Layered Manganese Bismuth Tellurides with GeBi4Te7– and GeBi6Te10–type Structures: Towards Multifunctional Materials

The crystal structures of new layered manganese bismuth tellurides with the compositions Mn0.85(3)Bi4.10(2)Te7 and Mn0.73(4)Bi6.18(2)Te10 were determined by single-crystal X-ray diffraction, including the use of microfocused synchrotron radiation. These analyses reveal that the layered structures deviate from the idealized stoichiometry of the 12P-GeBi4Te7 (space group P3m1) and 51R-GeBi6Te10 (space group R3m) structure types they adopt. Modified compositions Mn1–xBi4+2x/3Te7 (x = 0.15 – 0.2) and Mn1–xBi6+2x/3Te10 (x = 0.19 – 0.26) assume cation vacancies and lead to homogenous bulk samples as confirmed by Rietveld refinements. Electron diffraction patterns exhibit no diffuse streaks that would indicate stacking disorder. The alternating quintuple-layer [M2Te3] and septuple-layer [M3Te4] slabs (M = mixed occupied by Bi and Mn) with 1:1 sequence (12P stacking) in Mn0.85Bi4.10Te7 and 2:1 sequence (51R stacking) in Mn0.81Bi6.13Te10 were also observed in HRTEM images. Temperature-dependent powder diffraction and differential scanning calorimetry show that the compounds are high temperature phases, which are metastable at ambient temperature. Magnetization measurements are in accordance with a MnII oxidation state and point at predominantly ferromagnetic coupling in both compounds. The thermoelectric figures of merit of n-type conducting Mn0.85Bi4.10Te7 and Mn0.81Bi6.13Te10 reach zT = 0.25 at 375 °C and zT = 0.28 at 325 °C, respectively. Although the compounds are metastable, compact ingots exhibit still up to 80% of the main phases after thermoelectric measurements up to 400 °C.

Download Full-text

Structure determination of forms I and II of phenobarbital from X-ray powder diffraction

Acta Crystallographica Section B Structural Science ◽

10.1107/s0108768104031143 ◽

2005 ◽

Vol 61 (1) ◽

pp. 80-88 ◽

Cited By ~ 19

Author(s):

Cyril Platteau ◽

Jacques Lefebvre ◽

Stephanie Hemon ◽

Carsten Baehtz ◽

Florence Danede ◽

...

Keyword(s):

X Ray Diffraction ◽

Rietveld Refinements ◽

Space Group ◽

X Ray ◽

Bragg Peak Profiles ◽

Monte Carlo Simulated Annealing ◽

Crystal Structural ◽

Diffraction Patterns ◽

Annealing Method

From pure powders of forms I and II of phenobarbital, X-ray diffraction patterns were recorded at room temperature. The starting crystal structural models were found by a Monte-Carlo simulated annealing method. The structures of the two forms were obtained through Rietveld refinements. Soft restraints were applied on bond lengths and bond angles, all H-atom positions were calculated. The cell of form I is monoclinic with the space group P21/n, Z = 12, Z′ = 3. Form II has a triclinic cell, with the space group P\bar 1, Z = 6, Z′ = 3. For both forms, the crystal cohesion is achieved by networks of N—H...O hydrogen bonds along [101]. The broadening of the Bragg peak profiles is interpreted in terms of isotropic strain effects and anisotropic size effects.

Download Full-text

Crystallographic studies and X-ray diffraction patterns of Ba5R8Zn4O21 by Rietveld refinements

Powder Diffraction ◽

10.1154/1.1367261 ◽

2001 ◽

Vol 16 (3) ◽

pp. 131-143 ◽

Cited By ~ 8

Author(s):

W. Wong-Ng ◽

J. A. Kaduk ◽

J. Dillingham

Keyword(s):

X Ray Diffraction ◽

Rietveld Refinements ◽

Space Group ◽

X Ray ◽

Diffraction Patterns ◽

Trigonal Prisms

The structure of the Ba5R8Zn4O21 series (R=lanthanides) was investigated using X-ray Rietveld refinements. The compounds were successfully prepared for R=Eu, Gd, Dy, Ho, Er, Tm, and Yb. Ba5R8Zn4O21 crystallizes in the tetragonal space group I4/m; for R=Yb to Eu, a ranges from 13.635 02(5) to 13.960 62(9) Å, c from 5.658 46(3) to 5.784 83(5) Å, and V from 1051.987(8) to 1127.459(14) Å3. The Zn2+ ions adopt a fivefold distorted square pyramidal coordination. The seven-coordinate R3+ reside in monocapped trigonal prisms. These prisms share edges, and form layers stacked along the c axis. There are two types of BaO polyhedra: bicapped square prisms (BaO10), and irregular BaO10 polyhedra. For larger R, Ba5R8Zn4O21 was not stable, and tetragonal BaR2ZnO5(La, Nd) and orthorhombic BaR2ZnO5(Sm) phases were observed instead.

Download Full-text

X-ray diffraction patterns for BaR2PdO5 (R=Nd, Sm, Eu, and Gd)

Powder Diffraction ◽

10.1017/s0885715600008800 ◽

1996 ◽

Vol 11 (1) ◽

pp. 9-12

Author(s):

W. Wong-Ng

Keyword(s):

Materials Characterization ◽

X Ray Diffraction ◽

Space Group ◽

X Ray ◽

Cell Parameters ◽

Diffraction Patterns ◽

The Eu

Calculated patterns for the BaR2PdO5 series, in which X is Pd and R=Nd, Sm, Eu, or Gd, have been prepared for materials characterization until experimental patterns can be determined. These compounds are isostructural to the superconductor related “brown phases” BaLa2CuO5 and BaNd2CuO5, which are tetragonal with space group P4/mbm, Z=4. The cell parameters of the Eu and Gd compounds were derived from the La and Nd analogs. The calculated patterns of these four compounds compared well to an experimental pattern of BaNd2CuO5.

Download Full-text

CRYSTAL STRUCTURE OF ZIRCONIUM TRICHLORIDE

Canadian Journal of Physics ◽

10.1139/p64-177 ◽

1964 ◽

Vol 42 (10) ◽

pp. 1886-1889 ◽

Cited By ~ 8

Author(s):

B. Swaroop ◽

S. N. Flengas

Keyword(s):

Crystal Structure ◽

Room Temperature ◽

X Ray Diffraction ◽

Space Group ◽

X Ray ◽

Main Cell ◽

Diffraction Patterns

The crystal structure of zirconium trichloride was determined from X-ray diffraction patterns. Zirconium trichloride belongs to the [Formula: see text]space group. The dimensions of the main cell at room temperature are: a = 5.961 ± 0.005 Å and c = 9.669 ± 0.005 Å.The density of zirconium trichloride was measured and gave the value of 2.281 ± 0.075 g/cm3 while, from the X-ray calculations, the value was found to be 2.205 g/cm3.

Download Full-text

Preparation by solution mixing and characterization of condensation type poly(dimethyl siloxane)/graphene nanoplatelets composites

Journal of Composite Materials ◽

10.1177/00219983211055824 ◽

2021 ◽

pp. 002199832110558

Author(s):

Panayiotis Ketikis ◽

Efthimios Damopoulos ◽

Georgios Pilatos ◽

Panagiotis Klonos ◽

Apostolos Kyritsis ◽

...

Keyword(s):

Graphene Nanoplatelets ◽

Matrix Composites ◽

Dielectric Relaxation Spectroscopy ◽

X Ray Diffraction ◽

Scanning Calorimetry ◽

Melting Temperatures ◽

Dimethyl Siloxane ◽

Diffraction Patterns ◽

The Impact

The impact of the incorporation of graphene nanoplatelets (GN) on the properties of hydroxyl-terminated poly(dimethylsiloxane) (PDMS) matrices was investigated. The composites were prepared by solution mixing, using tetrahydrofuran (THF) as a solvent. Brookfield viscosimetry, implemented during the vulcanization process, revealed that GN increases the viscosity of the system, compared to pristine PDMS, proportionally to its concentration. X-ray diffraction patterns suggested an efficient dispersion of GN in the polysiloxane matrix. The D and G bands ratio (ID/IG) calculation, based on RAMAN spectra of GN/PDMS specimens, revealed more defects in graphene nanoplatelets when incorporated in the PDMS matrix. By differential scanning calorimetry (DSC), a marginal increase in crystallization, glass transition and melting temperatures of PDMS in GN/PDMS composites was observed. Improvement of the thermal stability of LMW PDMS composites, especially for higher GN concentrations (3 and 5 phr), was noticed by thermogravimetric analysis (TGA). Additionally, GN enhanced the tensile strength of composites, up to 73% for the 3 phr GN/LMW PDMS composite. A significant increase in the elongation at break was recorded, whereas no effect on the modulus of elasticity was recorded. The decrease in toluene-swelling, for the LMW PDMS matrix composites, was attributed to the increase in the tortuosity path because of the efficient dispersion of GN. A decrease in oxygen permeability of 55–65% and 44–58% was measured in membranes made of PDMS composites containing 0.5 phr and 1 phr GN, respectively. Dielectric relaxation spectroscopy (DRS) measurements recorded a significant increase in the conductivity of the higher graphene content composites.

Download Full-text

The structures and phase transitions in 4-aminopyridinium tetraaquabis(sulfato)iron(III), (C5H7N2)[FeIII(H2O)4(SO4)2]

Acta Crystallographica Section B Structural Science Crystal Engineering and Materials ◽

10.1107/s2052520619013155 ◽

2019 ◽

Vol 75 (6) ◽

pp. 1144-1151

Author(s):

Tamara J. Bednarchuk ◽

Wolfgang Hornfeck ◽

Vasyl Kinzhybalo ◽

Zhengyang Zhou ◽

Michal Dušek ◽

...

Keyword(s):

Phase Transitions ◽

Single Crystal ◽

Room Temperature ◽

Variable Temperature ◽

Temperature Phase ◽

X Ray Diffraction ◽

Scanning Calorimetry ◽

Hybrid Compound ◽

Space Group ◽

X Ray

The organic–inorganic hybrid compound 4-aminopyridinium tetraaquabis(sulfato)iron(III), (C5H7N2)[FeIII(H2O)4(SO4)2] (4apFeS), was obtained by slow evaporation of the solvent at room temperature and characterized by single-crystal X-ray diffraction in the temperature range from 290 to 80 K. Differential scanning calorimetry revealed that the title compound undergoes a sequence of three reversible phase transitions, which has been verified by variable-temperature X-ray diffraction analysis during cooling–heating cycles over the temperature ranges 290–100–290 K. In the room-temperature phase (I), space group C2/c, oxygen atoms from the closest Fe-atom environment (octahedral) were disordered over two equivalent positions around a twofold axis. Two intermediate phases (II), (III) were solved and refined as incommensurately modulated structures, employing the superspace formalism applied to single-crystal X-ray diffraction data. Both structures can be described in the (3+1)-dimensional monoclinic X2/c(α,0,γ)0s superspace group (where X is ½, ½, 0, ½) with modulation wavevectors q = (0.2943, 0, 0.5640) and q = (0.3366, 0, 0.5544) for phases (II) and (III), respectively. The completely ordered low-temperature phase (IV) was refined with the twinning model in the triclinic P{\overline 1} space group, revealing the existence of two domains. The dynamics of the disordered anionic substructure in the 4apFeS crystal seems to play an essential role in the phase transition mechanisms. The discrete organic moieties were found to be fully ordered even at room temperature.

Download Full-text

Structure and properties of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate)/poly(L-lactic acid) quasi core/sheath melt-electrospun microfibers

Textile Research Journal ◽

10.1177/0040517518779997 ◽

2018 ◽

Vol 89 (9) ◽

pp. 1770-1781 ◽

Cited By ~ 1

Author(s):

Huaizhong Xu ◽

Benedict Bauer ◽

Masaki Yamamoto ◽

Hideki Yamane

Keyword(s):

Mechanical Properties ◽

Tensile Strength ◽

Lactic Acid ◽

Tensile Tests ◽

Processing Parameters ◽

Structure And Properties ◽

X Ray Diffraction ◽

Scanning Calorimetry ◽

X Ray ◽

Diffraction Patterns

A facile route was proposed to fabricate core–sheath microfibers, and the relationships among processing parameters, crystalline structures and the mechanical properties were investigated. The compression molded poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH)/poly(L-lactic acid) (PLLA) strip enhanced the spinnability of PHBH and the mechanical properties of PLLA as well. The core–sheath ratio of the fibers was determined by the prefab strip, while the PLLA sheath component did not completely cover the PHBH core component due to the weak interfacial tension between the melts of PHBH and PLLA. A rotational target was applied to collect aligned fibers, which were further drawn in a water bath. The tensile strength and the modulus of as-spun and drawn fibers increased with increasing the take-up velocities. When the take-up velocity was above 500 m/min, the jet became unstable and started to break up at the tip of the Taylor cone, decreasing the mechanical properties of the fibers. The drawing process facilitated the crystallization of PLLA and PHBH, and the tensile strength and the modulus increased linearly with the increasing the draw ratio. The crystal information displayed from wide-angle X-ray diffraction patterns and differential scanning calorimetry heating curves supported the results of the tensile tests.

Download Full-text

New crystal structures in the realm of 5,5′-azotetrazolates

Zeitschrift für Naturforschung B ◽

10.1515/znb-2014-0222 ◽

2015 ◽

Vol 70 (2) ◽

pp. 125-134 ◽

Cited By ~ 1

Author(s):

Martin Lampl ◽

Gerhard Laus ◽

Doris E. Braun ◽

Volker Kahlenberg ◽

Klaus Wurst ◽

...

Keyword(s):

Differential Scanning Calorimetry ◽

Single Crystal ◽

Crystal Structures ◽

Organic Cations ◽

X Ray Diffraction ◽

Scanning Calorimetry ◽

X Ray ◽

Diffraction Patterns

AbstractThe preparation of six new 5,5′-azotetrazolates with organic cations is reported. Differential scanning calorimetry of all compounds showed exothermic decompositions. The crystal structures of the six 5,5′-azotetrazolates were determined by single-crystal X-ray diffraction analyses. The phase purities of the bulk samples were confirmed by Pawley fits of the experimental and calculated powder X-ray diffraction patterns.

Download Full-text

Crystal structure, electrical, and thermal properties of Ca0.5Th0.5VO4

Journal of Materials Research ◽

10.1557/jmr.2009.0449 ◽

2009 ◽

Vol 24 (12) ◽

pp. 3551-3558 ◽

Cited By ~ 7

Author(s):

S.J. Patwe ◽

S. Nagabhusan Achary ◽

Avesh K. Tyagi

Keyword(s):

Crystal Structure ◽

Thermal Expansion ◽

X Ray Diffraction ◽

Temperature Dependent ◽

Rietveld Refinements ◽

Cell Parameters ◽

Expansion Behavior ◽

High Temperature Xrd ◽

Zircon Type

Ca0.5Th0.5VO4 was prepared by a solid-state reaction of component oxides and characterized by powder x-ray diffraction (XRD) at ambient and higher temperatures and impedance spectroscopy. Crystal structure was refined by Rietveld refinements from powder XRD data. At room temperature, Ca0.5Th0.5VO4 has a zircon-type tetragonal (I41/amd) lattice with unit cell parameters: a = 7.2650(1) and c = 6.4460(1) Å. Despite the large charge difference, Ca2+ and Th4+ are statistically distributed over a single site. The crystal structure of Ca0.5Th0.5VO4 is built from the (Ca/Th)O8 (bisdisphenoid) and VO4 tetrahedra. The in situ high-temperature XRD studies on Ca0.5Th0.5VO4 revealed anisotropic thermal expansion behavior with coefficients of thermal expansion αc = 10.96 × 10−6/°C and αa = 5.32 × 10−6/°C. The impedance measurements carried out in the temperature range from ambient to 800 °C indicate semiconducting behavior with appreciable ionic conductivity above 400 °C. The activation energy obtained from the temperature-dependent AC conductivity data is ∼1.37 eV. In wider range of frequencies and temperatures, the relative permittivity of approximately 50 to 60 is observed for Ca0.5Th0.5VO4.

Download Full-text