Some of the letter jumbles can form many different words while others can have you wracking your brain to figure out even one. The player is given six letters (in no particular order) to form as many words as they can before the game's timer runs out. The structural transitions identified under pressure match with all the previously reported electronic modifications confirming that lattice and electronic degrees of freedom are closely coupled in this correlated material.Forget Scrabble, Outspell, Letter Garden, Just Words, Bookworm or 7 Little Words – Text Twist will have you playing for hours on end.
Upon decompression, phase X transforms, between 20 and 3 GPa, to another phase that is neither the M 1 ′ nor M 1 phase. A second transformation in the metallic phase X, which is found triclinic ( P 1 ¯) is observed starting at 32 GPa, with a wide coexistence region (up to 42 GPa). In particular, the A g ( 1 ) + B g ( 1 ) modes at 145 c m − 1 are identified as the vanadium displacive phonons. Pressure-induced shifts of the Raman peaks allow for new assignment of several Raman modes. The spontaneous displacements of oxygen and the spontaneous deformations of the ( b M 1, c M 1 ) plane follow the same quadratic dependence with pressure and scales with spontaneous shifts of the Raman phonons located at 225, 260, and 310 c m − 1. The M 1 ′ is characterized by spontaneous displacements of the oxygen sublattice without any strong modification of the VV dimers distances nor the twist angle of vanadium chains. An analysis based on the Landau theory of phase transitions gives a complete description of the P − T phase diagram. The features of this transformation (no apparent volume jump) indicate that the compression at ambient temperature passes close to a critical point. At this pressure, an isostructural phase transition between two monoclinic phases M 1 and M 1 ′ hinders this instability. A soft mode is observed up to P c = 13.9 ( 1 ) GPa.
The high-pressure behavior of monoclinic VO 2 is revisited by a combination of Raman spectroscopy and x-ray diffraction on a single crystal under hydrostatic conditions at room temperature.
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