Processing of yttrium-doped barium zirconate for high proton conductivity

The factors governing the transport properties of yttrium-doped barium zirconate (BYZ) have been explored, with the aim of attaining reproducible proton conductivity in well-densified samples. It was found that a small initial particle size (50–100 nm) and high-temperature sintering (1600 °C) in the presence of excess barium were essential. By this procedure, BaZr0.8Y0.2O3-d with 93% to 99% theoretical density and total (bulk plus grain boundary) conductivity of 7.9 × 10^-3 S/cm at 600 °C [as measured by alternating current (ac) impedance spectroscopy under humidified nitrogen] could be reliably prepared. Samples sintered in the absence of excess barium displayed yttria-like precipitates and a bulk conductivity that was reduced by more than 2 orders of magnitude

Alcohol Fuel Cells at Optimal Temperatures

High-power-density alcohol fuel cells can relieve many of the daunting challenges facing a hydrogen energy economy. Here, such fuel cells are achieved using CsH2PO4 as the electrolyte and integrating into the anode chamber a Cu-ZnO/Al2O3 methanol steam-reforming catalyst. The temperature of operation, ~250°C, is matched both to the optimal value for fuel cell power output and for reforming. Peak power densities using methanol and ethanol were 226 and 100 mW/cm^2, respectively. The high power output (305 mW/cm^2) obtained from reformate fuel containing 1% CO demonstrates the potential of this approach with optimized reforming catalysts and also the tolerance to CO poisoning at these elevated temperatures

Solid acid proton conductors: from laboratory curiosities to fuel cell electrolytes

The compound CsH2PO4 has emerged as a viable electrolyte for intermediate temperature (200–300 °C) fuel cells. In order to settle the question of the high temperature behavior of this material, conductivity measurements were performed by two-point AC impedance spectroscopy under humidified conditions (p[H2O] = 0.4 atm). A transition to a stable, high conductivity phase was observed at 230 °C, with the conductivity rising to a value of 2.2 × 10^–2 S cm^–1 at 240 °C and the activation energy of proton transport dropping to 0.42 eV. In the absence of active humidification, dehydration of CsH2PO4 does indeed occur, but, in contradiction to some suggestions in the literature, the dehydration process is not responsible for the high conductivity at this temperature. Electrochemical characterization by galvanostatic current interrupt (GCI) methods and three-point AC impedance spectroscopy (under uniform, humidified gases) of CsH2PO4 based fuel cells, in which a composite mixture of the electrolyte, Pt supported on carbon, Pt black and carbon black served as the electrodes, showed that the overpotential for hydrogen electrooxidation was virtually immeasurable. The overpotential for oxygen electroreduction, however, was found to be on the order of 100 mV at 100 mA cm^–2. Thus, for fuel cells in which the supported electrolyte membrane was only 25 µm in thickness and in which a peak power density of 415 mW cm^–2 was achieved, the majority of the overpotential was found to be due to the slow rate of oxygen electrocatalysis. While the much faster kinetics at the anode over those at the cathode are not surprising, the result indicates that enhancing power output beyond the present levels will require improving cathode properties rather than further lowering the electrolyte thickness. In addition to the characterization of the transport and electrochemical properties of CsH2PO4, a discussion of the entropy of the superprotonic transition and the implications for proton transport is presented

High Performance Protonic Ceramic Fuel Cells with Acid-Etched Surfaces

We focus on the proton-conducting doped - barium zirconate, which has large proton conductivity at intermediate temperature. We found here a phenomenon that acid - etching of the doped barium zirconate in a solution having a specific pH leaves a porous structure on the surface, and demonstrated power generation of hydrogen fuel cell using electroless-plated Pd and Pt on the porously acid-etched electrolyte surface. The short circuit current density of the hydrogen fuel cell was about 430 mA/cm2 at 600°C using thick electrolyte of 500 μm

Thin-Membrane Solid-Acid Fuel Cell

Solid-acid fuel cells (SCFCs) utilize an anhydrous, nonpolymeric proton conducting electrolyte that can operate at slightly elevated temperatures. By supporting thin CsH2PO4 electrolyte membranes (25-36 µm), on porous stainless steel gas-diffusion electrodes, SAFCs with peak power densities as high as 415 mW/cm^2 were obtained. Cells were operated at ~240°C with humidified H2 supplied to the anode and humidified O2 supplied to the cathode. Despite the thinness of the membranes, the open-circuit voltages were high, 0.91-1.01 V. These results transform SAFCs from laboratory curiosities into highly competitive energy conversion devices

A comprehensive understanding of structure and site occupancy of Y in Y-doped BaZrO_3

Y-doped BaZrO_3 (BZY) is of the perovskite structure (ABO_3), and is promising as an electrolyte in protonic ceramic fuel cells (PCFCs). However, factors limiting its protonic conductivity have not been clarified entirely, such as the unclear site occupancy of Y. In this work, X-ray diffraction patterns were collected utilizing synchrotron radiation with an incident energy close to the energy of the Y K absorption edge. Therefore, precise Rietveld refinement was performed to determine the site occupancy of Y by the anomalous dispersion effect. The results revealed that for the stoichiometric sample of BaZr_{0.8}Y_{0.2}O_{3−δ}, Y only occupied the B-site. But in the Ba-deficient sample of Ba_{0.9}Zr_{0.8}Y_{0.2}O_{3−δ}, two perovskite phases with different compositions were observed. In the Y-poor phase, all Y occupied the B-site, while in the other greatly Y-rich and Ba-deficient phase, Y was found to occupy both A and B-sites. These results clearly indicate the tendency towards A-site occupation of Y with an increasing Ba-deficiency

Construction of 21st Century Archives for the Research Foundation of the Library and Information Professions and Education: Towards a Methodological Synthesis of Library and Information Science and Archival Science

We launched a project aimed to organize and create digital archives for library and information professions that will contribute to both research and education. The archive will comprise historical materials owned by the University of Tsukuba\u27s Graduate School of Library, Information and Media Studies, which shaped the history of the education of library and information professions for most of the 20th century.This project includes the formation of a comprehensive system for collecting and conserving materials and the implementation of a system for their utilization. The aims of this project are twofold: (1) to examine a methodological synthesis of library and information science and archival science and (2) to re-examine the history of the library and information professions and education.Major users of the archives are library and information science researchers specialized in library and information professions and the history of librarianship. This system will establish a multilingual interface for international researchers who are interested in comparing professional development models of education for librarianship. Museum materials will be used for educational content on the history of media technology.There are no precedents for a comprehensive archival system for the education of library and information professions that includes archival documents and museum documents. This archive thus has the potential to serve as an international model for knowledge-sharing on library and information science.Six subordinate cross-disciplinary studies are in progress under the project. They comprise (1) A detailed examination of the collection and oral histories investigation, (2) Information architecture for digital archives, (3) Historical research on library and information professions and education, using archival materials, (4) Modeling, implementation and evaluation of the archive, (5) Modeling of the exhibition space, and (6) Analysis of the research project (museums, libraries and archives collaboration). This poster presentation focuses on studies in progress on (2) Information Architecture for digital archives and (3) Historical research on library and information professions and education, using archival materials.The first study reconsidered “digital archives” to drive forward the project entitled “21st Century Archives for the Research Foundation of the Library and Information Professions and Education.” As a result, digital archives are defined as mapping of the original archives, holding to the principles of provenance, respect for the original order, preservation of the original forms of the archives, and permanent preservation. A real digital archive must be constructed based on an information architecture methodology.Information architecture is the structural design of shared information environments; the art and science of organizing and labeling websites, intranets, online communities and software to support usability and findability. It involves analysis of information context and organization, labeling, navigation and retrieval using a consistent design philosophy. Information design prioritizes how information is presented on a website. Information architecture, on the other hand, is a website construction method that focuses on how to organize information elements. This study aims to achieve faithful mapping between the context of the original resources and electronic resources through the application of information architecture methodology to the establishment of digital archives.In the second study, we adopted the methodology of digital humanities as our analytical scheme to clarify the historical development, current conditions, and future vision of the library and information professions and education. The materials in our archive collections for historical research of librarianship are periodicals, annual reports, minutes of meetings, syllabuses, business diaries, photographs, audio materials, video materials and films. They include unpublished and handwritten materials. Whatever their form, these materials are an aggregation of the memory of the philosophy of an institution and records of past activities. Previous studies have not included these materials due to their uncatalogued nature and often poor state of preservation.We used two illustrative examples that utilize digital archive collections to demonstrate the progress of research. The first attempt was to trace the history of library and information professions focusing on changes in nominal designations of librarians/information professionals. The other was a consideration of the gender issue concerning female librarians, using digital images from the archive. These primary investigations have suggested the potential for reconstructing a discourse on the library and information professions and education.Japanese Association for Digital Humanities Conference 2014, at University of Tsukuba, September 19-21, 2014 (Poster session 2