Exploring the use of impedance spectroscopy in relaxation and electrochemical studies

Shin, Dong‐Myeong; Choi, Jong-ryul; Oh, Jin‐Woo; Kim, Hyung Kook; Kim, Kyujung; Hwang, Yoon‐Hwae

doi:10.1080/05704928.2017.1328425

Cited by 5 publications

(6 citation statements)

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“…54,55 For many materials, a secondary β-relaxation, or Johari−Goldstein relaxation, has been observed in their dielectric or impedance spectra, which manifests as a high-frequency contribution on an individual timescale and temperature dependence. 56 Its exact nature is still debated but has been associated with hindered noncooperative reorientations or translations in the local regions of low mobility. 57 Within this model, the two observed minima may be attributed to the above-described structural primary and secondary β-relaxation.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…The clear observation of two relaxation processes around T g with distinct time constants is intriguing and raises questions about their structural origins . In amorphous polymers and glass-forming liquids, the primary or structural α-relaxation determines the glass transition and has been related to cooperative molecular rearrangements. , For many materials, a secondary β-relaxation, or Johari–Goldstein relaxation, has been observed in their dielectric or impedance spectra, which manifests as a high-frequency contribution on an individual timescale and temperature dependence . Its exact nature is still debated but has been associated with hindered noncooperative reorientations or translations in the local regions of low mobility …”

Section: Results and Discussionmentioning

confidence: 99%

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Preparation and Structure of the Ion-Conducting Mixed Molecular Glass Ga₂I_3.17

et al. 2021

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Modern functional glasses have been prepared from a wide range of precursors, combining the benefits of their isotropic disordered structures with the innate functional behavior of their atomic or molecular building blocks. The enhanced ionic conductivity of glasses compared to their crystalline counterparts has attracted considerable interest for their use in solid-state batteries. In this study, we have prepared the mixed molecular glass Ga 2 I 3.17 and investigated the correlations between the local structure, thermal properties, and ionic conductivity. The novel glass displays a glass transition at 60 °C, and its molecular make-up consists of GaI 4 – tetrahedra, Ga 2 I 6 2– heteroethane ions, and Ga + cations. Neutron diffraction was employed to characterize the local structure and coordination geometries within the glass. Raman spectroscopy revealed a strongly localized nonmolecular mode in glassy Ga 2 I 3.17 , coinciding with the observation of two relaxation mechanisms below T g in the AC admittance spectra.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Section: Results and Discussionmentioning

confidence: 99%

Preparation and Structure of the Ion-Conducting Mixed Molecular Glass Ga₂I_3.17

et al. 2021

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“…In the last few years, the EIS method has become a very promising method for studying heterostructured photoactive materials with the aim of improving their performance by identifying the origin of the limitations of their energy conversion and stability. The number of publications devoted to the application of this technique to the study of photoprocesses involving various heterostructures is quite large and constantly continues to grow [123,124,[137][138][139][140][141][142][143][144][145][146][147][148][149][150][151][152][153][154]. By studying the system's response to an exciting small-amplitude signal in a broad frequency range one can obtain information on both the charge transfer kinetics through the solid/solid interface and the structure and the properties of this interface.…”

Section: Electrophysical Characterizationmentioning

confidence: 99%

“…The impedance spectroscopy of heterostructures is also based on the analysis of the dependence of the complex electrical resistance Z (impedance) on the frequency of the alternating current (AC) [137][138][139][140][141][142][143][144][145][146][147][148][149][150][151][152][153][154]. It is possible to determine the structural features of the studied heterostructures (sizes of the heterostructure components, their local resistance), as well as other characteristics.…”

Section: Electrophysical Characterizationmentioning

confidence: 99%

“…The frequency dependences of impedance are determined by various physical factors, some of which may appear at the same frequency values. These factors include electronic relaxation processes at the phase interface, relaxation processes at the phase interface associated with the transfer of ions, as well as with the occurrence of the electrochemical reactions, and the amplitude-phase dependence of the electrical characteristics on frequency (dispersion) for the system studied [124,[137][138][139][140].…”

Section: Electrophysical Characterizationmentioning

confidence: 99%

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Photoactive Heterostructures: How They Are Made and Explored

et al. 2021

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In our review we consider the results on the development and exploration of heterostructured photoactive materials with major attention focused on what are the better ways to form this type of materials and how to explore them correctly. Regardless of what type of heterostructure, metal–semiconductor or semiconductor–semiconductor, is formed, its functionality strongly depends on the quality of heterojunction. In turn, it depends on the selection of the heterostructure components (their chemical and physical properties) and on the proper choice of the synthesis method. Several examples of the different approaches such as in situ and ex situ, bottom-up and top-down, are reviewed. At the same time, even if the synthesis of heterostructured photoactive materials seems to be successful, strong experimental physical evidence demonstrating true heterojunction formation are required. A possibility for obtaining such evidence using different physical techniques is discussed. Particularly, it is demonstrated that the ability of optical spectroscopy to study heterostructured materials is in fact very limited. At the same time, such experimental techniques as high-resolution transmission electron microscopy (HRTEM) and electrophysical methods (work function measurements and impedance spectroscopy) present a true signature of heterojunction formation. Therefore, whatever the purpose of heterostructure formation and studies is, the application of HRTEM and electrophysical methods is necessary to confirm that formation of the heterojunction was successful.

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