By electron beam evaporation, noble metals (Au, Co, Pt, and Ag) with 2 and 4 nm nominal thicknesses were coated onto multi-walled carbon nanotube layers. The metals were in the form of nanoparticles mounted onto the side walls of carbon nanotubes (CNTs) to create a metal/CNT junction. The CNTs were directly grown on patterned Pt-electrode alumina substrates through chemical vapor deposition to produce a resistivity-based ammonia gas sensor. The metallic surface-modified CNT-based sensors were found sensitive to NH3 gas at room temperature. Compared with pristine CNT sensor, the response of Au/CNTs sensor increased slightly, whereas the responses of the Pt/CNTs, Co/CNTs, and Ag/CNTs increased by two, three, and more than four times, respectively.

Complex ferroelectric PbTiO3-modified 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 materials were synthesized by a conventional solid-state reaction method. The addition of PbTiO3 into host 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 materials are modified the ferroelectric properties of host materials where the maximum polarization slightly increased from 23.09 C\cm2 to 23.28 C\cm2 and the remnant polarization is found to increase from 10.07 C\cm2 to 11.31 C\cm2. The large piezoelectric dynamic coefficient value of 662 pm\V is obtained for 7 mol. % PbTiO3 modified 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 compounds as solid solution. Our work is expected to contribute to the role of A-site modification in lead-free ferroelectric BaTiO3-based materials for advanced function materials for electronic device applications.