scholarly journals Pressure-Induced Variation of The Crystal Stacking Order in the Hydrogen-Bonded Quasi-Two-Dimensional Layered Material Cu(OH)Cl

Materials ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 5019
Author(s):  
Hui Tian ◽  
Meiling Wang ◽  
Jian Zhang ◽  
Yanmei Ma ◽  
Hang Cui ◽  
...  
Keyword(s):  
Monoclinic Phase ◽  
Orthorhombic Phase ◽  
Building Blocks ◽  
Layered Materials ◽  
Stacking Sequence ◽  
X Ray Diffraction ◽  
Stacking Order ◽  
2D Layered Materials ◽  
Induced Changes ◽  
Hydrogen Bonded

The crystal stacking order plays a crucial role in determining the structure and physical properties of 2D layered materials. A variation in the stacking sequence of adjacent 2D building blocks causes drastic changes in their functionalities. In this work, the structural variation of belloite (Cu(OH)Cl), as a function of pressure, is presented. Through in situ synchrotron X-ray diffraction and Raman scattering studies, in combination with first-principles theoretical simulations, a structural transformation from the initial monoclinic phase into an orthorhombic one has been established at 18.7 GPa, featuring variations in the stacking sequence of the tectonic monolayers. In the monoclinic phase, they are arranged in an AAAA sequence. While in the orthorhombic phase, the monolayers are stacked in an ABAB sequence. Such phenomena are similar to those observed in van der Waals 2D materials, with pressure-induced changes in the stacking order between layers. In addition, an isostructural phase transition within the initial monoclinic phase is also observed to occur at 12.9–16 GPa, which is associated with layer-sliding and a change in hydrogen bond configuration. These results show that Cu(OH)Cl, as well as other hydrogen-bonded 2D layered materials, can provide a convenient platform for studying the effects of the crystal stacking order.

Microdomains in BaFeO3-y (0.35 < y < 0.50)

1990 ◽  
Vol 48 (4) ◽  
pp. 780-781
Author(s):  
M. Vallet-Regí ◽  
M. Parras ◽  
J.M. González-Calbet ◽  
J.C. Grenier
Keyword(s):  
Electron Diffraction ◽  
Chemical Analysis ◽  
Monoclinic Phase ◽  
Orthorhombic Phase ◽  
Total Iron ◽  
Zone Axis ◽  
Electron Micrograph ◽  
X Ray Diffraction ◽  
X Ray ◽  
Compositional Variations

BaFeO3-y compositions (0.35<y<0.50) have been investigated by means of electron diffraction and microscopy to resolve contradictory results from powder X-ray diffraction data.The samples were obtained by annealing BaFeO2.56 for 48 h. in the temperature range from 980°C to 1050°C . Total iron and barium in the samples were determined using chemical analysis and gravimetric methods, respectively.In the BaFeO3-y system, according to the electron diffraction and microscopy results, the nonstoichiometry is accommodated in different ways as a function of the composition (y):In the domain between BaFeO2.5+δBaFeO2.54, compositional variations are accommodated through the formation of microdomains. Fig. la shows the ED pattern of the BaFeO2.52 material along thezone axis. The corresponding electron micrograph is seen in Fig. 1b. Several domains corresponding to the monoclinic BaFeO2.50 phase, intergrow with domains of the orthorhombic phase. According to that, the ED pattern of Fig. 1a, can be interpreted as formed by the superposition of three types of diffraction maxima : Very strong spots corresponding to a cubic perovskite, a set of maxima due to the superposition of three domains of the monoclinic phase along [100]m and a series of maxima corresponding to three domains corresponding to the orthorhombic phase along the [100]o.

scholarly journals Формирование и трансформация моноклинной и орторомбической фаз в реакторных порошках сверхвысокомолекулярного полиэтилена

2018 ◽  
Vol 60 (9) ◽  
pp. 1847
Author(s):  
М.В. Байдакова ◽  
П.В. Дороватовский ◽  
Я.В. Зубавичус ◽  
Е.М. Иванькова ◽  
С.С. Иванчев ◽  
...  
Keyword(s):  
Mechanical Stress ◽  
Room Temperature ◽  
Monoclinic Phase ◽  
Orthorhombic Phase ◽  
Ultrahigh Molecular Weight Polyethylene ◽  
Polymer Synthesis ◽  
X Ray Diffraction ◽  
Reactor Powder ◽  
X Ray ◽  
The One

AbstractUsing powerful synchrotron X-ray radiation of the beamline “Belok” operated by the National Research Center “Kurchatov Institute,” we perform X-ray diffraction (XRD) study of an intact, virgin (not subjected to any external mechanical loads) particle isolated from reactor powder of ultrahigh molecular weight polyethylene. Along with the peaks originating from the orthorhombic phase, we detect the peaks characteristic of the monoclinic phase that is stable only under mechanical stress, suggesting that the mechanical stress that leads to the formation of the monoclinic phase and persists at room temperature develops during the polymer synthesis. The monoclinic phase gradually disappears when the particle is heated stepwise in increments of 5 K, and its peaks become undetectable when the temperature reaches 340 K. We contrast the results obtained for the phase composition of the virgin particle to those for a tablet prepared by compaction of the same reactor powder at room temperature. XRD analyses of the tablet were performed on D2 Phaser (Bruker) instrument. The monoclinic phase that originates during the polymer synthesis and the one that forms in the tablet during compaction have different parameters. We discuss the mechanisms by which these two different monoclinic phases originate during the processes involved.

scholarly journals Growth and Properties of Dislocated Two-dimensional Layered Materials

MRS Advances ◽  
2020 ◽  
Vol 5 (64) ◽  
pp. 3437-3452
Author(s):  
Rui Chen ◽  
Jinhua Cao ◽  
Stephen Gee ◽  
Yin Liu ◽  
Jie Yao
Keyword(s):  
Catalytic Properties ◽  
Large Strain ◽  
Layered Materials ◽  
Research Field ◽  
Two Dimensional ◽  
Research Attention ◽  
Stacking Order ◽  
2D Layered Materials ◽  
Considerable Research ◽  
Local Modification

AbstractTwo-dimensional (2D) layered materials hosting dislocations have attracted considerable research attention in recent years. In particular, screw dislocations can result in a spiral topology and an interlayer twist in the layered materials, significantly impacting the stacking order and symmetry of the layers. Moreover, the dislocations with large strain and heavily distorted atomic registry can result in a local modification of the structures around the dislocation. The dislocations thus provide a useful route to engineering optical, electrical, thermal, mechanical and catalytic properties of the 2D layered materials, which show great potential to bring new functionalities. This article presents a comprehensive review of the experimental and theoretical progress on the growth and properties of the dislocated 2D layered materials. It also offers an outlook on the future works in this promising research field.

One-pot Preparation of Cu2(OH)3NO3 Nanosheets and Cu(OH)2 Nanowires

2019 ◽  
Vol 9 (4) ◽  
pp. 467-471
Author(s):  
Wenzhe Zhang ◽  
Ailing Yang ◽  
Xichang Bao
Keyword(s):  
Crystal Structures ◽  
Monoclinic Phase ◽  
Orthorhombic Phase ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
One Pot ◽  
Molar Ratios ◽  
Transmission Electron ◽  
Reaction Solution ◽  
Cuo Nanosheets

Introduction: By using Cu(NO3)2 as precursor and polyvinylpyrrolidone (PVP) as surfactant, nanosheets of Cu2(OH)3NO3, nanowires of Cu(OH)2 or the mixture of the two were prepared under different molar ratios of OH− to Cu2+. Materials and Methods: The crystal structures and morphologies of the products were characterized by X-Ray Diffraction (XRD) and Transmission Electron Microscope (TEM). Results: When the molar ratio of OH− to Cu2+ in reaction solution is lower than 1.28, pure Cu2(OH)3NO3 nanosheets were obtained. The thickness of one piece of nanosheet is about 167 nm. The Cu2(OH)3NO3 nanosheets consists of two types of crystal structures, monoclinic phase and orthorhombic phase. With increase of the molar ratio of OH− to Cu2+, the monoclinic phase of Cu2(OH)3NO3 was transferred to the orthorhombic phase of Cu2(OH)3NO3. When the molar ratio of OH− to Cu2+ is within 1.28-2.24, the product is the mixture of Cu2(OH)3NO3 nanosheets and Cu(OH)2 nanowires. And when this molar ratio is higher than 2.24, only Cu(OH)2 nanowires were produced. The lengths and the diameters of the Cu(OH)2 nanowires are in the region of 50-250 nm and 10 nm, respectively. Conclusion: The reason of the Cu2(OH)3NO3 nanosheets changing into the Cu(OH)2 nanowires is that the OH− anions replace the NO3 − anions in the layered Cu2(OH)3NO3 nanosheets, which causes the rupture of hydrogen bonds connecting the adjacent layers. The Cu(OH)2 nanowires were not stable and found to become spindled CuO nanosheets in air at room temperature.

scholarly journals Тепловой эффект перехода моноклинной фазы в орторомбическую в сверхвысокомолекулярном полиэтилене

2019 ◽  
Vol 61 (10) ◽  
pp. 1965 ◽  
Author(s):  
В.М. Егоров ◽  
В.А. Марихин ◽  
Л.П. Мясникова ◽  
А.К. Борисов ◽  
Е.М. Иванькова ◽  
...  
Keyword(s):  
Phase Transition ◽  
Molecular Weight ◽  
Solid State ◽  
Monoclinic Phase ◽  
Orthorhombic Phase ◽  
Ultrahigh Molecular Weight Polyethylene ◽  
X Ray Diffraction ◽  
X Ray ◽  
Heat Effects ◽  
Ultrahigh Molecular Weight

AbstractWe analyze heat effects associated with the solid-state phase transition in ultrahigh molecular weight polyethylene from the unstable monoclinic phase into thermodynamically stable orthorhombic phase. The model proposed here for the structure of supramolecular formations of monoclinic phase does not contradict to earlier X-ray diffraction data for this polymer.

scholarly journals Локализация моноклинной фазы в насцентных частицах сверхвысокомолекулярного полиэтилена

2020 ◽  
Vol 62 (8) ◽  
pp. 1326
Author(s):  
Д.В. Анохин ◽  
К.Н. Графская ◽  
Д.А. Иванов ◽  
Е.М. Иванькова ◽  
В.А. Марихин ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Synchrotron Radiation ◽  
Room Temperature ◽  
Monoclinic Phase ◽  
Orthorhombic Phase ◽  
European Synchrotron Radiation Facility ◽  
X Ray Diffraction ◽  
X Ray ◽  
External Stresses ◽  
Ultra High Molecular Weight

Annotation The X-ray analysis of a virgin particle taken directly from the synthesis products of an ultra-high molecular weight polyethylene (UHMWPE) and not subjected to any external stresses was carried out using nanofocus beamline ID13 European Synchrotron Radiation Facility (ESRF, Grenoble,France). In the X-ray diffraction curves obtained by scanning an arbitrarily selected portion of a particle with a size of (100 x 20) μm2 by a microbeam (0.3 x 0.3) μm2 with a step of 2 μm horizontally and 0.5 μm vertically, along with reflections from the orthorhombic phase, reflexes from the metastable monoclinic phase were observed. It is believed that the cause of its occurrence may be stresses that develop during specific structure formation in slurry synthesis and persist when cooled to room temperature and the solvent evaporates. The possibility of localization of the monoclinic phase in various morphological formations is discussed.

Effect of Small Amount of Zn Additions on the Magnetocaloric Properties of Gd5Si2Ge2 Alloy

2011 ◽  
Vol 685 ◽  
pp. 307-310
Author(s):  
Xue Zhen Wang ◽  
Jie Xiang ◽  
Zhi Zeng ◽  
Xing Hao Hu ◽  
Xue Ling Hou ◽  
...  
Keyword(s):  
Magnetocaloric Effect ◽  
Monoclinic Phase ◽  
Magnetic Entropy Change ◽  
Orthorhombic Phase ◽  
Entropy Change ◽  
Type Structure ◽  
X Ray Diffraction ◽  
Arc Melting ◽  
Magnetocaloric Properties ◽  
Magnetic Field Change

The structural and magnetic property of Gd5Si1.99Ge2Zn0.01and Gd5Si2Ge2 alloys prepared by arc-melting the starting materials with commercial available purity (99.95wt%) was investigated by x-ray diffraction and Vibrating Sample Magnetometer. The result shows that the Gd5Si1.99Ge2Zn0.01alloy has monoclinic phase with Gd5Si2Ge2-type structure. The polymorphic orthorhombic phase with Gd5Si4-type structure coexists with the monoclinic phase in Gd5Si2Ge2alloy. The addition of small Zn element in Gd5Si2Ge2alloy results in a considerable enhancement of its magnetocaloric effect. The maximum magnetic entropy change rapidly increases from 5.03J/(kg K) to 20.70J/(kg K) for a magnetic field change from 0 to 1.5T. The magnetic order temperature is 278K in Gd5Si1.99Ge2Zn0.01alloy and 278.5K in Gd5Si2Ge2 alloy respectively. The magnetocaloric effect of Gd5Si2Ge2 with the small addition of Zn is significantly improved.

scholarly journals Thin film transistors based on two dimensional graphene and graphene/semiconductor heterojunctions

RSC Advances ◽  
2017 ◽  
Vol 7 (28) ◽  
pp. 17387-17397 ◽  
Author(s):  
Zhongcheng Zhu ◽  
Imran Murtaza ◽  
Hong Meng ◽  
Wei Huang
Keyword(s):  
Thin Film ◽  
Thin Film Transistors ◽  
Optoelectronic Devices ◽  
Building Blocks ◽  
Layered Materials ◽  
Two Dimensional ◽  
The Past ◽  
2D Layered Materials ◽  
Semiconductor Heterojunctions

During the past few years, two-dimensional (2D) layered materials have emerged as the most fundamental building blocks of a wide variety of optoelectronic devices.

Defect structures of Nb1+αS2 sulfidation scales

1992 ◽  
Vol 50 (1) ◽  
pp. 38-39
Author(s):  
Chuxin Zhou ◽  
L. W. Hobbs
Keyword(s):  
Stacking Faults ◽  
Rhombohedral Structure ◽  
Stacking Sequence ◽  
Defect Structures ◽  
X Ray Diffraction ◽  
X Ray ◽  
Plane Normal ◽  
Lower Case ◽  
Sulfur Layer ◽  
Two Phases

One of the major purposes in the present work is to study the high temperature sulfidation properties of Nb in severe sulfidizing environments. Kinetically, the sulfidation rate of Nb is satisfactorily slow, but the microstructures and non-stoichiometry of Nb1+αS2 challenge conventional oxidation/sulfidation theory and defect models of non-stoichiometric compounds. This challenge reflects our limited knowledge of the dependence of kinetics and atomic migration processes in solid state materials on their defect structures.Figure 1 shows a high resolution image of a platelet from the middle portion of the Nb1+αS2 scale. A thin lamellar heterogeneity (about 5nm) is observed. From X-ray diffraction results, we have shown that Nb1+αS2 scale is principally rhombohedral structure, but 2H-NbS2 can result locally due to stacking faults, because the only difference between these 2H and 3R phases is variation in the stacking sequence along the c axis. Following an ABC notation, we use capital letters A, B and C to represent the sulfur layer, and lower case letters a, b and c to refer to Nb layers. For example, the stacking sequence of 2H phase is AbACbCA, which is a ∼12Å period along the c axis; the stacking sequence of 3R phase is AbABcBCaCA to form an ∼18Å period along the c axis. Intergrowth of these two phases can take place at stacking faults or by a shear in the basal plane normal to the c axis.

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