اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدIon transport study of mechanically-milled amorphous AgI-Ag2O-V2O5 fast ionic conductors
112
0
0.0
(
0
)
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
The structural and electrical characterizations of mechanically-milled (MM) amorphous fast ionic conductors (a-FICs), viz. xAgI (100-x)[0.67 Ag_2 O-0.33V_2O_5] (x = 40, 50, 55 and 70) have been reported. The amorphisation is restricted only to the compositions which are well within the glass forming region and all samples are found to be highly agglomerated and X-ray amorphous in nature. The frequency dependent ac conductivity, sigma(omega), of the amorphous samples investigated in the frequency range 5Hz -13 MHz and temperature range 100- 350 K shows a dc conductivity regime at low frequencies and a dispersive regime at higher frequencies. The spectra can be described by the Jonscher power law (JPL), simga(omega) = sigma_dc +A(T) omega_n. However, the values sigma_dc (T) and A(T) both show two distinct Arrhenius regions and n (< 1) is found to be temperature dependent, i.e., decreasing with increasing temperature.
قيم البحث
اقرأ أيضاً
New emerging disciplines such as Nanoionics and Iontronics are dealing with the exploitation of mesoscopic size effects in materials, which become visible (if not predominant) when downsizing the system to the nanoscale. Driven by the worldwide stand
ardisation of thin film deposition techniques, the access to radically different properties than those found in the bulk macroscopic systems can be accomplished. This opens up promising approaches for the development of advanced microdevices, by taking advantage of the nanostructural deviations found in nanometre sized, interface dominated materials compared to the ideal relaxed structure of the bulk. A completely new set of functionalities can be explored, with implications in many different fields such as energy conversion and storage, or information technologies. This manuscript reviews the strategies, employed and foreseen, for engineering mass transport properties in thin film ceramics, with the focus in oxide ionic and mixed ionic electronic conductors and their application in micro power sources.
Ferroelectrics that are also ionic conductors offer possibilities for novel applications with high tunability, especially if the same atomic species causes both phenomena. In particular, at temperatures just below the Curie temperature, polarized sta
tes may be sustainable as the mobile species is driven in a controlled way over the energy barrier that governs ionic conduction, resulting in unique control of the polarization. This possibility was recently demonstrated in CuInP2S6, a layered ferroelectric ionic conductor in which Cu ions cause both ferroelectricity and ionic conduction. Here, we show that the commonly used approach to calculate the polarization of evolving atomic configurations in ferroelectrics using the modern theory of polarization, namely concerted (synchronous) migration of the displacing ions, is not well suited to describe the polarization evolution as the Cu ions cross the van der Waals gaps. We introduce an asynchronous Cu-migration scheme, which reflects the physical process by which Cu ions migrate, resolves the difficulties, and describes the polarization evolution both for normal ferroelectric switching and for transitions across the van der Waals gaps, providing a single framework to discuss ferroelectric ionic conductors.
Ion assisted deposition (IAD) has been investigated for the growth of GaN, and the resulting films studied by x-ray diffraction and absorption spectroscopy and by transmission electron microscopy. IAD grown stoichiometric GaN consists of random-stack
ed quasicrystals of some 3 nm diameter. Amorphous material is formed only by incorporation of 15% or more oxygen, which we attribute to the presence of non-tetrahedral bonds centered on oxygen. The ionic favourability of heteropolar bonds and its strikingly simple constraint to even-membered rings is the likely cause of the instability of stoichiometric a-GaN.
We report on density-functional-based tight-binding (DFTB) simulations of a series of amorphous arsenic sulfide models. In addition to the charged coordination defects previously proposed to exist in chalcogenide glasses, a novel defect pair, [As4]--
[S3]+, consisting of a four-fold coordinated arsenic site in a seesaw configuration and a three-fold coordinated sulfur site in a planar trigonal configuration, was found in several models. The valence-alternation pairs S3+-S1- are converted into [As4]--[S3]+ pairs under HOMO-to-LUMO electronic excitation. This structural transformation is accompanied by a decrease in the size of the HOMO-LUMO band gap, which suggests that such transformations could contribute to photo-darkening in these materials.
Solid-state ionic conduction is a key enabler of electrochemical energy storage and conversion. The mechanistic connections between material processing, defect chemistry, transport dynamics, and practical performance are of considerable importance, b
ut remain incomplete. Here, inspired by studies of fluids and biophysical systems, we re-examine anomalous diffusion in the iconic two-dimensional fast-ion conductors, the $beta$- and $beta^{primeprime}$-aluminas. Using large-scale simulations, we reproduce the frequency dependence of alternating-current ionic conductivity data. We show how the distribution of charge-compensating defects, modulated by processing, drives static and dynamic disorder, which lead to persistent sub-diffusive ion transport at macroscopic timescales. We deconvolute the effects of repulsions between mobile ions, the attraction between the mobile ions and charge-compensating defects, and geometric crowding on ionic conductivity. Our quantitative framework based on these model solid electrolytes connects their atomistic defect chemistry to macroscopic performance with minimal assumptions and enables mechanism-driven atoms-to-device optimization of fast-ion conductors.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
