Developing low-cost, realistic low temperature operable ammonia sensor is highly desirable in industrial for environmental monitoring. This paper focuses on the preparation of Ag nanoparticles-loaded SnO 2 /In 2 O 3 ternary composites by combining both indium oxide and metal-organic frameworks (MOFs) compounds by hydrothermal method . They both remain as pure In 2 O 3 flakes and the size of each flake matrix is about 2 μm, which indicates that both Ag loading and SnO 2 composite have not damaged or changed the crystal structure of the In 2 O 3 -based composites. The best response gas for the Ag/SnO 2 /In 2 O 3 material was ammonia with a response value of 9.783 at the optimum operating temperature of 160 °C. The difference in each set of data after three cycles of testing was not more than 0.25. The tests showed that the sensor had good reproducibility and sensitivity, and had a low detection limit.
To overcome the inherent limitations of Ag–SnO 2 electrical contact materials, this study employed a combined strategy of In 2 O 3 doping and hot pressing sintering, establishing a direct interrelationship among material composition, microstructural evolution, electrical conductivity, and microstrain. Four Ag–SnO 2 –In 2 O 3 powder compositions were synthesized, and the effects of conventional sintering versus hot pressing sintering on microstructure and functional properties were systematically investigated. Results show that hot pressing sintering enables near-complete densification (99% relative density) and significantly improves hardness by 42.5% (57.3HV), primarily by suppressing interfacial porosity and refining microstructural uniformity. Optimal In 2 O 3 addition (4 wt%) not only facilitates homogeneous phase distribution but also minimizes bulk resistivity (2.52 × 10 −6 O·cm), leading to the highest electrical conductivity (3.98 × 10 5 S/cm). Rietveld refinement reveals a pronounced reduction in microstrain (0.01% for In 2 O 3 , 1.7% for SnO 2 ) in the best-performing samples, directly linking lattice relaxation and phase stability to enhanced electron mobility. This mechanistic insight provides a foundation for the rational design and optimization of advanced Ag-based electrical contact materials.