scholarly journals On how the mechanochemical and co-precipitation synthesis method changes the sensitivity and operating range of the Ba2Mg1-xEuxWO6 optical thermometer

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Quan T. H. Vu ◽  
Bartosz Bondzior ◽  
Dagmara Stefańska ◽  
Natalia Miniajluk-Gaweł ◽  
Maciej J. Winiarski ◽  
...  
Keyword(s):  
Density Functional ◽  
Synthesis Method ◽  
Double Perovskite ◽  
Relative Sensitivity ◽  
The Novel ◽  
Temperature Detection ◽  
The Density Functional Theory ◽  
Precision Temperature ◽  
Optical Thermometer ◽  
Co Precipitation

AbstractThe suitability of Ba2MgWO6 (BMW) double perovskite doped with Eu3+ for the construction of an optical thermometer was tested. It has been shown that by controlling the conditions of BMW synthesis, the sensitivity of the optical thermometer and the useful range of its work can be changed. Pure BMW and doped with Eu3+ samples were prepared using the mechano-chemical and co-precipitation methods. Both the absolute sensitivity and the relative sensitivity in relation to the synthesis route were estimated. The findings proved that the relative sensitivity can be modulated from 1.17%K−1 at 248 K, to 1.5%K−1 at 120 K for the co-precipitation and the mechanochemical samples, respectively. These spectacular results confirm the applicability of the Ba2MgWO6: Eu3+ for the novel luminescent sensors in high-precision temperature detection devices. The density-functional theory was applied to elucidate the origin of the host emission.

scholarly journals Changing the Sensitivity and Operating Range of the Ba2MgWO6 : Eu3+ Optical Thermometer by Applying the Distinct Synthesis Routes

2021 ◽  
Author(s):  
T. H. Quan Vu ◽  
Bartosz Bondzior ◽  
Dagmara Stefańska ◽  
Natalia Miniajluk-Gaweł ◽  
Maciej J. Winiarski ◽  
...  
Keyword(s):  
Density Functional ◽  
Double Perovskite ◽  
Relative Sensitivity ◽  
The Novel ◽  
Functional Theory ◽  
Temperature Detection ◽  
Precision Temperature ◽  
Synthesis Routes ◽  
Optical Thermometer ◽  
Co Precipitation

Abstract The suitability of Ba2MgWO6 (BMW) double perovskite doped with Eu3+ for the construction of an optical thermometer was tested. It has been shown that by controlling the conditions of BMW synthesis, the sensitivity of the optical thermometer and the useful range of its work can be changed. Pure BMW and doped with Eu3+ samples were prepared using the mechano-chemical (MC) and co-precipitation (CP) methods. Both the absolute sensitivity and the relative sensitivity in relation to the synthesis route are estimated. The findings proved that the relative sensitivity can be modulated from 1.17 %K− 1 at 248 K, to 1.5%K− 1 at 120 K for the co-precipitation and the mechanochemical samples, respectively. These spectacular results confirm the applicability of the Ba2MgWO6: Eu3+ for the novel luminescent sensors in high-precision temperature detection devices. Density-functional theory (DFT) was applied to elucidate the origin of the host emission.

ELECTRONIC STRUCTURE OF Si20 FULLERENE AND SOLID Si20

1996 ◽  
Vol 03 (01) ◽  
pp. 721-728 ◽  
Author(s):  
SUSUMU SAITO
Keyword(s):  
Electronic Structure ◽  
Density Functional ◽  
Level Density ◽  
The Novel ◽  
Functional Theory ◽  
Metal Atoms ◽  
The Density Functional Theory ◽  
Real Geometry ◽  
Bond Network ◽  
The Ideal

The electronic structure of the dodecahedral Si 20 fullerene obtained in the density-functional theory is discussed. In addition, the Si 46 lattice, which is known to be the real geometry of the Si atoms when crystallized with metal atoms, is pointed out to be essentially solid Si 20, and its geometrical and electronic properties are also discussed. The novel pentagonal bond network in these materials is found to have strong influence on their electronic structure. In the case of Na 2 Ba 6 Si 46, which is the ideal phase of superconducting-doped solid Si 20, the high Fermi-level density of states due to the hybridization between the Ba states and the Si 46 conduction-band states is considered to be important for the observed superconductivity.

scholarly journals QTAIM investigations of decorated graphyne and boron nitride for Li detection

2017 ◽  
Vol 82 (3) ◽  
pp. 289-301 ◽  
Author(s):  
Maryam Dehestani ◽  
Leila Zeidabadinejad ◽  
Sedigheh Pourestarabadi
Keyword(s):  
Boron Nitride ◽  
Density Functional ◽  
Chemical Properties ◽  
Strong Interactions ◽  
The Novel ◽  
Theoretical Understanding ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
The Impact ◽  
Carbon Based

The interactions between thirteen Li atoms and graphyne (GY) and boron nitride (BN-yne) were investigated by the density functional theory (DFT). The electronic and structural properties of the interactions between the hollow sites of GY and BN-yne with Li atoms were unveiled within the quantum theory of atoms in molecules (QTAIM) framework. Theoretical understanding of the interactions between Li atoms and extended carbon-based network structures is crucial for the development of new materials. Herein, calculations to explore the impact of Li decoration on the GY and BN-yne are reported. It was predicted that Li decoration would increase the density of state of these sheets. Owing to strong interactions between Li and the GY and BNyne, dramatic changes in the electronic properties of the sheets together with large band gap variations have been observed. The present study sheds deep insight into the chemical properties of the novel carbon?based two-dimensional (2D) structures beyond the graphene sheet.

scholarly journals Preparation of a Novel Clay Loaded With Fe (VI) for Degradation of Cefazolin: Performance, Pathway and Mechanism

2021 ◽  
Author(s):  
Mingluo Zhou ◽  
Riyu Zhou ◽  
Peng Jiang ◽  
Huili Liang ◽  
Yi Zhou ◽  
...  
Keyword(s):  
Density Functional ◽  
Ph Value ◽  
Degradation Mechanism ◽  
Synthesis Method ◽  
Optimization Method ◽  
Decomposition Reaction ◽  
Potassium Ferrate ◽  
Response Surface Optimization ◽  
The Density Functional Theory ◽  
Spectroscopic Characteristics

Abstract Cephalosporin antibiotics, a group of widely prescribed antibiotics, are frequently detected in wastewater effluent and in the natural aquatic environment. Materials have been sought to effectively degrade the antibiotics. In this study, a novel high-iron clay was prepared with potassium ferrate and montmorillonite via a strong alkaline in-situ synthesis method. Degradation of cefazolin sodium (CFZ) by this novel Fe (VI)-clay was investigated. The optimal conditions for the degradation of CFZ were determined using a single factor experiment and response surface optimization method. We found that 89.84 % removal efficiency was obtained in 137 min when pH value was 5.16 and Fe (VI)-clay dosage was 0.79 g/100mL. The CFZ degradation mechanism was studied by the Density Functional Theory (DFT) in combination with spectroscopic and mass spectroscopic analysis. The spectroscopic characteristics of the products at different stages showed that the oxidation decomposition reaction occurred during the degradation of CFZ by Fe(VI) -clay. Further, DFT calculation combined with GC-MS results showed that the degradation pathways of CFZ by the Fe (VI)-clay was mainly the cleavage of β-lactam, thiadiazole, tetrazole and dihydrothiazine rings.

Experimental and First Principles' Characterization of Functionalized Magnetic Nanoparticles

2014 ◽  
Vol 605 ◽  
pp. 681-684
Author(s):  
E. Statharas ◽  
P. Tserotas ◽  
G.S.E. Antipas
Keyword(s):  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Magnetic Iron Oxide Nanoparticles ◽  
Functional Theory ◽  
Functionalized Magnetic Nanoparticles ◽  
The Density Functional Theory ◽  
Bulk Structure ◽  
Co Precipitation ◽  
Homo Lumo

Magnetic iron oxide nanoparticles synthesized via co precipitation and thermal decomposition yielded largely monodisperse size distributions. Both methods produced a mixture of magnetite and maghemite. However CP NPs were indexed as magnetite-rich while TD yielded largely maghemite NPs. XRD-and TEM-measured diameters of the co-precipitated particles were approximately between 9 to 15 nm, while thermally decomposed diameters were in the range of 8 to 10 nm. FTIR spectra revealed no distinct differences in the bulk structure of the two systems. Based on the Density functional theory calculations and on HOMO-LUMO gap energies, we propose that ferric Fe is the state of preference by the surfactant in bidentate linkage.

scholarly journals A facile synthesis methodology for preparation of Ag–Ni-reduced graphene oxide: a magnetically separable versatile nanocatalyst for multiple organic reactions and density functional study of its electronic structures

RSC Advances ◽  
2018 ◽  
Vol 8 (66) ◽  
pp. 37774-37788 ◽  
Author(s):  
Madhurya Chandel ◽  
Priyanka Makkar ◽  
Barun Kumar Ghosh ◽  
Debabrata Moitra ◽  
Narendra Nath Ghosh
Keyword(s):  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Density Functional ◽  
Synthesis Method ◽  
Functional Study ◽  
Reduced Graphene ◽  
Co Precipitation ◽  
Synthesis Methodology ◽  
Precipitation Reduction

Here, we report a simple ‘in situ’ co-precipitation reduction synthesis method for the preparation of nanocatalysts composed of Ag, Ni nanoparticles, and reduced graphene oxide (RGO).

scholarly journals The Electronic and Optical Properties of InSe-GeTe Heterobilayer via Applying Biaxial Strain

Nanomaterials ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1705 ◽  
Author(s):  
Guofeng Yang ◽  
Rui Sun ◽  
Yan Gu ◽  
Feng Xie ◽  
Yu Ding ◽  
...  
Keyword(s):  
Optical Properties ◽  
Density Functional ◽  
Band Alignment ◽  
The Novel ◽  
Biaxial Strain ◽  
Functional Theory ◽  
Electronic And Optical Properties ◽  
The Density Functional Theory ◽  
Small Lattice ◽  
Indirect Band Gap

A comprehensive insight into the electronic and optical properties of small-lattice-mismatched InSe-GeTe heterobilayer (HBL) is performed based on the density functional theory (DFT) with van der Waals corrections from first-principles perspective. The optimization of most stable geometric stacking mode for the InSe-GeTe HBL is demonstrated. In addition, it is found that the InSe-GeTe HBL forms a type-II heterostructure of staggered-gap band alignment, resulting in an indirect band gap of 0.78 eV, which could be employed as a separator for electron-hole pairs. Moreover, the influence of biaxial strain on the electronic and optical properties of the InSe-GeTe HBL are systematically explored by calculating the band structures, density of states (PDOS), electron density differences, and optical absorption spectra of InSe-GeTe HBL under compressive and tensile biaxial strains. The results indicate that the electronic structures and optical performance of InSe-GeTe HBL could be modulated by changing the biaxial strain conveniently. Our findings provide new opportunities for the novel InSe-GeTe HBL to be applied in the electronic and optoelectronic fields.

CRYSTALLOGRAPHIC, FERROELECTRIC AND ELECTRONIC PROPERTIES OF THE Sr2ZrTiO6 DOUBLE PEROVSKITE

2013 ◽  
Vol 27 (20) ◽  
pp. 1350141 ◽  
Author(s):  
D. A. LANDÍNEZ TÉLLEZ ◽  
L. A. CARRERO BERMÚDEZ ◽  
C. E. DELUQUE TORO ◽  
R. CARDONA ◽  
J. ROA-ROJAS
Keyword(s):  
Density Of States ◽  
Density Functional ◽  
Energy Gap ◽  
Double Perovskite ◽  
Crystallographic Analysis ◽  
Partial Density ◽  
X Ray Diffraction ◽  
Saturation Polarization ◽  
The Density Functional Theory ◽  
Diffraction Patterns

In this paper, we report structural analysis, ferroelectric behavior and electronic structure of Sr 2 ZrTiO 6 double perovskite. Samples were produced by the solid state reaction recipe. Crystallographic analysis was performed by Rietveld refinement of experimental X-ray diffraction patterns. Results show that this material crystallizes in a tetragonal perovskite structure which corresponds to the space group I4/m. The curve of polarization as a function of applied voltage evidences a ferroelectric character with saturation polarization on the application of voltages up to 1800 V. Calculations of density of states and band structure for this manganite-like material were carried out by means of the density functional theory implemented into the Wien2k code. Results of total and partial density of states reveal the insulator character of this material with an energy gap of 2.66 eV.

scholarly journals FORMATION OF A NOVEL DIAMOND-LIKg BILAYER BASED ON 5-7 GRAPHENE

2021 ◽  
pp. 76-84
Author(s):  
Владимир Андреевич Грешняков ◽  
Евгений Анатольевич Беленков
Keyword(s):  
Total Energy ◽  
Surface Density ◽  
Density Functional ◽  
Density Functional Theory Method ◽  
The Novel ◽  
Structure And Properties ◽  
Orthorhombic Crystal ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
The Difference

Выполнены первопринципные расчеты структуры и свойств орторомбического графена L и нового алмазоподобного бислоя, формируемого на его основе. Расчеты методом теории функционала плотности показали, что графен L, состоящий из топологических дефектов Стоуна-Уэльса, должен устойчиво существовать при нормальных условиях, и его структура должна волнообразно гофрироваться. При сильном одноосном сжатии бислойного графена L может происходить формирование нового алмазоподобного бислоя DL. Давление фазового перехода «L → DL» составляет 10,1 ГПа, когда межслоевое расстояние в бислойном графене уменьшается до 1,61 Å. Этот бислой имеет орторомбическую кристаллическую решетку (pbam) с параметрами a = 10,145 Å и b = 5,270 А. Элементарная ячейка бислоя DL pbam содержит 32 атома углерода. Длины связей изменяются в интервале от 1,5590 до 1,6226 Å, тогда как углы между связями принимают значения от 89,62 до 140,8°. Структура алмазоподобного бислоя должна быть стабильна до 270 К. Рассчитанные значения поверхностной плотности и разностной полной энергии этого бислоя относительно полной энергии алмаза равны 1,19·10 г/см и 1,31 эВ/атом, соответственно. Бислой DL pbam должен быть полупроводником с шириной прямой запрещенной зоны 1,63 эВ. Irst-principle calculations of the structure and properties of orthorhombic L graphene and a novel diamond-like bilayer formed on its basis are performed. The calculations using the density functional theory method showed that L- graphene of Stone-Wales defects should exist stably under normal conditions, and its structure should be corrugated in a wave-like manner. Under strong uniaxial compression of bilayer L graphene, the formation of the novel diamond-like DL bilayer can occur. The pressure of the « L → DL» phase transition is 10,1 GPa, when the interlayer distance in bilayer graphene decreases to 1,61 Å. This bilayer has an orthorhombic crystal lattice (pbam) with the parameters a = 10,145 Å and b = 5,270 Å. The unit cell of the DL- pbam bilayer contains 32 carbon atoms. The bond lengths vary in the range from 1,5590 to 1,6226 Å, while the angles between these bonds range from 89,62 to 140,8°. The structure of the diamond-like bilayer should be stable up to 270 K. The calculated values of the surface density and the difference total energy of this bilayer relative to the diamond total energy are 1,19 -10 g/cm and 1,31 eV/atom, respectively. The DL pbam bilayer should be a semiconductor with a straight bandgap of 1,63 eV.

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