Pub Date : 2020-03-10DOI: 10.1021/acs.jpcc.0c02030.s001
Saumyak Mukherjee, B. Bagchi
The solid–liquid interface of water is ∼50% narrower (or thinner) than that of argon. With the help of molecular dynamics simulations, we compare two water models, namely, TIP4P/ice and mW, with Lennard-Jones argon to understand the origin of this difference. We find that the sharpness of the ice–water interface is partly entropic in origin. The sharp drop in structural order from the crystalline to the liquid phase of water is assisted by a large increase in rotational entropy. We find that this change is strongly correlated to the number of hydrogen bond (HB) defects at the interface. The concentration of HB defects has earlier been correlated with entropy. We also find that the interfacial width is dependent on the order parameter chosen to define the interface. However, it always remains wider for the argon interface than that for water.
{"title":"Entropic Origin of the Attenuated Width of the Ice–Water Interface","authors":"Saumyak Mukherjee, B. Bagchi","doi":"10.1021/acs.jpcc.0c02030.s001","DOIUrl":"https://doi.org/10.1021/acs.jpcc.0c02030.s001","url":null,"abstract":"The\u0000solid–liquid\u0000interface of\u0000water is ∼50% narrower (or thinner) than that of argon. With\u0000the help of molecular dynamics simulations, we compare two water models,\u0000namely, TIP4P/ice and mW, with Lennard-Jones argon to understand the\u0000origin of this difference. We find that the sharpness of the ice–water\u0000interface is partly entropic in origin. The sharp drop in structural\u0000order from the crystalline to the liquid phase of water is assisted\u0000by a large increase in rotational entropy. We find that this change\u0000is strongly correlated to the number of hydrogen bond (HB) defects\u0000at the interface. The concentration of HB defects has earlier been\u0000correlated with entropy. We also find that the interfacial width is\u0000dependent on the order parameter chosen to define the interface. However,\u0000it always remains wider for the argon interface than that for water.","PeriodicalId":58,"journal":{"name":"The Journal of Physical Chemistry ","volume":null,"pages":null},"PeriodicalIF":2.781,"publicationDate":"2020-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141223623","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-03-05DOI: 10.1021/acs.jpcc.9b11579.s001
R. Marti, V. Sarou-kanian, Colton M. Moran, Krista S. Walton, S. Hayes
The structure of aluminum carbide (from two different manufacturers) has been interrogated by 27Al solid-state NMR in an effort to accurately characterize the material. Quadrupolar line shapes for 27Al sites such as these are important to catalogue, as efforts are underway to employ NMR crystallography tools to understand and predict both solid-state structures and perturbations to these that are relevant to NMR analyses. Impurities present in both of the samples are revealed to be aluminum oxycarbides, as well as an aluminum metal impurity in one and aluminum nitride in anotherpotentially important information for groups employing aluminum carbide in syntheses or in other applications. Triple-quantum magic-angle spinning (3Q-MAS) 27Al NMR was employed to help determine the quadrupolar parameters of the two crystallographically inequivalent aluminum sites in Al4C3. Revised values for the quadrupolar tensors of this material were measured and simulated through use of CASTEP-NMR.
{"title":"NMR Crystallography of Aluminum Carbide: Impuritiesin the Reagent and Improved 27Al NMR Tensors","authors":"R. Marti, V. Sarou-kanian, Colton M. Moran, Krista S. Walton, S. Hayes","doi":"10.1021/acs.jpcc.9b11579.s001","DOIUrl":"https://doi.org/10.1021/acs.jpcc.9b11579.s001","url":null,"abstract":"The\u0000structure of aluminum carbide (from two different manufacturers)\u0000has been interrogated by 27Al solid-state NMR in an effort\u0000to accurately characterize the material. Quadrupolar line shapes for 27Al sites such as these are important to catalogue, as efforts\u0000are underway to employ NMR crystallography tools to understand and\u0000predict both solid-state structures and perturbations to these that\u0000are relevant to NMR analyses. Impurities present in both of the samples\u0000are revealed to be aluminum oxycarbides, as well as an aluminum metal\u0000impurity in one and aluminum nitride in anotherpotentially\u0000important information for groups employing aluminum carbide in syntheses\u0000or in other applications. Triple-quantum magic-angle spinning (3Q-MAS) 27Al NMR was employed to help determine the quadrupolar parameters\u0000of the two crystallographically inequivalent aluminum sites in Al4C3. Revised values for the quadrupolar tensors\u0000of this material were measured and simulated through use of CASTEP-NMR.","PeriodicalId":58,"journal":{"name":"The Journal of Physical Chemistry ","volume":null,"pages":null},"PeriodicalIF":2.781,"publicationDate":"2020-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73769495","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The ligand exchange of 6-mercaptohexanol on the surface CuInS2 quantum dots not only improves their solution processability in alcoholic solvents such as methanol, ethanol, and N,N-dimethylformamide but also modulates their electrical band gap and thus the charge injection and extraction at the charge transport interfaces. Bifunctional light-emitting and photodetection devices based on these alcohol-soluble CuInS2 quantum dots are realized adopting an inverted structure with ZnO as the electron transport layer and poly[(9,9-dioctylfluorenyl-2,7-diyl)-alt-(4,4′-(N-(4-butylphenyl)diphenylaminel)] and poly(3,4-ethylenedioxythiophene):polystyrenesulfonate as the hole transport layers. The optimized device with selected active layer thickness exhibits red emission at 647 nm with a maximum luminance of 1600 cd/m2 under forward bias and works as a photodetector at zero bias with a maximum responsibility of 0.53 mA/W and detectivity of 2.5 × 1010 jones. Furthermore, with interface engineering of the polyethylenimine ethoxylated (PEIE) layer at the electron transport side, more balanced charge injection is achieved, leading to reducing electroluminescence roll-off effect. The insulating PEIE layer also blocks the current leakage, giving rise to reduced dark current and improved detectivity of 3.5 × 1010 jones. The effective bidirectional charge transfer achieved under simplified device design using the alcohol-soluble quantum dots brings a new candidate for multifunctional devices.
{"title":"Balanced Carrier Injection and Charge Separation of CuInS₂ Quantum Dots for Bifunctional Light-Emitting and Photodetection Devices","authors":"Shuai Chang, Yeling Zhao, Jialun Tang, Zelong Bai, Liangyu Zhao, Haizheng Zhong","doi":"10.1021/acs.jpcc.0c00723.s001","DOIUrl":"https://doi.org/10.1021/acs.jpcc.0c00723.s001","url":null,"abstract":"The\u0000ligand exchange of 6-mercaptohexanol on the surface CuInS2 quantum dots not only improves their solution processability\u0000in alcoholic solvents such as methanol, ethanol, and N,N-dimethylformamide but also modulates their electrical\u0000band gap and thus the charge injection and extraction at the charge\u0000transport interfaces. Bifunctional light-emitting and photodetection\u0000devices based on these alcohol-soluble CuInS2 quantum dots\u0000are realized adopting an inverted structure with ZnO as the electron\u0000transport layer and poly[(9,9-dioctylfluorenyl-2,7-diyl)-alt-(4,4′-(N-(4-butylphenyl)diphenylaminel)]\u0000and poly(3,4-ethylenedioxythiophene):polystyrenesulfonate as the hole\u0000transport layers. The optimized device with selected active layer\u0000thickness exhibits red emission at 647 nm with a maximum luminance\u0000of 1600 cd/m2 under forward bias and works as a photodetector\u0000at zero bias with a maximum responsibility of 0.53 mA/W and detectivity\u0000of 2.5 × 1010 jones. Furthermore, with interface engineering\u0000of the polyethylenimine ethoxylated (PEIE) layer at the electron transport\u0000side, more balanced charge injection is achieved, leading to reducing\u0000electroluminescence roll-off effect. The insulating PEIE layer also\u0000blocks the current leakage, giving rise to reduced dark current and\u0000improved detectivity of 3.5 × 1010 jones. The effective\u0000bidirectional charge transfer achieved under simplified device design\u0000using the alcohol-soluble quantum dots brings a new candidate for\u0000multifunctional devices.","PeriodicalId":58,"journal":{"name":"The Journal of Physical Chemistry ","volume":null,"pages":null},"PeriodicalIF":2.781,"publicationDate":"2020-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79675086","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-02-28DOI: 10.1021/acs.jpcc.9b11074.s001
Madhumita Bhar, Saoni Rudra, P. Mukherjee
The role of surface capping ligands in controlling dopant photoluminescence in semiconductor nanoparticles is examined by monitoring emission in terbium cation incorporated zinc sulfide [Zn(Tb)S] nanoparticles, as a function of [H+] that is varied postsynthetically. Increases in Tb3+ emission of ∼6 and ∼1.3 times are observed on changing the pH from 4 to 7 and from 7 to 11, respectively. An increased contribution of host sensitization over direct excitation is observed under basic conditions. Subtle structural modification of the capping ligand is argued to be solely responsible for the dopant emission in the acidic–neutral range. The neutral–basic range in addition to this effect has a minor contribution from alteration in band alignment as well. A major outcome from this work relates to identifying the role of the terminally placed functional group in the capping ligand to control emissions from both the host (zinc sulfide nanoparticles) and guest (Tb3+), with a pronounced effect on dopant Tb3+ emission in the 1-thioglycerol capped Zn(Tb)S nanoparticles. These results identify surface engineering as an important modulator, in addition to the primary criteria of (a) band gap engineering and (b) breaking (or optimizing) dopant local site symmetry in maximizing (or guiding) dopant emission in doped semiconductor nanoparticles.
{"title":"What Role Can Surface Capping Ligand Play To Control Dopant Emission in Semiconductor Nanoparticles","authors":"Madhumita Bhar, Saoni Rudra, P. Mukherjee","doi":"10.1021/acs.jpcc.9b11074.s001","DOIUrl":"https://doi.org/10.1021/acs.jpcc.9b11074.s001","url":null,"abstract":"The\u0000role of surface capping ligands in controlling dopant photoluminescence\u0000in semiconductor nanoparticles is examined by monitoring emission\u0000in terbium cation incorporated zinc sulfide [Zn(Tb)S] nanoparticles,\u0000as a function of [H+] that is varied postsynthetically.\u0000Increases in Tb3+ emission of ∼6 and ∼1.3\u0000times are observed on changing the pH from 4 to 7 and from 7 to 11,\u0000respectively. An increased contribution of host sensitization over\u0000direct excitation is observed under basic conditions. Subtle structural\u0000modification of the capping ligand is argued to be solely responsible\u0000for the dopant emission in the acidic–neutral range. The neutral–basic\u0000range in addition to this effect has a minor contribution from alteration\u0000in band alignment as well. A major outcome from this work relates\u0000to identifying the role of the terminally placed functional group\u0000in the capping ligand to control emissions from both the host (zinc\u0000sulfide nanoparticles) and guest (Tb3+), with a pronounced\u0000effect on dopant Tb3+ emission in the 1-thioglycerol capped\u0000Zn(Tb)S nanoparticles. These results identify surface engineering\u0000as an important modulator, in addition to the primary criteria of\u0000(a) band gap engineering and (b) breaking (or optimizing) dopant local\u0000site symmetry in maximizing (or guiding) dopant emission in doped\u0000semiconductor nanoparticles.","PeriodicalId":58,"journal":{"name":"The Journal of Physical Chemistry ","volume":null,"pages":null},"PeriodicalIF":2.781,"publicationDate":"2020-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80048077","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-01-01DOI: 10.1021/acs.jpcc.9b09665.s001
Jia-Hui Li, Jie Wu, Yang-Xin Yu
Two-dimensional transition-metal oxides have been widely explored as catalysts in high-capacity nonaqueous lithium–oxygen batteries due to their excellent electrochemical performance in the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), but little attention has been paid to non-transition-metal oxides. Here, we employ density functional methods based on the Perdew–Burke–Ernzerhof (PBE) functional with dispersion correction and the Heyd–Scuseria–Ernzerhof hybrid functional (HSE06) to investigate the mechanisms of the nucleation and decomposition processes of Li₄O₂(s), i.e., discharge and charge processes on single-layer Tl₂O (SL-Tl₂O) in lithium–oxygen batteries. HSE06 with the spin–orbital coupling effect is adopted to calculate the band gap of SL-Tl₂O. It is demonstrated that the spin–orbital coupling effect is significant in predictions of not only electronic but also thermodynamic properties for heavy-element compounds such as Tl₂O. The formation of LiO₂(s) is initiated by the adsorption of oxygen molecules instead of lithium atoms on the surface. The intermediate reaction products strongly interact with SL-Tl₂O, which causes an overpotential of 1.47 V during the electrochemical reaction. The electronic conductivity analysis of lithium oxides adsorbed on SL-Tl₂O demonstrates that the electronic conductance of the layer does not change during the ORR/OER. The adsorption enthalpies of five frequently used nonaqueous solvents (tetrahydrofuran, 1,2-dimethoxyethane, 1,3-dioxolane, dimethyl carbonate, and propiolic acid) on SL-Tl₂O indicate that SL-Tl₂O is stable in the electrolytes. All of these calculated results indicate that SL-Tl₂O is a feasible catalyst for the ORR/OER in nonaqueous lithium–oxygen batteries.
{"title":"Theoretical Exploration of Single-Layer Tl₂O as a Catalyst in Lithium–Oxygen Battery Cathodes","authors":"Jia-Hui Li, Jie Wu, Yang-Xin Yu","doi":"10.1021/acs.jpcc.9b09665.s001","DOIUrl":"https://doi.org/10.1021/acs.jpcc.9b09665.s001","url":null,"abstract":"Two-dimensional transition-metal oxides have been widely explored as catalysts in high-capacity nonaqueous lithium–oxygen batteries due to their excellent electrochemical performance in the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), but little attention has been paid to non-transition-metal oxides. Here, we employ density functional methods based on the Perdew–Burke–Ernzerhof (PBE) functional with dispersion correction and the Heyd–Scuseria–Ernzerhof hybrid functional (HSE06) to investigate the mechanisms of the nucleation and decomposition processes of Li₄O₂(s), i.e., discharge and charge processes on single-layer Tl₂O (SL-Tl₂O) in lithium–oxygen batteries. HSE06 with the spin–orbital coupling effect is adopted to calculate the band gap of SL-Tl₂O. It is demonstrated that the spin–orbital coupling effect is significant in predictions of not only electronic but also thermodynamic properties for heavy-element compounds such as Tl₂O. The formation of LiO₂(s) is initiated by the adsorption of oxygen molecules instead of lithium atoms on the surface. The intermediate reaction products strongly interact with SL-Tl₂O, which causes an overpotential of 1.47 V during the electrochemical reaction. The electronic conductivity analysis of lithium oxides adsorbed on SL-Tl₂O demonstrates that the electronic conductance of the layer does not change during the ORR/OER. The adsorption enthalpies of five frequently used nonaqueous solvents (tetrahydrofuran, 1,2-dimethoxyethane, 1,3-dioxolane, dimethyl carbonate, and propiolic acid) on SL-Tl₂O indicate that SL-Tl₂O is stable in the electrolytes. All of these calculated results indicate that SL-Tl₂O is a feasible catalyst for the ORR/OER in nonaqueous lithium–oxygen batteries.","PeriodicalId":58,"journal":{"name":"The Journal of Physical Chemistry ","volume":null,"pages":null},"PeriodicalIF":2.781,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75097423","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-01-01DOI: 10.1021/acs.jpcc.9b03225.s001
Taisei Kimura, H. Yao
Magnetic circular dichroism (MCD) is demonstrated for the first time in substoichiometric molybdenum oxide (MoO₃–ₓ) nanoarchitectures to explore the origin of their near-IR (NIR) transitions. Various nanostructures of MoO₃–ₓ are synthesized by a simple hydrothermal process using an ionic Mo(VI) or metallic Mo(0) precursor. The phase, morphology, and spectroscopic properties of the obtained nanostructures are dependent both on the reaction temperature and the molybdenum precursor. In particular, hexagonal MoO₃–ₓ nanostructures are colored blue with different degrees. To better understand the nature of the electronic states in these nanomaterials, MCD spectroscopy is conducted. A derivative-like MCD response is detected in the vis-NIR region, but it is not attributed to surface magnetoplasmonic modes because of the absence of the peak-energy shift with the increasing refractive index of the dispersion medium. Then, the bisignate MCD signal can be attributed to Faraday B-terms for small-polaronic transitions, arising from two interacting polaronic states close in energy that would give opposite signs under an applied magnetic field. We believe that MCD evaluation for polaronic nanomaterials will expand promising new applications in fields such as semiconductor-based nanophotonics and magneto-optical devices.
{"title":"Magnetic Circular Dichroism of Substoichiometric Molybdenum Oxide (MoO₃–ₓ) Nanoarchitectures with Polaronic Defects","authors":"Taisei Kimura, H. Yao","doi":"10.1021/acs.jpcc.9b03225.s001","DOIUrl":"https://doi.org/10.1021/acs.jpcc.9b03225.s001","url":null,"abstract":"Magnetic circular dichroism (MCD) is demonstrated for the first time in substoichiometric molybdenum oxide (MoO₃–ₓ) nanoarchitectures to explore the origin of their near-IR (NIR) transitions. Various nanostructures of MoO₃–ₓ are synthesized by a simple hydrothermal process using an ionic Mo(VI) or metallic Mo(0) precursor. The phase, morphology, and spectroscopic properties of the obtained nanostructures are dependent both on the reaction temperature and the molybdenum precursor. In particular, hexagonal MoO₃–ₓ nanostructures are colored blue with different degrees. To better understand the nature of the electronic states in these nanomaterials, MCD spectroscopy is conducted. A derivative-like MCD response is detected in the vis-NIR region, but it is not attributed to surface magnetoplasmonic modes because of the absence of the peak-energy shift with the increasing refractive index of the dispersion medium. Then, the bisignate MCD signal can be attributed to Faraday B-terms for small-polaronic transitions, arising from two interacting polaronic states close in energy that would give opposite signs under an applied magnetic field. We believe that MCD evaluation for polaronic nanomaterials will expand promising new applications in fields such as semiconductor-based nanophotonics and magneto-optical devices.","PeriodicalId":58,"journal":{"name":"The Journal of Physical Chemistry ","volume":null,"pages":null},"PeriodicalIF":2.781,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79809701","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-01-01DOI: 10.1021/acs.jpcc.9b09028.s001
Sian-Hong Tseng, Hung-Yi Chen, W. Hsu, Hsiang-Chen Wang, Yuan-Yao Li, Wen‐Hao Chang, Ming-Pei Lu, M. Lu
The growth of large-area MoS₂ films was achieved through atmospheric pressure chemical vapor deposition via vapor management in this study. The thickness of the MoS₂ film changed upon varying the amount of vapor deposited on the substrate. Gratifyingly, large-area monolayer MoS₂ was obtained under controlled conditions. Studies using transmission electron microscopy and second harmonic generation confirmed that the MoS₂ films were composed of grains having sizes ranging from 40 to 70 μm. Flexible MoS₂ device arrays were fabricated on a polyimide substrate; the device arrays displayed high spatial uniformity in their carrier transport properties. The contact metals affected the electrical characteristics of the MoS₂ devices under strain; the sensitivity of devices featuring Schottky contacts was higher than that of those with ohmic contacts. Importantly, the device arrays exhibit sensitive and endurance performances under strain cycles of up to 10⁵ times. These results suggest a means for the feasible growth of large-area single-layer MoS₂ films, as well as the exploitation of flexible MoS₂ device arrays in strain and human motion sensor applications.
{"title":"Influences of Contact Metals on the Performances of MoS₂ Devices under Strains","authors":"Sian-Hong Tseng, Hung-Yi Chen, W. Hsu, Hsiang-Chen Wang, Yuan-Yao Li, Wen‐Hao Chang, Ming-Pei Lu, M. Lu","doi":"10.1021/acs.jpcc.9b09028.s001","DOIUrl":"https://doi.org/10.1021/acs.jpcc.9b09028.s001","url":null,"abstract":"The growth of large-area MoS₂ films was achieved through atmospheric pressure chemical vapor deposition via vapor management in this study. The thickness of the MoS₂ film changed upon varying the amount of vapor deposited on the substrate. Gratifyingly, large-area monolayer MoS₂ was obtained under controlled conditions. Studies using transmission electron microscopy and second harmonic generation confirmed that the MoS₂ films were composed of grains having sizes ranging from 40 to 70 μm. Flexible MoS₂ device arrays were fabricated on a polyimide substrate; the device arrays displayed high spatial uniformity in their carrier transport properties. The contact metals affected the electrical characteristics of the MoS₂ devices under strain; the sensitivity of devices featuring Schottky contacts was higher than that of those with ohmic contacts. Importantly, the device arrays exhibit sensitive and endurance performances under strain cycles of up to 10⁵ times. These results suggest a means for the feasible growth of large-area single-layer MoS₂ films, as well as the exploitation of flexible MoS₂ device arrays in strain and human motion sensor applications.","PeriodicalId":58,"journal":{"name":"The Journal of Physical Chemistry ","volume":null,"pages":null},"PeriodicalIF":2.781,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81567272","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-01-01DOI: 10.1021/acs.jpcc.9b04123.s001
R. L. Tranquilin, L. Lovisa, C. R. Almeida, C. A. Paskocimas, M. Li, M. C. Oliveira, L. Gracia, J. Andrés, E. Longo, F. Motta, M. Bomio
In this article, the synthesis by means of the spray pyrolysis method, of the CaMoO₄ and rare-earth cation (RE³⁺)-doped CaMoO₄:xRE³⁺ (RE³⁺ = Eu³⁺, Tb³⁺, and Tm³⁺; and x = 1, 2, and 4% mol) compounds, is presented. The as-synthesized samples were characterized using X-ray diffraction, Rietveld refinement, field emission scanning electron microscopy (FE-SEM), Raman spectroscopy, and photoluminescence (PL) spectroscopy. To complement and rationalize the experimental results, first-principles calculations, at the density functional theory level, have been performed to analyze the band structure and density of states. In addition, a theoretical method based on the calculations of surface energies and Wulff construction was applied to obtain the morphology transformation of the CaMoO₄ and CaMoO₄:RE³⁺ microstructures. The experimental morphologies can be observed in the FE-SEM images. The PL behavior of the Co-doped samples exhibited well-defined bands in the visible region. The samples with 2 and 4% of RE³⁺ released white emission according to the chromaticity coordinates (0.34, 0.34) and (0.34, 0.33), respectively. The present results provide not only a deep understanding of the structure–property relationships of CaMoO₄-based phosphor but also can be employed as a guideline for the design of the electronic structure of the materials and the fabrication of photofunctional materials with optimal properties, which allows for the modeling of new phosphors for applications in solid-state lighting.
{"title":"Understanding the White-Emitting CaMoO₄ Co-Doped Eu³⁺, Tb³⁺, and Tm³⁺ Phosphor through Experiment and Computation","authors":"R. L. Tranquilin, L. Lovisa, C. R. Almeida, C. A. Paskocimas, M. Li, M. C. Oliveira, L. Gracia, J. Andrés, E. Longo, F. Motta, M. Bomio","doi":"10.1021/acs.jpcc.9b04123.s001","DOIUrl":"https://doi.org/10.1021/acs.jpcc.9b04123.s001","url":null,"abstract":"In this article, the synthesis by means of the spray pyrolysis method, of the CaMoO₄ and rare-earth cation (RE³⁺)-doped CaMoO₄:xRE³⁺ (RE³⁺ = Eu³⁺, Tb³⁺, and Tm³⁺; and x = 1, 2, and 4% mol) compounds, is presented. The as-synthesized samples were characterized using X-ray diffraction, Rietveld refinement, field emission scanning electron microscopy (FE-SEM), Raman spectroscopy, and photoluminescence (PL) spectroscopy. To complement and rationalize the experimental results, first-principles calculations, at the density functional theory level, have been performed to analyze the band structure and density of states. In addition, a theoretical method based on the calculations of surface energies and Wulff construction was applied to obtain the morphology transformation of the CaMoO₄ and CaMoO₄:RE³⁺ microstructures. The experimental morphologies can be observed in the FE-SEM images. The PL behavior of the Co-doped samples exhibited well-defined bands in the visible region. The samples with 2 and 4% of RE³⁺ released white emission according to the chromaticity coordinates (0.34, 0.34) and (0.34, 0.33), respectively. The present results provide not only a deep understanding of the structure–property relationships of CaMoO₄-based phosphor but also can be employed as a guideline for the design of the electronic structure of the materials and the fabrication of photofunctional materials with optimal properties, which allows for the modeling of new phosphors for applications in solid-state lighting.","PeriodicalId":58,"journal":{"name":"The Journal of Physical Chemistry ","volume":null,"pages":null},"PeriodicalIF":2.781,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88491801","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-01-01DOI: 10.1021/acs.jpcc.9b04888.s001
Pei Zhao, Yandong Ma, Hao Wang, Baibiao Huang, Ying Dai
The quantum anomalous Hall (QAH) effect is a fascinating quantum phenomenon characterized by a nonzero Chern number defined in the bulk and chiral edge states in the boundary. Up to now, only one magnetically doped topological insulator, suffering from a small bulk band gap, is confirmed to host the QAH effect experimentally. Here, through first-principles calculations, we propose a novel QAH insulator in single-layer (SL) CrP₂S₆. The nontrivial topology in SL CrP₂S₆, identified with the nonzero Chern number (C = −1) and chiral edge states, harbors a nontrivial band gap of 53 meV. Meanwhile, using Monte Carlo simulations, the Curie temperature Tc for its ferromagnetic order is estimated to be 350 K, which is above room temperature and comparable with most of the previously reported two-dimensional ferromagnetic semiconductors. Our findings thus present a feasible platform for achieving the QAH effect at room temperature.
{"title":"Room-Temperature Quantum Anomalous Hall Effect in Single-Layer CrP₂S₆","authors":"Pei Zhao, Yandong Ma, Hao Wang, Baibiao Huang, Ying Dai","doi":"10.1021/acs.jpcc.9b04888.s001","DOIUrl":"https://doi.org/10.1021/acs.jpcc.9b04888.s001","url":null,"abstract":"The quantum anomalous Hall (QAH) effect is a fascinating quantum phenomenon characterized by a nonzero Chern number defined in the bulk and chiral edge states in the boundary. Up to now, only one magnetically doped topological insulator, suffering from a small bulk band gap, is confirmed to host the QAH effect experimentally. Here, through first-principles calculations, we propose a novel QAH insulator in single-layer (SL) CrP₂S₆. The nontrivial topology in SL CrP₂S₆, identified with the nonzero Chern number (C = −1) and chiral edge states, harbors a nontrivial band gap of 53 meV. Meanwhile, using Monte Carlo simulations, the Curie temperature Tc for its ferromagnetic order is estimated to be 350 K, which is above room temperature and comparable with most of the previously reported two-dimensional ferromagnetic semiconductors. Our findings thus present a feasible platform for achieving the QAH effect at room temperature.","PeriodicalId":58,"journal":{"name":"The Journal of Physical Chemistry ","volume":null,"pages":null},"PeriodicalIF":2.781,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84552273","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-01-01DOI: 10.1021/acs.jpcb.7b06590.s001
Conti Nibali, Valéria, Morra, Giulia, Havenith, Martina, Colombo, Giorgio
{"title":"Role of Terahertz (THz) Fluctuations in the Allosteric Properties of the PDZ Domains","authors":"Conti Nibali, Valéria, Morra, Giulia, Havenith, Martina, Colombo, Giorgio","doi":"10.1021/acs.jpcb.7b06590.s001","DOIUrl":"https://doi.org/10.1021/acs.jpcb.7b06590.s001","url":null,"abstract":"","PeriodicalId":58,"journal":{"name":"The Journal of Physical Chemistry ","volume":null,"pages":null},"PeriodicalIF":2.781,"publicationDate":"2017-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74897009","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：