Disorders solid electrolytes

In disordered solid electrolytes, conductivity spectra taken at different temperatures typically show a gradual transition from one universality to the other, as seen in the example of Fig. 4. 

Solid electrolytes based on chemical disorder Solid electrolytes based oti structural disorder (super-ionic conductors)... 

AgsSBr, /3-AgsSI, and a-AgsSI are cationic conductors due to the structural disorder of the cation sublattices. AgsSI (see Fig. 5) has been discussed for use in solid-electrolyte cells (209,371, 374,414-416) because of its high silver ionic conductivity at rather low temperatures (see Section II,D,1). The practical use seems to be limited, however, by an electronic part of the conductivity that is not negligible (370), and by the instability of the material with respect to loss of iodine (415). 

Cul) is not due to point defects but to partial occupation of crystallographic sites. The defective structure is sometimes called structural disorder to distinguish it from point defects. There are a large number of vacant sites for the cations to move into. Thus, ionic conductivity is enabled without use of aliovalent dopants. A common feature of both compounds is that they are composed of extremely polarizable ions. This means that the electron cloud surrounding the ions is easily distorted. This makes the passage of a cation past an anion easier. Due to their high ionic conductivity, silver and copper ion conductors can be used as solid electrolytes in solid-state batteries. 

Sprik et al, 1993 Signorini et al, 1990), a typical example being the orientational disorder associated with NH in NH Br. Detailed simulations have been reported on (NaCN),, t(KCN),t and other mixed alkali halides and alkali cyanides. Other systems studied include potassium and calcium nitrate crystals and their mixtures. The transition from the crystalline to the superionic conductor phase in solid electrolytes has also been successfully investigated. Molecular dynamics studies of Agl were carried out by Parrinello, Rahman Vashishta (1983). LijSO has been investigated by molecular dynamics by Impey et al. (1985). Here, the Li ions become mobile at high temperatures. The ions exhibit orientational disorder and the orientational... 

Often this term is used for - solid electrolytes and/or for solids with structural disorder (see -> defects in solids), although all these designations are not synonyms. The high concentration of defects, necessary for fast ionic conduction, may be induced by external factors such as - doping, electromagnetic forces, radiation, etc. Creation of these defects may lead to the generation of - electron - charge carriers and, thus, induce electronic - conductivity. 

Prelot, B. et al. Structural -chemical disorder of manganese dioxides. 1. Influence on surface properties al lire solid-electrolyte interface, J. Colloid Interf. Sci., 257, 77, 2003. 

The crystallographic structure in solids with fixed positions for atoms or ions restricts the free mobility of the ions. The ionic conductivity observed in solid electrolytes is based on defects and disorder in the crystallographic structure. One can distinguish... 

Glasses and polymer electrolytes are in a certain sense not solid electrolytes but neither are they considered as liquid ones. A glass can be regarded as a supercooled liquid and solvent-free polymer electrolytes are good conductors only above their glass transition temperature (7 ), where the structural disorder is dynamic as well as static. These materials appear macroscopically as solids because of their very high viscosity. A conductivity relation of the Vogel-Tamman-Fulcher (VTF) type is usually... 

Historically, Agl-based (soft framework, a situation similar to that in plastic acid sulphate) materials were the first solid electrolytes to be studied in detail. Their structural disorder is believed to correspond to Ag ion sublattice melting and the transport is governed by the immobile , counter ion lattice potential (low density approximation). This quasi-liquid state can be described by generalized Langevin dynamics... 

One of the first solid electrolytes exhibiting a very high ionic conductivity, found in 1914, is a-Agl. This conducting o -phase is stable above 149°C and its high conductivity is caused by structural disorder. A similar disorder exists in RbAg4l5. This solid electrolyte exhibits the highest silver ion conductivity at room temperature at present. Therefore, it is of great technical interest. A... 

---