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The high pressure structural changes of Cu3TeO6 have been investigated by using synchrotron radiation X-ray diffraction and Raman spectroscopy up to 23.2(4) and 45.9(7) GPa, respectively. It was found that Cu3TeO6 transformed from the cubic (Ia-3) structure to the orthorhombic (Ibca) structure around 8.6(1) GPa, and the phase transition was reversible. The phase transformation was subtle because of the similarity between two crystal structures. A large internal lattice strain could be the cause to the pressure-induced structural phase transition. [ABSTRACT FROM AUTHOR]

Obtaining both high hardness and toughness is a challenge in B4C-nano-adhesive composites. Solving the inhomogeneous distribution of nano-adhesives in B4C and forming the chemical bonding at grain boundary is an effective method. Here, we reported that the uniform distribution of titanium diboride (TiB2)-reinforced B4C composites synthesized by high-pressure and high temperature (HPHT). It is found that HPHT sintering can effectively inhibit the grain growth and increase the relative density. Moreover, HPHT sintering can cross high reaction energy barrier and effectively promote the formation of chemical bonding at grain boundary between B4C and TiB2. The optimal hardness and toughness value reach 30.0 ± 0.9 GPa and 7.87 MPa·m1/2, respectively. The improvement of hardness and toughness in the final products are ascribed to the strengthening of nanoTiB2 connection of B4C boundary and intergranular fracture mechanism. This work suggests a new way to achieve the uniform distribution of nanoTiB2 in B4C and form the chemical bonding at grain boundary, which is of great significance to the further development of TiB2-reinforced B4C composites with excellent mechanical properties. [ABSTRACT FROM AUTHOR]

The structural properties of pyrochlore Eu2Zr2O7under high pressure have been studied by using Raman spectroscopy andin situangle-dispersive X-ray diffraction (ADXRD). The results of Raman spectra indicate that Eu2Zr2O7undergoes a reversible structural change around 21.2 GPa. The results of Rietveld refinements fromin situADXRD data indicate that the ordered pyrochlore structure (Fd-3m) transforms to the defect-cotunnite structure (Pnma) at 26.5 GPa. The phase transition is irreversible and the transformation process is mainly induced by the accumulations of anti-site defects of the cation sublattice and Frenkel defects on the anion sublattice. Besides, the bonds should play a more important role than the bonds in the process of the phase transformation. [ABSTRACT FROM AUTHOR]

The high pressure structural changes of Cu3TeO6 have been investigated by using synchrotron radiation X-ray diffraction and Raman spectroscopy up to 23.2(4) and 45.9(7) GPa, respectively. It was found that Cu3TeO6 transformed from the cubic (Ia-3) structure to the orthorhombic (Ibca) structure around 8.6(1) GPa, and the phase transition was reversible. The phase transformation was subtle because of the similarity between two crystal structures. A large internal lattice strain could be the cause to the pressure-induced structural phase transition. [ABSTRACT FROM AUTHOR]