CRYSTAL STRUCTURE OF THE QUATERNARY SEMICONDUCTOR COMPOUND CuFeCrSe3

The compounds with ternary structures of the chalcopyrite family Cu-III-Se2 (III = Al, Ga, In, Cr) form a wide group of semiconductor materials with diverse optical and electrical properties, and the addition of FeSe binary compound produces alloys of the type (Cu-III-Se2)1-x(Fe-Se)x. These types of materials have received increasing attention as promising thermoelectric materials due to their high efficiency, tunable transport properties, high elemental abundance and low toxicity. This work aims to synthesize and characterize structurally a new material belonging to this semiconductor system with x = ½, the quaternary compound CuFeCrSe3. This material was prepared by the melt and anneal technique and its structure was refined from Xray powder diffraction pattern using the Rietveld method. The X-ray powder pattern was mainly composed of CuFeCrSe3 (79.1%) with CuCr2Se4 (20.9%) appearing as secondary phase. The principal phase crystallizes with tetragonal symmetry in the space group P 4 2c (Nº 112), Z = 1, with a = 5.5082(2) Å, c = 10.943(1) Å, V = 332.01(1) Å3. The refinement of 18 instrumental and structural parameters led to Rp = 8.8 %, Rwp = 9.1 %, Rexp = 7.8 % and S = 1.2. This material, belonging to the semiconductor system I-II-III-VI3, crystallizes with a CuFeInSe3-type structure in a normal adamantane-structure. CuFeCrSe3 is a new semiconductor compound, related to the superionic phase CuCrSe2, and can be considered as a potential candidate for mediumtemperature thermoelectric applications.

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Selective Occupancy of Sites by Rare Earths in K2Nd(1-X)EuxNb5O15 Nanopowders, where X = 0, 0.0025, 0.025, 0.05 and 0.1, Prepared by Modified Polyol Method

Materials Science Forum ◽

10.4028/www.scientific.net/msf.820.361 ◽

2015 ◽

Vol 820 ◽

pp. 361-366

Author(s):

Eliane Ayumi Namikuchi ◽

Marcos Augusto Lima Nobre ◽

Silvania Lanfredi

Keyword(s):

Rietveld Method ◽

Structural Parameters ◽

Tungsten Bronze ◽

Average Crystallite Size ◽

Polyol Method ◽

Type Structure ◽

Tetragonal Symmetry ◽

Tetragonal Tungsten Bronze ◽

Host Structure ◽

Modified Polyol Method

Niobates with tetragonal tungsten bronze TTB-type structure have presented great technological potential due to their dielectric, ferroelectric, pyroelectric properties. The preparation by the modified polyol method and structural characterization of K2Nd(1-x)EuxNb5O15 nanopowders, where x = 0; 0.0025; 0.025; 0.05 e 0.1, were investigated. The structural parameters were analyzed as a function of concentration of europium ions in the K2NdNb5O15 host structure using the Rietveld method. From structural parameters was determined the TTB-type structure with tetragonal symmetry, where the pentagonal sites is occupied by K+ and Eu3+ ions and tetragonal sites is occupied only by Nd3+ ions. The addition of europium in the host structure led to a decrease in the lattice parameters, compatible with the increasing degree of distortion of NbO6 polyhedra. The average crystallite size showed values between 18.25 and 26nm.

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High Efficiency Fluorinated Oligo(ethylenesuccinamide) Coating for Stone

Coatings ◽

10.3390/coatings11040452 ◽

2021 ◽

Vol 11 (4) ◽

pp. 452

Author(s):

Mara Camaiti ◽

Villiam Bortolotti ◽

Yijian Cao ◽

Alessandra Papacchini ◽

Antonella Salvini ◽

...

Keyword(s):

Porous Structure ◽

High Efficiency ◽

Surface Characteristic ◽

Surface Wettability ◽

Structure Evolution ◽

Potential Candidate ◽

Protective Agent ◽

Irradiation Test ◽

Improved Performance ◽

Photo Stability

The protection of stone cultural assets is related to the transformation of the surface characteristic from hydrophilic to hydrophobic/superhydrophobic through the application of a coating. The suitability of a coating depends not only on its capability to dramatically change the surface wettability, but also on other parameters such as the modification of kinetics of water absorption, the permanence of vapor diffusivity, the resistance of the coating to aging and the low volatile organic compound emissions during its application. In this work, an oligo(ethylensuccinamide) containing low molecular pendant perfluoropolyether segments (SC2-PFPE) and soluble in environmentally friendly solvents was tested as a protective agent for historic stone artifacts. Magnetic resonance imaging and relaxometry were employed to evaluate the effects of the surface wettability change, to follow the water diffusion inside the rock and to study the porous structure evolution after the application of SC2-PFPE. A sun-like irradiation test was used to investigate the photo-stability of the product. The results demonstrate that the highly photo-stable SC2-PFPE minimizes the surface wettability of the stone by modifying the water sorptivity without significantly affecting its porous structure and vapor diffusivity. The improved performance of SC2-PFPE in comparison to other traditional coatings makes it a potential candidate as an advanced coating for stone cultural heritage protection.

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Advances in Quantum-Dot-Based Displays

Nanomaterials ◽

10.3390/nano10071327 ◽

2020 ◽

Vol 10 (7) ◽

pp. 1327 ◽

Cited By ~ 4

Author(s):

Yu-Ming Huang ◽

Konthoujam James Singh ◽

An-Chen Liu ◽

Chien-Chung Lin ◽

Zhong Chen ◽

...

Keyword(s):

High Efficiency ◽

Low Cost ◽

Flexible Substrate ◽

Potential Candidate ◽

White Leds ◽

Full Color ◽

Color Displays ◽

High Illumination ◽

Coating Methods ◽

Good Potential

In terms of their use in displays, quantum dots (QDs) exhibit several advantages, including high illumination efficiency and color rendering, low-cost, and capacity for mass production. Furthermore, they are environmentally friendly. Excellent luminescence and charge transport properties of QDs led to their application in QD-based light-emitting diodes (LEDs), which have attracted considerable attention in display and solid-state lighting applications. In this review, we discuss the applications of QDs which are used on color conversion filter that exhibit high efficiency in white LEDs, full-color micro-LED devices, and liquid-type structure devices, among others. Furthermore, we discuss different QD printing processes and coating methods to achieve the full-color micro-LED. With the rise in popularity of wearable and see-through red, green, and blue (RGB) full-color displays, the flexible substrate is considered as a good potential candidate. The anisotropic conductive film method provides a small controllable linewidth of electrically conductive particles. Finally, we discuss the advanced application for flexible full-color and highly efficient QD micro-LEDs. The general conclusion of this study also involves the demand for a more straightforward QD deposition technique, whose breakthrough is expected.

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Rietveld Refinement of the BaTiO3 from X-Ray Powder Diffraction

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.79-82.593 ◽

2009 ◽

Vol 79-82 ◽

pp. 593-596

Author(s):

Feng Sun ◽

Yan Sheng Yin

Keyword(s):

Rietveld Refinement ◽

Powder Diffraction ◽

Diffraction Data ◽

Rietveld Method ◽

Structural Parameters ◽

Ferroelectric Ceramic ◽

Powder Diffraction Data ◽

Ceramic Powders ◽

Space Group ◽

X Ray

The ferroelectric ceramic BaTiO3 was synthesized at 1000 °C for 5 h. The structure of the system under study was refined on the basis of X-ray powder diffraction data using the Rietveld method. The system crystallizes in the space group P4mm（99）. The refinement of instrumental and structural parameters led to reliable values for the Rp, Rwp and Rexp.We use the TOPAS software of Bruker AXS to refine this ceramic powders and show its conformation

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Preparation and Characterization of Gradient Compressed Porous Metal for High-Efficiency and Thin-Thickness Acoustic Absorber

Materials ◽

10.3390/ma12091413 ◽

2019 ◽

Vol 12 (9) ◽

pp. 1413 ◽

Cited By ~ 6

Author(s):

Xiaocui Yang ◽

Xinmin Shen ◽

Panfeng Bai ◽

Xiaohui He ◽

Xiaonan Zhang ◽

...

Keyword(s):

Sound Absorption ◽

High Efficiency ◽

Structural Parameters ◽

Porous Metal ◽

Theoretical Models ◽

Absorption Efficiency ◽

Total Thickness ◽

Porous Metals ◽

Absorption Coefficients ◽

Optimal Average

Increasing absorption efficiency and decreasing total thickness of the acoustic absorber is favorable to promote its practical application. Four compressed porous metals with compression ratios of 0%, 30%, 60%, and 90% were prepared to assemble the four-layer gradient compressed porous metals, which aimed to develop the acoustic absorber with high-efficiency and thin thickness. Through deriving structural parameters of thickness, porosity, and static flow resistivity for the compressed porous metals, theoretical models of sound absorption coefficients of the gradient compressed porous metals were constructed through transfer matrix method according to the Johnson–Champoux–Allard model. Sound absorption coefficients of four-layer gradient compressed porous metals with the different permutations were theoretically analyzed and experimentally measured, and the optimal average sound absorption coefficient of 60.33% in 100–6000 Hz was obtained with the total thickness of 11 mm. Sound absorption coefficients of the optimal gradient compressed porous metal were further compared with those of the simple superposed compressed porous metal, which proved that the former could obtain higher absorption efficiency with thinner thickness and fewer materials. These phenomena were explored by morphology characterizations. The developed high-efficiency and thin-thickness acoustic absorber of gradient compressed porous metal can be applied in acoustic environmental detection and industrial noise reduction.

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Synergistic effect of carboxyl and sulfate groups for effective removal of radioactive strontium ion in a Zr-metal-organic framework

Water Science & Technology ◽

10.2166/wst.2021.103 ◽

2021 ◽

Author(s):

Lin Ren ◽

Xudong Zhao ◽

Baosheng Liu ◽

Hongliang Huang

Keyword(s):

Adsorption Capacity ◽

High Efficiency ◽

Metal Organic Framework ◽

Maximum Adsorption Capacity ◽

Potential Candidate ◽

Dual Groups ◽

Metal Organic ◽

Strontium Ion ◽

Rapid Adsorption ◽

Organic Framework

Abstract Rapid removal of radioactive strontium from nuclear wastewater is of great significance for environment safety and human health. This work reported the effective adsorption of strontium ion in a stable dual-group metal-organic framework, Zr6(OH)14(BDC-(COOH)2)4(SO4)0.75 (Zr-BDC-COOH-SO4), which contains strontium-chelating groups (-COOH and SO4) and strongly ionizable group (-COOH). Zr-BDC-COOH-SO4 exhibits very rapid adsorption kinetics (<5 min) and a maximum adsorption capacity of 67.5 mg g−1. The adsorption behaviors can be well evaluated by pseudo-second-order model and Langmuir isotherm model. Further investigations indicate that the adsorption of Sr2+ in Zr-BDC-COOH-SO4 would not be interfered by solution pH and adsorption temperature obviously. Feasible regeneration of the adsorbent was also demonstrated through a simple elution method. Mechanism investigation suggests that free -COOH contributes to the rapid adsorption based on electrostatic interaction while introduction of -SO4 can enhance the adsorption capacity largely. Thus, these results suggest that Zr-BDC-COOH-SO4 might be a potential candidate for Sr2+ removal and introducing dual groups is an effective strategy for designing high-efficiency adsorbents.

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Engineering and experimental testing of two-wavelength laser-assisted device for photocoagulation of eye tissue

Ophthalmology journal ◽

10.17816/ov2013210-15 ◽

2013 ◽

Vol 6 (2) ◽

pp. 10-15

Author(s):

Yury Sergeevich Astakhov ◽

Yevgeny Leonidovich Akopov ◽

Aleksandr Anatolevich Ivanov ◽

Mariya Alexeevna Smirnova ◽

Leonid Nikolaevich Panteleev ◽

...

Keyword(s):

High Efficiency ◽

Experimental Testing ◽

Wide Spectrum ◽

Retinal Disease ◽

Primary Objective ◽

3D Analysis ◽

Potential Candidate ◽

Living Tissue ◽

Wide Range ◽

Retinal Photocoagulation

Retinal photocoagulation is believed to be one of most efficient methods to treat many retinal abnormalities. By now, a number of lasers operating at different wavelengths, irradiation intensities, and exposure times have been tested in search of optimal parameters for each type of retinal photocoagulation. Taking into consideration a wide range of such parameters, the primary objective of the present study was to develop a device that would combine the potentials of different lasers into a single universal laser-assisted coagulator (ULAC) equally suitable for a wide diversity of retinal disease. Important issue would be the creation of an experimental model allowing an operative evaluation of the coagulating effect induced by the ULAC. The sources of coherent irradiation to be combined were DPSS and diode lasers (532 and 810 nm, respectively). Through two individual fibers, irradiation generated by each of the lasers entered the optical blender to be further directed to the target, now via a single fiber. The target termed the “surrogate of living tissue” was a mixture of donor human blood and chicken egg white, which corresponded, respectively, to the chromophore and thermocoagulating agent, both sensitive to laser beams at 532 and 810 nm. As a result, irradiation of surrogate of living tissue by a laser under the trial caused the formation of a coagulate and its firm adhesion to the coverslip, after that the coagulate was separated from the unaffected surrogate of living tissue followed by its 3D-analysis. In conclusion, the whole procedure, while being relatively non-expensive and easy to perform, has proved to be simple enough for testing of a wide spectrum of coagulation-inducing parameters, whatever laser was used. Moreover, even the initial experiments have shown the high efficiency of the ULAC as a potential candidate for the application in ophthalmological practice.

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Ba5(IO6)2: crystal structure evolution from room temperature to 80 K

Acta Crystallographica Section E Crystallographic Communications ◽

10.1107/s2056989021004990 ◽

2021 ◽

Vol 77 (6) ◽

pp. 634-637

Author(s):

David Wenhua Bi ◽

Priya Ranjan Baral ◽

Arnaud Magrez

Keyword(s):

Crystal Structure ◽

Room Temperature ◽

Structural Transition ◽

Rietveld Method ◽

Structural Parameters ◽

Structure Evolution ◽

X Ray Diffraction ◽

Lattice Contraction ◽

Interatomic Distances ◽

Crystallographic Axes

The crystal structure of Ba5(IO6)2, pentabarium bis(orthoperiodate), has been re-investigated at room temperature based on single-crystal X-ray diffraction data. In comparison with a previous crystal structure determination by the Rietveld method, an improved precision of the structural parameters was achieved. Additionally, low-temperature measurements allowed the crystal structure evolution to be studied down to 80 K. No evidence of structural transition was found even at the lowest temperature. Upon cooling, the lattice contraction is more pronounced along the b axis. This contraction is found to be inhomogeneous along different crystallographic axes. The interatomic distances between different Ba atoms reduce drastically with lowering temperature, resulting in a closer packing around the IO6 octahedra, which remain largely unaffected.

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Nature Inspired MIMO Antenna System for Future mmWave Technologies

Micromachines ◽

10.3390/mi11121083 ◽

2020 ◽

Vol 11 (12) ◽

pp. 1083

Author(s):

Saifur Rahman ◽

Xin-cheng Ren ◽

Ahsan Altaf ◽

Muhammad Irfan ◽

Mujeeb Abdullah ◽

...

Keyword(s):

Communication Systems ◽

High Efficiency ◽

Multiple Input Multiple Output ◽

Antenna System ◽

Potential Candidate ◽

Mimo Antenna ◽

Communication Devices ◽

Input Multiple Output ◽

Measured Efficiency ◽

5G Communication

In this work, a new Multiple Input Multiple Output (MIMO) antenna system with a novel shape inspired by nature is proposed for Fifth-Generation (5G) communication systems. The antenna is designed on a Rogers 5880. The dielectric constant of the substrate is 2.2, and the loss tangent is assumed to be 0.0009. The gain of the system for the desired bandwidth is nearly 8 dB. The simulated and the measured efficiency of the proposed system is 95% and 80%, respectively. To demonstrate the capability of the system as a potential candidate for future 5G communication devices, MIMO key performance parameters such as the Envelope Correlation Coefficient (ECC) and Diversity Gain (DG) are computed. It is found that the proposed system has low ECC, constant DG, and high efficiency for the desired bandwidth.

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