Colossal Seebeck coefficient in Aurivillius Phase-Perovskite Oxide Composite

TL;DR

This paper reports a simple, scalable method to create oxide composites with an exceptionally high Seebeck coefficient (~319 mV/K at 300K), promising for thermoelectric and sensor applications.

Contribution

It introduces a novel composite approach exploiting natural superlattice structures to achieve colossal Seebeck coefficients in oxide materials.

Findings

Achieved a Seebeck coefficient of approximately 319 mV/K at 300K.

The composite exhibits low thermal conductivity and moderate electrical conductivity.

Potential applications in thermopile sensors and bolometric devices.

Abstract

We propose an inexpensive scalable approach for achieving extremely high values of Seebeck coefficient ($\alpha$) by exploiting the natural superlattice structure in Aurivillius phase oxides. In particular, we report an $\alpha \approx $ 319\,mV/K at 300\,K in a composite of Aurivillius phase compound SrBi$_4$Ti$_4$O$_{15}$ (as a matrix) and a perovskite phase material (e.g., La$_{0.7}$Sr$_{0.3}$MnO$_3$ or, La$_{0.7}$Sr$_{0.3}$CoO$_3$ as filler). Such a colossal value of $\alpha$ can be attributed to contributions from the enhanced density of states due to the effective low dimensional character of Bi$_2$O$_2$ layer. The corresponding thermal conductivity ($\kappa$) and the electrical conductivity ($\sigma$) lies in the range 0.7 - 1.25 W/m-K and 10 - 100 $\mu$S/m, respectively at 300\,K. Attributed to the high $\alpha$ values, such oxide composites can be used as thermopile sensors and highly sensitive bolometric applications. We anticipate that the demonstration of colossal $\alpha$ in oxide composites using a simple synthesis strategy also sets the stage for future material innovations for high temperature thermoelectric applications.