Triclinic Structure Research Articles

Synthesis and Investigation on Structural, Thermal, Mechanical, Linear Optical, and Nonlinear Optical Nature of Potassium Sulphato Oxalate Single Crystals

AbstractThe new semiorganic potassium sulphato oxalate (KSO) single crystals are grown at room temperature by a slow evaporation method using an aqueous solution. The Fourier transform infrared spectroscopy is used to ascertain the various functional groups present in the grown KSO sample. The single crystal X‐ray diffractometer (XRD) results confirm the grown KSO crystal is a triclinic structure with lattice parameters a = 6.37 Å; b = 7.03 Å; c = 10.61 Å; and space group P1. Powder XRD study proves the crystallinity and purity of the grown crystal. The optical behaviors of KSO are analyzed by UV–vis‐near infrared reflectance (NIR) spectrophotometer. Photoluminescence (PL) studies of KSO reveal its strong green emission at 576 nm. The laser damage threshold (LDT) of the title compound is measured to be 6.135 GW/cm2. The thermo gravimetric and differential thermal analysis indicated that KSO is stable up to 103 °C. From the Vickers microhardness tester, the mechanical behaviors of the title compound are studied. The frequency conversion property of KSO crystal is analyzed using Kurtz–Perry method, and it is found to be 1.16 times higher than that of the reference potassium dihydrogen phosphate which indicates KSO is well suited for optoelectronic device fabrication.

One-Drop Self-Assembly and Size Control of Organic Nonlinear Optical Crystal DSNS Nanowires

In this study, we demonstrate a one-drop self-assembly method for fabricating nanowires (NWs) of organic second-order nonlinear optical (NLO) material, 4-N,N-dimethylamino-4′-N′-methyl-stilbazolium 2-naphthalenesulfonate (DSNS). By controlling the parameters of the self-assembly process, we successfully controlled the length of DSNS from a few micrometers to millimeters. The obtained NWs have very high surface quality with surface roughness < 150 pm, which is highly beneficial for fabricating integrated optical devices. DSNS NW has the same triclinic crystal structure as that of bulk crystal and exhibits excellent second-order NLO and fluorescent properties, which could provide wide opportunities for on-chip optoelectronic devices and integrated photonic systems. Furthermore, the one-drop self-assembly method only requires reagents in microgram quantities, and thus this method is extremely environmentally friendly.

Single-Crystal Poly[4-(4,4-dihexadecyl-4H-cyclopenta[1,2-b:5,4-b']dithiophen-2-yl)- alt-[1,2,5]thiadiazolo[3,4- c]pyridine] Nanowires with Ultrahigh Mobility.

We fabricated single-crystal poly[4-(4,4-dihexadecyl-4H-cyclopenta[1,2-b:5,4-b']-dithiophen-2-yl)- alt-[1,2,5]thiadiazolo-[3,4- c]pyridine] (PCDTPT) nanowires with ultrahigh mobility using a liquid-bridge-mediated nanotransfer molding method. The structural analysis of the single-crystal PCDTPT nanowires reveals that PCDTPT crystals have a triclinic structure, and the nanowires grow parallel to PCDTPT backbone chains, which provide important insights into its intrinsic charge transport. The single-crystal PCDTPT nanowire exhibits a superior charge carrier mobility of 72.94 ± 18.02 cm2 V-1 s-1 (maximum mobility up to 92.64 cm2 V-1 s-1), which is a record high value among conjugated polymers to date. In the single-crystal PCDTPT nanowire, the backbone chains in the linear structure along the nanowire growth axis lead to strong backbone delocalization, resulting in highly conductive polymer backbones and a drastic increase in charge carrier mobility. In addition, the single-crystal PCDTPT nanowire shows good environmental stability under air conditions compared to small-molecule organic semiconductors.

Sol–Gel Driving LiFe(MoO4)2 Microcrystals: High Capacity and Superior Cycling Stability for Anode Material in Lithium Ion Batteries

LiFe(MoO4)2 microcrystals have been fabricated via a facile sol–gel driving process. The obtained LiFe(MoO4)2 microcrystals are characterized through X-ray diffraction, thermal analysis, scanning electron microscope, transmission electron microscope and high resolution transmission electron microscope. The results demonstrate that the as-synthesized microcrystals possess triclinic structure and exhibit uniform particle size of 1–2 μm. When served as anode material for lithium ion batteries, LiFe(MoO4)2 microcrystals display a very high specific capacity of 925 mAh g−1 at a current rate of 1 C after 500 cycles and a high retention rate of 88%, showing superior electrochemical performance.

Further structural studies of the lytic polysaccharide monooxygenase AoAA13 belonging to the starch-active AA13 family

Abstract Lytic polysaccharide monooxygenases (LPMOs) are recently discovered copper enzymes that cleave recalcitrant polysaccharides by oxidation. The structure of an Aspergillus oryzae LPMO from the starch degrading family AA13 (AoAA13) has previously been determined from an orthorhombic crystal grown in the presence of copper, which is photoreduced in the structure. Here we describe how crystals reliably grown in presence of Zn can be Cu-loaded post crystallization. A partly photoreduced structure was obtained by severely limiting the X-ray dose, showing that this LPMO is much more prone to photoreduction than others. A serial synchrotron crystallography structure was also obtained, showing that this technique may be promising for further studies, to reduce even further photoreduction. We additionally present a triclinic structure of AoAA13, which has less occluded ligand binding site than the orthorhombic one. The availability of the triclinic crystals prompted new ligand binding studies, which lead us to the conclusion that small starch analogues do not bind to AoAA13 to an appreciable extent. A number of disordered conformations of the metal binding histidine brace have been encountered in this and other studies, and we have previously hypothesized that this disorder may be a consequence of loss of copper. We performed molecular dynamics in the absence of active site metal, and showed that the dynamics in solution differ somewhat from the disorder observed in the crystal, though the extent is equally dramatic.

The effect of long-range order on intermolecular interactions in organic semiconductors: zinc octaethyl porphyrin molecular thin film model systems.

In order to optimize the performance of devices based on porphyrin thin films it is of great importance to gain a physical understanding of the various factors which affect their charge transport and light-harvesting properties. In this work, we have employed a multi-technique approach to study vacuum deposited zinc octaethyl porphyrin (ZnOEP) thin films with different degrees of long-range order as model systems. An asymmetrical stretching of the skeletal carbon atoms of the porphyrin conformer has been observed and attributed to ordered molecular stacking and intermolecular interactions. For ordered films, a detailed fitting analysis of the X-ray absorption near edge structure (XANES) using the MXAN code establishes a symmetry reduction in the molecular conformer involving the skeletal carbon atoms of the porphyrin ring; this highlights the consequences of increased π-π stacking of ZnOEP molecules adopting the triclinic structure. The observed asymmetrical stretching of the π conjugation network of the porphyrin structure can have significant implications for charge transport and light harvesting, significantly influencing the performance of porphyrin based devices.

High-pressure-induced phase transition in cinchomeronic acid polycrystalline form-I**Project supported by the National Natural Science Foundation of China (Grant Nos. 11604224, 51805336, and 11774120), the Open Project of State Key Laboratory of Superhard Materials of Jilin University, China (Grant No. 201708), the Natural Science Foundation of Liaoning Province, China (Grant No. 20180550861), the Education Department of Liaoning Province, China (Grant Nos.

Diamond anvil cells combined with Raman spectroscopy and angle-dispersive x-ray diffraction (ADXRD) were used to investigate the compression behavior of cinchomeronic acid (C7H5NO4, CA), a hydrogen-bonded polymorphs. The compression of form-I at approximately 6.5 GPa caused an irreversible phase transition that produced the new polymorph form-III. Lattice and internal modes in the Raman spectra were analyzed to determine the modifications in the local environment of CA form-I molecules. The form-III was indexed and refined to a low-symmetry triclinic structure with space group P1. The mechanism for the phase transition involved the reconstructions in the hydrogen-bonded networks in CA form-I.

Structure of crystalline CaAl2Si2O8 precipitated in a CaO–Al2O3–SiO2 glass-ceramic

Metastable CaAl2Si2O8 crystalline phase was obtained via heat treatment of CaO–Al2O3–SiO2 glass with metallic molybdenum particles as nucleating agents. Its crystal structure was determined by aberration-corrected scanning transmission electron microscopy (Cs-STEM), Raman spectroscopy, and X-ray diffraction (XRD). Although the hexagonal structure was observed by Cs-STEM and Raman spectroscopy, Rietveld analysis revealed that a triclinic structure with space group P1 provided the best description of the crystal structure. The most appropriate lattice parameters were a = 5.1163(5) Å, b = 5.1155(5) Å, c = 15.0031(15) Å, α = 91.319(3)°, β = 88.172(3)°, and γ = 120.279(3)°. The c-axis layers composing the hexagonal plane were slightly distorted a few degrees from their arrangement in the hexagonal CaAl2Si2O8 crystal.

Crystal structures and microwave dielectric properties of novel low-permittivity Ba1-xSrxZnSi3O8 ceramics

Ba1-xSrxZnSi3O8 (x = 0.2–1.0) microwave dielectric ceramics were synthesized using the solid-state method at the temperature from 1087 °C to 1150 °C for 3 h. All compositions showed a single phase for Ba1-xSrxZnSi3O8 when x increased from 0.2 to 1.0, and a phase transition from monoclinic to triclinic structure occurred between 0.8 and 1.0. The relative permittivity of Ba1-xSrxZnSi3O8 ceramics decreased from 6.57 to 6.12 when the Ba2+ ions substituted by Sr2+ ions. However, the quality factor initially decreased from 34,735 GHz (x = 0.2) to 28,986 GHz (x = 0.4) and subsequently increased monotonously. The variation in the temperature coefficient of resonant frequency showed an opposite, slightly changing trend compared with that of the quality factor. A novel single-phase SrZnSi3O8, which possesses good microwave dielectric properties of εr = 6.12, Q×f = 78,064 GHz, and τf = −33.2 ppm/°C, was obtained for the first time at the sintering temperature of 1150 °C.

Crystal Structure of Kristiansenite from Szklarska Poręba, Southwestern Poland

Kristiansenite, ideally Ca2ScSn(Si2O7)(Si2O6OH), a rare late-stage hydrothermal Sc-bearing sorosilicate mineral, was found in a gadolinite-fergusonite-type pegmatite of the MI-REE subclass related to the Karkonosze granite, exposed in a quarry at Szklarska Poręba, Lower Silesia, Poland. Kristiansenite occurs in an association with andradite, epidote, allanite-(Ce), titanite, fersmite, scheelite, Sc-bearing columbite-(Fe), a YNbO4 mineral as fergusonite-(Y) or fergusonite-(Y)-beta, silesiaite and wolframite. Single-crystal study of the mineral (R1 of 4.96%), with composition Ca2.00(Sn0.97Sc0.69Fe3+0.17Mn0.05Ti0.04Zr0.03Nb0.02Al0.02Ta0.01)Σ2(Si2O7)[(Si1.98Al0.02)Σ2O6.03(OH)0.97], corroborates its triclinic structure with space group-symmetry C1, Z = 2, and unit-cell parameters a = 10.0304(5), b = 8.4056(4), c = 13.3228(6) Å, α = 90.001(3), β = 109.105(3), γ = 89.997(3)° and V = 1061.40(9) Å3. In the structure of the mineral, the Ca and Si sites are dominantly occupied with Ca and Si, whereas the M1–M4 sites are disordered. The M3 and M4 sites are occupied dominantly by Sn and subordinately Sc, whereas the M1 and M2 sites are occupied dominantly by Sc and subordinately by remaining occupants, including Sn.

Structure-Forming Role of Heavy Cations in Sr3B2SiO8 (Sr(B,Si)O2.67) and Ba3B6Si2O16 Borosilicates

The crystallographic analysis of the orthorhombic (Pnma) structure of Sr3B2SiO8 ≈ (Sr(B,Si)O2.67) shows that its experimentally found symmetry is determined by the geometry of the Sr sublattice where the anion radical without this symmetry simulates it by the statistical averaging of four variants of real configurations. With a reduced fraction of heavy atoms in the triclinic (Р1) structure of Ba3B6Si2O16, the Ba and Si cations whose sublattice determines the presence of additional pseudosymmetry form the skeleton of the structure.

Iron-doping as an effective strategy to enhance supercapacitive properties of nickel molybdate

Iron-doped hydrated nickel molybdate (FexNi1-xMoO4.0.75H2O, x = 0–0.10) nanorods were successfully synthesized via a simple one-pot hydrothermal route. Our investigations showed that hydrated nickel molybdate (HNMO) possesses identical crystal structure to CoMoO4.0.75H2O with a triclinic crystal structure and P1¯ space group. Electron microscopy studies showed that the HNMO powders consist of single crystalline nanorods with [12¯2] growth direction. The effectiveness of iron-doping into the crystalline lattice of the HNMO was demonstrated by powder x-ray diffraction (PXRD), UV–visible spectroscopy and electrochemical impedance spectroscopy (EIS). Upon iron-doping, the band gap energy values reduced from 4.03 eV for the un-doped powder to 3.48 eV for 10 at.% iron-doped HNMO. Electrochemical performance of the nanorods was characterized by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and EIS. The electrochemical properties along the optical data demonstrate that there is a direct relation between the electrochemical performance and the level of iron-doping due to improvement of electrical conductivity. A specific capacitance of 718 F/g related to the HNMO was improved by 47%–1057 F/g upon 10 at.% iron-doping.

Characterization of coumarin-6 polycrystalline films growth from vacuum deposition at various substrate temperatures

Coumarin-6 polycrystalline films were fabricated from vacuum deposition at various substrate temperatures Tsub from 106 to 178 °C with a fixed source temperature of 185 °C. Because of its slenderer and more asymmetric structure, the adhered coumarin-6 molecule on top of the growing interface encounters a larger steric energetic barrier of 0.92 eV as estimated from the Arrhenius plot of growth rate versus 1/Tsub. From top-view SEM pictures, the as-deposited coumarin-6 thin films exhibit a twisted pattern and a kinematic roughness for Tsub < 150 °C; while clear facets emerge for Tsub ≥ 150 °C due to the increase of surface diffusion energy of the adhered molecules. From XRD analysis, besides the confirmation of the triclinic structure two anomalous peaks observed at 2θ ~ 9.007° and 7.260° are explained due to the co-existence of N- and S-coumarin-6-isomers within the crystalline grains. Furthermore, for coumarin-6 polycrystalline films deposited at Tsub = 150 °C with high crystallinity of the constituent grains, the bandgap determined from optical transmission is around 2.392 eV; and from photoluminescence spectra, the fitted four emission components are assigned to the Frenkel and charge transfer excitons recombination with participation of molecular vibrational states.

Growth and characterization of an efficient semi organic single crystal: Sodium hydrogen oxalate monohydrate

A highly proficient nonlinear optical compound Sodium Hydrogen Oxalate Monohydrate (SHOM) single crystal under semi organic category has been grown-up by the process of slow solvent evaporation. The triclinic structure and cell parameters of SHOM was revealed from X-ray diffraction analysis. The examination of FTIR was done to determine the existence of various functional groups present in the SHOM crystal. The mechanical stability is evaluated from Vicker's microhardness tester and related mechanical parameters were assessed. The multiple shot laser damage threshold was examined to be 2.65 GW/cm2. TG/DTA analysis is carried out to appraise the thermal limit of the grown material. The absorbance spectrum was analyzed from UV–vis analysis which verifies high transparency of the grown crystal and various optical constants were also estimated. The third order nonlinearity, two-photon absorption and self-defocussing effect of the grown material was established from the Z-Scan approach. The results favoring the materials suitability over nonlinear optical applications are reported.

Effects of Ti Doping on the Structural Stability and Enhanced Electrochemical Performance of α‐LiVOPO4

Lithium vanadyl phosphate has seven different crystallographic phases. Among them, α‐LiVOPO4 is chosen because of its relatively high energy density and redox voltage of 3.9 V compared to the other phosphates. In this study, Ti4+‐doped α‐LiV1−xTixOPO4 (x = 0.00, 0.003, 0.005, 0.007, and 0.01) was prepared using a sol–gel method to increase the structure stability and electrochemical performance. The triclinic structure with the space group P‐1 was confirmed by X‐ray diffraction, Fourier‐transform infrared spectroscopy, and X‐ray photoelectron spectroscopy. Inductively coupled plasma–optical emission spectroscopy was conducted to determine the precise state. The shape and size of the particles were observed by field‐emission scanning electron microscopy. In situ X‐ray absorption spectroscopy was performed to confirm the structural behavior during the electrochemical reaction. Electrochemical measurements such as cyclic voltammetry and galvanostatic charge–discharge were conducted. α‐LiV1−xTi xOPO4 (x = 0.003, 0.005, 0.007, and 0.01) showed structural stability during cycling as well as decreased polarization during charge and discharge with the increased diffusion coefficient of lithium ions. α‐LiV0.995Ti0.005OPO4 showed the best cycling stability and rate capability among all the samples examined because Ti doping retained its site to prevent structural collapse.

Effect of non-metallic X(X=F, N, S) and Cr co-doping on properties of BiFeO3: A first-principles study

In this study, the structural, magnetic, electric and optical properties in X (X=F, N, S) and Cr co-doped BiFeO3 (BFO) are calculated using the density functional theory. For Cr–X co-doping case, the structure of BFO undergo a phase transition from monoclinic to triclinic structure accompanying net magnetic moments of 5.92 μB, 6.04 μB and 7.80 μB, for Cr–F co-doping, Cr–N co-doping and Cr–S co-doping, respectively. The underlying physical mechanisms are the lattice distortions tunned by doping. The decreased Fe–O–Fe bond angles and Fe–O bond lengths will bring weak antiferromagnetism superexchange interaction. In addition, the band gaps of Cr–X co-doping cases are decreased from 2.20 eV (BFO bulk) to 1.31 eV and 1.80 eV for Cr–F co-doping and Cr–S co-doping, respectively, which are well for photovoltaic applications according to the well-known Shockley-Queisser criterion, suggesting a possible great improvement optical properties in Cr–X co-doped samples.

High-Pressure Synthesis, Structural, and Spectroscopic Studies of the Ni-U-O System.

The first comprehensive structural study of the Ni-U-O system is reported. Single crystals of α-NiUO4, β-NiUO4, and NiU3O10 were synthesized, and their structures were refined-using synchrotron single-crystal X-ray diffraction data supported by X-ray absorption spectroscopic measurements. α-NiUO4 adopts an orthorhombic structure in space group Pbcn and is isostructural to CrUO4 containing corrugated two-dimensional (2D) layers of corner-sharing UO6 polyhedra and edge-sharing one-dimensional (1D) zigzag α-PbO2 rutile-like chains of NiO6 polyhedra in the [001] direction. β-NiUO4 is isostructural to MgUO4 and has an orthorhombic structure in space group Ibmm, which contains alternating 1D chains of edge-sharing UO6 and NiO6 polyhedra in the [001] direction as in regular TiO2 rutile. NiU3O10 forms a triclinic structure in space group P1̅ and is isostructural with CuU3O10, where it forms a three-dimensional (3D) framework structure built through a mixture of UO6 and UO7 polyhedra in which the NiO6 polyhedra sit isolated within the framework. X-ray absorption near-edge structure (XANES) measurements, conducted using XANES mapping of single crystals, support the presence of hexavalent uranium in the three structures. The polymorphs of NiUO4 were found to only form under high-pressure and high-temperature conditions (≥4 GPa and 700 °C). It is argued that this is a consequence of the relative size difference between the Ni2+ and U6+ cations, where the Ni2+ cation is effectively too small for the Ibmm structure and too large for the Pbcn structure to form under ambient pressure conditions. This does not appear to be an issue for NiU3O10, which forms under ambient pressure conditions, where NiO6 polyhedra sit isolated within the framework of 3D connected UO6/UO7 polyhedra. Synthesis conditions indicate that β-NiUO4 is the preferred higher-pressure phase and that the transformation to this occurs irreversibly at a temperature between 950 and 1000 °C, when P = 4 GPa. The routes toward the synthesis of the oxides and the associated structural and spectroscopic results are described with respect to the structural chemistry of the Ni-U-O system, the larger AUO4 family of oxides (A = divalent or trivalent cation), and also their relation to the rutile-related family of oxides.

Crystal symmetry aspects of materials with magnetic spin reorientation.

The symmetry of materials which undergo a continuous spin reorientation has been analysed. It is shown that continuous spin reorientation is possible only in materials with triclinic or monoclinic crystal structure symmetry, i.e. other symmetries - orthorhombic, tetragonal, trigonal, hexagonal and cubic - are forbidden.

Superconductivity at 3.5 K and/or 7.2 K in potassium-doped triphenylbismuth.

We develop a two-step synthesis method-ultrasound treatment and low temperature annealing to explore superconductivity in potassium-doped triphenylbismuth, which is composed of one bismuth atom and three phenyl rings. The combination of dc and ac magnetic measurements reveals that one hundred percent of synthesized samples exhibit superconductivity at 3.5 K and/or 7.2 K at ambient pressure. The magnetization hysteresis loops provide a strong piece of evidence of type-II superconductors. It is found that the doped materials crystallize into the triclinic P1 structure, with a mole ratio of 4:1 between potassium and triphenylbismuth. Both the calculated electronic structure and measured Raman spectra indicate that superconductivity is realized by transferring electrons from the K-4s to C-2p orbital. Our study opens an encouraging window for the search of organic superconductors in organometallic molecules.

EPR and NEXAFS spectroscopy of BiNb1-xFexO4-δ ceramics

The methods of EPR and NEXAFS spectroscopy were employed for the study of BiNb1-xFexO4-δ solid solutions of triclinic and orthorhombic modifications. The analysis of the NEXAFS Fe2p-spectra of iron oxides and the iron-containing solid solutions revealed that Fe atoms were mainly in an oxidation state of +3. In the EPR spectra of the BiNb1-xFexO4-δ samples of orthorhombic modification, a broad line with the center at g of 2.16–2.37 was registered along with the low-intensity signal with a g-factor of ∼4.3 observed on its low-field wing. EPR spectra of the triclinic structure samples exhibited a complex system of lines in the range of 80–300 mT. An intense complex line having features at g of 4.74–4.80, 4.04–4.10 and 3.76–3.80 was recognized in the low-field signal. The low-field wing of the line was complicated by a shoulder with g of 5.3 and by a line in the form of an absorption signal with g of 7.7–8.0. As a result of the modeling of EPR spectra, the spin-Hamiltonian parameters of Fe(III) in the structure of BiNb1-xFexO4-δ of triclinic modification were obtained.