Neutron diffraction is used to reveal the origin and control of the thermal expansion properties of the cubic intermetallic compounds Mn3ZnxN and Mn3[Zn-(Ag,Ge)]xN. We show that the introduction of Zn vacancies induces and stabilizes an antiferromagnetic phase with huge spin-lattice coupling that can be tuned to achieve zero thermal expansion (ZTE) over a wide temperature range. We further show that the antiferromagnetic ordering temperature (TN) that controls this ZTE can be tuned by chemical substitution, again on the Zn site, to adjust the span of ZTE temperatures from well above room temperature to well below. This establishes a quantitative relationship and mechanism to precisely control the ZTE of a single material, enabling it to be tailored for specific device applications.

High-entropy amorphous NbTiAlSiW_xN_y films (x = 0 or 1, i.e., NbTiAlSiN_y and NbTiAlSiWN_y) were prepared by magnetron sputtering method in the atmosphere of a mixture of N₂ + Ar (N₂ + Ar = 24 standard cubic centimeter per minute (sccm)), where N₂ = 0, 4, and 8 sccm). All the as-deposited films present amorphous structures, which remain stable at 700 °C for over 24 h. After heat treatment at 1000 °C the films began to crystalize, and while the NbTiAlSiN_y films (N₂ = 4, 8 sccm) exhibit a face-centered cubic (FCC) structure, the NbTiAlSiW metallic films show a body-centered cubic (BCC) structure and then transit into a FCC structure composed of nanoscaled particles with increasing nitrogen flow rate. The hardness and modulus of the as-deposited NbTiAlSiN_y films reach maximum values of 20.5 GPa and 206.8 GPa, respectively. For the as-deposited NbTiAlSiWN_y films, both modulus and hardness increased to maximum values of 13.6 GPa and 154.4 GPa, respectively, and then decrease as the N₂ flow rate is increased. Both films could be potential candidates for protective coatings at high temperature.

The synthesis of lotus-root-like NiO nanosheets and flower-like NiO microspheres was realized through a simple hydrothermal method and subsequent calcination. The diameter of the lotus-root-like NiO nanosheets is about 400 nm and the pore size is about 5∼20 nm. The diameter of the flower-like NiO microspheres is about 2.5 μm, and are composed of staggered lotus-root-like nanosheets. During the synthetic procedure, aqueous ammonia was used as an alkaline complexing reagent, and PVP was used as the template. Interestingly, when the pH value of the precursor solution increased from 8.30 to 10.80, the NiO nanosheets gradually assembled into microspheres, indicating that aqueous ammonia plays a key role in controlling the final morphology. Based on the experimental observation and analysis, a possible mechanism is proposed to understand the formation of the NiO nanostructured materials. In addition, the resultant NiO nanostructures present anomalous magnetic properties and display a spin-glass state at low temperature.