A5083459020- Magnetic and transport properties of perovskites and related materials
- Advanced Condensed Matter Physics
- Topic Modeling
- Natural Language Processing Techniques
- Multiferroics and related materials
- Thermal Expansion and Ionic Conductivity
- Physics of Superconductivity and Magnetism
- Electrocatalysts for Energy Conversion
- Ferroelectric and Piezoelectric Materials
- Crystallization and Solubility Studies
- X-ray Diffraction in Crystallography
- Dielectric properties of ceramics
- Catalytic Processes in Materials Science
- Advanced battery technologies research
- Copper-based nanomaterials and applications
- Advancements in Battery Materials
- Multimodal Machine Learning Applications
- Advancements in Solid Oxide Fuel Cells
- Text and Document Classification Technologies
- Advanced Battery Materials and Technologies
- Fuel Cells and Related Materials
- Electronic and Structural Properties of Oxides
- Transition Metal Oxide Nanomaterials
- Crystal Structures and Properties
- Advanced Graph Neural Networks
Osaka Metropolitan University
2022-2025
Metropolitan University
2023-2025
Osaka Prefecture University
2014-2023
RIKEN Center for Advanced Intelligence Project
2018-2022
University of Washington
2021-2022
Tokyo Institute of Technology
2022
Tohoku University
2022
Kanagawa Industrial Technology Center
2022
National Institute of Informatics
2015-2022
RIKEN
2018-2022
We have investigated the structural, magnetic, and electric properties of ferromagnetic ${\mathrm{BiMnO}}_{3}$ with a highly distorted perovskite structure. At ${T}_{E}=750--770\mathrm{K},$ centrosymmetric--to--non-centrosymmetric structural transition takes place, which describes ferroelectricity in system. The changes dielectric constant were induced by magnetic ordering ${(T}_{M}\ensuremath{\approx}100\mathrm{K})$ as well application fields near ${T}_{M}.$ These features are attributed to...
Entity representations are useful in natural language tasks involving entities. In this paper, we propose new pretrained contextualized of words and entities based on the bidirectional transformer. The proposed model treats a given text as independent tokens, outputs them. Our is trained using pretraining task masked BERT. involves predicting randomly large entity-annotated corpus retrieved from Wikipedia. We also an entity-aware self-attention mechanism that extension transformer, considers...
Abstract The oxygen evolution reaction that occurs during water oxidation is of considerable importance as an essential energy conversion for rechargeable metal–air batteries and direct solar splitting. Cost-efficient ABO 3 perovskites have been studied extensively because their high activity the reaction; however, they lack stability, effective solution to this problem has not yet demonstrated. Here we report Fe 4+ -based quadruple perovskite CaCu 4 O 12 activity, which comparable or...
Named Entity Disambiguation (NED) refers to the task of resolving multiple named entity mentions in a document their correct references knowledge base (KB) (e.g., Wikipedia).In this paper, we propose novel embedding method specifically designed for NED.The proposed jointly maps words and entities into same continuous vector space.We extend skip-gram model by using two models.The KB graph learns relatedness link structure KB, whereas anchor context aims align vectors such that similar occur...
Bifunctional electrocatalysts for oxygen evolution/reduction reaction (OER/ORR) are desirable the development of energy conversion technologies. It is discovered that manganese quadruple perovskites CaMn7 O12 and LaMn7 show bifunctional catalysis in OER/ORR. A possible origin high OER activity unique surface structure through corner-shared planar MnO4 octahedral MnO6 units to promote direct OO bond formations.
Ikuya Yamada, Akari Asai, Jin Sakuma, Hiroyuki Shindo, Hideaki Takeda, Yoshiyasu Takefuji, Yuji Matsumoto. Proceedings of the 2020 Conference on Empirical Methods in Natural Language Processing: System Demonstrations. 2020.
Ferri interesting: CaCuII3FeIV4O12, prepared at 15 GPa and 1300 K, undergoes a charge disproportionation (2 FeIV→FeIII+FeV) electrical, magnetic, structural changes 210 K. The FeIIIO6 FeVO6 octahedra are ordered in rock-salt manner (see picture; Ca gray, O blue, Cu red), the low-temperature phase has ferrimagnetic structure CuII(S=1/2,↓)3FeIII(S=5/2,↑)2FeV(S=3/2,↑)2.
Big and cold: Strong internal compression of the Sr ion in novel perovskite SrCu3Fe4O12 (see structure) leads to giant negative thermal expansion (NTE) between 170 270 K. Mössbauer spectroscopy shows charge disproportionation FeIV FeIII FeV below 200 Thus, isoelectric substitution A-site cation can induce a drastic change structural electronic properties ACu3Fe4O12 perovskites. Detailed facts importance specialist readers are published as "Supporting Information". Such documents...
Adversarial evaluation stress-tests a model’s understanding of natural language. Because past approaches expose superficial patterns, the resulting adversarial examples are limited in complexity and diversity. We propose human- in-the-loop generation, where human authors guided to break models. aid with interpretations model predictions through an interactive user interface. apply this generation framework question answering task called Quizbowl, trivia enthusiasts craft questions. The...
Ever-proposed descriptors of catalytic activity for the oxygen evolution reaction (OER) were systematically investigated. A wide variety stoichiometric perovskite oxides ABO3 (A = Ca, Sr, Y, La; B Ti, V, Cr, Mn, Fe, Co, Ni, Cu) examined as OER catalysts. The simplest descriptor, eg, electron number transition-metal ions at B-site, was not applicable overpotentials (η) compounds tested in this study. Another 2p band center relative to Fermi energy (ε2p), necessarily adequate most part oxides....
We describe a neural network model that jointly learns distributed representations of texts and knowledge base (KB) entities. Given text in the KB, we train our proposed to predict entities are relevant text. Our is designed be generic with ability address various NLP tasks ease. using large corpus their entity annotations extracted from Wikipedia. evaluated on three important (i.e., sentence textual similarity, linking, factoid question answering) involving both unsupervised supervised...
We address the task of Named Entity Disambiguation (NED) for noisy text. present WikilinksNED, a large-scale NED dataset text fragments from web, which is significantly noisier and more challenging than existing news-based datasets. To capture limited local context surrounding each mention, we design neural model train it with novel method sampling informative negative examples. also describe new way initializing word entity embeddings that improves performance. Our outperforms...
We review the EfficientQA competition from NeurIPS 2020. The focused on open-domain question answering (QA), where systems take natural language questions as input and return answers. aim of was to build that can predict correct answers while also satisfying strict on-disk memory budgets. These budgets were designed encourage contestants explore trade-off between storing retrieval corpora or parameters learned models. In this report, we describe motivation organization competition, best...
When electrons pair in a superconductor, quasi-particles develop an acute sensitivity to different types of scattering potential that is described by the appearance coherence factors amplitudes. Although effects are well established isotropic superconductors, they much harder detect their anisotropic counterparts, such as high-superconducting-transition-temperature cuprates. We demonstrate approach highlights momentum-dependent Ca 2– x Na CuO 2 Cl . used Fourier-transform scanning tunneling...
The magnetic properties of PbVO3, a PbTiO3-type perovskite with large tetragonal distortion (c/a = 1.229), were investigated. temperature dependence the measured magnetization multidomain single-crystal samples showed broad maximum centered around 180 K, indicating two-dimensional antiferromagnetism. μSR measurement revealed presence long-range order below 43 K. magnetism is due to ordering dxy orbitals, which thought also be related PbVO3.
Multiferroic materials have been the subject of intense study, but it remains a great challenge to synthesize those presenting both magnetic and ferroelectric polarizations at room temperature. In this work, we successfully obtained LiNbO3-type ScFeO3, metastable phase converted from orthorhombic perovskite formed under 15 GPa elevated temperatures. A combined structure analysis by synchrotron X-ray neutron powder diffraction high-angle annular dark-field scanning transmission electron...
Bimetallic sulfides have been attracting considerable attention because of their high catalytic activities for oxygen reduction reaction (ORR) and evolution reaction; thus, they are considered efficient catalysts important energy conversion devices such as fuel cells metal–air batteries. Here, the activity a novel catalyst composed Co9–xNixS8 nanoparticles immobilized on N-doped carbons (Co9–xNixS8/NC) is reported. The synthesized using Ni-adsorbed Co–Zn zeolitic imidazolate framework (ZIF)...
Transition metal oxides have been extensively investigated as novel catalysts for oxygen evolution reaction (OER). Partial elemental substitutions are effective ways to increase catalytic performance and such electronic interactions between multiple elements known synergistic effects. However, serious issues random atomic arrangement ambiguous roles of constituent humper theoretical investigations rational materials design. Herein, we describe systematic study on OER activity AA′3B4O12-type...
Ikuya Yamada, Akari Asai, Hannaneh Hajishirzi. Proceedings of the 59th Annual Meeting Association for Computational Linguistics and 11th International Joint Conference on Natural Language Processing (Volume 2: Short Papers). 2021.
Ikuya Yamada, Koki Washio, Hiroyuki Shindo, Yuji Matsumoto. Proceedings of the 2022 Conference North American Chapter Association for Computational Linguistics: Human Language Technologies. 2022.
Unusual electronic phase transitions in the A-site ordered perovskites LnCu3Fe4O12 (Ln: trivalent lanthanide ion) are investigated. All compounds identical valence states of Ln3+Cu2+3Fe3.75+4O12 at high temperature. with larger Ln ions (Ln = La, Pr, Nd, Sm, Eu, Gd, Tb) show an intersite charge transfer transition (3Cu2+ + 4Fe3.75+ → 3Cu3+ 4Fe3+) which temperature decreases from 360 to 240 K decreasing ion size. In contrast, smaller Dy, Ho, Er, Tm Yb, Lu) transform into a...
Perovskite PbCoO3 synthesized at 12 GPa was found to have an unusual charge distribution of Pb2+Pb4+3Co2+2Co3+2O12 with orderings in both the A and B sites perovskite ABO3. Comprehensive studies using density functional theory (DFT) calculation, electron diffraction (ED), synchrotron X-ray (SXRD), neutron powder (NPD), hard photoemission spectroscopy (HAXPES), soft absorption (XAS), measurements specific heat as well magnetic electrical properties provide evidence lead ion cobalt ordering...
The oxygen evolution reaction (OER) is a crucial energy conversion for achieving sustainable society. Highly active OER catalysts were reported in Fe–Co mixed oxides such as perovskite-type Ba0.5Sr0.5Co0.8Fe0.2O3−δ (BSCF) and brownmillerite-type Ca2FeCoO5. synergistic effects of mixing on the activity are expected these oxides. However, details have not been discussed yet because their structure randomness. In this study, we examine catalytic several perovskite brownmillerite with trivalent...