Engineering of Pore Design and Oxygen Vacancy on High-Entropy Oxides by a Microenvironment Tailoring Strategy.

High-entropy oxides (HEOs) exhibit abundant structural diversity due to cationic and anionic sublattices with independence, rendering them superior in catalytic applications compared to monometallic oxides. Nevertheless, the conventional high-temperature calcination approach undermines the porosity and reduces the exposure of active sites (such as oxygen vacancies, OVs) in HEOs, leading to diminished catalytic efficiency. Herein, we fabricate a series of HEOs with a large surface area utilizing a microenvironment modulation strategy (m-NiMgCuZnCo: 86 m2/g, m-MnCuCoNiFe: 67 m2/g, and m-FeCrCoNiMn: 54 m2/g). The enhanced porosity in m-NiMgCuZnCo facilitates the presentation of numerous OVs, exhibiting an exceptional catalytic performance. This tactic creates inspiration for designing HEOs with rich porosity and active species with vast potential applications.

[Structure characterization of calcium polyphosphate bioceramics during sintering process].

Calcium polyphosphate (CPP) may be a promising bone substitute with controllably-degraded ability. In this investigation, the effects of sintering temperatures on its phase transformation and structure parameters, such as crystalline size distribution and micro-strain were investigated by X-ray diffraction (XRD). The phase composition was calculated with reference intensity ratio (RIR). The crystalline size distribution and micro-strain were calculated with Warren-Averbach Fourier transfer (W-A/FT) method. The results demonstrated that at the temperature of 585 degrees C-900 degrees C, the phase transformation of amorphous CPP into crystalline gamma-CPP and then into beta-CPP occurred,and the course of such transformation was accompanied with the significant change of the mean crystalline size (D) and the mean micro-strain (epsilon).