interesting properties. For example, hydrogen-dominant materials, which are hydrides with the highest hydrogen content for a particular metal/semimetal composition, are predicted to display high-temperature superconductivity. On the other side of the spectrum are hydrides with small amounts of hydrogen (0.1 - 1 at.%) that are investigated as viable magnetic, thermoelectric or semiconducting materials. Research of metal hydride materials is generally important to gain fundamental understanding of metal-hydrogen interactions in materials. Hydrogenation of Zintl phases, which are defined as compounds between an active metal (alkali, alkaline earth, rare earth) and a p-block metal/semimetal, were attempted by a hot sintering method utilizing an autoclave loaded with gaseous hydrogen (< 9 MPa). Hydride formation competes with oxidative decomposition of a Zintl phase. The oxidative decomposition, which leads to a mixture of binary active metal hydride and p-block element, was observed for investigated aluminum (Al) and gallium (Ga) containing Zintl phases. However, a new phase Li2Al was discovered when Zintl phase precursors were synthesized. Using the single crystal x-ray diffraction (SCXRD), the Li2Al was found to crystallize in an orthorhombic unit cell (Cmcm) with the lattice parameters a = 4.6404(8) Å, b = 9.719(2) Å, and c = 4.4764(8) Å. Increased demand for materials with improved properties necessitates the exploration of alternative synthesis methods. Conventional metal hydride synthesis methods, like ball-milling and autoclave technique, are not responding to the demands of finding new materials. A viable alternative synthesis method is the application of high pressure for the preparation of hydrogen-dominant materials. Extreme pressures in the gigapascal ranges can open access to new metal hydrides with novel structures and properties, because of the drastically increased chemical potential of hydrogen. Pressures up to 10 GPa can be easily achieved using the multi-anvil (MA) hydrogenations while maintaining sufficient sample volume for structure and property characterization. Gigapascal MA hydrogenations using ammonia borane (BH3NH3) as an internal hydrogen source were employed in the search for new hydrogen-dominant materials. Ammonia borane has high gravimetric volume of hydrogen, and additionally the thermally activated decomposition at high pressures lead to a complete hydrogen release at reasonably low temperature. These properties make ammonia borane a desired hydrogen source material. The missing member Li2PtH6 of the series of A2PtH6 compounds (A = Na to Cs) was accessed by employing MA technique. As the known heavier analogs, the Li2PtH6 also crystallizes in a cubic K2PtCl6-type structure with a cell edge length of 6.7681(3) Å. Further gigapascal hydrogenations afforded the compounds K2SiH6 and Rb2SiH6 which are isostructural to Li2PtH6. The cubic K2SiH6 and Rb2SiH6 are built from unique hypervalent SiH62- entities with the lattice parameters of 7.8425(9) and 8.1572(4) Å, respectively. Spectroscopic analysis of hexasilicides confirmed the presence of hypervalent bonding. The Si-H stretching frequencies at 1550 cm-1 appeared considerably decreased in comparison with a normal-valent (2e2c) Si-H stretching frequencies in SiH4 at around 2200 cm-1. However, the observed stretching modes in hypervalent hexasilicides were in a reasonable agreement with Ph3SiH2- (1520 cm-1) where the hydrogen has the axial (3e4c bonded) position in the trigoal bipyramidal environment.
ContributorsPuhakainen, Kati (Author) / Häussermann, Ulrich (Thesis advisor) / Seo, Dong (Thesis advisor) / Kouvetakis, John (Committee member) / Wolf, George (Committee member) / Arizona State University (Publisher)
Created2013
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Description
Simultaneously culture heroes and stumbling buffoons, Tricksters bring cultural tools to the people and make the world more habitable. There are common themes in these figures that remain fruitful for the advancement of culture, theory, and critical praxis. This dissertation develops a method for opening a dialogue with Trickster figures.

Simultaneously culture heroes and stumbling buffoons, Tricksters bring cultural tools to the people and make the world more habitable. There are common themes in these figures that remain fruitful for the advancement of culture, theory, and critical praxis. This dissertation develops a method for opening a dialogue with Trickster figures. It draws from established literature to present a newly conceived and more flexible Trickster archetype. This archetype is more than a collection of traits; it builds on itself processually to form a method for analysis. The critical Trickster archetype includes the fundamental act of crossing borders; the twin ontologies of ambiguity and liminality; the particular tactics of humor, duplicity, and shape shifting; and the overarching cultural roles of culture hero and stumbling buffoon. Running parallel to each archetypal element, though, are Trickster's overarching critical spirit of Quixotic utopianism and underlying telos of manipulating human relationships. The character 'Q' from Star Trek: The Next Generation is used to demonstrate the critical Trickster archetype. To be more useful for critical cultural studies, Trickster figures must also be connected to their socio-cultural and historical contexts. Thus, this dissertation offers a second set of analytics, a dialogical method that connects Tricksters to the worlds they make more habitable. This dialogical method, developed from the work of M. M. Bakhtin and others, consists of three analytical tools: utterance, intertextuality, and chronotope. Utterance bounds the text for analysis. Intertextuality connects the utterance, the text, to its context. Chronotope suggests particular spatio-temporal relationships that help reveal the cultural significance of a dialogical performance. Performance artists Andre Stitt, Ann Liv Young, and Steven Leyba are used to demonstrate the method of Trickster dialogics. A concluding discussion of Trickster's unique chronotope reveals its contributions to conceptions of utopia and futurity. This dissertation offers theoretical advancements about the significance and tactics of subversive communication practices. It offers a new and unique method for cultural and performative analyses that can be expanded into different kinds of dialogics. Trickster dialogics can also be used generatively to direct and guide the further development of performative praxis.
ContributorsSalinas, Chema (Author) / de la Garza, Amira (Thesis advisor) / Carlson, Cheree (Committee member) / Olson, Clark (Committee member) / Ellsworth, Angela (Committee member) / Arizona State University (Publisher)
Created2013
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Description
Topological insulators with conducting surface states yet insulating bulk states have generated a lot of interest amongst the physics community due to their varied characteristics and possible applications. Doped topological insulators have presented newer physical states of matter where topological order co&ndashexists; with other physical properties (like magnetic order). The

Topological insulators with conducting surface states yet insulating bulk states have generated a lot of interest amongst the physics community due to their varied characteristics and possible applications. Doped topological insulators have presented newer physical states of matter where topological order co&ndashexists; with other physical properties (like magnetic order). The electronic states of these materials are very intriguing and pose problems and the possible solutions to understanding their unique behaviors. In this work, we use Electron Energy Loss Spectroscopy (EELS) – an analytical TEM tool to study both core&ndashlevel; and valence&ndashlevel; excitations in Bi2Se3 and Cu(doped)Bi2Se3 topological insulators. We use this technique to retrieve information on the valence, bonding nature, co-ordination and lattice site occupancy of the undoped and the doped systems. Using the reference materials Cu(I)Se and Cu(II)Se we try to compare and understand the nature of doping that copper assumes in the lattice. And lastly we utilize the state of the art monochromated Nion UltraSTEM 100 to study electronic/vibrational excitations at a record energy resolution from sub-nm regions in the sample.
ContributorsSubramanian, Ganesh (Author) / Spence, John (Thesis advisor) / Jiang, Nan (Committee member) / Chen, Tingyong (Committee member) / Chan, Candace (Committee member) / Arizona State University (Publisher)
Created2013
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Description
Buddhism is thriving in US-America, attracting many converts with college and post-graduate degrees as well as selling all forms of popular culture. Yet little is known about the communication dynamics behind the diffusion of Buddhist religious/spiritual traditions into the United States. Religion is an underexplored area of intercultural communication studies

Buddhism is thriving in US-America, attracting many converts with college and post-graduate degrees as well as selling all forms of popular culture. Yet little is known about the communication dynamics behind the diffusion of Buddhist religious/spiritual traditions into the United States. Religion is an underexplored area of intercultural communication studies (Nakayama & Halualani, 2010) and this study meets the lacuna in critical intercultural communication scholarship by investigating the communication practices of US-Americans adopting Asian Buddhist religious/spiritual traditions. Ethnographic observations were conducted at events where US-Americans gathered to learn about and practice Buddhist religious/spiritual traditions. In addition, interviews were conducted with US-Americans who were both learning and teaching Buddhism. The grounded theory method was used for data analysis. The findings of this study describe an emerging theory of the paracultural imaginary -- the space of imagining that one could be better than who one was today by taking on the cultural vestments of (an)Other. The embodied communication dynamics of intercultural exchange that take place when individuals adopt the rituals and philosophies of a foreign culture are described. In addition, a self-reflexive narrative of my struggle with the silence of witnessing the paracultural imaginary is weaved into the analysis. The findings from this study extend critical theorizing on cultural identity, performativity, and cultural appropriation in the diffusion of traditions between cultural groups. In addition, the study addresses the complexity of speaking out against the subtle prejudices in encountered in intercultural communication.
ContributorsWong, Terrie Siang-Ting (Author) / de la Garza, Sarah Amira (Thesis advisor) / Margolis, Eric (Committee member) / Budruk, Megha (Committee member) / Chen, Vivian Hsueh-Hua (Committee member) / Arizona State University (Publisher)
Created2013
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Description
The academic literature on science communication widely acknowledges a problem: science communication between experts and lay audiences is important, but it is not done well. General audience popular science books, however, carry a reputation for clear science communication and are understudied in the academic literature. For this doctoral dissertation, I

The academic literature on science communication widely acknowledges a problem: science communication between experts and lay audiences is important, but it is not done well. General audience popular science books, however, carry a reputation for clear science communication and are understudied in the academic literature. For this doctoral dissertation, I utilize Sam Harris's The Moral Landscape, a general audience science book on the particularly thorny topic of neuroscientific approaches to morality, as a case-study to explore the possibility of using general audience science books as models for science communication more broadly. I conduct a literary analysis of the text that delimits the scope of its project, its intended audience, and the domains of science to be communicated. I also identify seven literary aspects of the text: three positive aspects that facilitate clarity and four negative aspects that interfere with lay public engagement. I conclude that The Moral Landscape relies on an assumed knowledge base and intuitions of its audience that cannot reasonably be expected of lay audiences; therefore, it cannot properly be construed as popular science communication. It nevertheless contains normative lessons for the broader science project, both in literary aspects to be salvaged and literary aspects and concepts to consciously be avoided and combated. I note that The Moral Landscape's failings can also be taken as an indication that typical descriptions of science communication offer under-detailed taxonomies of both audiences for science communication and the varieties of science communication aimed at those audiences. Future directions of study include rethinking appropriate target audiences for science literacy projects and developing a more discriminating taxonomy of both science communication and lay publics.
ContributorsJohnson, Nathan W (Author) / Robert, Jason S (Thesis advisor) / Creath, Richard (Committee member) / Martinez, Jacqueline (Committee member) / Sylvester, Edward (Committee member) / Lynch, John (Committee member) / Arizona State University (Publisher)
Created2013
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Description
The alkali activation of aluminosilicate materials as binder systems derived from industrial byproducts have been extensively studied due to the advantages they offer in terms enhanced material properties, while increasing sustainability by the reuse of industrial waste and byproducts and reducing the adverse impacts of OPC production. Fly ash and

The alkali activation of aluminosilicate materials as binder systems derived from industrial byproducts have been extensively studied due to the advantages they offer in terms enhanced material properties, while increasing sustainability by the reuse of industrial waste and byproducts and reducing the adverse impacts of OPC production. Fly ash and ground granulated blast furnace slag are commonly used for their content of soluble silica and aluminate species that can undergo dissolution, polymerization with the alkali, condensation on particle surfaces and solidification. The following topics are the focus of this thesis: (i) the use of microwave assisted thermal processing, in addition to heat-curing as a means of alkali activation and (ii) the relative effects of alkali cations (K or Na) in the activator (powder activators) on the mechanical properties and chemical structure of these systems. Unsuitable curing conditions instigate carbonation, which in turn lowers the pH of the system causing significant reductions in the rate of fly ash activation and mechanical strength development. This study explores the effects of sealing the samples during the curing process, which effectively traps the free water in the system, and allows for increased aluminosilicate activation. The use of microwave-curing in lieu of thermal-curing is also studied in order to reduce energy consumption and for its ability to provide fast volumetric heating. Potassium-based powder activators dry blended into the slag binder system is shown to be effective in obtaining very high compressive strengths under moist curing conditions (greater than 70 MPa), whereas sodium-based powder activation is much weaker (around 25 MPa). Compressive strength decreases when fly ash is introduced into the system. Isothermal calorimetry is used to evaluate the early hydration process, and to understand the reaction kinetics of the alkali powder activated systems. A qualitative evidence of the alkali-hydroxide concentration of the paste pore solution through the use of electrical conductivity measurements is also presented, with the results indicating the ion concentration of alkali is more prevalent in the pore solution of potassium-based systems. The use of advanced spectroscopic and thermal analysis techniques to distinguish the influence of studied parameters is also discussed.
ContributorsChowdhury, Ussala (Author) / Neithalath, Narayanan (Thesis advisor) / Rajan, Subramanium D. (Committee member) / Mobasher, Barzin (Committee member) / Arizona State University (Publisher)
Created2013
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Description
The rapid advancement of wireless technology has instigated the broad deployment of wireless networks. Different types of networks have been developed, including wireless sensor networks, mobile ad hoc networks, wireless local area networks, and cellular networks. These networks have different structures and applications, and require different control algorithms. The focus

The rapid advancement of wireless technology has instigated the broad deployment of wireless networks. Different types of networks have been developed, including wireless sensor networks, mobile ad hoc networks, wireless local area networks, and cellular networks. These networks have different structures and applications, and require different control algorithms. The focus of this thesis is to design scheduling and power control algorithms in wireless networks, and analyze their performances. In this thesis, we first study the multicast capacity of wireless ad hoc networks. Gupta and Kumar studied the scaling law of the unicast capacity of wireless ad hoc networks. They derived the order of the unicast throughput, as the number of nodes in the network goes to infinity. In our work, we characterize the scaling of the multicast capacity of large-scale MANETs under a delay constraint D. We first derive an upper bound on the multicast throughput, and then propose a lower bound on the multicast capacity by proposing a joint coding-scheduling algorithm that achieves a throughput within logarithmic factor of the upper bound. We then study the power control problem in ad-hoc wireless networks. We propose a distributed power control algorithm based on the Gibbs sampler, and prove that the algorithm is throughput optimal. Finally, we consider the scheduling algorithm in collocated wireless networks with flow-level dynamics. Specifically, we study the delay performance of workload-based scheduling algorithm with SRPT as a tie-breaking rule. We demonstrate the superior flow-level delay performance of the proposed algorithm using simulations.
ContributorsZhou, Shan (Author) / Ying, Lei (Thesis advisor) / Zhang, Yanchao (Committee member) / Zhang, Junshan (Committee member) / Xue, Guoliang (Committee member) / Arizona State University (Publisher)
Created2013
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Description
In order to adapt to a new culture and new language, children of immigrant families are faced daily with the responsibility of being the intermediaries between the family and the host culture through their language proficiency (Weisskirch & Alva, 2002). This thesis looks into the experiences of English-Spanish bilingual children

In order to adapt to a new culture and new language, children of immigrant families are faced daily with the responsibility of being the intermediaries between the family and the host culture through their language proficiency (Weisskirch & Alva, 2002). This thesis looks into the experiences of English-Spanish bilingual children as they bridge the gap between the family and the non-Spanish speaking community through their interpreting/translating skills. With an emphasis on children of Mexican-origin, the goal is to further understand and illuminate how these children manage this communication in an adult society, their feelings and thoughts about their experiences, and the child's perceptions about the influence that this experience may or may not have on their future. A sample of seventeen children agreed to participate in a semi-structured face-to-face interview to share their experiences. The data from these interviews were analyzed using a thematic analysis approach (Braun & Clarke, 2006). A priori themes of circumstantial bilingual and adaptive parentification were the initial focus of the research while being open to emerging themes. The children's accounts of their experiences indicated primarily that the Mexican-origin values of familism and respeto (respect) were a significant influence on them when they interpreted/translated for their family. With these traditional cultural values and norms as the groundwork, the sub-themes of normalcy and stress emerged as supportive elements of the circumstantial bilingual experience. Furthermore, the theme of adaptive parentification and the sub-themes of choice, expectation/responsibility to assist, and equality to parents offered further insight on how adaptive parentification can result as the roles of these children change. There was an emergent theme, identity negotiation, which increases our understanding of what the circumstantial bilingual child encounters as the attempt is made to negotiate his identity as an individual who has to mediate language between two opposing cultures. Due to the language brokering responsibility that are bestowed upon these children, it is concluded that communicative support by the parents is a necessary component of the parent-child relationship in order to nurture and develop these children as they negotiate and create their identity to become the successful leaders of tomorrow.
ContributorsCayetano, Catalina (Author) / Mean, Lindsey (Thesis advisor) / Waldron, Vincent (Committee member) / Gaffney, Cynthia (Committee member) / Arizona State University (Publisher)
Created2013
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Description
The thesis studies new methods to fabricate optoelectronic Ge1-ySny/Si(100) alloys and investigate their photoluminescence (PL) properties for possible applications in Si-based photonics including IR lasers. The work initially investigated the origin of the difference between the PL spectrum of bulk Ge, dominated by indirect gap emission, and the PL spectrum

The thesis studies new methods to fabricate optoelectronic Ge1-ySny/Si(100) alloys and investigate their photoluminescence (PL) properties for possible applications in Si-based photonics including IR lasers. The work initially investigated the origin of the difference between the PL spectrum of bulk Ge, dominated by indirect gap emission, and the PL spectrum of Ge-on-Si films, dominated by direct gap emission. It was found that the difference is due to the supression of self-absorption effects in Ge films, combined with a deviation from quasi-equilibrium conditions in the conduction band of undoped films. The latter is confirmed by a model suggesting that the deviation is caused by the shorter recombination lifetime in the films relative to bulk Ge. The knowledge acquired from this work was then utilized to study the PL properties of n-type Ge1-ySny/Si (y=0.004-0.04) samples grown via chemical vapor deposition of Ge2H6/SnD4/P(GeH3)3. It was found that the emission intensity (I) of these samples is at least 10x stronger than observed in un-doped counterparts and that the Idir/Iind ratio of direct over indirect gap emission increases for high-Sn contents due to the reduced gamma-L valley separation, as expected. Next the PL investigation was expanded to samples with y=0.05-0.09 grown via a new method using the more reactive Ge3H8 in place of Ge2H6. Optical quality, 1-um thick Ge1-ySny/Si(100) layers were produced using Ge3H10/SnD4 and found to exhibit strong, tunable PL near the threshold of the direct-indirect bandgap crossover. A byproduct of this study was the development of an enhanced process to produce Ge3H8, Ge4H10, and Ge5H12 analogs for application in ultra-low temperature deposition of Group-IV semiconductors. The thesis also studies synthesis routes of an entirely new class of semiconductor compounds and alloys described by Si5-2y(III-V)y (III=Al, V= As, P) comprising of specifically designed diamond-like structures based on a Si parent lattice incorporating isolated III-V units. The common theme of the two thesis topics is the development of new mono-crystalline materials on ubiquitous silicon platforms with the objective of enhancing the optoelectronic performance of Si and Ge semiconductors, potentially leading to the design of next generation optical devices including lasers, detectors and solar cells.
ContributorsGrzybowski, Gordon (Author) / Kouvetakis, John (Thesis advisor) / Chizmeshya, Andrew (Committee member) / Menéndez, Jose (Committee member) / Arizona State University (Publisher)
Created2013
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Description
Since the September 11, 2001 terrorist attacks and subsequent creation of the Transportation Security Administration (TSA), airport security has become an increasingly invasive, cumbersome, and expensive process. Fraught with tension and discomfort, "airport security" is a dirty phrase in the popular imagination, synonymous with long lines, unimpressive employees, and indignity.

Since the September 11, 2001 terrorist attacks and subsequent creation of the Transportation Security Administration (TSA), airport security has become an increasingly invasive, cumbersome, and expensive process. Fraught with tension and discomfort, "airport security" is a dirty phrase in the popular imagination, synonymous with long lines, unimpressive employees, and indignity. In fact, the TSA and its employees have featured as topic and punch line of news and popular culture stories. This image complicates the TSA's mission to ensure the nation's air travel safety and the ways that its officers interact with passengers. Every day, nearly two million people fly domestically in the United States. Each passenger must interact with many of the approximately 50,000 agents in airports. How employees and travelers make sense of interactions in airport security contexts can have significant implications for individual wellbeing, personal and professional relationships, and organizational policies and practices. Furthermore, the meaning making of travelers and employees is complexly connected to broad social discourses and issues of identity. In this study, I focus on the communication implications of identity and emotional performances in airport security in light of discourses at macro, meso, and micro levels. Using discourse tracing (LeGreco & Tracy, 2009), I construct the historical and discursive landscape of airport security, and via participant observation and various types of interviews, demonstrate how officers and passengers develop and perform identity, and the resulting interactional consequences. My analysis suggests that passengers and Transportation Security Officers (TSOs) perform three main types of identities in airport security contexts--what I call Stereotypical, Ideal, and Mindful--which reflect different types and levels of discourse. Identity performances are intricately related to emotional processes and occur dynamically, in relation to the identity and emotional performances of others. Theoretical implications direct attention to the ways that identity and emotional performances structure interactions, cause burdensome emotion management, and present organizational actors with tension, contradiction, and paradox to manage. Practical implications suggest consideration of passenger and TSO emotional wellbeing, policy framing, passenger agency, and preferred identities. Methodologically, this dissertation offers insight into discourse tracing and challenges of embodied "undercover" research in public spaces.
ContributorsRedden, Shawna Malvini (Author) / Tracy, Sarah J. (Thesis advisor) / Corley, Kevin (Committee member) / Alberts, Janet (Committee member) / Trethewey, Angela (Committee member) / Arizona State University (Publisher)
Created2013