Shifts of X-ray diffraction reflections of polycaproamide (nylon 6) owing to small crystal size

1987 ◽  
Vol 25 (12) ◽  
pp. 2561-2566 ◽  
Author(s):  
D. R. Salem
Keyword(s):  
Crystal Size ◽  
Nylon 6 ◽  
X Ray Diffraction ◽  
X Ray ◽  
Small Crystal ◽  
Small Crystal Size

Crystal Structure of K6Nb44O113 from HREM

1990 ◽  
Vol 48 (1) ◽  
pp. 42-43
Author(s):  
F.H. Li ◽  
C.M. Teng ◽  
J.J. Hu ◽  
F. Nagata ◽  
C. Tsuruta
Keyword(s):  
Crystal Structure ◽  
Electron Diffraction ◽  
Crystal Size ◽  
Fold Axis ◽  
Structure Model ◽  
X Ray Diffraction ◽  
X Ray ◽  
Tetragonal System ◽  
Small Crystal Size ◽  
Different Shapes

Different results about the crystal structure of K6Nb44O113 (KNO) were obtained by X-ray diffraction analysis[1,2]. This might be due to the small crystal size and the impurity of crystalline powders. Such sample are suitable for HREM investigation. Teng et al. studied the crystal by electron diffraction and HREM[3]. They compared the image of KNO with the structure model of Rb3Nb54O146(RNO) proposed by Gatehouse et al.[4]. The latter’s structure which is formed by Nb-O octahedra belongs to the tetragonal system and contains tunnels of different shapes along the four-fold axis(Fig.1). An image of KNO given by Teng et al. shows four-leaf and three-leaf shaped bright dots whose arrangement is in agreement with that of heptagonal and hexagonal tunnels in the structure of RNO respectively. Although Teng et al. proposed that the crystal structure of KNO might also be formed by Nb-O octahedra and contains various tunnels as RNO, they concluded that the symmetry of KNO should be lower than that of RNO. In this abstract it is reported that the crystal structure of KNO is isomorphic to that of RNO as well as that of CsxNb54(O,F)146[5].

Vanadium, V – a new native element mineral from the Colima volcano, State of Colima, Mexico, and implications for fumarole gas composition

2016 ◽  
Vol 80 (2) ◽  
pp. 371-382 ◽  
Author(s):  
M. Ostrooumov ◽  
Y. Taran
Keyword(s):  
Crystal Size ◽  
New Mineral ◽  
Gas Composition ◽  
X Ray Diffraction ◽  
Calculated Density ◽  
X Ray ◽  
Colima Volcano ◽  
Glancing Angle ◽  
Small Crystal Size ◽  
Adjacent Rock

AbstractVanadium, V, is a new mineral found in sublimates of high-temperature fumaroles of the Colima volcano, Mexico. The mineral precipitates over a narrow temperature range of 550–680°C, and occurs in association with colimaite (K3VS4) and shcherbinaite (V2O5). Native vanadium was been found on the inner wall of an inserted silica tube and subsequently in the adjacent rock of the Z3 fumarole. Vanadium forms smooth, irregular to flattened crystals, 5–20 μm in diameter. Smaller irregular crystals have also been observed in silica tubes. Due to its small crystal size, its physical properties (hardness, cleavage and density) could not be determined. An EDS spectrum indicated the presence of V, Fe, Al and Ti with an empirical formula calculated on the basis of EPMA analyses of V0.86Fe0.09Al0.04Ti0.01. Gandolfi and glancing-angle X-ray diffraction data showed that the microcrystals were body-centred cubic, space group Im3̄m, a = 3.022(3) Å, V = 27.60 (5) Å3, Z = 2. The five strongest calculated diffraction lines are [ d spacings in Å, (I) (hkl)]: 2.1411 (100)(110), 1.5126 (12)(200), 1.2301 (19)(211), 0.9565 (8)(310) and 8.8090 (11)(321). The calculated density is 6.033 g cm–3. Thermochemical modelling was used to explain why very oxidized gas at Colima precipitates V-bearing minerals and some native elements (vanadium and gold). Vanadium, is the second newly recognized mineral species (after colimaite) collected from an active fumarole in this volcanic crater. The mineral and its name have been approved by the CNMNC (IMA 2012-021a).

scholarly journals Study on the Electrical, Structural, Chemical and Optical Properties of PVD Ta(N) Films Deposited with Different N2 Flow Rates

Coatings ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 937
Author(s):  
Yingying Hu ◽  
Md Rasadujjaman ◽  
Yanrong Wang ◽  
Jing Zhang ◽  
Jiang Yan ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Optical Properties ◽  
Photoelectron Spectroscopy ◽  
Crystal Size ◽  
Silicon Substrates ◽  
X Ray Diffraction ◽  
Dc Magnetron Sputtering ◽  
Flow Rates ◽  
X Ray ◽  
N2 Flow Rate

By reactive DC magnetron sputtering from a pure Ta target onto silicon substrates, Ta(N) films were prepared with different N2 flow rates of 0, 12, 17, 25, 38, and 58 sccm. The effects of N2 flow rate on the electrical properties, crystal structure, elemental composition, and optical properties of Ta(N) were studied. These properties were characterized by the four-probe method, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and spectroscopic ellipsometry (SE). Results show that the deposition rate decreases with an increase of N2 flows. Furthermore, as resistivity increases, the crystal size decreases, the crystal structure transitions from β-Ta to TaN(111), and finally becomes the N-rich phase Ta3N5(130, 040). Studying the optical properties, it is found that there are differences in the refractive index (n) and extinction coefficient (k) of Ta(N) with different thicknesses and different N2 flow rates, depending on the crystal size and crystal phase structure.

Structural changes in titanium dioxide nanocrystals during plastic deformation

2005 ◽  
Vol 38 (5) ◽  
pp. 749-756 ◽  
Author(s):  
Ulrich Gesenhues
Keyword(s):  
Structural Changes ◽  
Crystal Size ◽  
Lower Layer ◽  
High Energy ◽  
Primary Crystal ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Hall Method ◽  
Means Of Transmission

The polygonization of 200 nm rutile crystals during dry ball-milling at 10gwas monitored in detail by means of transmission electron microscopy (TEM) and X-ray diffraction (XRD). The TEM results showed how to modify the Williamson–Hall method for a successful evaluation of crystal size and microstrain from XRD profiles. Macrostrain development was determined from the minute shift of the most intense reflection. In addition, changes in pycnometrical density were monitored. Accordingly, the primary crystal is disintegrated during milling into a mosaic of 12–35 nm pieces where the grain boundaries induce up to 1.2% microstrain in a lower layer of 6 nm thickness. Macrostrain in the interior of the crystals rises to 0.03%. The pycnometrical density, reflecting the packing density of atoms in the grain boundary, decreases steadily by 1.1%. The results bear relevance to our understanding of plastic flow and the mechanism of phase transitions of metal oxides during high-energy milling.

scholarly journals Structural and thermoelectric properties of the Pr2Zr2O7 compound

2019 ◽  
pp. 4-9
Author(s):  
Adolfo Quiroz-Rodríguez ◽  
Cesia Guarneros-Aguilar ◽  
Ricardo Agustin-Serrano
Keyword(s):  
Electron Microscopy ◽  
Thermal Conductivity ◽  
Thermoelectric Properties ◽  
Crystal Size ◽  
Ambient Pressure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Increasing Temperature ◽  
Thermal Stability Of ◽  
Scanning Electron

In this research, it is presented a detailed study of the structural and thermoelectric properties of the pyrochlore zirconium Pr2Zr2O7 compound prepared by solid-state reaction (SSR) in air at ambient pressure. The synthesized sample was characterized using powder X-ray diffraction. The thermal stability of the thermoelectric compound (TE) Pr2Zr2O7 was tested by thermogravimetric analysis (TGA) and differential thermal analysis (DTA). Scanning electron microscopy shows that the crystal size varies between 0.69 and 2.81μm. Electrical conductivity (\sigma) of the sample calcined at 1400 °C presented values increase irregularly with the increasing temperature from 0.001 to 0.018 S cm-1 as expected in a semiconductor material. The thermal conductivity is lower than 0.44 - 775 W m-1 K-1 which is quite anomalous in comparison with the thermal conductivity of other oxides.

Structure Characterization of Sintered CaO-Al2O3-SiO2 Glass-Ceramic Reinforced with Spodumene

2013 ◽  
Vol 834-836 ◽  
pp. 309-314
Author(s):  
Zi Fan Xiao ◽  
Jin Shu Cheng ◽  
Jun Xie
Keyword(s):  
Glass Ceramic ◽  
Energy Dispersive Spectrometry ◽  
Crystal Size ◽  
Bending Strength ◽  
Glass Ceramics ◽  
Structure Characterization ◽  
X Ray Diffraction ◽  
Crystalline Phases ◽  
X Ray

A glass-ceramic belonging to the CaO-Al2O3-SiO2(CAS) system with different composition of spodumene and doping the Li2O with amount between 0~2.5 % (mass fraction) were prepared by onestage heat treatment, under sintering and crystallization temperature at 1120 °C for two hours. In this paper, differential thermal analysis, X-ray diffraction, scanning electron microscopy, energy dispersive spectrometry and bending strength test were employed to investigate the microstructure and properties of all samples. β-wollastonite crystals were identified as the major crystalline phases, and increasing Li2O was found to be benefit for the crystallization and tiny crystalline phases remelting, resulting in the content of major crystalline phases increased first and then decreased with increasing the expense of spodumene. Meanwhile, the crystal size can be positively related with the content of Li2O. The preferable admixed dosage of spodumene can be obtained, besides the strength of glass-ceramics can be more than 90 MPa.

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