Influence of Reduced Na Vacancy Concentrations in the Sodium Superionic Conductors Na11+xSn2P1−xMxS12 (M = Sn, Ge)

10.26434/chemrxiv.14576802.v1 ◽

2021 ◽

Author(s):

Marvin Kraft ◽

Lara Gronych ◽

Theodosios Famprikis ◽

Wolfgang Zeier

Keyword(s):

Structural Changes ◽

Electrochemical Impedance ◽

Vacancy Concentration ◽

Structure Type ◽

Superionic Conductors ◽

X Ray Diffraction ◽

Rietveld Refinements ◽

Sodium Batteries ◽

Aliovalent Substitution ◽

Vacancy Concentrations

Exploration of sulfidic sodium solid electrolytes and their design contributes to advances in solid state sodium batteries. Such design is guided by a better understanding of fast sodium transport, for instance in the herein studied Na11Sn2PS12-type materials. By using Rietveld refinements against synchrotron X-ray diffraction and electrochemical impedance spectroscopy, the influence of aliovalent substitution onto the structure and transport in Na11+xSn2P1−xMxS12 with M = Ge and Sn is investigated. Whereas Sn induces stronger structural changes than Ge, the found influence on the sodium sublattice and the ionic transport properties are comparable. Overall, a reduced in-grain activation energy of Na+ transport can be found with the reducing Na+ vacancy concentration. This work explores previously unreported phases in the Na11Sn2PS12 structure type that, based on their determined properties reveal Na+ vacancy concentrations to be an important factor guiding further understanding within Na11Sn2PS12-type materials.

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Structural, Morphological, Electrical and Electrochemical Properties of PVA: CS-Based Proton-Conducting Polymer Blend Electrolytes

Membranes ◽

10.3390/membranes10040071 ◽

2020 ◽

Vol 10 (4) ◽

pp. 71 ◽

Cited By ~ 17

Author(s):

Ayub Shahab Marf ◽

Ranjdar M. Abdullah ◽

Shujahadeen B. Aziz

Keyword(s):

Polymer Blend ◽

Structural Changes ◽

Electrochemical Impedance ◽

Low Frequency ◽

Linear Sweep Voltammetry ◽

Transference Number ◽

Poly Vinyl Alcohol ◽

X Ray Diffraction ◽

The Relationship ◽

Added Salt

Polymer blend electrolytes based on poly(vinyl alcohol):chitosan (PVA:CS) incorporated with various quantities of ammonium iodide were prepared and characterized using a range of electrochemical, structural and microscopic techniques. In the structural analysis, X-ray diffraction (XRD) was used to confirm the buildup of the amorphous phase. To reveal the effect of dopant addition on structural changes, field-emission scanning electron microscope (FESEM) was used. The protrusions of salt aggregates with large quantity were seen at the surface of the formed films at 50 wt.% of the added salt. The nature of the relationship between conductivity and dielectric properties was shown using electrochemical impedance spectroscopy (EIS). The EIS spectra were fitted with electrical equivalent circuits (EECs). It was observed that both dielectric constant and dielectric loss were high in the low-frequency region. For all samples, loss tangent and electric modulus plots were analyzed to become familiar with the relaxation behavior. Linear sweep voltammetry (LSV) and transference number measurement (TNM) were recorded. A relatively high cut-off potential for the polymer electrolyte was obtained at 1.33 V and both values of the transference number for ion (tion) and electronic (telec) showed the ion dominant as charge carrier species. The TNM and LSV measurements indicate the suitability of the samples for energy storage application if their conductivity can be more enhanced.

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Thermal Stability and Thermoelectric Properties of NaZnSb

Materials ◽

10.3390/ma12010048 ◽

2018 ◽

Vol 12 (1) ◽

pp. 48 ◽

Cited By ~ 4

Author(s):

Volodymyr Gvozdetskyi ◽

Bryan Owens-Baird ◽

Sangki Hong ◽

Julia Zaikina

Keyword(s):

High Temperature ◽

Thermoelectric Properties ◽

Structural Changes ◽

Theoretical Calculations ◽

Sodium Hydride ◽

Structure Type ◽

X Ray Diffraction ◽

Plasma Sintering ◽

Semiconductor Behavior ◽

Spark Plasma

A layered Zintl antimonide NaZnSb (PbClF or Cu2Sb structure type; P4/nmm) was synthesized using the reactive sodium hydride NaH precursor. This method provides comprehensive compositional control and facilitates the fast preparation of high-purity samples in large quantities. NaZnSb is highly reactive to humidity/air and hydrolyzes to NaOH, ZnO, and Sb in aerobic conditions. On the other hand, NaZnSb is thermally stable up to 873 K in vacuum, as no structural changes were observed from high-temperature synchrotron powder X-ray diffraction data in the 300–873 K temperature range. The unit cell expansion upon heating is isotropic; however, interatomic distance elongation is not isotropic, consistent with the layered structure. Low- and high-temperature thermoelectric properties were measured on pellets densified by spark plasma sintering. The resistivity of NaZnSb ranges from 11 mΩ∙cm to 31 mΩ∙cm within the 2–676 K range, consistent with heavily doped semiconductor behavior, with a narrow band gap of 0.23 eV. NaZnSb has a large positive Seebeck coefficient (244 μV∙K−1 at 476 K), leading to the maximum of zT of 0.23 at 675 K. The measured thermoelectric properties are in good agreement with those predicted by theoretical calculations.

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Surface and Electrochemical Analysis of Titanium Submitted to Alkaline Treatment by SEM, XRD and EIS

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.396-398.381 ◽

2008 ◽

Vol 396-398 ◽

pp. 381-384 ◽

Cited By ~ 1

Author(s):

Eduardo Mioduski Szesz ◽

Cláudia E. B. Marino ◽

Haroldo A. Ponte ◽

Fabiana C. Nascimento ◽

Carlos M. Lepienski ◽

...

Keyword(s):

Structural Changes ◽

Electrochemical Impedance ◽

Alkali Treatment ◽

Sodium Titanate ◽

Impedance Analysis ◽

Alkaline Treatment ◽

Electrochemical Analysis ◽

Titanium Metal ◽

X Ray Diffraction ◽

X Ray

Although titanium metal has been used intensively in the last years as biomaterial in the medical and dental areas its surface is not bioactive. In this work, titanium metal was submitted to an alkali treatment in order to make the metal surface bioactive. The samples were submitted to alkaline treatment (AT) using NaOH 5M aqueous solution at 60°C for 24 h and after that they were heated thermically to stabilize the layer obtained with AT. The bioactivity of the samples was evaluated soaking them into the simulated body fluid (SBF) at 36,5°C for 28 days. The morphological, structural changes and the electrochemical characterization were analyzed using scanning electron microscopy, x-ray diffraction and electrochemical impedance spectroscopy (EIS), respectively. It was verified that after AT plus heat treatment (HT) a sodium titanate layer was formed on the samples surface and after the bioactivity tests an apatite layer was formed. Impedance analysis show that the resistance of film on Ti is high and this value increases when the sample is soaked in SBF. It means that the apatite (HPA) film is occurring and the value of the capacitance with the presence of the HPA film (Cp) values indicate that the film maintain a compact and uniform characteristics.

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A Comparative Study of Lithium and Sodium Insertion in Two Block Structure Type Phases, W3Nb14O44 and W4Nb26O77

MRS Proceedings ◽

10.1557/proc-453-659 ◽

1996 ◽

Vol 453 ◽

Cited By ~ 1

Author(s):

Antonio F. Fuentes ◽

A. Martinez De La Cruz ◽

Leticia M. Torres-Martinez

Keyword(s):

Comparative Study ◽

Structural Changes ◽

Block Structure ◽

Substantial Reduction ◽

Structure Type ◽

Lithium Insertion ◽

X Ray Diffraction ◽

Lithium Ions ◽

X Ray ◽

Metal Atoms

AbstractA comparative study of lithium insertion in W4Nb26O77 and W3Nb14O44, two block structure type phases, has been carried out. This process is, in both cases, reversible for a similar number of lithium ions incorporated to total metal atoms ratio (Li/ΣM), 1.15 in W3Nb14O44 and 1.23 in W4Nb26O77. No significant structural changes are seen by X-ray diffraction upon insertion. Sodium insertion in W3Nb14O44 has been also studied observing a substantial reduction on the number of ions incorporated when compared with lithium (Na/ΣM: 0.03).

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On the Properties of an Ion Conductive System Incorporated in Hybrid Films

MRS Proceedings ◽

10.1557/proc-628-cc6.19 ◽

2000 ◽

Vol 628 ◽

Author(s):

G. González ◽

P. J. Retuert ◽

S. Fuentes

Keyword(s):

Electrochemical Impedance ◽

Ternary Phase Diagram ◽

Lithium Perchlorate ◽

Molar Ratio ◽

Ionic Conductors ◽

X Ray Diffraction ◽

Poly Ethylene Oxide ◽

Ion Conducting ◽

Poly Ethylene ◽

High Degree

ABSTRACTBlending the biopolymer chitosan (CHI) with poly (aminopropilsiloxane) oligomers (pAPS), and poly (ethylene oxide) (PEO) in the presence of lithium perchlorate lead to ion conducting products whose conductivity depends on the composition of the mixture. A ternary phase diagram for mixtures containing 0.2 M LiClO4 shows a zone in which the physical properties of the products - transparent, flexible, mechanically robust films - indicate a high degree of molecular compatibilization of the components. Comparison of these films with binary CHI-pAPS nanocomposites as well as the microscopic aspect, thermal behavior, and X-ray diffraction pattern of the product with the composition PEO/CHI/pAPS/LiClO4 1:0.5:0.6:0.2 molar ratio indicates that these films may be described as a layered nanocomposite. In this composite, lithium species coordinated by PEO and pAPS should be inserted into chitosan layers. Electrochemical impedance spectroscopy measurements indicate the films are pure ionic conductors with a maximal bulk conductivity of 1.7*10-5 Scm-1 at 40 °C and a sample-electrode interface capacitance of about 1.2*10-9 F.

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Effect of Zn Content on Structure, Roughness and Corrosion Behavior of Zn-Ni Alloys

Scientific Bulletin of Valahia University - Materials and Mechanics ◽

10.2478/bsmm-2019-0013 ◽

2019 ◽

Vol 17 (17) ◽

pp. 17-22

Author(s):

Hayette Faid

Keyword(s):

Corrosion Behavior ◽

Electrochemical Impedance ◽

Stripping Voltammetry ◽

X Ray Diffraction ◽

X Ray ◽

Ni Alloys ◽

Sulfate Bath ◽

Zn Content ◽

Polarization Test ◽

Δ Phase

AbstractIn this work, Zn-Ni alloys have been deposited on steel from sulfate bath, by electrodeposition method. The effect of Zn content on deposits properties was studied by cyclic voltammetry (CV), chronoaperometry (CA), linear stripping voltammetry (ALSV) and diffraction (XRD) and scanning electronic microscopy (SEM). The corrosion behavior in 3.5 wt. NaCl solution was examined using anodic polarization test and electrochemical impedance spectroscopy. X-ray diffraction of show that Zn-Ni alloys structure is composed of δ phase and γ phase, which increase with the decrease of Zn content in deposits. Results show that deposits obtained from bath less Zn2+ concentration exhibited better corrosion resistance.

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Exploring the Influence of Substitution on the Structure and Transport Properties in the Sodium Superionic Conductor Na11+xSn2+x(Sb1−yPy)1−xS12

10.26434/chemrxiv.12278237.v1 ◽

2020 ◽

Author(s):

Marvin Kraft ◽

Lara Gronych ◽

Theodosios Famprikis ◽

Saneyuki Ohno ◽

Wolfgang Zeier

Keyword(s):

Electrochemical Impedance ◽

Structural Phase ◽

Ionic Transport ◽

Sodium Ion ◽

Ionic Conductors ◽

Temperature Dependent ◽

Activation Barriers ◽

Rietveld Refinements ◽

High Performing ◽

The Given

Sulfidic sodium ion conductors are currently investigated for the possible use in all-solid-state sodium ion batteries. The design of high performing electrolytes in terms of temperature-dependent ionic transport is based upon the fundamental understanding of structure – transport relationships within the given structural phase boundaries inherent to the investigated materials class. In this work, the Na+ superionic structural family of Na11Sn2PS12 is explored by using the systematic antimony substitution with phosphorous in Na11+xSn2+x(Sb1-yPy)1-xS12. A combination of Rietveld refinements against X-ray synchrotron diffraction data with electrochemical impedance spectroscopy is used to monitor the changes in the anionic framework, the Na+ substructure and the ionic transport. A new simplified descriptor for the average Na+ diffusion pathways, the average Na+ polyhedral volume is introduced, which is used to correlate the contraction of the overall lattice and the found activation barriers in the system. This study exemplifies how substitution affects diffusion pathways in ionic conductors and widens the knowledge about the related structural motifs and their influence on the ionic transport in this novel class of ionic conductors.

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Defect-Mediated Conductivity Enhancements in Na3-xPn1-xWxS4 (Pn = P, Sb) using Aliovalent Substitutions

10.26434/chemrxiv.9943961.v2 ◽

2019 ◽

Author(s):

Till Fuchs ◽

Sean Culver ◽

Paul Till ◽

Wolfgang Zeier

Keyword(s):

Ionic Conductivity ◽

Vacancy Concentration ◽

Sodium Ion ◽

High Ionic Conductivity ◽

Ionic Conductors ◽

X Ray Diffraction ◽

X Ray ◽

Solid State Batteries ◽

Ion Conducting ◽

Very High

The sodium-ion conducting family of Na3PnS4, with Pn = P, Sb, have gained interest for the use in solid-state batteries due to their high ionic conductivity. However, significant improvements to the conductivity have been hampered by the lack of aliovalent dopants that can introduce vacancies into the structure. Inspired by the need for vacancy introduction into Na3PnS4, the solid solutions with WS42- introduction are explored. The influence of the substitution with WS42- for PS43- and SbS43-, respectively, is monitored using a combination of X-ray diffraction, Raman and impedance spectroscopy. With increasing vacancy concentration improvements resulting in a very high ionic conductivity of 13 ± 3 mS·cm-1 for Na2.9P0.9W0.1S4 and 41 ± 8 mS·cm-1 for Na2.9Sb0.9W0.1S4 can be observed. This work acts as a stepping-stone towards further engineering of ionic conductors using vacancy-injection via aliovalent substituents.

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Defect-Mediated Conductivity Enhancements in Na3-xPn1-xWxS4 (Pn = P, Sb) using Aliovalent Substitutions

10.26434/chemrxiv.9943961.v1 ◽

2019 ◽

Author(s):

Till Fuchs ◽

Sean Culver ◽

Paul Till ◽

Wolfgang Zeier

Keyword(s):

Ionic Conductivity ◽

Vacancy Concentration ◽

Sodium Ion ◽

High Ionic Conductivity ◽

Ionic Conductors ◽

X Ray Diffraction ◽

X Ray ◽

Solid State Batteries ◽

Ion Conducting ◽

Very High

The sodium-ion conducting family of Na3PnS4, with Pn = P, Sb, have gained interest for the use in solid-state batteries due to their high ionic conductivity. However, significant improvements to the conductivity have been hampered by the lack of aliovalent dopants that can introduce vacancies into the structure. Inspired by the need for vacancy introduction into Na3PnS4, the solid solutions with WS42- introduction are explored. The influence of the substitution with WS42- for PS43- and SbS43-, respectively, is monitored using a combination of X-ray diffraction, Raman and impedance spectroscopy. With increasing vacancy concentration improvements resulting in a very high ionic conductivity of 13 ± 3 mS·cm-1 for Na2.9P0.9W0.1S4 and 41 ± 8 mS·cm-1 for Na2.9Sb0.9W0.1S4 can be observed. This work acts as a stepping-stone towards further engineering of ionic conductors using vacancy-injection via aliovalent substituents.

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