scholarly journals SYNTHESIS, INVESTIGATION AND CONDUCTIVE PROPERTIES OF ALLUAUDITE-RELATED PHASES

2020 ◽  
pp. 6-9
Author(s):  
N. Strutynska ◽  
А. Spivak ◽  
R. Kuzmin ◽  
M. Slobodyanik
Keyword(s):  
Specific Conductivity ◽  
Complex Oxide ◽  
Structural Type ◽  
Partial Substitution ◽  
X Ray Diffraction ◽  
Monoclinic System ◽  
X Ray ◽  
Sodium Cations ◽  
Temperature Ranges ◽  
Conductive Properties

Complex oxide phosphates Na1.5Co1.5Fe1.5(PO4)3, Na1.75Co1.75Fe1.25(PO4)3, Na2Co2Fe(PO4)3 and Li0.25Na1.75Co2Fe(PO4)3, belonging to the alluaudite structural type (monoclinic system, space group C2/c) were synthesized by the melting method with further annealing of the homogenous glasses at a temperature 600°C. According to powder X-ray diffraction data the partial substitution of sodium cations by lithium cations in the initial phosphate matrix Na2Co2Fe(PO4)3 led to decreasing of lattice parameters for Li0.25Na1.75Co2Fe(PO4)3 (a = 11.7572(3) Å, b = 12.4528(4) Å, c = 6.4416(2) Å and β = 113.911(1)°). The FTIR-spectroscopy results confirmed the presence of PO4-tetrahedra in the composition of prepared phases. Modes in the regions of 400–600 cm-1 and 900–1000 cm–1 were assigned to symmetric and asymmetric stretching vibrations of phosphate tetrahedron in the alluaudite-type structure, respectively. The effect of partial substitution of sodium cations by lithium cations in the phosphate matrix Na2Co2Fe(PO4)3 as well as the decrease of sodium cations amounts in the alluauditerelated structure for the phases of Na1.5Co1.5Fe1.5(PO4)3 and Na1.75Co1.75Fe1.25(PO4)3 on the conductive properties of compounds were analyzed. It was found that increasing of sodium cations amount in the channels of the alluaudite-related structure leads to an increase of the specific conductivity from 0.011 Om-1m-1 for Na1.75Co1.75Fe1.25(PO4)3 to 0.15 Om–1m–1 for Na2Co2Fe(PO4)3 at a temperature of 550 °C. It was also found that partial substitution of sodium cations by lithium cations in the initial phosphate matrix Na2Co2Fe(PO4)3 no significant influence on conductivity of phase Li0.25Na1.75Co2Fe(PO4)3 (σ = 0.095 Оm–1m–1 at a temperature of 550 °C). In the case of phosphates Na1.75Co1.75Fe1.25(PO4)3 and Li0.25Na1.75Co2Fe(PO4)3 decreasing of conductive properties in the temperature ranges 190–250 °С and 550–590 °С, respectively are caused by contribution of different components in general conductivity. The synthesized phases can be used in the development of materials with conductive properties.

Structural Study of a new Compound Based on Acid 1,4-Cyclohexanedicarboxylic (1,4-CDC)

2010 ◽  
Vol 6 (1) ◽  
pp. 891-896
Author(s):  
Manel Halouani ◽  
M. Dammak ◽  
N. Audebrand ◽  
L. Ktari
Keyword(s):  
Aqueous Solution ◽  
Water Molecules ◽  
Carboxyl Group ◽  
X Ray Diffraction ◽  
Compound I ◽  
Unit Cell Parameters ◽  
Monoclinic System ◽  
X Ray ◽  
Cell Parameters ◽  
Cyclohexanedicarboxylic Acid

One nickel 1,4-cyclohexanedicarboxylate coordination polymers, Ni2 [(O10C6H4)(COO)2].2H2O  (I), was hydrothermally synthesized from an aqueous solution of Ni (NO3)2.6H2O, (1,4-CDC) (1,4-CDC = 1,4-cyclohexanedicarboxylic acid) and tetramethylammonium nitrate. Compound (I) crystallizes in the monoclinic system with the C2/m space group. The unit cell parameters are a = 20.1160 (16) Å, b = 9.9387 (10) Å, c = 6.3672 (6) Å, β = 97.007 (3) (°), V= 1263.5 (2) (Å3) and Dx= 1.751g/cm3. The refinement converged into R= 0.036 and RW = 0.092. The structure, determined by single crystal X-ray diffraction, consists of two nickel atoms Ni (1) and Ni (2). Lots of ways of which is surrounded by six oxygen atoms, a carboxyl group and two water molecules.

Synthesis and Properties of Thermotropic Liquid Crystalline Polyesters with Flexible Polymethylene Spacer

2010 ◽  
Vol 428-429 ◽  
pp. 126-131
Author(s):  
Wei Zhong Lu ◽  
Chun Wei ◽  
Qui Shan Gao
Keyword(s):  
Optical Microscopy ◽  
Liquid Crystalline ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Structure Morphology ◽  
Temperature Ranges ◽  
Ft Ir ◽  
Diffraction Peaks ◽  
Ubbelohde Viscometer

Polymethylene bis(p-hydroxybenzoates) were prepared from methyl p-hydroxybenzoate and different diols by melted transesterification reaction. Three liquid crystalline polyesters were synthesized from terephthaloyl dichloride and polymethylene bis(p-hydroxybenzoates). Its structure, morphology and properties were characterized by Ubbelohde viscometer, Fourier transform infrared spectroscopy (FT-IR), Differential scanning calorimetry (DSC), polarized optical microscopy (POM) with a hot stage, and wide-angle X-ray diffraction (WAXD). Results indicated that the intrinsic viscosities were between 0.088 and 0.210 dL/g. Optical microscopy showed that the TLCP has a highly threaded liquid crystalline texture and a high birefringent schlieren texture character of nematic phase and has wider mesophase temperature ranges for all polyesters. DSC analysis were found that the melting point (Tm), isotropic temperature (Ti) of TLCPs decreased and the temperature range of the liquid crystalline phase became wider with increased number of methylene spacers in the polyester. The WAXD results showed that TLCPs owned two strong diffraction peaks at 2θ near 19° and 23°.

scholarly journals The hydrocarbon-bearing clathrasil chibaite and its host–guest structure at low temperature

IUCrJ ◽  
2018 ◽  
Vol 5 (5) ◽  
pp. 595-607 ◽  
Author(s):  
K. S. Scheidl ◽  
H. S. Effenberger ◽  
T. Yagi ◽  
K. Momma ◽  
Ronald Miletich
Keyword(s):  
Room Temperature ◽  
Guest Molecule ◽  
Chemical Formula ◽  
X Ray Diffraction ◽  
Continuous Symmetry ◽  
Monoclinic System ◽  
X Ray ◽  
Anisotropic Displacement Parameters ◽  
Hydrocarbon Molecules ◽  
Silicate Framework

The natural sII-type clathrasil chibaite [chemical formula SiO2·(M 12,M 16), where M x denotes a guest molecule] was investigated using single-crystal X-ray diffraction and Raman spectroscopy in the temperature range from 273 to 83 K. The O atoms of the structure at room temperature, which globally conforms to space group Fd{\overline 3}m [V = 7348.9 (17) Å3, a = 19.4420 (15) Å], have anomalous anisotropic displacement parameters indicating a static or dynamic disorder. With decreasing temperature, the crystal structure shows a continuous symmetry-lowering transformation accompanied by twinning. The intensities of weak superstructure reflections increase as temperature decreases. A monoclinic twinned superstructure was derived at 100 K [A2/n, V = 7251.0 (17) Å3, a′ = 23.7054 (2), b′ = 13.6861 (11), c′ = 23.7051 (2) Å, β′ = 109.47°]. The transformation matrix from the cubic to the monoclinic system is ai ′ = (½ 1 ½ / ½ 0 −½ / ½ −1 ½). The A2/n host framework has Si—O bond lengths and Si—O—Si angles that are much closer to known values for stable silicate-framework structures compared with the averaged Fd{\overline 3}m model. As suggested from band splitting observed in the Raman spectra, the [512]-type cages (one crystallographically unique in Fd{\overline 3}m, four different in A2/n) entrap the hydrocarbon species (CH4, C2H6, C3H8, i-C4H10). The [51264]-type cage was found to be unique in both structure types. It contains the larger hydrocarbon molecules C2H6, C3H8 and i-C4H10.

Crystal structure of microwave dielectric ceramics Ba[(Mg1−xCdx)0.33Nb0.67]O3

2007 ◽  
Vol 22 (4) ◽  
pp. 295-299
Author(s):  
J. X. Deng ◽  
X. R. Xing ◽  
J. Chen ◽  
R. B. Yu ◽  
G. R. Liu ◽  
...  
Keyword(s):  
Synthesis Temperature ◽  
Partial Substitution ◽  
Quantitative Phase Analysis ◽  
X Ray Diffraction ◽  
Low Frequencies ◽  
X Ray ◽  
Microwave Dielectric ◽  
Trigonal Structure ◽  
Ordering Degree ◽  
Dielectric Ceramics

A series of complex perovskite solid solutions of Ba[(Mg1−xCdx)0.33Nb0.67]O3 have been synthesized by the columbite method. Detailed Rietveld refinement of their X-ray diffraction data show that Ba[(Mg1−xCdx)0.33Nb0.67]O3 has an order trigonal structure. The ordering degree as determined by the B-site occupancies increases with the partial substitution of Cd for Mg. However, a decrease in the ordering degree in the Ba(Cd0.33Nb0.67)O3 sample is observed, which can be attributed to a relatively lower synthesis temperature. All the impurity phases are successfully identified by X-ray quantitative phase analysis. Dielectrics properties at low frequencies for all the Ba[(Mg1−xCdx)0.33Nb0.67]O3 compounds have been measured successfully.

Synthesis, crystal structure, and vibrational spectra of the complex maleic acid•2H2O•18-crown-6

1990 ◽  
Vol 68 (12) ◽  
pp. 2183-2189 ◽  
Author(s):  
Pierre Audet ◽  
Rodrigue Savoie ◽  
Michel Simard
Keyword(s):  
Crystal Structure ◽  
Water Molecule ◽  
Maleic Acid ◽  
Water Molecules ◽  
Infrared And Raman Spectra ◽  
X Ray Diffraction ◽  
Monoclinic System ◽  
X Ray ◽  
O 18 ◽  
Stoichiometric Complex

A stoichiometric complex of formula maleic acid•2H2O•18-crown-6 has been obtained from maleic acid and the macrocyclic polyether 18-crown-6. Crystals of this complex have been shown by X-ray diffraction crystallography to belong to the Cc space group of the monoclinic system. The acid molecules in the adduct are linked to each other through a water molecule, giving infinite [-acid-H2O-]n chains. They are also linked to the crown ether via water molecules. The infrared and Raman spectra of the complex are presented and compared to those of crystalline maleic acid. Keywords: maleic acid/18-crown-6, structure, X-ray, spectra.

scholarly journals Synthesis, structure, semiconductive and photoluminescent properties of [{Eu(NC5H4COOH)3(H2O)2}(1.5ZnCl4)·(2H2O)]n

2009 ◽  
Vol 74 (7) ◽  
pp. 755-764 ◽  
Author(s):  
Wen-Tong Chen ◽  
Xiao-Niu Fang ◽  
Qiu-Yan Luo ◽  
Ya-Ping Xu
Keyword(s):  
Hydrothermal Reaction ◽  
Isonicotinic Acid ◽  
Luminescence Spectra ◽  
X Ray Diffraction ◽  
Monoclinic System ◽  
One Dimensional ◽  
X Ray ◽  
Organic Hybrid ◽  
Hybrid Complex ◽  
A Cell

A novel bimetallic 4f-3d metal-isonicotinic acid inorganic-organic hybrid complex [{Eu(NC5H4COOH)3(H2O)2}(1.5ZnCl4)?(2H2O)]n (1) was synthesized via a hydrothermal reaction and structurally characterized by single- crystal X-ray diffraction. Complex 1 crystallizes in the space group C2/c of the monoclinic system with eight formula units in a cell: a = 23.878(8) ?, b = 20.573(6) ?, c = 15.358(5) ?, ? = 127.276(5)?, V = 6003(3) ?3, C18H23Cl6EuN3O10Zn1.5, Mr = 904.11 g/mol, ? = 2.001 g/cm3, S = 1.077, ?(MoK?) = 3.846 mm-1, F(000) = 3536, R = 0.0270 and wR = 0.0672. Complex 1 has a characteristic, one-dimensional polycationic chain-like structure. A photoluminescent investigation revealed that the title complex displays intense emissions in the orange and red regions. The luminescence spectra show that the red emission is stronger than the orange emission. Optical absorption spectra of 1 revealed the presence of an optical gap of 3.56 eV.

Evaluation of Cu-Ni-Based Alloys for Thermoelectric Energy Conversion

2021 ◽  
Vol 1016 ◽  
pp. 107-112
Author(s):  
Timon Steinhoff ◽  
Mario Wolf ◽  
Florian Nürnberger ◽  
Gregory Gerstein ◽  
Armin Feldhoff
Keyword(s):  
Electrical Conductivity ◽  
Thermoelectric Material ◽  
Power Factor ◽  
Partial Substitution ◽  
Specific Electrical Conductivity ◽  
X Ray Diffraction ◽  
X Ray ◽  
Arc Melting ◽  
Lattice Symmetry ◽  
Thermoelectric Energy

The recent revitalization of Ioffe plots (entropy conductivity versus electrical conductivity) reminds us that Isotan (Cu55Ni44Mn1) is an outstanding thermoelectric material with a power factor of up to 60 W cm-1 K-2 at a specific electrical conductivity of almost 20,000 S cm-1 at elevated temperature. Even though, Isotan is widely used in thermoelements for temperature measurement, its high open-circuited thermal conductivity of approximately 70 W cm-1 K-2 [1] hindered further research as a promising thermoelectric material. Isotan was chosen as a starting composition. Influence of partial substitution of Cu and Ni with heavy elements (Sn,W) on the thermoelectric properties was studied. The alloys were fabricated by arc-melting and microstructurally characterized for grain size and elemental composition by scanning electron microscope (SEM) combined with energy-dispersive X-ray (EDXS). Lattice symmetry and parameters were estimated by X-ray diffraction (XRD). Functional properties as Seebeck coefficient, electrical conductivity and power factor were used to evaluate the thermoelectric performance.

scholarly journals X-ray Crystallographic Study of Ranaconitine

2011 ◽  
Vol 6 (11) ◽  
pp. 1934578X1100601
Author(s):  
Yang Li ◽  
Jun-Hui Zhou ◽  
Gui-Jun Han ◽  
Min-Juan Wang ◽  
Wen-Ji Sun ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Diffraction Analysis ◽  
Critical Role ◽  
X Ray Diffraction ◽  
Monoclinic System ◽  
X Ray ◽  
Crystallographic Study ◽  
Cell Dimensions ◽  
Unit Cell Dimensions

The crystal structure of natural diterpenoid alkaloid ranaconitine isolated from Aconitum sinomontanum Nakai has been determined by single crystal X-ray diffraction analysis. The crystal presents a monoclinic system, space group C2 with Z = 4, unit cell dimensions a = 30.972(19) Å, b = 7.688(5) Å, and c = 19.632(12) Å. Moreover, the intermolecular O–H···O hydrogen bonds and weak π-π interactions play a critical role in expanding the dimensionality.

The Oxide Scale Growth Mechanism on Fe20Cr5Al+RE Alloy in SO2+O2

2009 ◽  
Vol 289-292 ◽  
pp. 541-550 ◽  
Author(s):  
Jerzy Jedlinski ◽  
Zbigniew Żurek ◽  
Martah Homa ◽  
G. Smoła ◽  
J. Camra
Keyword(s):  
Phase Composition ◽  
Secondary Ion Mass Spectrometry ◽  
Grazing Angle ◽  
Oxidation Mechanism ◽  
Complex Oxide ◽  
X Ray Diffraction ◽  
X Ray ◽  
Thin Foils ◽  
Manufacturing Procedure ◽  
Secondary Ion

The oxidation mechanism of FeCrAl (+RE), RE: reactive elements: Y and Hf) thin foils was studied at temperatures ranging from 1093 K to 1173 K in SO2+1%O2 atmosphere. Materials were subjected to isothermal and thermal cycling exposures as well as to the so-called two-stage-oxidation. In the latter, an oxygen isotope 18O2 was used as a tracer. Starting materials and scales were characterized using Grazing Angle X-Ray Diffraction (GA-XRD), EDX, SEM, XPS and High Spatial Resolution Secondary Ion Mass Spectrometry (HSR-SIMS). The obtained results showed within the studied range of exposure conditions the scales on all the studied alloys grow via outward mechanism typical for transient oxides and not for the -Al2O3 which is consistent with phase composition results and scale morphology and/or microstructure. It was also found that ‘as received’ foils are not bare metals but complex oxide-on-metal systems resulting from their manufacturing procedure. The obtained results are discussed in terms of the diffusion-related transport properties of the scale and of the scale phase composition.

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