Amorphization of crystalline orthoboric acid on a vitreous B2O3 substrate

2002 ◽  
Vol 17 (12) ◽  
pp. 3098-3104 ◽  
Author(s):  
Eric McCalla ◽  
Ralf Brüning
Keyword(s):  
Amorphous Phase ◽  
Room Temperature ◽  
Metastable Equilibrium ◽  
Oxide Glass ◽  
X Ray Diffraction ◽  
Humid Air ◽  
Time Resolved ◽  
X Ray ◽  
Equilibrium Phases ◽  
State Amorphization

Time-resolved x-ray diffraction measurements were carried out during and after the exposure of anhydrous boron oxide glass films to humid air. B(OH)3 crystals grew on the glass substrate with planar sheets of B(OH)3 molecules aligned parallel to the surface. After the space above the sample was evacuated, the crystal peaks began to disappear. During the decay, new crystals of orthoboric acid grew with the orientation of the B(OH)3 sheets perpendicular to the substrate. Then crystals with all orientations decayed completely, and an amorphous scattering pattern remained. The water acquired by the sample during the exposure eventually reacted with the anhydrous B2O3 glass to produce amorphous BO(3+y)/2Hy. The decay of the crystals took from one to several days, depending on the length of the exposure to humid air. Measurements of the metastable equilibrium phases in the B2O3–H2O binary system showed that at room temperature the amorphous phase could reach the composition BO1.85H0.7. At higher water concentrations this saturated amorphous phase coexisted with crystalline B(OH)3. This result is consistent with the instability of the crystalline B(OH)3 film in contact with anhydrous glass, and we present a thermodynamic model for this process. In the present case, amorphization is driven by the outdiffusion of water from a crystalline phase rather than interdiffusion in conventional solid-state amorphization.

scholarly journals Room temperature hidden state in a manganite observed by time-resolved X-ray diffraction

2019 ◽  
Vol 4 (1) ◽  
Author(s):  
Haijuan Zhang ◽  
Yuanyuan Zhang ◽  
Runze Li ◽  
Junxiao Yu ◽  
Wenxia Dong ◽  
...  
Keyword(s):  
Room Temperature ◽  
X Ray Diffraction ◽  
Time Resolved ◽  
X Ray

Solid State Amorphization in the Interfacial Reactions of Yttrium Thin Films on (111)Si

1993 ◽  
Vol 311 ◽  
Author(s):  
T.T. Lee ◽  
L.L. Chen
Keyword(s):  
Thin Films ◽  
Electron Spectroscopy ◽  
Room Temperature ◽  
Amorphous Layer ◽  
Interfacial Reactions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
State Amorphization ◽  
Amorphous Interlayer

ABSTRACTInterfacial reactions of ultrahigh vacuum deposited yttrium thin films on atomically clean (111)Si at low temperatures have been studied by both conventional and high resolution transmission electron microscopy, Auger electron spectroscopy and x-ray diffraction. A 10–nm–thick yttrium thin film, deposited onto (lll)Si at room temperature, was found to completely intermix with Si to form an 11–nm–thick amorphous interlayer. Crystalline Y5Si3 and Si were observed to nucleate first within the amorphous interlayer in samples annealed at temperatures lower than 200 °C. Epitaxial YSi2−x was found to be the only phase formed at the interface of amorphous interlayer and crystalline Si in samples annealed at temperatures higher than 250 °C. In as deposited 20– to 60–nm thick Y thin films on silicon samples, crystalline Y5Si3, Si, and YSi and a 2.5–nm–thick amorphous layer were found to be present simultaneously.

Influence of boron content on the amorphization rate of Co–B mixtures by mechanical alloying

1993 ◽  
Vol 8 (6) ◽  
pp. 1327-1333 ◽  
Author(s):  
A. Corrias ◽  
G. Ennas ◽  
G. Marongiu ◽  
A. Musinu ◽  
G. Paschina
Keyword(s):  
Electron Microscopy ◽  
Ball Milling ◽  
Ball Mill ◽  
Room Temperature ◽  
Boron Content ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Transmission Electron ◽  
State Amorphization

Amorphous cobalt-boron alloy powders have been prepared by a high energetic ball mill at room temperature starting from different Co/B ratios. They were characterized by means of x-ray diffraction, scanning and transmission electron microscopy, and differential scanning calorimetry. Ball milling of Co–B mixtures induces solid-state amorphization which becomes faster with increasing boron content. After maximum amorphization ball milling leads to crystallization of t-Co2B in all the binary samples.

Synthesis and Aggregation of BiBi2S3 Nanocapsules

2005 ◽  
Vol 879 ◽  
Author(s):  
Marina Vega-González ◽  
Xim Bokhimi ◽  
Manuel Aguilar-Franco ◽  
Antonio Morales ◽  
Amado F. García-Ruiz
Keyword(s):  
Diffraction Pattern ◽  
Amorphous Phase ◽  
Crystalline Phase ◽  
Spherical Symmetry ◽  
Room Temperature ◽  
Bismuth Sulfide ◽  
X Ray Diffraction ◽  
X Ray ◽  
Annealing Temperatures ◽  
Porous Walls

AbstractNanocapsules of Bi2S3 with diameters between 5 and 10 nm and shells with an amorphous atomic distribution were synthesized at room temperature, with bismuth nitrate and thiourea as precursors. Aging the solution for several days a black powder precipitated made of a mixture of one amorphous phase and crystalline Bi2S3. When two capsules interacted between each other, the capsule regions in contact crystallized into bismuth sulfide, which explains the origin of the crystalline phase observed in the X-ray diffraction pattern. At this temperature, aggregation of the small nanocapsules also gave rise to necklaces of capsules, which eventually gave rise to nanotubes; these necklaces ordered forming bundles parallel to their largest dimension. When the solution was annealed at temperatures lower than 100 °C, aggregation gave rise to capsules as large as 1 μm in diameter, and tubes with similar diameters; in this case aggregation occurred between small and large nanocapsules. Because of the monomers aggregating had an external spherical symmetry and the low annealing temperatures, which were not high enough to produce sintering, all capsules and tubes formed during aggregation had porous walls, making these materials interesting for many applications.

scholarly journals X-Ray Study of Interfacial Interactions in Highly Milled Sn-Ge Powders

1991 ◽  
Vol 238 ◽  
Author(s):  
J.K.D.S. Jayanetti ◽  
S. M. Heald ◽  
Z. Tan
Keyword(s):  
Melting Point ◽  
Amorphous Phase ◽  
Room Temperature ◽  
Structural Changes ◽  
X Ray Diffraction ◽  
Interfacial Interactions ◽  
X Ray ◽  
Milled Powders

ABSTRACTWe have studied possible structural changes occur ing at the Sn/Ge interface of highly milled Sn/Ge composites. EXAFS and X-ray Diffraction measurements were made on mechanically milled powders having compositions ranging from 20 to SO vol.% Sn. X-ray diffraction measurements indicate the increasing amorphization of Sn as the Sn content is decreased. EXAFS results indicate that this amorphous phase is due to the formation of an a-Sn/Ge alloy. The EXAFS from this alloy did not change significantly at the Sn melting point. X-ray diffraction measurements made at room temperature show a systematic decrease in the intensity of Sn peaks and broadening of Ge peaks with the decreasing Sn content.

A microstructural study of mechanical alloying of Fe and Sn powders

1992 ◽  
Vol 7 (6) ◽  
pp. 1387-1395 ◽  
Author(s):  
Gérard Le Caër ◽  
Paolo Matteazzi ◽  
Brent Fultz
Keyword(s):  
Ball Milling ◽  
Amorphous Phase ◽  
Room Temperature ◽  
Blocking Temperature ◽  
Small Particles ◽  
Major Phase ◽  
Microstructural Study ◽  
X Ray ◽  
Transmission Electron ◽  
State Amorphization

Elemental Fe and Sn powders in the ratio of 1:2 were ball-milled for various times at room temperature, and phase transformations in the powders were studied by 57Fe and 119Sn Mössbauer spectrometries, transmission electron microscopy, and x-ray diffractometry. Although Fe-Sn alloys are not obvious candidates for solid-state amorphization reactions, an amorphous phase formed after only a few hours of ball milling. Nanocrystalline intermetallic FeSn2 particles nucleated and grew within the amorphous phase, and FeSn2 became the major phase after 10–20 h of ball milling. These small particles were superparamagnetic, and were above the blocking temperature at room temperature.

scholarly journals Solid State Room Temperature Dual Phosphorescence from 3-(2-Fluoropyridin-4-yl)triimidazo[1,2-a:1′,2′-c:1″,2″-e][1,3,5]triazine

Molecules ◽  
2019 ◽  
Vol 24 (14) ◽  
pp. 2552 ◽  
Author(s):  
Andrea Previtali ◽  
Elena Lucenti ◽  
Alessandra Forni ◽  
Luca Mauri ◽  
Chiara Botta ◽  
...  
Keyword(s):  
Solid State ◽  
Room Temperature ◽  
Theoretical Calculations ◽  
Multicomponent System ◽  
Xrd Analysis ◽  
X Ray Diffraction ◽  
Time Resolved ◽  
X Ray ◽  
Molecular Fluorescence ◽  
Pmma Blends

Organic room temperature persistent luminescence is a fascinating but still largely unexplored phenomenon. Cyclic-triimidazole and its halogenated (Br, I) derivatives have recently revealed as intriguing phosphors characterized by multifaceted emissive behavior including room temperature ultralong phosphorescence (RTUP) associated with the presence of H-aggregates in their crystal structure. Here, we move towards a multicomponent system by incorporating a fluoropyridinic fragment on the cyclic-triimidazole scaffold. Such chromophore enhances the molecular properties resulting in a high photoluminescence quantum yield (PL QY) in solution but preserves the solid-state RTUP. By means of X-ray diffraction (XRD) analysis, theoretical calculations, steady-state and time-resolved spectroscopy on solutions, polymethylmethacrylate (PMMA) blends and crystals, the nature of the different radiative deactivation channels of the compound has been disclosed. In particular, the molecular fluorescence and phosphorescence, this latter observed in frozen solution and in PMMA blends, are associated to deactivation from S1 and T1 respectively, while the low energy RTUP, observed only for crystals, is interpreted as originated from H aggregates.

Electron Microscopy of Human Gallstones

1971 ◽  
Vol 29 ◽  
pp. 296-297
Author(s):  
C. Wolpers ◽  
R. Blaschke
Keyword(s):  
Electron Microscopy ◽  
Room Temperature ◽  
Bile Pigment ◽  
X Ray Diffraction ◽  
Triclinic Crystal System ◽  
X Ray ◽  
Follow Up Study ◽  
Infra Red ◽  
Main Components

Scanning microscopy was used to study the surface of human gallstones and the surface of fractures. The specimens were obtained by operation, washed with water, dried at room temperature and shadowcasted with carbon and aluminum. Most of the specimens belong to patients from a series of X-ray follow-up study, examined during the last twenty years. So it was possible to evaluate approximately the age of these gallstones and to get information on the intensity of growing and solving.Cholesterol, a group of bile pigment substances and different salts of calcium, are the main components of human gallstones. By X-ray diffraction technique, infra-red spectroscopy and by chemical analysis it was demonstrated that all three components can be found in any gallstone. In the presence of water cholesterol crystallizes in pane-like plates of the triclinic crystal system.

Electron Microscope study of commensurate-incommensurate phase transition in BaZnGeO4

1990 ◽  
Vol 48 (4) ◽  
pp. 172-173
Author(s):  
Naoki Yamamoto ◽  
Makoto Kikuchi ◽  
Tooru Atake ◽  
Akihiro Hamano ◽  
Yasutoshi Saito
Keyword(s):  
Phase Transition ◽  
Electron Microscope Study ◽  
Room Temperature ◽  
Hexagonal Lattice ◽  
Ferroelectric Materials ◽  
Temperature Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Periodic Arrays ◽  
Modulation Wave Vector

BaZnGeO4 undergoes many phase transitions from I to V phase. The highest temperature phase I has a BaAl2O4 type structure with a hexagonal lattice. Recent X-ray diffraction study showed that the incommensurate (IC) lattice modulation appears along the c axis in the III and IV phases with a period of about 4c, and a commensurate (C) phase with a modulated period of 4c exists between the III and IV phases in the narrow temperature region (—58°C to —47°C on cooling), called the III' phase. The modulations in the IC phases are considered displacive type, but the detailed structures have not been studied. It is also not clear whether the modulation changes into periodic arrays of discommensurations (DC’s) near the III-III' and IV-V phase transition temperature as found in the ferroelectric materials such as Rb2ZnCl4.At room temperature (III phase) satellite reflections were seen around the fundamental reflections in a diffraction pattern (Fig.1) and they aligned along a certain direction deviated from the c* direction, which indicates that the modulation wave vector q tilts from the c* axis. The tilt angle is about 2 degree at room temperature and depends on temperature.

Xenon Trioxide Adducts of O-Donor Ligands; [(CH3)2CO]3XeO3, [(CH3)2SO]3(XeO3)2, (C5H5NO)3(XeO3)2, and [(C6H5)3PO]2XeO3

2018 ◽  
Author(s):  
Katherine Marczenko ◽  
James Goettel ◽  
Gary Schrobilgen
Keyword(s):  
Room Temperature ◽  
Triphenylphosphine Oxide ◽  
Donor Ligands ◽  
Mechanical Shock ◽  
X Ray Diffraction ◽  
X Ray ◽  
Oxygen Coordination ◽  
Xenon Trioxide ◽  
Distorted Octahedra ◽  
Coordination Spheres

Oxygen coordination to the Xe(VI) atom of XeO<sub>3</sub> was observed in its adducts with triphenylphosphine oxide, dimethylsulfoxide, pyridine-N-oxide, and acetone. The crystalline adducts were characterized by low-temperature, single-crystal X-ray diffraction and Raman spectroscopy. Unlike solid XeO<sub>3</sub>, which detonates when mechanically or thermally shocked, the solid [(C<sub>6</sub>H<sub>5</sub>)<sub>3</sub>PO]<sub>2</sub>XeO<sub>3</sub>, [(CH<sub>3</sub>)<sub>2</sub>SO]<sub>3</sub>(XeO<sub>3</sub>)<sub>2</sub>,<sub> </sub>and (C<sub>5</sub>H<sub>5</sub>NO)<sub>3</sub>(XeO<sub>3</sub>)<sub>2</sub> adducts are insensitive to mechanical shock, but undergo rapid deflagration when ignited by a flame. Both [(C<sub>6</sub>H<sub>5</sub>)<sub>3</sub>PO]<sub>2</sub>XeO<sub>3 </sub>and (C<sub>5</sub>H<sub>5</sub>NO)<sub>3</sub>(XeO<sub>3</sub>)<sub>2</sub> are air-stable whereas [(CH<sub>3</sub>)<sub>2</sub>SO]<sub>3</sub>(XeO<sub>3</sub>)<sub>2</sub> slowly decomposes over several days and [(CH<sub>3</sub>)<sub>2</sub>CO]<sub>3</sub>XeO<sub>3</sub> undergoes adduct dissociation at room temperature. The xenon coordination sphere of [(C<sub>6</sub>H<sub>5</sub>)<sub>3</sub>PO]<sub>2</sub>XeO<sub>3</sub> is a distorted square pyramid which provides the first example of a five-coordinate XeO<sub>3</sub> adduct. The xenon coordination spheres of the remaining adducts are distorted octahedra comprised of three Xe---O secondary contacts that are approximately trans to the primary Xe–O bonds of XeO<sub>3</sub>. Quantum-chemical calculations were used to assess the Xe---O adduct bonds, which are predominantly electrostatic σ-hole bonds between the nucleophilic oxygen atoms of the bases and the σ-holes of the xenon atoms.

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