Abstract The current study investigates the lead-free halide double perovskites Cs 2 AsNaX 6 (X = F, Cl, Br) using first-principles calculations to assess their potential in optoelectronic and thermoelectric applications. The study comprises the electronic, mechanical, thermodynamic, optical, and transport properties of these compounds. All systems crystallize in the cubic phase and exhibit thermodynamic and mechanical stability. Electronic structure calculations employing the Trans-Blaha modified Becke Johnson potential reveal indirect band gaps of 3.55 and 2.81 eV for Cs 2 AsNaCl 6 and Cs 2 AsNaBr 6 , respectively. However, Cs 2 AsNaF 6 shows a wide gap exceeding 4 eV, indicating an insulating nature. Optical profile confirms strong ultraviolet absorption. Transport properties demonstrate high power factors and notable thermoelectric performance. The results suggest that the Cs 2 AsNaX 6 (X = F, Cl, Br) double perovskites are promising candidates for UV-responsive optoelectronic devices and efficient thermoelectric applications.
Abstract Due to the toxicity and instability of lead-containing perovskites, high-performance lead-free perovskite attracts considerable attention. Lead-free vacancy-ordered double perovskites (VODP) emerge as environmentally friendly and efficient solutions as lead-containing solar cell substitutes. In this study, electronic properties of vacancy-ordered double perovskites Cs2BX6 (B = Zr, Pd, Sn; X = Cl, Br, I) under high pressure are investigated using first-principles methods. Semiconductors with bandgaps between 1.1 to 1.6 eV are considered for application. Our results show Cs2PdCl6 giving 1.60 and 1.32 eV bandgaps at 5 and 10 GPa, Cs2PdBr6 yielding 1.22 eV at ambient pressure, Cs2SnBr6 having 1.31 and 1.03 eV bandgap at 5 and 10 GPa, and Cs2ZrI6 showing 1.52 and 1.28 eV bandgap at 15 and 20 GPa. Furthermore, we considered the absorption coefficient and spectrum to ensure the materials’ optical performance. Cs2PdCl6, Cs2PdBr6, and Cs2ZrI6 display competent absorbance in the visible light range and proved these vacancy-ordered double perovskites as promising lead-free solar cell materials.
Abstract In this work, density-functional theory based theoretical investigations of novel and less studied double perovskites Cs 2 InSbX 6 (X = Cl, Br, I) are performed to analyze the structural and electronic behaviors. The electronic structures computed using PBEsol are further subjected to Tran-Blaha modified Becke-Johnson (TB-mBJ) potential, and tuning of the semiconducting direct band gap is observed as 1.77 eV, 1.07 eV and 0.35 eV for Cs 2 InSbX 6 (X = Cl, Br, I), respectively. The structural stability is confirmed from the computed tolerance factors and enthalpy of formation. Thermodynamic stability is also revealed by the computed phonon spectra. The halogen ions based band gap tuning in Cs 2 InSbX 6 (X = Cl, Br, I) show systematic variation of the computed optical parameters against impinging energies. The thermoelectric properties are found consistent with various transport parameters. The narrow band gap Cs 2 InSbI 6 (0.35 eV) results comparatively high power factor. The band gap tuning based variations in the optical and thermoelectric parameters have revealed potential applications in energy absorption and conversion devices, respectively.
Benjamin Scheibe, Antti J. Karttunen, Ulrich Müller
et al.
AbstractWird CsF mit flüssigem ClF3 im Überschuss umgesetzt, so kann das Salz Cs[Cl3F10] erhalten werden. Es enthält ein molekulares, propellerförmiges [Cl3F10]−‐Anion, in dem drei T‐förmig gebaute ClF3‐Moleküle an ein zentrales und somit μ3‐verbrückendes F‐Atom koordinieren. Dieses Heteropolyhalogenidanion stellt das erste Beispiel eines Interhalogenanions mit höherem ClF3‐Gehalt als dem [ClF4]−‐Anion dar. Weiterhin ist es die erste chlorhaltige Interhalogenspezies in der ein verbrückendes Fluoratom vorliegt. Die chemischen Bindungen zu diesem zentralen μ3‐F‐Atom sind praktisch ionisch und offenbar recht schwach, da die X‐F‐Bindungslängen (X=Cl, und auch berechnet für Br, I) der koordinierenden XF3‐Einheiten im Vergleich zu denen freier XF3‐Moleküle praktisch unverändert sind. Cs[Cl3F10] kristallisiert in einem bisher äußerst selten beobachteten A[5]B[5]‐Strukturtyp, in dem Kationen und Anionen jeweils pseudohexagonal gepackt vorliegen. Die Ionen weisen die Koordinationszahl fünf auf und befinden sich jeweils in den trigonal‐bipyramidalen Lücken der Packung der anderen Ionensorte.
This paper explores proof-theoretic aspects of hybrid type-logical grammars , a logic combining Lambek grammars with lambda grammars. We prove some basic properties of the calculus, such as normalisation and the subformula property and also present both a sequent and a proof net calculus for hybrid type-logical grammars. In addition to clarifying the logical foundations of hybrid type-logical grammars, the current study opens the way to variants and extensions of the original system, including but not limited to a non-associative version and a multimodal version incorporating structural rules and unary modes.
Mokanarangan Thayaparan, Marco Valentino, André Freitas
This paper presents a systematic review of benchmarks and approaches for explainability in Machine Reading Comprehension (MRC). We present how the representation and inference challenges evolved and the steps which were taken to tackle these challenges. We also present the evaluation methodologies to assess the performance of explainable systems. In addition, we identify persisting open research questions and highlight critical directions for future work.
We propose an unsupervised neural model for learning a discrete embedding of words. Unlike existing discrete embeddings, our binary embedding supports vector arithmetic operations similar to continuous embeddings. Our embedding represents each word as a set of propositional statements describing a transition rule in classical/STRIPS planning formalism. This makes the embedding directly compatible with symbolic, state of the art classical planning solvers.
We solve difficult word-based substitution codes by constructing a decoding lattice and searching that lattice with a neural language model. We apply our method to a set of enciphered letters exchanged between US Army General James Wilkinson and agents of the Spanish Crown in the late 1700s and early 1800s, obtained from the US Library of Congress. We are able to decipher 75.1% of the cipher-word tokens correctly.
Named Entity Recognition (NER) has greatly advanced by the introduction of deep neural architectures. However, the success of these methods depends on large amounts of training data. The scarcity of publicly-available human-labeled datasets has resulted in limited evaluation of existing NER systems, as is the case for Danish. This paper studies the effectiveness of cross-lingual transfer for Danish, evaluates its complementarity to limited gold data, and sheds light on performance of Danish NER.
This work systematically analyzes the smoothing effect of vocabulary reduction for phrase translation models. We extensively compare various word-level vocabularies to show that the performance of smoothing is not significantly affected by the choice of vocabulary. This result provides empirical evidence that the standard phrase translation model is extremely sparse. Our experiments also reveal that vocabulary reduction is more effective for smoothing large-scale phrase tables.
DEMorphy is a morphological analyzer for German. It is built onto large, compactified lexicons from German Morphological Dictionary. A guesser based on German declension suffixed is also provided. For German, we provided a state-of-art morphological analyzer. DEMorphy is implemented in Python with ease of usability and accompanying documentation. The package is suitable for both academic and commercial purposes wit a permissive licence.
We present BPEmb, a collection of pre-trained subword unit embeddings in 275 languages, based on Byte-Pair Encoding (BPE). In an evaluation using fine-grained entity typing as testbed, BPEmb performs competitively, and for some languages bet- ter than alternative subword approaches, while requiring vastly fewer resources and no tokenization. BPEmb is available at https://github.com/bheinzerling/bpemb
A new Python API, integrated within the NLTK suite, offers access to the FrameNet 1.7 lexical database. The lexicon (structured in terms of frames) as well as annotated sentences can be processed programatically, or browsed with human-readable displays via the interactive Python prompt.
We show how eye-tracking corpora can be used to improve sentence compression models, presenting a novel multi-task learning algorithm based on multi-layer LSTMs. We obtain performance competitive with or better than state-of-the-art approaches.
We model and compute the probability distribution of the letters in random generated words in a language by using the theory of set partitions, Young tableaux and graph theoretical representation methods. This has been of interest for several application areas such as network systems, bioinformatics, internet search, data mining and computacional linguistics.
A Dialogue System is a system which interacts with human in natural language. At present many universities are developing the dialogue system in their regional language. This paper will discuss about dialogue system, its components, challenges and its evaluation. This paper helps the researchers for getting info regarding dialogues system.
Evgeny V. Nazarchuk, Oleg I. Siidra, Sergey V. Krivovichev
AbstractLemon‐yellow transparent needles of Cs2(UO2)(NO3)Cl3 are hydrothermally synthesized from a mixture of CsCl, UO2(NO3)2, NaOH, and H2O (autoclave, pH 10, 205 °C, 96 h).