SYNTHESIS AND MAGNETIC PROPERTIES OF CHROMIUM-BASED Cu(Cr2-xTi x)S4 THIOSPINELS AND THEIR DEFICIENT STRUCTURES Cu1-y□yCr2-xTi xS4 OBTAINED BY COPPER EXTRACTION

Abstract

The crystalline structure of spinels is extremely flexible due to the presence of several sublattices in which the cations can be distributed and localized in different crystallographic sites depending on their sizes, oxidation states or coordination numbers. Cationic substitution and ions-extraction are appropriate tools to change the oxidation state inside the spinel structure, thus substantially modifying the magnetic properties. The spinel sulfide CuCr 2 S 4 is a metallic ferromagnet with T C = 377 K, where Cr is mixed-valence Cr

Insights into Mg2+ Intercalation in a Zero-Strain Material: Thiospinel MgxZr2S4

“…21 It is theoretically possible to increase the operating voltage by using transition metals with high theoretical redox potentials such as Cr 2 S 4 ; however, attempts to do so have failed to produce notable electrochemical reversibility. 22 This is thought to be due to significant overlap between the sulfur 3p and transition metal 3d orbitals in these compounds, which effectively means that anion redox (S 2− /S − ) would govern the electrochemistry. The formation of electron holes in the sulfur 3p states is not favorable, rendering these materials electrochemically inactive.…”

“…Despite these kinetic advantages, sulfides present high mass and low operating voltages, which leads to poor energy densities . It is theoretically possible to increase the operating voltage by using transition metals with high theoretical redox potentials such as Cr 2 S 4 ; however, attempts to do so have failed to produce notable electrochemical reversibility . This is thought to be due to significant overlap between the sulfur 3p and transition metal 3d orbitals in these compounds, which effectively means that anion redox (S 2– /S – ) would govern the electrochemistry.…”