Zirconia nanoparticles were synthesized by using the supercritical hydrothermal method from zirconium basic carbonate, which is insoluble in water at ambient temperature. The diameters of these nanoparticles were 10–20 nm. They contained both tetragonal and monoclinic phases. A long treatment in supercritical water induced the phase transition from the tetragonal phase to the monoclinic phase with the desorption of carbonate ions. These results indicated that the carbonate ions absorbed on the surface works as a stabilizer of the unstable tetragonal phase. The process developed here allows us to bypass wastewater treatment along with the product refining because byproducts are only water and carbon dioxide.

In this work, a superhydrophobic diatomite porous ceramic was successfully prepared via a straightforward impregnation and heat-treatment way using isobutylene-maleic anhydride copolymer and SiO₂ nanoparticles (NPs) as co-modifier. Due to the removal of the hydroxyl group after 1 h heating at 573 K in a 5 % H₂/Ar atmosphere, the amide group in the original isobutylene-maleic anhydride copolymer was transformed to imide group, endowing the porous ceramics with excellent hydrophobic property. Furthermore, the addition of SiO₂ NPs which enhanced the surface roughness resulted in the superhydrophobic properties of the final products. The continuous oil-water separation test of as-prepared superhydrophobic diatomite porous ceramics exhibited an initial separation flux of over 205.5 kg·min⁻¹·m⁻² with a separation selectivity of over 93 % for various oil-water mixtures. Moreover, their oil-adsorption tests demonstrated an 1.6–57 times adsorption capacity as high as these of other traditional inorganic sorbent materials.

Lead-free (0.955 − x)NaNbO₃–0.045La(Nb_1/3Mg_2/3)O₃–xCaZrO₃ ceramics were prepared by the conventional method, the influences of CaZrO₃ content on dielectric properties, energy storage performance and electrocaloric effect (ECE) were studied. The introduction of CaZrO₃ could efficaciously reduce sintering temperature from 1270 to 1230 °C with stabilized anti-ferroelectric (AFE) provskite structure. Obvious thermal hysteresis was observed during phase transition, while the phase transition temperature was reduced from 233 to 177 °C. And the room temperature dielectric properties were also improved with enhanced dielectric constant and suppressed dielectric loss. As a result, the optimum recoverable energy storage density of 1.90 J/cm³ with a noteworthy efficiency of 84.5 % was obtained under 21.3 kV/mm when x = 1.0 %, which was resulted from the AFE-liked hysteresis loops. Moreover, it also presented attractive ECE aspect with positive ECE and negative ECE due to a mixed AFE and ferroelectric phase structure. This study contributes to the development of NaNbO₃-based ceramics in energy storage and solid refrigeration areas.

The magnetic particles with high saturation magnetization and superparamagnetism are needed to detect highly sensitive viruses. The magnetic property of magnetite (Fe₃O₄) particles synthesized by spray pyrolysis and a subsequent heating process depended on the citric acid content. The magnetic particles consist of nano-sized Fe₃O₄ crystallite about 10 nm in diameter and the decomposed C with high dispersion. The edge-to-edge separation of the crystallites is about 8 nm. As a result, the superparamagnetic Fe₃O₄ particles can be synthesized. The saturation magnetization of the synthesized beads (51 A·m² kg⁻¹) is much higher than that of commercial magnetic microbeads (17 A·m² kg⁻¹), and the coercive force is 0.24 kA m⁻¹. Superparamagnetism can likely be attained because of the high dispersion of Fe₃O₄ crystallites below 10 nm in diameter. The Fe₃O₄ crystallites did not magnetically interact with each other. These unique Fe₃O₄ particles may hold promise as magnetic particles for enzyme immobilization due to the high possibility of antibody bonding and the ease of separation by magnetic fields.

Zinc oxide (ZnO) thermoelectric ceramics were consolidated by spark plasma sintering (SPS) along with one-step/two-step sintering (OS/TS) temperature profiles, the latter employing a strategy of heating to a higher temperature (T₁) followed by prolonged sintering at a lower temperature (T₂) for densification while preventing grain growth. In the first step, the temperatures and holding times were 1100 and 1150 °C for 15 and 5 min, respectively, and the second-step was maintained at 1050 °C for 30, 60, and 120 min. By combining TS and SPS processes (TS-SPS), high relative densities of 91.4–94.9 % were achieved without significant grain growth. Electron backscatter diffraction (EBSD) revealed a noticeable grain-growth suppression of 56 % for the TS-SPS sample with T₁ = 1100 °C. The highest power factor of 7.8 × 10⁻⁵ W K⁻² m⁻¹ was achieved for the TS-SPS ZnO, while the lowest thermal conductivity of 4.7 W K⁻¹ m⁻¹ was achieved for the OS-SPS ZnO, attaining a figure of merit (ZT) of 0.017 at 775 °C.

A phenomenon often appears that the final achieved density is limited during conventional flash sintering even under alternative current electric field. By observing the cross-sectional microstructure of the flash sintered 8 mol %Y₂O₃-doped ZrO₂ at this state, we found that a thin surface portion with near full density surrounds a porous inside with lower density. The densified thin surface portion is shell-like structure covering a whole of the sintered compact. The formation of this characteristic shell-like structure in the early stage of flash sintering greatly restricts subsequent densification of porous inside. In order to suppress the formation of the shell that inhibit densification, a technique of controlling a steep power spike at a flash event must be necessary to be appropriately transitioned.