scholarly journals Layered manganese bismuth tellurides with GeBi4Te7- and GeBi6Te10-type structures: towards multifunctional materials

2019 ◽  
Vol 7 (32) ◽  
pp. 9939-9953 ◽  
Author(s):  
Daniel Souchay ◽  
Markus Nentwig ◽  
Daniel Günther ◽  
Simon Keilholz ◽  
Johannes de Boor ◽  
...  
Keyword(s):  
Single Phase ◽  
Layered Compounds ◽  
Multifunctional Materials ◽  
Bismuth Tellurides ◽  
Manganese Bismuth ◽  
Multifunctional Properties

Non-stoichiometry is the key to single-phase layered compounds in the system Mn/Bi/Te, which is essential to evaluate their multifunctional properties.

Electrolytic V2O5: Synthesis, Characterization and Lithium Insertion Behavior

1999 ◽  
Vol 575 ◽  
Author(s):  
E. Potiron ◽  
A. Le Galla Salle ◽  
A. Verbaere ◽  
Y Piffard ◽  
D. Guyomard
Keyword(s):  
Single Phase ◽  
Mixed Valence ◽  
Reversible Capacity ◽  
Layered Compounds ◽  
Lithium Insertion ◽  
Capacity Retention ◽  
Electrochemical Intercalation ◽  
Soluble Species ◽  
Water Contents ◽  
Better Than

ABSTRACTElectrolytic V2O5 materials were prepared by electrochemical oxidation of vanadyl ions in aqueous solution. The electrodeposition reaction includes two steps: an oxidation into soluble species followed by a precipitation. With the use of various electrodeposition conditions and subsequent heat treatment it is possible to obtain e-V2O5 compounds with different VIV and water contents.e-V2O5 compounds are mixed valence, hydrated vanadic acids and their formula can be written as H0.4V2O5.2−δ.nH2 with 0.04<8<0.22 and 0<n<1.8. These poorly crystallized layered compounds undergo a phase transformation into α-V2O5 starting at 240°C.The electrochemical intercalation of lithium into these compounds shows two main single phase phenomena at ≈3.2V/Li and ≈2.6V/Li. Their capacity retention is better than that of other V2O5 reference compounds, but the reversible capacity down to 2V is only ≈100Ah/kg at a rate faster than C/5, due to kinetic limitations.

Carboxylated graphene–TiO2 hybrids as multifunctional materials: from photocatalysis to peroxidase alternatives

RSC Advances ◽  
2016 ◽  
Vol 6 (55) ◽  
pp. 49845-49851 ◽  
Author(s):  
M. Sarro ◽  
M. Cerruti ◽  
P. Calza ◽  
L. Anfossi
Keyword(s):  
Hybrid Materials ◽  
Graphene Nanoplatelets ◽  
Multifunctional Materials ◽  
Carboxylic Groups ◽  
Multifunctional Properties

Hybrid materials with multifunctional properties were synthetized by coupling graphene nanoplatelets modified with carboxylic groups to TiO2 and applied as photocatalyst and as tracers of the presence of a model antigen in immunochemical assays.

Novel ternary layered manganese bismuth tellurides of the MnTe-Bi2Te3 system: Synthesis and crystal structure

2019 ◽  
Vol 789 ◽  
pp. 443-450 ◽  
Author(s):  
Ziya S. Aliev ◽  
Imamaddin R. Amiraslanov ◽  
Daria I. Nasonova ◽  
Andrei V. Shevelkov ◽  
Nadir A. Abdullayev ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Synthesis And Crystal Structure ◽  
System Synthesis ◽  
Bismuth Tellurides ◽  
Manganese Bismuth

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

2019 ◽  
Author(s):  
Daniel Souchay ◽  
Markus Nentwig ◽  
Daniel Günther ◽  
Simon Keilholz ◽  
Johannes de Boor ◽  
...  
Keyword(s):  
X Ray Diffraction ◽  
Temperature Dependent ◽  
Scanning Calorimetry ◽  
Rietveld Refinements ◽  
Space Group ◽  
Thermoelectric Measurements ◽  
Diffraction Patterns ◽  
Bismuth Tellurides ◽  
Manganese Bismuth ◽  
Stacking Disorder

<p>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 12<i>P</i>-GeBi4Te7 (space group <i>P</i>3<i>m</i>1) and 51<i>R</i>-GeBi6Te10 (space group <i>R</i>3<i>m</i>) structure types they adopt. Modified compositions Mn1–<i>x</i>Bi4+2<i>x</i>/3Te7 (<i>x </i>= 0.15 – 0.2) and Mn1–<i>x</i>Bi6+2<i>x</i>/3Te10 (<i>x </i>= 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 (12<i>P </i>stacking) in Mn0.85Bi4.10Te7 and 2:1 sequence (51<i>R </i>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 <i>zT </i>= 0.25 at 375 °C and <i>zT </i>= 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.</p>

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

2019 ◽  
Author(s):  
Daniel Souchay ◽  
Markus Nentwig ◽  
Daniel Günther ◽  
Simon Keilholz ◽  
Johannes de Boor ◽  
...  
Keyword(s):  
X Ray Diffraction ◽  
Temperature Dependent ◽  
Scanning Calorimetry ◽  
Rietveld Refinements ◽  
Space Group ◽  
Thermoelectric Measurements ◽  
Diffraction Patterns ◽  
Bismuth Tellurides ◽  
Manganese Bismuth ◽  
Stacking Disorder

<p>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 12<i>P</i>-GeBi4Te7 (space group <i>P</i>3<i>m</i>1) and 51<i>R</i>-GeBi6Te10 (space group <i>R</i>3<i>m</i>) structure types they adopt. Modified compositions Mn1–<i>x</i>Bi4+2<i>x</i>/3Te7 (<i>x </i>= 0.15 – 0.2) and Mn1–<i>x</i>Bi6+2<i>x</i>/3Te10 (<i>x </i>= 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 (12<i>P </i>stacking) in Mn0.85Bi4.10Te7 and 2:1 sequence (51<i>R </i>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 <i>zT </i>= 0.25 at 375 °C and <i>zT </i>= 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.</p>

Nanocomposites — the Multifunctional Family of Materials

1989 ◽  
Vol 175 ◽  
Author(s):  
Rustum Roy
Keyword(s):  
Single Phase ◽  
Sol Gel ◽  
Multifunctional Materials ◽  
Gel Processing ◽  
Successes And Failures

AbstractThis paper starts by discussing the concept of multifunctional materials. Multifunctionality can be achieved in a single phase in a composite or a mixture. While a few exceptional single phase materials such as diamond, Al2O3, CaSrZr4P6O24 exhibit peak values of more than one function, it will be argued that the “invention” of the nanocomposite class of materials made by solution sol-gel processing has opened up the potential for designing several multifunctional materials.Examples will be drawn from our recent results—both successes and failures—in trying to design and synthesize nanocomposites of two or more ceramic phases for various chemical, thermal, and electrical functions.

Two luminescent metal–organic frameworks with multifunctional properties for nitroaromatic compounds sensing and photocatalysis

RSC Advances ◽  
2015 ◽  
Vol 5 (86) ◽  
pp. 70086-70093 ◽  
Author(s):  
Fengqin Wang ◽  
Chengmiao Wang ◽  
Zongchao Yu ◽  
Qingguo He ◽  
Xiuyu Li ◽  
...  
Keyword(s):  
Metal Organic Frameworks ◽  
Nitroaromatic Compounds ◽  
Multifunctional Materials ◽  
Metal Organic ◽  
Multifunctional Properties

Two luminescent MOFs were employed as multifunctional materials for selectively sensing of nitroaromatic compounds and photodegradation of RhB.

Influence of Heat Treatments on Microstructures in an Fe-Co-V Alloy

1974 ◽  
Vol 32 ◽  
pp. 512-513
Author(s):  
S. Mahajan ◽  
M. R. Pinnel ◽  
J. E. Bennett
Keyword(s):  
Single Phase ◽  
Alloy Composition ◽  
Supersaturated Solid Solution ◽  
Cell Formation ◽  
Heat Treatments ◽  
Air Cooling ◽  
Iced Brine ◽  
Transmission Electron ◽  
The Matrix ◽  
Bcc Structure

The microstructural changes in an Fe-Co-V alloy (composition by wt.%: 2.97 V, 48.70 Co, 47.34 Fe and balance impurities, such as C, P and Ni) resulting from different heat treatments have been evaluated by optical metallography and transmission electron microscopy. Results indicate that, on air cooling or quenching into iced-brine from the high temperature single phase ϒ (fcc) field, vanadium can be retained in a supersaturated solid solution (α2) which has bcc structure. For the range of cooling rates employed, a portion of the material appears to undergo the γ-α2 transformation massively and the remainder martensitically. Figure 1 shows dislocation topology in a region that may have transformed martensitically. Dislocations are homogeneously distributed throughout the matrix, and there is no evidence for cell formation. The majority of the dislocations project along the projections of <111> vectors onto the (111) plane, implying that they are predominantly of screw character.

Raman And Fluorescence Spectra Observed in Laser Microprobe Measurements of Several Compositions in the Ln-Ba-Cu-O System

1990 ◽  
Vol 48 (2) ◽  
pp. 278-279
Author(s):  
Edgar S. Etz ◽  
Thomas D. Schroeder ◽  
Winnie Wong-Ng
Keyword(s):  
Fluorescence Spectra ◽  
Single Phase ◽  
X Ray Diffraction ◽  
Ceramic Powders ◽  
Conventional Solid State Reaction ◽  
X Ray ◽  
Raman Microprobe ◽  
Methods Of Synthesis ◽  
Compositional Homogeneity ◽  
Processing Techniques

We are investigating by Raman microprobe measurements the superconducting and related phases in the LnBa2Cu3O7-x (for x=0 to 1) system where yttrium has been replaced by several of the lanthanide (Ln = Nd,Sm,Eu,Ho,Er) elements. The aim is to relate the observed optical spectra (Raman and fluorescence) to the compositional and structural properties of these solids as part of comprehensive materials characterization. The results are correlated with the methods of synthesis, the processing techniques of these materials, and their superconducting properties. Of relevance is the substitutional chemistry of these isostructural systems, the differences in the spectra, and their microanalytical usefulness for the detection of impurity phases, and the assessment of compositional homogeneity. The Raman spectra of most of these compounds are well understood from accounts in the literature.The materials examined here are mostly ceramic powders prepared by conventional solid state reaction techniques. The bulk samples are of nominally single-phase composition as determined by x-ray diffraction.

Observation of pseudo 10-fold symmetry in the ordered iron-zinc delta phase

1992 ◽  
Vol 50 (1) ◽  
pp. 36-37
Author(s):  
L. A. Giannuzzi ◽  
A. S. Ramani ◽  
P. R. Howell ◽  
H. W. Pickering ◽  
W. R. Bitler
Keyword(s):  
Single Phase ◽  
X Ray Diffraction ◽  
Rich Region ◽  
Average Cell ◽  
X Ray ◽  
Delta Phase ◽  
Cell Dimensions ◽  
Δ Phase ◽  
Morphological Differences ◽  
Concentration Discontinuity

The δ phase is a Zn-rich intermetallic, having a composition range of ∼ 86.5 - 92.0 atomic percent Zn, and is stable up to 665°C. The stoichiometry of the δ phase has been reported as FeZn7 and FeZn10 The deviation in stoichiometry can be attributed to variations in alloy composition used by each investigator. The structure of the δ phase, as determined by powder x-ray diffraction, is hexagonal (P63mc or P63/mmc) with cell dimensions a = 1.28 nm, c = 5.76 nm, and 555±8 atoms per unit cell. Later work suggested that the layer produced by hot-dip galvanizing should be considered as two distinct phases which are characterized by their morphological differences, namely: the iron-rich region with a compact appearance (δk) and the zinc-rich region with a columnar or palisade microstructure (δp). The sub-division of the δ phase was also based on differences in diffusion behavior, and a concentration discontinuity across the δp/δk boundary. However, work utilizing Weisenberg photographs on δ single crystals reported that the variation in lattice parameters with composition was small and hence, structurally, the δk phase and the δp phase were the same and should be thought of as a single phase, δ. Bastin et al. determined the average cell dimensions to be a = 1.28 nm and c = 5.71 nm, and suggested that perhaps some kind of ordering process, which would not be observed by x-ray diffraction, may be responsible for the morphological differences within the δ phase.

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