SiO$_2$-mediated facile hydrothermal synthesis of spiroffite-type Co$_2$Te$_3$O$_8$

TL;DR

This study demonstrates that SiO$_2$ as a mineralizer enables the hydrothermal synthesis of a novel Co$_2$Te$_3$O$_8$ material with tunable magnetic properties, highlighting the role of mineralizer combinations in complex material synthesis.

Contribution

It introduces a new hydrothermal synthesis route using SiO$_2$ to stabilize and modify Co$_2$Te$_3$O$_8$, revealing effects of silicon substitution and magnetic behavior.

Findings

SiO$_2$ enables synthesis under milder conditions.

Silicon substitution causes structural disorder.

Enhanced low-temperature ferromagnetism observed.

Abstract

The hydrothermal synthesis of novel materials typically relies on both knowledge of the redox activities of all cations present in the reaction solution and a small toolset of so-called mineralizers to tune the solution's overall chemical potential. Upon the use of a less conventional mineralizer species, SiO$_2$, we show the stabilization of spiroffite-type Co$_2$Te$_3$O$_8$ under less forceful hydrothermal conditions than in previous reports. When synthesized in the presence of both SiO$_2$ and each respective alkali carbonate as a secondary mineralizer, silicon substitution in place of tellurium in the host structure becomes apparent, and the corresponding introduced disorder gives rise to enhanced low-temperature ferromagnetism. Our results highlight the complexities of underutilized and combined mineralizer species in the stabilization and tuning of complex magnetic ground states via hydrothermal synthesis techniques.