scholarly journals Toward Elusive Iodoplumbic Acid HPbI3: High-Energy Isochoric Synthesis of Hydronium Forms of the PbI3- Anion at Elevated Temperature and Pressure

Author(s):  
Szymon Sobczak ◽  
Athena M. Fidelli ◽  
Jean-Louis Do ◽  
George P. Demopoulos ◽  
Audrey Moores ◽  
...  

High-pressure and -temperature crystallization and X-ray diffraction crystallography have revealed hydronium forms of the proposed but never demonstrated iodoplumbic acid HPbI<sub>3</sub>. Depending on the pressure range, the reaction of PbI2 and aqueous concentrated hydriodic acid under isochoric conditions in a diamond anvil cell (DAC) held between 0.11 and 1.20 GPa produces two hydrated hydronium salts with compositions [H<sub>3</sub>O][PbI<sub>3</sub>].<i>n</i>H<sub>2</sub>O (<i>n</i>=3,4). Comprised of polymeric one-dimensional PbI<sub>3</sub><sup>-</sup> anions, these hydronium salts represent the so far best match for the elusive HPbI<sub>3</sub> progenitor of hybrid lead perovskites. We also reveal a new three-dimensional polymorph of lead iodide (PbI<sub>2</sub>), so far known only as a layered structure.<br>

2021 ◽  
Author(s):  
Szymon Sobczak ◽  
Athena M. Fidelli ◽  
Jean-Louis Do ◽  
George P. Demopoulos ◽  
Audrey Moores ◽  
...  

High-pressure and -temperature crystallization and X-ray diffraction crystallography have revealed hydronium forms of the proposed but never demonstrated iodoplumbic acid HPbI<sub>3</sub>. Depending on the pressure range, the reaction of PbI2 and aqueous concentrated hydriodic acid under isochoric conditions in a diamond anvil cell (DAC) held between 0.11 and 1.20 GPa produces two hydrated hydronium salts with compositions [H<sub>3</sub>O][PbI<sub>3</sub>].<i>n</i>H<sub>2</sub>O (<i>n</i>=3,4). Comprised of polymeric one-dimensional PbI<sub>3</sub><sup>-</sup> anions, these hydronium salts represent the so far best match for the elusive HPbI<sub>3</sub> progenitor of hybrid lead perovskites. We also reveal a new three-dimensional polymorph of lead iodide (PbI<sub>2</sub>), so far known only as a layered structure.<br>


2018 ◽  
Vol 74 (5) ◽  
pp. 425-446 ◽  
Author(s):  
Ashley Nicole Bucsek ◽  
Darren Dale ◽  
Jun Young Peter Ko ◽  
Yuriy Chumlyakov ◽  
Aaron Paul Stebner

Modern X-ray diffraction techniques are now allowing researchers to collect long-desired experimental verification data sets that are in situ, three-dimensional, on the same length scales as critical microstructures, and using bulk samples. These techniques need to be adapted for advanced material systems that undergo combinations of phase transformation, twinning and plasticity. One particular challenge addressed in this article is direct analysis of martensite phases in far-field high-energy diffraction microscopy experiments. Specifically, an algorithmic forward model approach is presented to analyze phase transformation and twinning data sets of shape memory alloys. In the present implementation of the algorithm, the crystallographic theory of martensite (CTM) is used to predict possible martensite microstructures (i.e. martensite orientations, twin mode, habit plane, twin plane and twin phase fractions) that could form from the parent austenite structure. This approach is successfully demonstrated on three single- and near-single-crystal NiTi samples where the fundamental assumptions of the CTM are not upheld. That is, the samples have elastically strained lattices, inclusions, precipitates, subgrains, R-phase transformation and/or are not an infinite plate. The results indicate that the CTM still provides structural solutions that match the experiments. However, the widely accepted maximum work criterion for predicting which solution of the CTM should be preferred by the material does not work in these cases. Hence, a more accurate model that can simulate these additional structural complexities can be used within the algorithm in the future to improve its performance for non-ideal materials.


Author(s):  
D.M. Scruggs

Abstract This paper describes the wear induced transformation of crystaline metal surfaces into amorphous and/or microcrystalline surfaces that exhibit gross changes in the fundamental properties of friction, wear, hardness and toughness. The coatings are applied using wire and powder feed to TWAS and HVOF equipment. Wear processes investigated include adhesive wear, low stress abrasion, grinding wear and galling. The effects of chemical makeup of the surfaces and the alloy structure are examined using microscopy and x-ray diffraction. The surface & underlying coating characteristics including roughness, microstructure, hardness and friction coefficient are determined. Results show that the surface structure is dependent on the wear vector. The structural transformation is a function of the chemical makeup and intrinsic wear resistance of the crystalline alloy coupled with the energy input of the wear process. High energy wear such as grinding wear can overcome the transformation. The results also suggest that the micro-welding that occurs between asperities in crystalline alloys is replaced by a flow process on the transformed surface. Coating structure, glass transition temperature, crystallization temperature and critical cooling rate of the transformed surface are much more significant than the chemistry of the alloy once the transformation takes place.


Polymers ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 126 ◽  
Author(s):  
Pei-Chi Cheng ◽  
Bing-Han Li ◽  
Feng-Shuen Tseng ◽  
Po-Ching Liang ◽  
Chia-Her Lin ◽  
...  

Four lithium coordination polymers, [Li3(BTC)(H2O)6] (1), [Li3(BTC)(H2O)5] (2), [Li3(BTC)(μ2-H2O)] (3), and [Li(H2BTC)(H2O)] (4) (H3BTC = 1,3,5-benzenetricarboxylatic acid), have been synthesized and characterized. All the structures have been determined using single crystal X-ray diffraction studies. Complexes 1 and 2 have two-dimensional (2-D) sheets, whereas complex 3 has three-dimensional (3-D) frameworks and complex 4 has one-dimensional (1-D) tubular chains. The crystal-to-crystal transformation was observed in 1–3 upon removal of water molecules, which accompanied the changes in structures and ligand bridging modes. Furthermore, the electrochemical properties of complexes 3 and 4 have been studied to evaluate these compounds as electrode materials in lithium ion batteries with the discharge capacities of 120 and 257 mAhg−1 in the first thirty cycles, respectively.


Author(s):  
Jun Wang ◽  
Jian-Qing Tao ◽  
Xiao-Juan Xu ◽  
Chun-Yun Tan

In the title mixed-ligand metal–organic polymeric compound, {[Cd(C14H8O6S)(C16H16N2)]·3H2O}n, the asymmetric unit contains a crystallographically unique CdIIatom, one doubly deprotonated 4,4′-sulfonyldibenzoic acid (H2SDBA) ligand, one 3,4,7,8-tetramethyl-1,10-phenanthroline (TMPHEN) molecule and three solvent water molecules. Each CdIIcentre is six-coordinated by two O atoms from a chelating carboxylate group of a SDBA2−ligand, two O atoms from monodentate carboxylate groups of two different SDBA2−ligands and two N atoms from a chelating TMPHEN ligand. There are two coordination patterns for the carboxylate groups of the SDBA2−ligand, with one in a μ1-η1:η1chelating mode and the other in a μ2-η1:η1bis-monodentate mode. Single-crystal X-ray diffraction analysis revealed that the title compound is a one-dimensional double-chain polymer containing 28-membered rings based on the [Cd2(CO2)2] rhomboid subunit. More interestingly, a chair-shaped water hexamer cluster is observed in the compound.


1999 ◽  
Vol 13 (09n10) ◽  
pp. 991-996
Author(s):  
M. Salvato ◽  
C. Attanasio ◽  
G. Carbone ◽  
T. Di Luccio ◽  
S. L. Prischepa ◽  
...  

High temperature superconducting multilayers have been obtained depositing Bi2Sr2CuO6+δ(2201) and ACuO2 layers, where A is Ca or Sr, by Molecular Beam Epitaxy (MBE) on MgO and SrTiO3 substrates. The samples, formed by a sequence of 2201/ACuO2 bilayers, have different thickness of ACuO2 layers while the thickness of the 2201 layers is kept constant. The surface structure of each layer has been monitored by in situ Reflection High Energy Electron Diffraction (RHEED) analysis which has confirmed a 2D nucleation growth. X-ray diffraction (XRD) analysis has been used to confirm that the layered structure has been obtained. Moreover, one-dimensional X-ray kinematic diffraction model has been developed to interpret the experimental data and to estimate the period of the multilayers. Resistive measurements have shown that the electrical properties of the samples strongly depend on the thickness of the ACuO2 layers.


2015 ◽  
Vol 71 (2) ◽  
pp. 93-96 ◽  
Author(s):  
Qiang Li ◽  
Hui-Ting Wang ◽  
Lin Zhou

A new tetrazole–metal supramolecular compound, di-μ-chlorido-bis(trichlorido{1-[(1H-tetrazol-5-yl-κN2)methyl]-1,4-diazoniabicyclo[2.2.2]octane}cadmium(II)), [Cd2(C8H16N6)2Cl8], has been synthesized and structurally characterized by single-crystal X-ray diffraction. In the structure, each CdIIcation is coordinated by five Cl atoms (two bridging and three terminal) and by one N atom from the 1-[(1H-tetrazol-5-yl)methyl]-1,4-diazoniabicyclo[2.2.2]octane ligand, adopting a slightly distorted octahedral coordination geometry. The bridging bicyclo[2.2.2]octane and chloride ligands link the CdIIcations into one-dimensional ribbon-like N—H...Cl hydrogen-bonded chains along thebaxis. An extensive hydrogen-bonding network formed by N—H...Cl and C—H...Cl hydrogen bonds, and interchain π–π stacking interactions between adjacent tetrazole rings, consolidate the crystal packing, linking the poymeric chains into a three-dimensional supramolecular network.


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