NASICON \documentclass[12pt]{minimal}
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\begin{document}$$\left( {Na_{1 + x} Zr_2 Si_x P_{x - 3} O_{12} ;0 \leqslant x \leqslant 3} \right)$$\end{document} powders were prepared by solid-state synthesis, a fraction was ion exchanged by Li or K, verified by X-ray diffraction and energy dispersive X-ray analysis, blended with tin oxide powder, transferred to thick film pastes, and dispensed on a commercial sensor substrate (Heraeus, Germany). Simultaneous gas sensitivity measurements on nine SnO2/NASICON-type (\documentclass[12pt]{minimal}
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\begin{document}$$M_{1 + x} Zr_2 Si_x P_{x - 3} O_{12} $$\end{document}, x = 0, 2.2, 3, M = Li, Na, K) composites in thermocyclic sensor operation mode by exposure to different concentrations of Ethanol, Toluene, Propylene, CO, and H2 in humidified synthetic air show a strong correlation of the gas-sensing properties with the mobile ion concentration and type of the solid electrolyte additive.