X-Ray Studies of Synthetic Radiation-Counting Diamonds

1993 ◽  
Vol 302 ◽  
Author(s):  
Andrew Yacoot ◽  
Moreton Moore ◽  
Anthony Makepeace
Keyword(s):  
Electric Field ◽  
Nitrogen Content ◽  
Medical Applications ◽  
X Ray Diffraction ◽  
X Ray ◽  
Crystal Imperfections ◽  
Synthetic Diamonds ◽  
Counting Mode

ABSTRACTSynthetic diamonds with a nitrogen content less than 100ppm may be used as radiation dosimeters in a conduction counting mode, and are especially useful in medical applications. Crystal imperfections, revealed by X-ray diffraction topography, were found to affect counting performance. The best quality diamond gave the highest photocurrent (500nA at 50 V mm−1 and 2.75 Gy min−l). Diamonds containing dislocations had lower photocurrents but had the advantage of shorter settling times (seconds rather than minutes). Placing contacts on two opposite cube {100} faces gave a higher photocurrent than on a pair of octahedral {111} faces. Higher photocurrents were also achieved when the majority of dislocations were perpendicular rather than parallel to the electric field. Some recommendations for selecting synthetic diamonds for dosimeters are given.

scholarly journals Enhanced apatite precipitation on a biopolymer-coated bioactive glass

2015 ◽  
Vol 1 (1) ◽  
Author(s):  
M. Araújo ◽  
M. Miola ◽  
A. Venturello ◽  
G. Baldi ◽  
J. Perez ◽  
...  
Keyword(s):  
Bioactive Glass ◽  
Body Fluid ◽  
Organic Coating ◽  
Medical Applications ◽  
Sintering Process ◽  
X Ray Diffraction ◽  
Ph Measurements ◽  
X Ray ◽  
Ft Ir ◽  
Scanning Electron

AbstractIn this work, sintered pellets of a silica-based bioactive glass were dip-coated with a biocompatible natural-derived polymer in order to investigate the influence of the organic coating on the glass bioactivity. After the sintering process optimization, uncoated and coated pellets have been characterized by means of scanning electron microscopy with energy dispersive spectroscopy (SEM, EDS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and pH measurements, after the immersion in a simulated body fluid (SBF). An increased apatite forming ability and a better control of the pH during soaking of the samples in SBF were observed in the presence of the biopolymer. This result opens a new insight on the simple fabrication of highly bioactive hybrid inorganic-organic materials for medical applications.

scholarly journals Revealing the mechanism of electric-field-induced phase transition in antiferroelectric NaNbO3 by in situ high-energy x-ray diffraction

2021 ◽  
Vol 118 (13) ◽  
pp. 132903
Author(s):  
Mao-Hua Zhang ◽  
Changhao Zhao ◽  
Lovro Fulanović ◽  
Jürgen Rödel ◽  
Nikola Novak ◽  
...  
Keyword(s):  
Phase Transition ◽  
Electric Field ◽  
High Energy ◽  
X Ray Diffraction ◽  
X Ray

Electric-field-induced lattice distortion in epitaxial BiFeO3 thin films as determined by in situ time-resolved x-ray diffraction

2017 ◽  
Vol 111 (8) ◽  
pp. 082907 ◽  
Author(s):  
Seiji Nakashima ◽  
Osami Sakata ◽  
Hiroshi Funakubo ◽  
Takao Shimizu ◽  
Daichi Ichinose ◽  
...  
Keyword(s):  
Thin Films ◽  
Electric Field ◽  
Lattice Distortion ◽  
X Ray Diffraction ◽  
Time Resolved ◽  
X Ray ◽  
Bifeo3 Thin Films

Multipurpose diffractometer for in situ X-ray crystallography of functional materials

2021 ◽  
Vol 54 (3) ◽  
Author(s):  
Semën Gorfman ◽  
David Spirito ◽  
Netanela Cohen ◽  
Peter Siffalovic ◽  
Peter Nadazdy ◽  
...  
Keyword(s):  
Electric Field ◽  
Materials Science ◽  
Functional Materials ◽  
X Ray Diffraction ◽  
Reciprocal Space Mapping ◽  
X Ray ◽  
X Ray Crystallography ◽  
Area Detector ◽  
Characterization Of Materials

Laboratory X-ray diffractometers play a crucial role in X-ray crystallography and materials science. Such instruments still vastly outnumber synchrotron facilities and are responsible for most of the X-ray characterization of materials around the world. The efforts to enhance the design and performance of in-house X-ray diffraction instruments benefit a broad research community. Here, the realization of a custom-built multipurpose four-circle diffractometer in the laboratory for X-ray crystallography of functional materials at Tel Aviv University, Israel, is reported. The instrument is equipped with a microfocus Cu-based X-ray source, collimating X-ray optics, four-bounce monochromator, four-circle goniometer, large (PILATUS3 R 1M) pixel area detector, analyser crystal and scintillating counter. It is suitable for a broad range of tasks in X-ray crystallography/structure analysis and materials science. All the relevant X-ray beam parameters (total flux, flux density, beam divergence, monochromaticity) are reported and several applications such as determination of the crystal orientation matrix and high-resolution reciprocal-space mapping are demonstrated. The diffractometer is suitable for measuring X-ray diffraction in situ under an external electric field, as demonstrated by the measurement of electric-field-dependent rocking curves of a quartz single crystal. The diffractometer can be used as an independent research instrument, but also as a training platform and for preparation for synchrotron experiments.

Lateral deformations of a crystal of potassium acid phthalate in an external electric field

2021 ◽  
Vol 54 (5) ◽  
pp. 1317-1326
Author(s):  
Arsen Petrenko ◽  
Nataliya Novikova ◽  
Alexander Blagov ◽  
Anton Kulikov ◽  
Yury Pisarevskii ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Electrical Conductivity ◽  
Electric Field ◽  
External Electric Field ◽  
Applied Field ◽  
X Ray Diffraction ◽  
Time Resolved ◽  
X Ray ◽  
Potassium Acid Phthalate ◽  
Acid Phthalate

The anisotropy of deformations in potassium acid phthalate crystals arising under the action of an external electric field up to 1 kV mm−1 applied along the [001] polar axis was studied using X-ray diffraction methods at room temperature. Electrical conductivity was measured and rocking curves for reflections 400, 070 and 004 were obtained by time-resolved X-ray diffractometry in Laue and Bragg geometries. Two saturation processes were observed from the time dependences of the electrical conductivity. A shift in the diffraction peaks and a change in their intensity were found, which indicated a deformation of the crystal structure. Rapid piezoelectric deformation and reversible relaxation-like deformation, kinetically similar to the electrical conductivity of a crystal, were revealed. The deformation depended on the polarity and strength of the applied field. The deformation was more noticeable in the [100] direction and was practically absent in the [001] direction of the applied field. X-ray diffraction analysis revealed a disordered arrangement of potassium atoms, i.e. additional positions and vacancies. The heights of potential barriers between the positions of K+ ions and the paths of their possible migration in the crystal structure of potassium acid phthalate were determined. The data obtained by time-resolved X-ray diffractometry and X-ray structure analysis, along with additional electrophysical measurements, allow the conclusion that the migration of charge carriers (potassium cations) leads to lateral deformation of the crystal structure of potassium phthalate in an external electric field.

scholarly journals Piezoelectricity in perovskite-type pseudo-cubic ferroelectrics by partial ordering of off-centered cations

2020 ◽  
Vol 1 (1) ◽  
Author(s):  
Yoshihiro Kuroiwa ◽  
Sangwook Kim ◽  
Ichiro Fujii ◽  
Shintaro Ueno ◽  
Yuki Nakahira ◽  
...  
Keyword(s):  
Electric Field ◽  
Applied Electric Field ◽  
Partial Ordering ◽  
Ferroelectric Ceramics ◽  
Piezoelectric Response ◽  
X Ray Diffraction ◽  
Cubic Symmetry ◽  
X Ray ◽  
Domain Structures ◽  
Perovskite Type

Abstract A large piezoelectric response in ferroelectric ceramics is typically associated with extrinsic contributions from ferroelectric domain structures. However, such domain structures cannot be expected in systems with pseudo-cubic symmetry. In this study, we determine the mechanism of significant piezoelectricity and ferroelectricity in 0.3BaTiO3–0.1Bi(Mg1/2Ti1/2)O3–0.6BiFeO3 ceramic with a perovskite-type pseudo-cubic symmetry. Synchrotron radiation X-ray diffraction reveals that the Bi ions in this ceramic essentially prefer to be off-centered at six sites by approximately 0.4 Å, in the cubic <100> directions. A phase transition occurs at TC ~725 K. However, the crystal seems to present a cubic symmetry even at room temperature. The large piezoelectric response is caused by the combinational partial ordering of the off-centered Bi ions, adapted to any direction of the applied electric field to the ceramic grains. The proposed mechanism for the emergence of a high polarization in the above system will enable designing novel Pb-free ceramics by controlling the fluctuated and off-centered ions under an applied electric field.

Use of an External Electric Field to Convert the Paraelectric Phase to the Ferroelectric Phase in Ultra-thin Copolymer Films of P(VDF-TrFE)

2000 ◽  
Vol 655 ◽  
Author(s):  
Matt Poulsen ◽  
S. Adenwalla ◽  
Stephen Ducharme ◽  
V.M. Fridkin ◽  
S.P. Palto ◽  
...  
Keyword(s):  
Phase Transition ◽  
Electric Field ◽  
External Electric Field ◽  
Ferroelectric Phase ◽  
Paraelectric Phase ◽  
Continuous Process ◽  
Structural Phase ◽  
X Ray Diffraction ◽  
Layer Spacing ◽  
X Ray

AbstractX-ray diffraction was used to probe the structural changes associated with the conversion of the paraelectric phase to the ferroelectric phase that results from the application of a large external electric field. The samples under study are ultrathin (150 to 250 Å) Langmuir-Blodgett films of the copolymer vinylidene fluoride (70%) with trifluoroethylene (30%) deposited on aluminum-coated silicon. Theta-2theta X-ray diffraction was used to measure the change in inter-layer spacing perpendicular to the film surface. Upon heating at zero external electric field, the crystalline films undergo a structural phase transition, at 100± 5°C, from the all-trans ferroelectric phase to the trans-gauche paraelectric phase. [1,2] Above the phase transition temperature, the non-polar paraelectric phase can be converted back to the polar ferroelectric phase, in a smooth continuous process, using a large external electric field (∼1 GV/m). For example, at 100° C the ferroelectric phase first appears above 0.2 GV/m and increases steadily in proportion while the paraelectric phase decreases until complete conversion to the ferroelectric phase is achieved at approximately 0.6 GV/m.

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