Interlayer-glide-driven isosymmetric phase transition in compressed In2Se3

Abstract

We report an anomalous phase transition in compressed In2Se3. The high-pressure studies indicate that In2Se3 transforms to a new isosymmetric R-3m structure at 0.8 GPa whilst the volume collapses by ∼7%. This phase transition involves a pressure-induced interlayer shear glide with respect to one another. Consequently, the outer Se atoms of one sheet locate into the interstitial sites of three Se atoms in the neighboring sheets that are weakly connected by van der Waals interaction. Interestingly, this interlayer shear glide changes the stacking sequence significantly but leaves crystal symmetry unaffected. This study provides an insight to the mechanisms of the intriguing isosymmetric phase transition.

Intercorrelated In-Plane and Out-of-Plane Ferroelectricity in Ultrathin Two-Dimensional Layered Semiconductor In2Se3

“…The atomic force microscopy (AFM) in Fig. 1b 11,12 In our case, we don't see obvious Raman shift between the quick cooling and slow cooling samples, because both samples are the mixtures of α-and β-In 2 Se 3 . The minor peak at ~170 cm -1 for the quick cooling sample indicates that it is dominated by β phase 11,12 , while the strong intensity of this peak for the slow cooling sample suggests that the portion of α-In 2 Se 3 flakes significantly increases in the slow cooling process.…”

Decompression‐Driven Superconductivity Enhancement in In2Se3

“…Desired electronic structure can be thus tuned. Furthermore, the pressure‐driven 2D–3D structural crossover in In 2 Se 3 is quite different from the transition of other layered chalcogenide materials, indicating the unusual variation of electronic states. We carried out the electrical transport measurements on single crystalline In 2 Se 3 during compression and decompression cycles, complemented by X‐ray diffraction (XRD) experiments to monitor the structural evolution.…”

“…The diffraction pattern of the high‐pressure phase remains unchanged when the sample is quenched to ambient pressure, indicating that the high‐pressure phase is quenchable. For the starting phase, the diffraction patterns of In 2 Se 3 below 35.6 GPa can be well indexed into a rhombohedral structure . Based on the Rietveld refinement with GSAS software (Figure b), the high‐pressure phase is found to have a body‐centered cubic structure.…”

“…Besides, In 2 Se 3 is considerably sensitive to the external conditions. It shows extremely large electronic anisotropy between in‐plane and cross‐plane conductivity, and large resistance variation between different electronic states with varying external conditions . Desired electronic structure can be thus tuned.…”

Experimental and Theoretical Studies on α-In2Se3 at High Pressure

“…39 Curiously, this soft phonon was not observed in two previous HP-RS studies that, in turn, did not identify the intermediate β′ phase between the α and β phases. 42,43 In this context, it is worthy to note that HP-RS studies of vibrational properties of the tetradymite phase of α-Sb2Te3, α-Bi2Se3 and α-Bi2Te3 have not reported any experimental or theoretical soft mode in the R-3m phase. 40 More recently, a HP study has revealed a superconductivity enhancement in α-In2Se3 under compression when it undergoes the transition to the defective cubic Th3P4 structure.…”