scholarly journals Synthesis and Luminescence of Optical Memory Active Tetramethylammonium Cyanocuprate(I) 3D Networks

Materials ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1211 ◽  
Author(s):  
Aaron D. Nicholas ◽  
Rebeka M. Bullard ◽  
Amelia M. Wheaton ◽  
Michaela Streep ◽  
Victoria A. Nicholas ◽  
...  
Keyword(s):  
Emission Intensity ◽  
Optical Memory ◽  
X Ray Diffraction ◽  
Electron Transfer Mechanism ◽  
X Ray ◽  
Tetramethylammonium Chloride ◽  
Td Dft ◽  
Experimental Findings ◽  
3D Networks ◽  
Triplet Emitter

The structures of three tetramethylammonium cyanocuprate(I) 3D networks [NMe4]2[Cu(CN)2]2•0.25H2O (1), [NMe4][Cu3(CN)4] (2), and [NMe4][Cu2(CN)3] (3), (Me4N = tetramethylammonium), and the photophysics of 1 and 2 are reported. These complexes are prepared by combining aqueous solutions of the simple salts tetramethylammonium chloride and potassium dicyanocuprate. Single-crystal X-ray diffraction analysis of complex 1 reveals {Cu2(CN)2(μ2-CN)4} rhomboids crosslinked by cyano ligands and D3h {Cu(CN)3} metal clusters into a 3D coordination polymer, while 2 features independent 2D layers of fused hexagonal {Cu8(CN)8} rings where two Cu(I) centers reside in a linear C∞v coordination sphere. Metallophilic interactions are observed in 1 as close Cu⋯Cu distances, but are noticeably absent in 2. Complex 3 is a simple honeycomb sheet composed of trigonal planar Cu(I) centers with no Cu…Cu interactions. Temperature and time-dependent luminescence of 1 and 2 have been performed between 298 K and 78 K and demonstrate that 1 is a dual singlet/triplet emitter at low temperatures while 2 is a triplet-only emitter. DFT and TD-DFT calculations were used to help interpret the experimental findings. Optical memory experiments show that 1 and 2 are both optical memory active. These complexes undergo a reduction of emission intensity upon laser irradiation at 255 nm although this loss is much faster in 2. The loss of emission intensity is reversible in both cases by applying heat to the sample. We propose a light-induced electron transfer mechanism for the optical memory behavior observed.

scholarly journals Determination of thermodynamic stability of FeB monoboride

2019 ◽  
Vol 27 (2) ◽  
pp. 69-76
Author(s):  
N. Yu. Filonenko ◽  
A. N. Galdina
Keyword(s):  
Thermodynamic Stability ◽  
Boron Content ◽  
Boron Concentration ◽  
Cast Alloy ◽  
Thermodynamic Characteristics ◽  
X Ray Diffraction ◽  
X Ray ◽  
High Temperature Expansion ◽  
Experimental Findings

In this paper we investigate the phase composition and phase transformations in the Fe-B system alloys with boron content in the range of 9.0–15.0 wt.%. We use microstructural, X-ray diffraction, differential thermal and durometric analyzes to determine the physical properties of the alloys. The experimental findings show that in the as-cast alloy structure there is Fe5B3 phase in small quantities along with FeB monoboride and Fe2B boride. The Fe5B3 phase is formed as a result of the peritectic reaction L+FeB→Fe5B3 at the temperature of 1680 K. The eutectic transformation L→Fe5B3 +Fe2B occurs in the boron concentration range of 8.8–10.5 wt.%. After annealing of the Fe-B alloys at the temperature of 1473 K and cooling with the rate of 102 K/s we observe the occurring of the Fe5B3 phase. To spot an opportunity of the secondary monoboride formation in the alloys under consideration, we calculate the thermodynamic characteristics of stability of the system. Accounting for the contribution of the first degree approximation of high-temperature expansion of thermodynamic potential of FeB iron monoboride in a Fe-B binary alloy enables us to study its thermodynamic stability. It is shown that stability decrease of FeB at 1423 K allows suggesting that at this temperature the phase transformation occurs and this fact correlates to the differential thermal analysis results.

1,2-Di(silyl)benzene and 1,4-Dibromo-2,5-di(silyl)benzene

1994 ◽  
Vol 49 (8) ◽  
pp. 1036-1040 ◽  
Author(s):  
Robert Schröck ◽  
Alexander Sladek ◽  
Hubert Schmidbaur
Keyword(s):  
Methanesulfonic Acid ◽  
Intermediate Compound ◽  
Molecular Structures ◽  
High Yield ◽  
Electronic Effects ◽  
X Ray Diffraction ◽  
X Ray ◽  
High Yields ◽  
Experimental Findings ◽  
Silylation Reaction

1,2-Di(silyl)benzene (3), has been prepared in a three-step process starting with the reac­tion of 1,2-dibromobenzene and p-tolyl(chloro)silane with magnesium in tetrahydrofuran. which affords 1,2-bis(p-tolylsilyl)benzene (1) as a stable high-yield intermediate. Compound 1 has been converted into 1,2-bis(trifluoromethanesulfonatosilyl)benzene (2) with trifluoro- methanesulfonic acid, and finally into 3 by reduction with lithiumaluminiumhydride, both again in high yields. - In an attempt to prepare 1,2,4,5-tetra(silyl)benzene in an analogous way. only the bis-silylated species could be obtained (from 1,2,4,5-C6H2Br4. p-MeC6H4SiClH2 and Mg powder: 1,4-dibromo-2,5-bis(p-tolylsilyl)benzene. 4, and 1,4-dibromo-2,5-di(silyl)- benzene, 6, via 1,4-dibromo-2,5-bis(trifluoromethanesulfonatosilyl)benzene, 5). The crystal structures of compounds 4 and 6 have been determined by X-ray diffraction. The results indicate no steric hindrance in these molecules and it is thus not obvious from the molecular structures why the silylation reaction does not proceed any further to give the tetrasilylated benzene derivatives. Electronic effects have to be invoked to rationalize the experimental findings.

Synthesis of Porous SnO2 with Superior Acetone Sensing Properties

2014 ◽  
Vol 1053 ◽  
pp. 181-184 ◽  
Author(s):  
Hui Hui Zhang ◽  
Dan Han ◽  
Peng Song ◽  
Qi Wang
Keyword(s):  
Porous Structures ◽  
X Ray Diffraction ◽  
Functional Nanomaterials ◽  
Macroscopic Scale ◽  
Promising Candidate ◽  
X Ray ◽  
Structure And Morphology ◽  
Porous Nanostructure ◽  
Acetone Sensor ◽  
3D Networks

Porous structures represent a unique class of functional nanomaterials with many applications. In this work, porous SnO2 with 3D networks structures were synthesized by a facile Lewis acid catalytic template method. Techniques of X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to characterize the structure and morphology of the products. The porous SnO2 posses large macroscopic scale and porous nanostructure with huge pore volume and large surface exposure area. The sensor based on SnO2 with porous structures exhibited high response to acetone gas (CH3COCH3). It suggests that the as-prepared porous SnO2 is promising candidate for good performance acetone sensor.

Position Resolved Residual Stress Determination in Alumina-Zirconia Multilayered Ceramics

2008 ◽  
Vol 571-572 ◽  
pp. 421-425
Author(s):  
Guenther A. Maier ◽  
Jozef Keckes ◽  
Jens Brechbuehl ◽  
Hugues Guerault ◽  
Raúl Bermejo
Keyword(s):  
Residual Stress ◽  
Stress Distribution ◽  
X Ray Diffraction ◽  
Correct Evaluation ◽  
Indentation Method ◽  
Element Analysis ◽  
Stress Evaluation ◽  
X Ray ◽  
Residual Stress State ◽  
Experimental Findings

Alumina-zirconia multilayered ceramics have been proposed as an alternative for the design of structural ceramics with improved fracture toughness and strength reliability. During the processing of these laminates, significant residual stresses may arise due to the thermal expansion mismatch between adjacent layers. The correct evaluation of such stress distribution in the laminate may determine its range of application. In this work, the residual stress state in a layered material designed with five thick alumina layers of approximately 650 microns alternated with four thin alumina-zirconia layers of approximately 140 microns was estimated using different methods. A finite element analysis (FEM) was performed for stress evaluation in the bulk and an indentation method and X-Ray diffraction to account for stresses at the surface. Experimental findings show a constant stress distribution within the bulk for each layer, while at the surface stress position dependence is observed in the alumina layers, being the maximum tensile stresses near the layer interface. The accuracy of the results provided by each technique is discussed.

Effect of Compositions, Crystal Structures and Morphologies on Photo-Luminescent Property of LaPO4:Gd3+

2016 ◽  
Vol 848 ◽  
pp. 413-418 ◽  
Author(s):  
Luo Zhang ◽  
Xiao Yan Wang ◽  
Xin Wang ◽  
Hong Tao Ni
Keyword(s):  
Crystal Structures ◽  
Emission Intensity ◽  
Photo Luminescence ◽  
Atom Fraction ◽  
X Ray Diffraction ◽  
Mass Percentage ◽  
Higher Symmetry ◽  
X Ray ◽  
Maximum Value ◽  
Percentage Concentration

Various LaPO4:Gd3+ samples were synthesized by the hydrothermal method under different conditions to investigate the influence of crystalline structures, compositions and morphologies on the photo-luminescence. The compositions, crystal structures and morphologies were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and photo-luminescence emission spectrum (PL). The results revealed that the emission intensity of LaPO4:Gd3+ reached the maximum value as the mass percentage concentration of Gd3+ ions ascended to 3%. Monoclinic LaPO4:Gd3+ had stronger emission intensity than hexagonal sample which had more zeolitic water, higher symmetry and lower crystallinity. The nanospheres which dispersed better and had higher uniformity and surface atom fraction had the stronger PL intensity than the nanorods. It has been found that the La0.97Gd0.03PO4, which was prepared under the condition of pH=1, T=20 °C and excess PO43-, performed the best PL property after heat treatment at 900 °C for 4h.

scholarly journals Влияние буферного слоя por-Si  на оптические свойства эпитаксиальных гетероструктур In-=SUB=-x-=/SUB=-Ga-=SUB=-1-x-=/SUB=-N/Si(111) с наноколончатой морфологией пленки

2019 ◽  
Vol 53 (1) ◽  
pp. 70
Author(s):  
П.В. Середин ◽  
Д.Л. Голощапов ◽  
Д.С. Золотухин ◽  
А.С. Леньшин ◽  
А.Н. Лукин ◽  
...  
Keyword(s):  
Buffer Layer ◽  
Emission Intensity ◽  
Molecular Beam ◽  
Single Crystal Silicon ◽  
X Ray Diffraction ◽  
Si Substrate ◽  
Crystal Silicon ◽  
X Ray ◽  
Plasma Activation ◽  
Single Crystal Silicon Substrate

AbstractIntegrated heterostructures exhibiting a nanocolumnar morphology of the In_ x Ga_1 –_ x N film are grown on a single-crystal silicon substrate ( c -Si(111)) and a substrate with a nanoporous buffer sublayer ( por -Si) by molecular-beam epitaxy with the plasma activation of nitrogen. Using a complex of spectroscopic methods of analysis, it is shown that the growth of In_ x Ga_1 –_ x N nanocolumns on the por -Si buffer layer offer a number of advantages over growth on the c -Si substrate. Raman and ultraviolet spectroscopy data support the inference about the growth of a nanocolumn structure and agree with the previously obtained X-ray diffraction (XRD) data indicative of the strained, unrelaxed state of the In_ x Ga_1 –_ x N layer. The growth of In_ x Ga_1 –_ x N nanocolumns on the por -Si layer positively influences the optical properties of the heterostructures. At the same half-width of the emission line in the photoluminescence spectrum, the emission intensity for the heterostructure sample grown on the por -Si buffer layer is ~25% higher than the emission intensity for the film grown on the c -Si substrate.

scholarly journals The syntheses, structures and spectroelectrochemical properties of 6-oxo-verdazyl derivatives bearing surface anchoring groups

2021 ◽  
Author(s):  
Varshini Kumar ◽  
Jian-Zhong Wu ◽  
Martyna Judd ◽  
Elodie Rousset ◽  
Marcus Korb ◽  
...  
Keyword(s):  
Closed Shell ◽  
Coupling Reactions ◽  
Terminal Alkynes ◽  
X Ray Diffraction ◽  
Surface Anchoring ◽  
X Ray ◽  
Verdazyl Radicals ◽  
Cross Coupling Reactions ◽  
Td Dft ◽  
Anchoring Groups

A series of 6-oxo verdazyl radicals functionalised at the 1- and 5-positions by methyl, thiomethyl and iodo groups were synthesised using conventional strategies. Facile Sonogashira cross-coupling reactions of terminal alkynes with the diiodo analogue were used for synthetic elaboration of the verdazyl core structure with π-conjugated ethynyl groups. The radicals were characterised by EPR spectroscopy, single-crystal X-ray diffraction, cyclic voltammetry and optical spectroscopy. The chemically and electrochemically reversible oxidation and reduction of these radicals within a convenient redox window permitted further studies on the closed-shell cationic and anionic forms using spectroelectrochemical methods, supported by (TD-)DFT calculations.

Structural investigation of one- and three-dimensional lanthanide(III) coordination polymers based on functionalized terpyridine carboxylate and aromatic dicarboxylate ligands

2019 ◽  
Vol 75 (4) ◽  
pp. 422-432 ◽  
Author(s):  
Chao Bai ◽  
Bin Liu ◽  
Huai-Ming Hu ◽  
Jin-Dian Li ◽  
Xiaofang Wang ◽  
...  
Keyword(s):  
Coordination Polymers ◽  
Structural Investigation ◽  
Three Dimensional ◽  
Topological Type ◽  
X Ray Diffraction ◽  
Hydrothermal Conditions ◽  
One Dimensional ◽  
X Ray ◽  
Lanthanide Coordination Polymers ◽  
3D Networks

Three series of lanthanide coordination polymers, namely catena-poly[[lanthanide(III)-μ2-(benzene-1,2-dicarboxylato)-μ2-[2-(2,2′:6′,2′′-terpyridin-4′-yl)benzoato]] monohydrate], {[Ln(C8H4O4)(C22H14N3O2)]·H2O} n or {[Ln(1,2-bdc)(L)]·H2O} n , with lanthanide (Ln) = dysprosium (Dy, 1), holmium (Ho, 2) and erbium (Er, 3), poly[bis(μ2-benzene-1,3-dicarboxylato)bis[μ2-2-(2,2′:6′,2′′-terpyridin-4′-yl)benzoato]dilanthanide(III)], [Ln2(C8H4O4)2(C22H14N3O2)2] n or [Ln2(1,3-bdc)2(L)2] n , with Ln = gadolinium (Gd, 4), Ho (5) and Er (6), and poly[(μ2-benzene-1,4-dicarboxylato)[μ2-2-(2,2′:6′,2′′-terpyridin-4′-yl)benzoato]lanthanide(III)], [Ln(C8H4O4)(C22H14N3O2)] n or [Ln(1,4-bdc)(L)] n , with Ln = Dy (7), Ho (8), Er (9) and ytterbium (Yb, 10), were synthesized under hydrothermal conditions and characterized by elemental analysis, IR and single-crystal X-ray diffraction. Compounds 1–3 possess one-dimensional loop chains with Ln2(COO)2 units, which are extended into three-dimensional (3D) supramolecular structures by π–π interactions. Isostructural compounds 5 and 6 show 6-connected 3D networks, with pcu topology consisting of Ln2(COO)2 units. Compounds 7–10 display 8-connected 3D frameworks with the topological type rob, consisting of Ln2(COO)2 units. The influence of the coordination orientations of the aromatic dicarboxylate groups on the crystal structures is discussed.

Preparation of M2SiO4:Tb3+, Mn2+, Nd3+ White-Emitting Phosphors (M = Mg2+, Ca2+, Sr2+, and Ba2+) and the Influence of M2+ Cations on their Luminescent Performance

2021 ◽  
Vol 904 ◽  
pp. 329-333
Author(s):  
Qun Si Wang ◽  
Jun Feng Ma ◽  
Tian Qing Cui ◽  
Dong Bin Tang ◽  
Qi Zhou
Keyword(s):  
High Temperature ◽  
Solid State ◽  
Solid State Reaction ◽  
Emission Intensity ◽  
Photoluminescence Spectra ◽  
X Ray Diffraction ◽  
X Ray ◽  
Near Ultraviolet ◽  
Violet Radiation ◽  
Luminescence Performance

M2SiO4: Tb3+, Mn2+, Nd3+ (M = Mg2+, Ca2+, Sr2+, and Ba2+) phosphors suitable for near-ultraviolet-violet radiation excitation were successfully prepared at 1400 °C in N2 atmosphere by a high-temperature solid-state reaction, and their phase compositions and luminescent performance were also studied by X-ray diffraction (XRD), photoluminescence spectra. Results show that their emission intensity increases in the order of Ca2SiO4 > Mg2SiO4 > Sr2SiO4 > Ba2SiO4 matrix phosphor. Ca1.94SiO4: 0.02Tb3 +, 0.02Mn2+, 0.02Nd2+ phosphor exhibits the best luminescence performance.

Luminescent Properties of Ca1-xBaxSnO3: Eu3+, Dy3+ Composites Prepared by Coprecipitation

2014 ◽  
Vol 989-994 ◽  
pp. 383-386
Author(s):  
Li Min Dong ◽  
Fei Lv ◽  
Qin Li ◽  
Zhi Dong Han ◽  
Xian You Zhang
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Fluorescence Spectroscopy ◽  
Emission Intensity ◽  
Luminescent Properties ◽  
Emission Characteristics ◽  
X Ray Diffraction ◽  
X Ray ◽  
Structure Morphology ◽  
Scanning Electron

A series of Eu3+, Dy3+ actived Ca1-xBaxSnO3 phosphors were synthesized by coprecipitation method. The structure, morphology and fluorescence property of phosphors were investigated by using X-ray diffraction (XRD), scanning electron microscopy (SEM) and fluorescence spectroscopy. SEM results showed that the as-prepared phosphors are smooth and uniform with the cubic morphology. The incorporation of a small amount of Ba to CaBaSnO3 improved the emission characteristics. Fluorescence spectrum showed the emission intensity is the best with the incorporation of Ba2+ (x = 0.3), when calcination temperature is 900°C.

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