Hooman Yaghoobnejad Asl

Phosphorous acid route synthesis of iron tavorite phases, LiFePO4(OH)xF1−x [0 ≤ x ≤ 1] and comparative study of their electrochemical activities

New synthesis routes were employed for the synthesis of three derivatives of iron hydroxo-, fluoro-, and mixed hydroxo-fluoro phosphates LiFePO4(OH)xF1−x where 0 ≤ x ≤ 1 with the tavorite structure type, and their detail electrochemical activities have been presented. The hydrothermal synthesis of the pure hydroxo-derivative, LiFePO4OH, using phosphorous acid as a source of phosphate yielded good quality crystals from which the crystal structure was solved for the first time using SC-XRD (single crystal X-ray diffraction). The fluoro derivative, LiFePO4F, was prepared as a very fine powder at low temperature in a solvent-less flux-based method employing phosphorous acid and mixed alkali metal nitrates. A mixed anionic hydroxo-fluoro iron tavorite phase, LiFePO4(OH)0.32F0.68, was also synthesized by a hydrothermal route. The electrochemical performance of the three phases was studied with galvanostatic charge–discharge tests, cyclic voltammetry, and electrochemical impedance spectroscopy (EIS). All three phases showed facile Li-insertion through the reduction of Fe3+ to Fe2+ at an average voltage in the range of 2.4–2.75 V, through the variation of the anion from pure OH to pure F. An increase of 0.35 V was observed as a result of F substitution in the OH position. Also, good cyclability and capacity retention were observed for all three phases and a reversible capacity of more than 90% was achieved for LiFePO4F. The results of EIS indicated that lithium ion mobility is highest in the mixed anion.

Li3Fe2(HPO3)3Cl: an electroactive iron phosphite as a new polyanionic cathode material for Li-ion battery

A novel lithium containing iron-chlorophosphite, Li3Fe2(HPO3)3Cl has been synthesized by employing low melting phosphorous acid flux. The single-crystal X-ray structure determination established that the compound has a 3-dimensional structure built up by edge-shared octahedral dimers and phosphite moieties that create narrow channels along the a- and b-axis. Two crystallographically independent Li ions are located in those channels. The compound was further characterized by TGA, IR, magnetic measurements, and Mossbauer spectroscopy. Magnetic measurements indicate that the compound has a field-induced metamagnetic transition. In this article we report for the first time an iron chloro-phosphite, Li3Fe2(HPO3)3Cl, as a new polyanion-based cathode with a promising electrochemical activity that shows an average voltage of 3.1 V vs. Li+/Li for the Fe2+/Fe3+ redox couple and a reversible capacity of 70 mA h g−1. Details of electrochemical studies including cyclic voltammetry, galvanostatic charge–discharge, and electro-impedance spectroscopy are reported here.

Phosphite as Polyanion-Based Cathode for Li-Ion Battery: Synthesis, Structure, and Electrochemistry of LiFe(HPO3)2.

A new lithium containing iron(III) phosphite, LiFe(HPO3)2, has been synthesized via a solvent-free, low temperature, solid-state synthesis route. The crystal structure of this material has been determined employing single-crystal X-ray diffraction, which indicates that the compound has a three-dimensional structure formed by isolated FeO6 octahedral units joined together via bridging HPO3 pseudopyramidal moieties. This arrangement leads to the formation of channels along all the three crystallographic directions, where channels along the a- and b-axes host Li(+) ions. The compound was further characterized by TGA, IR, and Mössbauer spectroscopic techniques. Additionally, it has been demonstrated that this phase is electrochemically active toward reversible intercalation of Li(+) ions and thus can be used as a cathode material in Li-ion cells. An average discharge potential of 2.8 V and a practical capacity of 70 mAh·g(-1) has been achieved as indicated by the results of cyclic voltammetry and galvanostatic charge-discharge tests.

Tetragonal versus Hexagonal: Structure-Dependent Catalytic Activity of Co/Zn Bimetallic Metal–Organic Frameworks

Tetragonal and hexagonal phases of monometallic Zn and bimetallic Co/Zn metal-organic frameworks (MOFs), with secondary building units (SBUs) containing a M3O (M = metal) cluster, were synthesized from identical constituents using a benzenetricarboxylate (BTC(3-)) linker that forms decorated 3,6- and 3,5-connected networks, respectively. There exist subtle differences between the SBUs; one of the metal atoms in the M3O cluster in the tetragonal phase has one dissociable DMF solvent molecule while that in the hexagonal phase has three. Connectivities between the SBUs form one-dimensional channels in both MOFs. These MOFs catalyze the chemoselective addition of amines to epoxides, giving exclusively β-hydroxyamine under heterogeneous conditions. A ring-opening reaction of a symmetrical epoxide showed that the hexagonal phase diastereoselectively yields trans-alcohol, exhibiting an exquisite model for structure-dependent activity.

An efficient and facile regioselective synthesis of new substituted (E)-1-(3-aryl-7,8-dihydrocinnoline-5(6H)-ylidene)hydrazines and (1E,2E)-1,2-bis(3-aryl-7,8-dihydrocinnoline-5(6H)-ylidene)hydrazines

A study concerning the new substituted cinnoline synthesis is described. The use of a one-pot three-component method allows a simple regioselective and efficient synthesis of cinnoline derivatives via reaction of arylglyoxals with 1,3-cyclohexanedione and dimedone in the presence of hydrazine hydrate.

Synthesis and characterization of novel polymeric organic–inorganic complex framework based on sodium 2,4-dioxo-6-aryl-3-oxa-bicyclo[3.1.0]hexane-1,5-dicarboxylate (SDAOBDC) with three-dimensional hybrid networks

Synthesis and characterization of novel polymeric organic–inorganic complex based on sodium 2,4-dioxo-6-aryl-3-oxa-bicyclo[3,1,0]hexane-1,5-dicarboxylate with three-dimensional hybrid networks were reported. The polymeric complex was crystallizing in the triclinic, space group P1. As determined by X-ray single-crystal analysis, in this compound each Na ion is coordinated by six O atoms: two from different carbonyl oxygen atom of carboxylic acid groups, two from bridged carbonyl oxygen atom of carboxylic acid groups, one from the carbonyl oxygen atom of cyclic anhydride and one from water molecule. The structure characterization was done by means of IR, 1H, 13C NMR, UV–Vis spectroscopies, Tg, flame photometry and X-ray crystallographic analysis.

catena-Poly[[chlorido[1-(3-nitro-phen-yl)-2-(triphenyl-phospho-ranyl-idene)ethanone-κC(2)]mercury(II)]-μ-chlorido].

In the title organometallic polymer, [HgCl2(C26H20NO3P)]n, the monodentate 1-(3-nitrophenyl)-2-(triphenylphosphoranylidene)ethanone ligand is coordinated to the HgII atom through the methine C atom. The HgII atom is four-coordinated in a distorted tetrahedral geometry by one terminal Cl atom, two bridging Cl atoms, and one C atom from the ylidic ligand, resulting in a polymeric chain parallel to [010]. The terminal Cl atom is more strongly bound to the HgII ion [2.3916 (9) Å] than the bridging Cl atoms. The bridge is asymmetric, as indicated by the two different Hg—Cl(bridging) bond lengths [2.5840 (8) and 2.7876 (8) Å]. Intramolecular C—H⋯O and weak C—H⋯Cl contacts stabilize the polymeric chain. In the crystal, adjacent chains interact via C—H⋯O hydrogen bonds.

Phase Identification by EBSD Analysis of Non-Metallic Crystallites

Currently, EBSD is used routinely for phase and crystallites orientation mapping and studying the grain boundary of metallic and alloy samples [1]; this is partially due to the well-suited nature of these sample types for EBSD as they show no charging effect and can be polished smoothly to provide a good diffraction path from specimen surface back to EBSD camera. On the other hand, though not greatly investigated, EBSD can be applied to non-conducting, individual single crystals of micron and submicron sizes. Here the purpose is to use EBSD for phase identification of powdered samples composed of small crystallites for which the usual sample preparation methods is not applicable.