Specific Heat Capacity of A2FeCoO6-δ (A = Ca or Sr)

A2FeCoO6-δ (A = Ca or Sr) is synthesized by the solid-state synthesis method and their specific heat capacities are evaluated at 40˚C using a heat flow meter. The effect of the A-cation size on the specific heat capacity of these compounds is observed. The specific heat capacity of Sr2FeCoO6-δ is found to be the highest, and that of Ca2FeCoO6-δ is the lowest while CaSrFeCoO6-δ shows the intermediate value. The specific heat capacity decreases with the decrease of the average A-site ionic radius, demonstrating the relationship between heat capacity and A-site ionic radius. The relationship between specific heat capacity and molar mass is also confirmed as the δ value decreases or molar mass increases from Ca2FeCoO6-δ to CaSrFeCoO6-δ to Sr2FeCoO6-δ.

Alkali Ionic Conductivity in Inorganic Glassy Electrolytes

Glassy electrolytes could be a potential candidate for all-solid-state batteries that are considered new-generation energy storage devices. As glasses are one of the potential fast ion-conducting electrolytes, progressive advances in glassy electrolytes have been undergoing to get commercial attention. However, the challenges offered by ionic conductivity at room temperature (10−5 - 10−3 S∙cm−1) in comparison to those of organic liquid electrolytes (10−2 S∙cm−1) hindered the applicability of such electrolytes. To enhance the research development on ionic conductivity, the overall picture of the ionic conductivity of glassy electrolytes is reviewed in this article with a focus on alkali oxide and sulfide glasses. We portray here the techniques applied for alkali ion conductivity enhancement, such as methods of glass preparation, host optimization, doping, and salt addition for enhancing alkali ionic conductivity in the glasses.