scholarly journals Single-crystal to single-crystal guest exchange and phase transformations in a porous metallocycle

CrystEngComm ◽  
2014 ◽  
Vol 16 (20) ◽  
pp. 4126-4132 ◽  
Author(s):  
Marike du Plessis ◽  
Vincent J. Smith ◽  
Leonard J. Barbour
Keyword(s):  
Phase Transformation ◽  
Solid State ◽  
Single Crystal ◽  
Phase Transformations ◽  
Guest Molecules ◽  
Solvent Molecules

The acetonitrile guest molecules in this porous metallocycle can be exchanged for different solvent molecules in a single-crystal to single-crystal manner. These guest exchanges are accompanied by a phase transformation in the solid state.

Partial rotation of the isopropyl group in the solid state: single-crystal-to-single-crystal phase transformation in a carvacrol derivative

CrystEngComm ◽  
2015 ◽  
Vol 17 (39) ◽  
pp. 7482-7485 ◽  
Author(s):  
Umesh D. Pete ◽  
Amol G. Dikundwar ◽  
Vaishali M. Sharma ◽  
Shridhar P. Gejji ◽  
Ratnamala S. Bendre ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Solid State ◽  
Single Crystal ◽  
Crystal Phase ◽  
Thermal Stimulus ◽  
Isopropyl Group ◽  
Group Rotation ◽  
Crystal Phase Transformation

Isopropyl group rotation observed in a single crystal of TACH appears to be a result of the counterbalance of molecular energetics and supramolecular packing in response to the thermal stimulus.

A Mixed-Mode Model Considering Soft Impingement Effects for Solid-State Partitioning Phase Transformations

2011 ◽  
Vol 172-174 ◽  
pp. 561-566 ◽  
Author(s):  
Hao Chen ◽  
Sybrand van der Zwaag
Keyword(s):  
Phase Transformation ◽  
Solid State ◽  
Numerical Solution ◽  
Phase Transformations ◽  
Concentration Gradient ◽  
Mixed Mode ◽  
Original Model ◽  
Polynomial Method ◽  
Soft Impingement ◽  
Kinetics Of

The original mixed-mode model is reformulated by considering the soft impingement effect and applying a general polynomial method of dealing with the concentration gradient in front of the interface. Comparison with the numerical solution shows that the reformulated mixed-mode model is more precise than the original model. The effect of soft impingement on the kinetics of partitioning phase transformation depends on both the growth mode and the degree of super-saturation.

scholarly journals Construction of pillar[4]arene[1]quinone–1,10-dibromodecane pseudorotaxanes in solution and in the solid state

2020 ◽  
Vol 16 ◽  
pp. 2954-2959
Author(s):  
Xinru Sheng ◽  
Errui Li ◽  
Feihe Huang
Keyword(s):  
Solid State ◽  
Hydrogen Bonds ◽  
Single Crystal ◽  
Guest Molecule ◽  
X Ray Diffraction ◽  
Guest Molecules ◽  
X Ray ◽  
Π Interactions ◽  
Host Molecules ◽  
Complexation Stoichiometry

We report novel pseudorotaxanes based on the complexation between pillar[4]arene[1]quinone and 1,10-dibromodecane. The complexation is found to have a 1:1 host–guest complexation stoichiometry in chloroform but a 2:1 host–guest complexation stoichiometry in the solid state. From single crystal X-ray diffraction, the linear guest molecules thread into cyclic pillar[4]arene[1]quinone host molecules in the solid state, stabilized by CH∙∙∙π interactions and hydrogen bonds. The bromine atoms at the periphery of the guest molecule provide convenience for the further capping of the pseudorotaxanes to construct rotaxanes.

Phase Transformations in Lutetium Borides at Heating in Vacuum

2011 ◽  
Vol 172-174 ◽  
pp. 464-469 ◽  
Author(s):  
Anatoliy Taran ◽  
Daniel Voronovich ◽  
Natalya Shitsevalova ◽  
Ganna Levchenko ◽  
Volodymyr Filipov ◽  
...  
Keyword(s):  
Phase Diagram ◽  
Phase Transformation ◽  
Surface Layer ◽  
Single Crystal ◽  
Phase Transformations ◽  
Single Crystals ◽  
X Ray ◽  
Before And After ◽  
Spontaneous Phase ◽  
Crystal Bulk

The LuB12 ® LuB4 ® LuB2 phase transformations on annealing in vacuum (T=(1400÷1800) K, p < 10-2 Pa) are investigated with use of the parent single crystals. SEM and X-ray researches of the corresponding lutetium boride single crystals were carried out before and after their annealing. It is shown that the LuB12 → LuB4 phase transformation takes place in surface layer and transition region spreads inwards the single crystal bulk with time. According to the assessed Lu-B phase diagram the LuB4 phase transformation into other individual phases is impossible, and at first it is shown that under corresponding conditions the LuB4 → LuB2 spontaneous phase transformation takes place both on the surface and in the LuB4 single crystal bulk.

The use of thin Film Substrates to Study Enhanced Solid-State Phase Transformations

1993 ◽  
Vol 319 ◽  
Author(s):  
PAUL G. Kotula ◽  
Dwight D. Erickson ◽  
C. Barry Carter
Keyword(s):  
Thin Film ◽  
Phase Transformation ◽  
Solid State ◽  
Phase Transformations ◽  
Pulsed Laser ◽  
Alumina Layer ◽  
Transition Alumina ◽  
Transmission Electron ◽  
Film Substrate ◽  
Alpha Alumina

AbstractA thin-film substrate geometry is described for the study of enhanced or seeded solid-state phase transformations. As an example of this approach, thin films of hematite have been used as substrates for the study of the seeded phase transformation of a boehmite-derived transition-alumina to α-A12O3. The hematite films were grown on bulk (0001) α-A12O3 single crystal substrates by pulsed-laser ablation. A layer of a boehmite sol was then spin-coated onto the thin film. The assemblages were then heated to 950°C, or 1000°C in order to induce the phase transformation. Specimens were imaged in cross section by transmission electron microscopy. No transformation was observed for specimens heated to 950°C. In specimens heated to 1000°C, the transition alumina was found to transform to alpha-alumina, starting at the surface of the hematite film, via solid-state heteroepitaxy. In this case, islands, growing out from the hematite film into the transition alumina layer, were observed.

scholarly journals Single-crystal guest exchange and phase transformations in a porous metallocycle

2014 ◽  
Vol 70 (a1) ◽  
pp. C998-C998
Author(s):  
Marike du Plessis ◽  
Vincent Smith ◽  
Leonard Barbour
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Empty Space ◽  
Close Packing ◽  
X Ray Diffraction ◽  
Guest Molecules ◽  
X Ray ◽  
Packing Arrangement ◽  
Solvent Molecules ◽  
Doughnut Shape

One of the target architectures for porous crystals investigated by our group is the "doughnut-shaped" metallocycle. The "doughnut" shape of the metallocycles prevents them from packing efficiently and results in the formation of crevices, cavities or channels in the packing arrangement. Naturally, owing to close-packing requirements the occurrence of empty space in the crystal structure is energetically unfavourable and therefore the available "space" is usually occupied by solvent molecules. Ideally, the porous phase can be obtained by removing the solvent molecules from the channels without disrupting the host framework. In this regard we have conducted a further investigation of the porous metallocycle previously reported by Barbour et al.[1] Single crystals of a previously reported porous metallocycle [Ag2L2](BF4)2·2CH3CN (1) were grown from acetonitrile and immersed in different organic solvents. The crystals thus treated were subjected to single-crystal X-ray diffraction analysis, which revealed that the acetonitrile guest molecules had been replaced by the solvent that the compound was exposed to, yielding five different solvates: [Ag2L2](BF4)2·2(CH3)2CO (2), [Ag2L2](BF4)2·2CHCl3 (3), [Ag2L2](BF4)2·C6H6 (4), [Ag2L2](BF4)2·C6H4F2 (5), [Ag2L2](BF4)2·C7H8 (6). Thermogravimetric analysis supports these findings.

scholarly journals Polycrystalline to preferred-(100) single crystal texture phase transformation of yttrium iron garnet nanoparticles

2019 ◽  
Vol 1 (1) ◽  
pp. 403-413 ◽  
Author(s):  
Rameshwar B. Borade ◽  
Sagar E. Shirsath ◽  
Gaurav Vats ◽  
Anil S. Gaikwad ◽  
S. M. Patange ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Solid State ◽  
Single Crystal ◽  
Yttrium Iron Garnet ◽  
Sol Gel ◽  
Yttrium Iron ◽  
Crystal Texture ◽  
Synthesis Techniques ◽  
Auto Combustion ◽  
Iron Garnet

Nanocrystalline Ce-substituted yttrium iron garnet (YIG) powders of different compositions, Y3−xCexFe5O12 (0 ≤ x ≤ 2.0), were synthesized by a combination of sol–gel auto-combustion and solid-state synthesis techniques.

scholarly journals Construction of pillar[4]arene[1]quinone/1,10-dibromodecane pseudorotaxanes in solution and the solid state

2020 ◽  
Author(s):  
Xinru Sheng ◽  
Errui Li ◽  
Feihe Huang
Keyword(s):  
Solid State ◽  
Hydrogen Bonds ◽  
Single Crystal ◽  
X Ray Diffraction ◽  
Guest Molecules ◽  
X Ray ◽  
Π Interactions ◽  
Host Molecules ◽  
Complexation Stoichiometry

We report novel pseudorotaxanes based on the complexation between a pillar[4]arene[1]quinone and 1,10-dibromodecane. The complexation is found to have a 1:1 host–guest complexation stoichiometry in chloroform but a 2:1 host–guest complexation stoichiometry in the solid state. From single crystal X-ray diffraction, the linear guest molecules thread into cyclic pillar[4]arene[1]quinone host molecules in the solid state, stabilized by CH∙∙∙π interactions and hydrogen bonds.

The use of high-resolution FESEM to study solid-state phase transformations and reactions

1994 ◽  
Vol 52 ◽  
pp. 1028-1029
Author(s):  
P. G. Kotula ◽  
D. D. Erickson ◽  
C. B. Carter
Keyword(s):  
Solid State ◽  
High Resolution ◽  
Phase Transformations ◽  
High Efficiency ◽  
Sol Gel ◽  
Quantitative Information ◽  
Solid State Reactions ◽  
Critical Dimensions ◽  
Backscattered Electrons ◽  
Backscattered Electron

High-resolution field-emission-gun scanning electron microscopy (FESEM) has recently emerged as an extremely powerful method for characterizing the micro- or nanostructure of materials. The development of high efficiency backscattered-electron detectors has increased the resolution attainable with backscattered-electrons to almost that attainable with secondary-electrons. This increased resolution allows backscattered-electron imaging to be utilized to study materials once possible only by TEM. In addition to providing quantitative information, such as critical dimensions, SEM is more statistically representative. That is, the amount of material that can be sampled with SEM for a given measurement is many orders of magnitude greater than that with TEM.In the present work, a Hitachi S-900 FESEM (operating at 5kV) equipped with a high-resolution backscattered electron detector, has been used to study the α-Fe2O3 enhanced or seeded solid-state phase transformations of sol-gel alumina and solid-state reactions in the NiO/α-Al2O3 system. In both cases, a thin-film cross-section approach has been developed to facilitate the investigation. Specifically, the FESEM allows transformed- or reaction-layer thicknesses along interfaces that are millimeters in length to be measured with a resolution of better than 10nm.

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