Search

In this work, single-phase (Ce 0.2 Zr 0.2 La 0.2 Sm 0.2 Nd 0.2)O 2-δ high-entropy fluorite oxides (HEFOs) were successfully prepared by conventional solid-phase reaction method and crystal structure and microstructure were studied in-depth. Single-phase (Ce 0.2 Zr 0.2 La 0.2 Sm 0.2 Nd 0.2)O 2-δ is formed at 1600 °C for 12 h, and five cationic elements are uniformly distributed without any segregation at the micrometer and nanometer scales. And the XRD patterns with Rietveld refinement reveal the formation of single-phase fluorite structure of (Ce 0.2 Zr 0.2 La 0.2 Sm 0.2 Nd 0.2)O 2-δ. The SAED patterns on the [0 1 ‾ 1] band axes are similar to the diffraction patterns of face-centered cubic fluorite structure, and the standard deviation of the cation radius (coordination VIII) distribution of the specimens is 0.1277, which is again identified as forming a single-phase fluorite structure. The bulk specimens are solid compacts free of obvious cracks with randomly distribution porosity at a rare level, and the powder specimens are irregular fragmented shapes with an average particles size of 5.41 μm. The average cation radius and interplanar spacings becomes larger compared with standard fluorite structure of CeO 2 due to the cation radius of La3+, Sm3+ and Nd3+ are larger than that of Ce4+, leading to an increase in lattice parameters of the HEFOs. In addition, the concentration of Ce3+ in the Ce cation is only 8.1 %, and the δ -value is calculated to be 0.3081 based on the content of all cations per mole of the substance, which indicates that the composition of the prepared specimen is (Ce 0.2 Zr 0.2 La 0.2 Sm 0.2 Nd 0.2)O 1.6919. [ABSTRACT FROM AUTHOR]

In this work, single-phase (Ce 0.2 Zr 0.2 La 0.2 Sm 0.2 Nd 0.2)O 2-δ high-entropy fluorite oxides (HEFOs) were successfully prepared by conventional solid-phase reaction method and crystal structure and microstructure were studied in-depth. Single-phase (Ce 0.2 Zr 0.2 La 0.2 Sm 0.2 Nd 0.2)O 2-δ is formed at 1600 °C for 12 h, and five cationic elements are uniformly distributed without any segregation at the micrometer and nanometer scales. And the XRD patterns with Rietveld refinement reveal the formation of single-phase fluorite structure of (Ce 0.2 Zr 0.2 La 0.2 Sm 0.2 Nd 0.2)O 2-δ. The SAED patterns on the [0 1 ‾ 1] band axes are similar to the diffraction patterns of face-centered cubic fluorite structure, and the standard deviation of the cation radius (coordination VIII) distribution of the specimens is 0.1277, which is again identified as forming a single-phase fluorite structure. The bulk specimens are solid compacts free of obvious cracks with randomly distribution porosity at a rare level, and the powder specimens are irregular fragmented shapes with an average particles size of 5.41 μm. The average cation radius and interplanar spacings becomes larger compared with standard fluorite structure of CeO 2 due to the cation radius of La3+, Sm3+ and Nd3+ are larger than that of Ce4+, leading to an increase in lattice parameters of the HEFOs. In addition, the concentration of Ce3+ in the Ce cation is only 8.1 %, and the δ -value is calculated to be 0.3081 based on the content of all cations per mole of the substance, which indicates that the composition of the prepared specimen is (Ce 0.2 Zr 0.2 La 0.2 Sm 0.2 Nd 0.2)O 1.6919. [ABSTRACT FROM AUTHOR]

• GLNSYMnO 3 has a single-phase orthorhombic perovskite structure sintered at 1250 °C. • The high configurational entropy drives the structural stability of GLNSYMnO 3 even at temperatures below T C. • GLNSYMnO 3 has good magnetism due to the lattice distortion and double-exchange. • GLNSYMnO 3 is a second-order magnetic phase transition material with potential applications in magnetic storage. Rare-earth transition element high-entropy perovskite ceramics (HEPCs) (Gd 0.2 La 0.2 Nd 0.2 Sm 0.2 Y 0.2)MnO 3 (GLNSYMnO 3) were prepared by using a solid-state reaction method, and the structure, morphology and magnetic properties of the GLNSYMnO 3 were studied. The crystalline structure of GLNSYMnO 3 is a smooth surface and similar to "cashews" tubular particles, and a single-phase orthorhombic (Pbnm Space group) perovskite without impurities is confirmed when the sintered temperature reaches or exceeds 1250 °C by the analysis of phase composition and microstructures. Magnetic measurements indicate that GLNSYMnO 3 HEPCs have low Curie temperature (T C = 61 K), but they exhibit a good magnetism by comparison with other high-entropy ceramics, which is caused by the lattice distortion and exchange interactions between high concentrations of Mn3+ (92.4 %) and non-magnetic oxygen ions, promoting the movement of circulating electrons. GLNSYMnO 3 HEPCs did not undergo a phase transition below T C due to high configurational entropy driving structural stability. In addition, GLNSYMnO 3 HEPCs undergo a second-order magnetic phase transition from isothermal magnetization curves and Arrot curves, which have potential applications in magnetic storage. [ABSTRACT FROM AUTHOR]