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1

Flotation performance of a novel collector, ethyl o-mesitylsulfonylacetohydroxamate, for bastnaesite ores

Di Yuli, Liu Xiankui, He Xia, Zhang Hao, Huang Haiyan, Cheng Wang, Jiao Yu

Physicochemical Problems of Mineral Processing

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2024

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Vol. 60, iss. 1

art. no. 185550

EN

Existing collectors used in the flotation process of bastnaesite ores are characterized by the poor flotation performance and low recovery. In this paper, from the perspective of molecular structure, ethyl O-mesitylsulfonylacetohydroxamate (C1) was selected as a novel collector for bastnaesite ores, and compared with the most commonly used collector, salicylhydroxamic acid (C2), in the flotation test with bastnaesite ore with fine mineral particles, complex embedding and a high mud content. The flotation test confirmed that C1 had the better collection ability and flotation performance than C2. Then, the adsorption mechanisms between collectors (C1 and C2) and bastnaesite surface were explored based on first principles thinking. The adsorption energies between collectors (C1 and C2) and the (110) plane of bastnaesite were respectively calculated as -1.79 eV and -1.44 eV and corresponding adsorption heights were respectively 1.65 Å and 2.43 Å. These data indicated that C1 had the better affinity to the (110) plane of bastnaesite and the better binding. The calculation results of partial density of states (PDOS) showed that both collectors underwent significant orbital hybridization with the (110) plane of bastnaesite, suggesting strong electronic interactions.

2

Adsorption behavior of poly(ethylene oxide) on kaolinite: Experimental and molecular simulation study

Wang Tingting, Wang Jing, Zhang Mingqing, Liu Bingfeng, Zhang Haijun, Li Jihui

Physicochemical Problems of Mineral Processing

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2024

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Vol. 60, iss. 2

art. no. 185900

EN

Poly(ethylene oxide) (PEO) adsorption behavior on kaolinite surfaces in an aqueous solution was investigated through experiments, the density functional theory (DFT), and molecular dynamics (MD) simulations. The experimental results showed that as the PEO concentration increased, the adsorption capacity first increased then slightly decreased and the turbidity change was opposite. The adsorption isotherm on the kaolinite surface was more suitable for the Langmuir model and valid for single-layer adsorption. The results of simulations showed that the PEO chains extended along the two basal surfaces of kaolinite or were partly adsorbed, forming loops and tails that caused most of the particles to flocculate, contributing to the turbidity lowering. When the number of PEO chains was excessive, their self- and inter-aggregation occurred with some PEO far from the surface, and the turbidity increased. On the kaolinite (001) surface, the hydrogen bonds between the PEO ether O and the hydroxyl groups constituted the main interaction mechanism. However, the hydrophobic force of the (CH2–CH2)–moiety of PEO might have dominated its adsorption on the (001̅) surface. The hydrogen bonds were stronger than the hydrophobic interactions.

3

Właściwości czasowo-rozdzielcze słabych międzycząsteczkowych wiązań wodorowych C-H···F

Polańska Marta, Rodziewicz Paweł

Wiadomości Chemiczne

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2023

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[Z] 77, 9-10

899--919

EN

The hydrogen bond is one of the most important and interesting phenomena in nature. In this publication we will shed light on the discovery of hydrogen bond and a time evolution of its definition in the last 100 years. Both structural and spectroscopic parameters of the hydrogen bond will be discussed. A special focus will be given to the latest IUPAC definition of the hydrogen bond and its consequences to scientific research. The main aim of this study is to highlight theoretical studies based on first principles calculations and molecular dynamics simulations which not only support experimental results but also provide parameters which are crucial to understand the nature of hydrogen bonds. Particular attention will be given to methods and theoretical ideas used in the computational studies of hydrogen bonds. Utilizing static DFT/ab initio calculations and molecular dynamics simulations enables comparison of different binding energies and studying time evolution of the hydrogen-bonded molecular system on the atomistic level. We will discuss time-resolved properties of weak intermolecular hydrogen bonds, using as an example C-H···F containing model systems, namely F3CH*(HF)n molecular complexes and (F3CH)2-4 aggregates.

4

Theoretical investigations into the Spectrophotometrically Analyzed Niobium (V)-6-Chloro-3-hydroxy-7-methyl-2-(2’-thienyl)-4H-chromen-4-one Complex

Dhonchak Chetna, Agnihotri Nivedita, Azam Mohammad, Javed Saleem, Muthu Sambantham, Al-Resayes Saud I., Min Kim

Polish Journal of Chemical Technology

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2023

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Vol. 25, nr 3

63--70

EN

Pentavalent niobium cation forms a stable yellow-colored binary complex with 6-chloro-3-hydroxy-7-methyl-2-(2’- thienyl)-4H-chromen-4-one (CHMTC) in the ratio of 1:2. The complex is quantitatively extractable into carbon tetrachloride from HClO4 solution maintained at pH 1.26–1.75 and strictly adheres to Beer’s law as verified by the Ringbom plot with an optimized range of determination as 0.385–1.211 ppm of Nb(V). The ligand-metal complex system shows good precision, accuracy, sensitivity, and selectivity and handles satisfactorily the analysis of several samples of varying complexity. The results are highly reproducible as confirmed by statistical data. The stability of the complex is theoretically confirmed with the help of HOMO-LUMO values and the energy gap [for CHMTC, ΔEgap = 3.62 V and for Nb(V)-CHMTC Complex, ΔEgap = 2.97 eV]. The reactivity descriptors were calculated for detailed computational study to probe into the chemical behavior of the studied ligand and its complex. Further, mapped electrostatic potential diagrams help in justifying the donor sites of CHMTC ligand which is in accordance with the analytical findings.

5

Adsorption of quaternary ammonium salt hydrophobic modifiers on the α-quartz (001) surface : a density functional theory study

Liu Chunfu, Wang Weitao, Wang Han, Zhu Chenyu, Ren Bao

Physicochemical Problems of Mineral Processing

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2023

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Vol. 59, iss. 3

art. no. 170260

EN

To investigate the adsorption mechanism of quaternary ammonium salt on the α-quartz (001) surface, the adsorption models of hydrophobic modifiers 1231, 1431, 1631 and 1831 were constructed and simulated using the density functional theory (DFT). Results indicate that the adsorption energy of quaternary ammonium salt increases with the increase of carbon chain length, and the adsorption energy reaches the maximum at 18 carbon atoms; however, the adsorption capacity of 1631 is weak owing to the carbon chain deflection. Based on the Mulliken bond population analysis, reagent 1831 has the strongest interaction with α-quartz (001) surface compared with 1231, 1431 and 1631; and during the adsorption process, charge transfer and electrostatic attraction occur between the reagent and α-quartz (001) surface with similar degrees of charge transfer observed. This study emphasizes that electrostatic attraction plays a key role in the adsorption process, while the week hydrogen bonding plays a secondary role.

6

Adsorption of hydrated Fe(OH)2+ on the kaolinite surface : A density functional theory study

Wu Hongqiang, Miao Yuqi, Long Qibang, Yan Huashan, Li Yong, Qiu Sen, Wu Hao, Zhao Guanfei, Qiu Tingsheng

Physicochemical Problems of Mineral Processing

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2023

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Vol. 59, iss. 6

art. no. 174415

EN

The present study employed density functional theory (DFT) to analyze the adsorption configuration and mechanism of Fe(OH)2+ on the kaolinite (001) surface. The findings demonstrated that Fe(OH)2(H2O)4+ is the main type in which hydrated Fe(OH)2+ can be found in aqueous solution. On the surface of kaolinite, Fe(OH)2(H2O)4+ will be adsorbed. There are two forms of adsorption: outer-sphere and inner-sphere coordination (monodentate/bidentate) adsorption. Fe(OH)2(H2O)4+ has a moderate propensity to adsorb on the alumina octahedral sheet of kaolinite when the outer-sphere coordination adsorption takes place. In cases of inner-sphere coordination adsorption, Fe exhibits a tendency to form monodentate adsorption compounds in conjunction with Ou atoms. Additionally, it prefers to create bidentate adsorption compounds through coordination with both Ot and Ou atoms. The adsorption mechanism analysis results show that the ionic property of Fe atom decreases after outer-sphere coordination adsorption. After inner-sphere coordination adsorption, some electrons of Fe atom are transferred to the surface O atom. The presence of electrons between the Fe and O atoms enhances the formation of bonds, hence enhancing the covalent nature of the Fe-O bond. Theoretical FT-IR (Fourier transform infrared spectroscopy) calculations show that the formation of Fe-O chemical bonds. Because of the lower adsorption energy and more chemical bonds, hydrate Fe(OH)2+ is more likely to be bidentate adsorbed on the kaolinite surface.

7

Density Functional Formalism as a Description of the Elastic Behavior of a Hard-Sphere Crystal

Pieprzyk Sławomir, Brańka Arkadiusz C., Heyes David M.

Computational Methods in Science and Technology

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2023

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Vol. 29, No. 1-4

57--64

EN

The density functional method of Jaric and Mohanty [Phys. Rev. B ´ 37, 4441 (1988)] for calculating the elastic moduli of crystalline solids is considered here from the perspective of some new findings. The very slow convergence of the reciprocal-lattice vector summations and presence of the three body term in the method’s computational scheme identified in [J. Chem. Phys. 118, 6594 (2003)] is confirmed and discussed. The sensitivity of the results to the scheme parameters, such as the width of the Gaussian density profiles and the Percus-Yevick approximation used for the direct correlation function is explored. The calculations are for a hard-sphere crystal but most conclusions can be applicable to model crystalline solids in general.

8

Study of flocculation performance and mechanism of ultrafine montmorillonite particles with NPAM

Wang Lujun, Min Fanfei, Chen Jun, Wang Ting, Zhou Zhuang

Physicochemical Problems of Mineral Processing

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2022

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Vol. 58, iss. 3

art. no. 147790

EN

Ultrafine montmorillonite particles are the main clay minerals in industrial wastewater. In order to explore the flocculation performance and mechanism of flocculant with montmorillonite, the effects of nonionic polyacrylamide (NPAM) dosage and molecular weight on flocculation effect were studied using a flocculation sedimentation experiment. The morphology of flocs was observed by metallographic microscope and scanning electron microscope, and the microscopic adsorption mechanism was studied utilizing density functional theory (DFT). The results show that the best reagent system for the montmorillonite sample is that the molecular weight of NPAM is 14 million and the added amount is 100 g/t. The floc size increases with rising NPAM dosage, forming a unique multi-level compact space network structure through polymer bridging. The adsorption energy of acrylamide on the Na-(001) surface of montmorillonite is -108.81 kJ/mol, which is significantly higher than -50.66 kJ/mol on the None-(001) surface. Hydrogen bonding is not the main reason for the adsorption of acrylamide on the montmorillonite surface. NPAM mainly causes the flocculation and sedimentation of montmorillonite through the processes of polymer bridging and electrostatic attraction. This study can provide a theoretical basis for the design and synthesis of new flocculants.

9

Effect of surface relaxation of rhodochrosite (104) and substitution of Mn by Ca on the electronic structure of rhodochrosite

Zhang Jingqi, Zhang Qin, Zhang Tiebin

Physicochemical Problems of Mineral Processing

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2022

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Vol. 58, iss. 3

art. no. 145991

EN

To explore the difference between the surface and crystal structure of rhodochrosite, relaxation and reconstruction of the rhodochrosite (104) surface are studied by using Density Functional Theory. The calculation results indicated that the C and O atoms with lower reactivity tend to be enriched on the surface, while the Mn atoms with the highest reactivity moved away from the surface. The band gap width decreased from 1.814 eV to 1.614 eV after the formation of the rhodochrosite (104) surface. The electrons on the rhodochrosite (104) surface are more active than crystal. Ca substitution makes the atomic activity on the (104) surface of rhodochrosite more stable. Ca substitution reduces the ability of the surface of rhodochrosite to absorb external electrons, and the surface electrical properties decrease.

10

A first-principle study of the effect of Fe/Al impurity defects on the surface wettability of dolomite

Chen Hong, Ao Xianquan, Cao Yang, Li Cuiqin, Jiang Chunyan

Physicochemical Problems of Mineral Processing

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2022

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Vol. 58, iss. 4

art. no. 150702

EN

The presence of Fe and Al atoms in large quantities in phosphate ores can significantly affect the surface properties of the minerals during flotation. In this study, the effects of Fe/Al impurities on the adsorption of H2O molecules on dolomite, including the density of states (DOS), Mulliken bond group values, and charge groups, were investigated and the adsorption energy was analyzed using density functional theory. The results show that the adsorption of H2O molecules on perfect and Fe/Al-substituted dolomites is weak chemisorption, and the Fe and Al impurities weaken and enhance the adsorption capacity of H2O molecules, respectively. Therefore, the hydrophilicity of the dolomite surface increases in the following order: Fe-substituted dolomite < perfect dolomite < Al-substituted dolomite. The Mulliken charge and bond group analysis shows that the adsorption of H2O molecules on dolomite is primarily through the interaction between Ow and Ca atoms, where the d orbitals of Ca atoms provide charges for Ow atoms to form ionic bonds, which related to the poor electronegativity of Ca atoms and their weak valence electron binding ability. The DOS analysis shows that, during the adsorption of H2O molecules on dolomite, Mg and Al atoms have less influence on the dolomite surface, whereas Fe and Ca atoms undergo competitive adsorption, which inhibits the interaction between Ca atoms and H2O molecules on the dolomite surface.

11

Do we still need a laboratory to study advanced oxidation processes? A review of the modelling of radical reactions used for water treatment

Wacławek Stanisław

Ecological Chemistry and Engineering. S

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2021

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Vol. 28, nr 1

11--28

EN

Environmental pollution due to humankind’s often irresponsible actions has become a serious concern in the last few decades. Numerous contaminants are anthropogenically produced and are being transformed in ecological systems, which creates pollutants with unknown chemical properties and toxicity. Such chemical pathways are usually examined in the laboratory, where hours are often needed to perform proper kinetic experiments and analytical procedures. Due to increased computing power, it becomes easier to use quantum chemistry computation approaches (QCC) for predicting reaction pathways, kinetics, and regioselectivity. This review paper presents QCC for describing the oxidative degradation of contaminants by advanced oxidation processes (AOP, i.e., techniques utilizing •OH for degradation of pollutants). Regioselectivity was discussed based on the Acid Blue 129 compound. Moreover, the forecasting of the mechanism of hydroxyl radical reaction with organic pollutants and the techniques of prediction of degradation kinetics was discussed. The reactions of •OH in various aqueous systems (explicit and implicit solvation) with water matrix constituents were reviewed. For example, possible singlet oxygen formation routes in the AOP systems were proposed. Furthermore, quantum chemical computation was shown to be an excellent tool for solving the controversies present in the field of environmental chemistry, such as the Fenton reaction debate [main species were determined to be: •OH < pH = 2.2 < oxoiron(IV)]. An ongoing discussion on such processes concerning similar reactions, e.g., associated with sulphate radical-based advanced oxidation processes (SR-AOP), could, in the future, be enriched by similar means. It can be concluded that, with the rapid growth of computational power, QCC can replace most of the experimental investigations related to the pollutant’s remediation in the future; at the same time, experiments could be pushed aside for quality assessment only.

12

Charakterystyka struktury elektronowej heteropolikwasu fosforowolframowego H3PW12O40 modyfikowanego kationem Fe2+

Niemiec Piotr Jan

Science, Technology and Innovation

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2020

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Vol. 11, no. 4

24--32

PL

W pracy zbadano wpływ podstawienia atomu wolframu atomem żelaza w pierwszorzędowej strukturze heteropolikwasu fosforowolframowego o budowie anionu Keggina. Charakterystykę struktury elektronową zmodyfikowanego heteropolikwasu przeprowadzono za pomocą: analizy populacyjnej NBO, całkowitych (PDOS) i parcjalnych (PDOS) widm gęstości stanów, energetyki i charakteru chemicznego orbitali granicznych (HOMO/LUMO) oraz rozmiaru przerwy wzbronionej (gap). Dodatkowo zbadano mechanizm oddziaływania modyfikowanego kationem Fe2+ heteropolikwasu fosforowolframowego z cząsteczką H2O pełniącą rolę środowiska reakcji chemicznej. W większości charakterystyk stwierdzono istotny wpływ wprowadzonego metalu przejściowego na ww. właściwości w stosunku do heteropolikwasu wyjściowego H3PW12O40.

EN

In this paper the influence of substituting the tungsten atom with an iron ion in the primary structure of the phosphotungstic heteropolyacid with the Keggin anion structure was investigated. Characterization of the electronic structure of the modified heteropolyacid was performed using: population analysis according to NBO scheme, total (TDOS) and partial (PDOS) density of states spectra, energy and chemical character of frontier orbitals (HOMO/LUMO) and the size of the HOMO-LUMO band gap. Additionally, the mechanism of interaction between the Fe2+ with H2O molecule, acting as a chemical reaction medium, was investigated. Most cases showed a significant effect of the introduced transition metal ion (Fe2+) on the above-mentioned properties in relation to the nonmodified heteropolyacid H3PW12O40.

13

Interaction of sulfuric acid with dolomite (104) surface and its impact on the adsorption of oleate anion: a DFT study

Cao Qinbo, Zou Heng, Chen Xiumin, Yu Xingcai

Physicochemical Problems of Mineral Processing

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2020

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Vol. 56, iss. 1

34--42

EN

Sulfuric acid (H2SO4) is a specific depressor for apatite rather than for dolomite. The H2SO4treated dolomite can still be floated effectively by oleate. However, the role of H2SO4 in the adsorption of oleate onto dolomite surface remains unclear. In this work, density functional theory calculations were conducted to probe the interactions among sulfate anion (SO42−), oleate anion and the dolomite surface. The adsorption behaviors of SO42− anion onto the perfect and CO3-defect dolomite surfaces were compared. Such results show that SO42−anion could only adsorb onto the defective dolomite surface, where it bonded with a Ca atom. The remaining Ca and Mg atoms at the defect site could further react with the oleate anion, generating new Ca/Mg–O ionic bond. In this regard, oleate and SO42−anions may both present on the dolomite surface. This phenomenon accounts for the flotation of H2SO4-treated dolomite.

14

Insights into the interaction between octyl hydroxamic acid and the rutile surface activated by lead ion

Cao Qinbo, Chen Xiumin, Zou Heng, Yu Xingcai

Physicochemical Problems of Mineral Processing

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2020

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Vol. 56, iss. 5

928--938

EN

The flotation of rutile can be enhanced using lead ion as an activator. However, the binding behavior of collector on the activated rutile surface is still not fully understood. In this work, flotation and theoretical calculation approaches were employed to evaluate the activation behavior of lead ion in the flotation of rutile with octyl hydroxamic acid (OHA). Flotation results indicated that the activation flotation with lead ion should be conducted at pH 6.5. The binding features of OHA molecule on the inactivated and Pb-activated rutile surfaces were both investigated by density functional theory (DFT) studies. The OHA molecule may dissociate into OHA− anion on the inactivated rutile surface, generating a new Ti–O bond. Differently, the chelate complex of Pb-OHA anion was generated on the activated rutile surface, producing two Pb–O bonds. The adsorption of OHA onto the activated rutile surface was more stable than that on the inactivated rutile surface, due to the formation of more chemical bonds on the activated rutile surface. The DFT calculation results delineated the role of Pb2+ in the rutile flotation with OHA.

15

Binding features of N-hexadecanoylglycine on two terminations of fluorapatite (001) surface and their effect on fluorapatite flotation

Zou Heng, Liu Dianwen, Cao Qinbo, Chen Xiumin

Physicochemical Problems of Mineral Processing

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2020

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Vol. 56, iss. 5

949--959

EN

N-hexadecanoylglycine (C16Gly) is a newly synthesized collector, which can be used as an efficient collector for fluorapatite (FA) rather than for dolomite. To extend our knowledge regarding the C16Gly collector, the contact angle method was employed to understand the flotation selectivity of C16Gly in the FA and dolomite system. On the other hand, the possible binding models of C16Gly anion on Ca-rich and PO4-rich terminations of FA (001) surface were investigated with density functional theory calculations to reveal the interaction between the C16Gly and the FA surface. Results showed that C16Gly anion could interact with these two terminations to generate 12 low-energy configurations, including bidentate, tridentate and chelating binding models. The C16Gly anion preferred to adsorb onto the Ca-rich termination, which is caused by the weaker electrostatic repulsion force between the C16Gly anion and the PO4 groups on this termination. The adsorption of C16Gly on these terminations was more stable than that on the dolomite (104) surface, which is one of the reasons for the preferential flotation of FA from dolomite using C16Gly as a collector. These findings provide further insights into the selectivity of C16Gly during the flotation of FA and dolomite.

16

Adsorption of methylamine cations on kaolinite basal surfaces : A DFT study

Chen Jun, Min Fan-fei, Liu Ling-yun, Jia Fei-fei

Physicochemical Problems of Mineral Processing

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2020

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Vol. 56, iss. 2

338--349

EN

To explore the interaction of alkylamine surfactants with kaolinite, the density functional theory (DFT) method was used to calculate the single adsorption of different methylamine cation on kaolinite basal surfaces and the competitive adsorption of methylamine cation and water molecule on kaolinite basal surfaces, respectively. Different methylamine cations can adsorb on kaolinite basal surfaces by electrostatic interaction and hydrogen bonds, and the methylamine cations more easily adsorbed on kaolinite Si-O surface. In the case of competitive adsorption with water molecule, the methylamine cation is capable of flushing out the surrounding water molecule to get rid of its steric effect and stably adsorbing on kaolinite basal surfaces, and the adsorption state of the competitive adsorption system is more stable. The adsorption mechanism of methylamine cation on kaolinite basal surface should be the result of electrostatic interaction and hydrogen bonds, and the electrostatic interaction plays the main role.

17

First principle analysis of electronic, optical and thermoelectric characteristics of XBiO3 (X = Al, Ga, In) perovskites

Mahmood Q., Rouf S. A., Algrafy E., Murtaza G., Ramay S. M., Mahmood A.

Opto-Electronics Review

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2020

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Vol. 28, No. 1

8--14

EN

The perovskites XBiO3 (X = Al, Ga, In) have been studied in terms of mechanical, optical and thermoelectric behavior for energy harvesting application. Density functional theory is applied to study electronic, optical and thermoelectric properties of the studied materials. Structural, mechanical and thermodynamic stabilities are confirmed from the tolerance factor, Born mechanical stability and formation energy/specific heat capacity. Poisson and Plough ratios show the studied materials are ductile and have ability to withstand pressure. Band structure analysis shows the indirect band gap 3.0/2.1/1.0 eV for ABO/GBO/IBO. A complete set of optical spectra is reported by dielectric constants, refractive index, optical conduction, absorption of light and optical loss energy. Shifting of maximum absorption band to visible region increases the potential of perovskites XBiO3. Transport characteristics are also investigated by electrical conductivity, Seebeck coefficient and figure of merit.

18

Density functional theory calculations and Hirshfeld surface analysis of propyl-para-hydroxybenzoate (PHB) for optoelectronic application

Mohankumar V., Karunagaran N., Pandian M. Senthil, Ramasamy P.

Materials Science Poland

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2020

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Vol. 38, No. 3

386--393

EN

The geometries, electrostatic potential, Mulliken charge analysis, Natural Bond Orbital analysis and polarizabilities of propyl-para-hydroxybenzoate were calculated using B3LYP functional with 6-311++G(d,p) basis set. The calculated geometries are well matched with the experimental values. The Mullliken atomic charge analysis shows that the eventual charges are contained in the molecule. The NBO analysis explains the intramolecular charge transfer in the PHB molecule. The bonding features of the molecule were analyzed with the aid of Hirshfeld surface analysis. The frontier molecular orbital analysis showed the charge transfer obtained within the molecule. The calculated hyperpolarizability of the PHB molecule was 6.977E -30 esu and it was 8.9 times that of standard urea molecule.

19

Density functional study of structures, stabilities and electronic properties of AgAuλn(λ = 0, ±1; n = 1 − 12) clusters: comparison with pure gold clusters

Ranjan Prabhat, Chakraborty Tanmoy, Kumar Ajay

Materials Science Poland

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2020

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Vol. 38, No. 1

97--107

EN

Geometrical structures, relative stabilities and electronic properties of neutral, cationic and anionic pure gold Auλn+1 and Ag-doped bimetallic AgAuλn(λ=0,±1;n=1−12) clusters have been systematically investigated by using density functional theory methodology. The optimized structures show that planar to three-dimensional structural transition occurs at n = 5 for cationic clusters. Due to strong relativistic effect of Au clusters, the ground state configurations of neutral and anionic bimetallic clusters favor planar geometry till n = 12. Silver atoms tend to occupy the most highly coordinated position and form the maximum number of bonds with Au atoms. The computed HOMO-LUMO energy gaps, fragmentation energies and second-order difference of energies show interesting odd-even oscillation behavior. The result indicates that AgAu5, AgAu+2−2 are the most stable clusters in this molecular system. The DFT based descriptors of bimetallic clusters are also discussed and compared with pure gold clusters. The high value of correlation coefficient between HOMO-LUMO energy gaps and DFT based descriptors supports our analysis. A good agreement between experimental and theoretical data has been obtained in this study.

20

Właściwości wewnątrzcząsteczkowych wiązań wodorowych w wybranych N-tlenkach pochodnych chinoliny

Jezierska Aneta, Panek Jarosław J., Błaziak Kacper

Wiadomości Chemiczne

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2019

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[Z] 73, 1-2

75--95

EN

In the current article we would like to summarize our research shedding light onto properties of intramolecular hydrogen bonds present in N-oxide quinoline derivatives. The compounds for the current study were chosen to contain diverse types of hydrogen bonds. Therefore, in the current study we analyze three kinds of hydrogen bonding and their properties. It is well known, that the presence of intramolecular hydrogen bonds stabilizes conformations of molecules. Substituent effects (inductive and steric) influence the strength of the H-bonding as well as its features. Moreover, the intramolecular hydrogen bond in the studied N-oxides belongs to the family of resonance assisted hydrogen bonds (RAHB). Our short overview presents the summary of results obtained for twelve N-oxides of quinoline derivatives. Quantum-chemical simulations were performed on the basis of static models (classical DFT and MP2 approaches) as well as ab initio molecular dynamics (Car-Parrinello MD). The metadynamics method was applied to reproduce the maps of free energy for the motion of the bridged proton. The computations were performed in the gas and in the crystalline phases. Electronic ground state is a natural framework in which chemical compounds exist most of the time. However, in many chemical species we observe a spontaneous internal reorganization of their chemical bonds and atoms e.g. proton transfer phenomenon and the appearance of tautomeric forms already in the ground state. Therefore, it was interesting to investigate some N-oxides in the excited electron state knowing that they exhibit excited- state-induced proton transfer (ESIPT effect). At the end of the article we draw some conclusions related to the intramolecular H-bond properties present in the discussed N-oxides of quinoline derivatives.