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Physical Properties of Ba0.95Pb0.05TiO3+0.1%Co2O3
2012
The single-phase perovskite structure of the Ba0.95Pb0.05TiO3+0.1%Co2O3 ceramics was confirmed by the X-ray diffraction method. Microstructural studies revealed that the samples were of good quality and chemically homogeneous. The thermal behaviour of ceramics was studied using the in situ high-temperature X-ray synchrotron powder diffraction investigation. The energy gap of about 3.2 eV was estimated using a reflectance spectroscopy. Measurements showed the influence of Pb and Co on the character of phase transition in the BaTiO3 structure. The results were compared to the ones obtained for pure BaTiO3.
The Crystal Structure of Nickel(II)-Azurin
1995
The nickel(II)-azurin metalloderivative has been crystallized and its structure solved at 0.205-nm resolution by X-ray diffraction. The overall structure is not modified by the metal exchange and the only differences with regard to the native copper(II)-azurin occur in the metal site region. These variations affect principally the axial ligands. Nickel co-ordinates more strongly to the carbonyl oxygen of Gly45 while its distance to the Met121 S4 enlarges up to 0.330 nm. The resulting metal center structure is intermediate between those of the Cu(II) and Zn(II) azurins, and can be described as distorted tetrahedral. However, the existence of contact interaction between Met121 and the nickel …
Three‐Component Self‐Assembly Changes its Course: A Leap from Simple Polymers to 3D Networks of Spherical Host–Guest Assemblies
2021
Angewandte Chemie / International edition 60(21), 12132 - 12142 (2021). doi:10.1002/anie.202103178
Thermal expansion of LiZr2(PO4)3: Water inclusion influence
1989
Abstract Lattice thermal expansion has been measured on three samples of composition LiZr 2 (PO 4 ) 3 , prepared by (i) a ceramic method, (ii) a gel-route and (iii) a nonstoichiometric ceramic. The first sample is monoclinic (?), with a transition at 50°C to rhombohedral. The second is clearly monoclinic with lattice parameters depending on the calcination temperature (700 to 1200°C. The third kind of synthesis yielded a new PO 4 -deficitary rhombohedral structure. X-ray diffraction measurements in a high temperature camera have been made from room temperature up to 1100°C. Lattice parameters, as well as their dependence on temperature are different for the three samples. While thermal expa…
Influence of Lithium Substitution on Structure, Electric and Pyroelectric Properties of Sodium Niobate Ceramics
2012
Li0.02Na0.98NbO3 ceramics were prepared by a conventional method. A single-phase perovskite structure was identified by an X-ray diffraction method. The SEM and EDS studies revealed that the Li0.02Na0.98NbO3 samples were perfectly sintered and chemically homogeneous. Electric measurements showed that Li0.02Na0.98NbO3 was sensitive to the frequency of the applied electric field and revealed that the ac conductivity changed with frequency according to the formula: σ(ω) = σdc +Aωn where n < 1. These results were discussed with a reference to the conduction mechanism as a type of polaron hopping.
Relative proportions of rutile and pseudo-brookite phases in the Fe(III)-TiO2 system at elevated temperature
1997
Abstract The Fe(III)-TiO2 system has been studied at T ≥ 1023 K in the range of concentration 2–10 at.% of iron by powder X-ray diffraction, transmission and scanning electron microscopy, and optical microscopy. The relationship between the relative proportions of the TiO2 rutile phase and the pseudo-brookite phase Fe2TiO5, has been investigated in powder samples. Single crystals of pure rutile and rutile doped with 0.5 at.% of iron have been examined to elucidate the microstructures found in the powders. The results suggest that a low degree of solid solubility exists and that doped crystals contain planar faults on 101 planes.
Ferroelectric domains in BaTiO3powders and ceramics evidenced by X-ray diffraction
1995
Abstract Through three different studies, using BaTiO3 samples, as a powder while heating over the Curie temperature, and as a ceramic while applying an electric field, it is shown how X-ray diffraction (XRD) is able to give information about the evolution of the ferroelectric domain microstructure. Firstly, the relative intensities of the 002 and 200 lines, as a function of the applied electric field, exhibit the motion of the 90[ddot] domain walls. However, XRD is unable to provide any distinction between two 180[ddot] domains. Secondly, the profile of those two lines and of the other double (hhl), (lhh) lines is particular: the unusual diffracted intensity between such double lines has t…
Fine grain barium titanate: ferroelectric domains and X-ray diffraction diagram
2002
Through three different studies using various kinds of BaTiO/sub 3/ samples: as a powder while heating over the Curie temperature; as a green ceramic as a function of the forming pressure; as a ceramic while applying a D.C. field. It is shown how X-ray diffraction is able to give information about the evolution of the 90/spl deg/ ferroelectric domain microstructure.
Density variations in liquid tellurium: Roles of rings, chains and cavities
2010
Liquid tellurium has been studied by density-functional/molecular-dynamics simulations at 560, 625, 722, and 970 K and by high-energy x-ray diffraction (HEXRD) at 763 K and 973 K. The HEXRD measurements agree very well with earlier neutron-scattering data of Menelle et al. The density maximum near the melting point (722 K) reflects the competition between twofold and threefold local coordination, which results in chain formation and changed ring statistics at lower $T$, and the variation with $T$ of the volume of cavities ($26--35\text{ }\mathrm{%}$ of the total). A higher-order gradient expansion of the exchange-correlation functional is needed to describe structural details. Changes in th…
X-Ray diffraction diagram evolution of a BaTiO3ceramic under an electric field
1994
Abstract The X-ray diffraction diagrams of a coarse grained pure BaTiO3 ceramic have been recorded as a function of the applied electric D.C. field. This field was perpendicular to the X-ray incoming surface. The experimental device used allows to record diffraction diagrams while the electric field step by step increases. The intensity ratio of the 002 line over the 200 line increases with the applied electric field. The evolution of the X-ray diffraction line intensities is in correlation with the first polarization curve of the ferroelectric ceramic. These results evidence a contribution of the 90° ferroelectric domains pattern to the X-ray diffraction diagram of BaTiO3.