Synthesis and High-Pressure Study of Corundum-Type In₂O₃

Structural and vibrational properties of corundum-type In2O3nanocrystals under compression

“…Our theoretical results provide both the frequencies of the normal modes and their polarization vectors and enable us to assign the Raman-active modes observed in nanocrystalline rh-In2O3 as previously done for bulk rh-In2O3. 37 faster under compression than that corresponding to the (110) reflection. In the second experiment, in addition to the Bragg peaks of the sample, Bragg peaks of Ar are also detected.…”

“…Additionally, a second XRD experiment with Ar as PTM was done in order to prove if nanopowders could be affected by non-hydrostatic effects using MEW and to compare with previous results described in the literature. 37 For pressure calibration in angle-dispersive powder XRD and RS measurements we introduced inside the pressure cavity Cu powder 62 and ruby, 63 respectively. In the XRD experiments we collected also two patterns, one in the region where the Cu peaks were strong and the other where there is no Cu signal.…”

“…52 Among them only the Pbcn phase has been claimed to be metastable at ambient conditions, [49][50][51] despite the Pbca phase is a phase reported at lower pressures than the Pbcn phase. 36,37 Working with nanocrystals opens the door to enhanced properties of materials; 53,54 and adds the possibility of obtaining metastable HP crystalline and amorphous phases at room conditions with different properties from the original material. 47,[55][56][57] It is well known that most nanocrystals undergo a pressure-induced phase transition at larger pressures than in the bulk and that many nanocrystals undergo a pressure-induced amorphization; 55 however, many questions remain open regarding the behaviour of nanocrystals at HP in comparison with bulk materials.…”

“…Gurlo et al, who studied nanocrystals of rh-In2O3, suggested that this compound is stable at room temperature between room pressure and 30 GPa; 49 however, two recent studies reported that bulk rh-In2O3 undergoes a transformation above 12-14 GPa in good agreement with theoretical simulations. 36,37 The apparent lack of phase transition in nanocrystals up to 30 GPa suggests the existence of large kinetic barriers to explain their extended structural stability.…”

Synthesis of corundum-type In2O3nanocrystals via hydro/solvothermal route and their photocatalytic properties

“…[1][2][3] As one of the most important part of new research area of functional materials, metastable materials, physical and chemical properties being different from their stable phase, are becoming ever more essential to resolve new problems. [4,5] As a key n-type III-VI semiconductor, Indium oxide (In 2 O 3 ), has attracted considerable attention because of the peculiar electronic and optical properties and increasingly extensive applications in solar cells, sensors, electrocatalyst and nanoscale transistors etc. [6,7] Normally, In 2 O 3 prefers to crystallize in the form of cubic structure (C-In 2 O 3 ), whereas metastable corundum-type In 2 O 3 (H-In 2 O 3 ) was obtained by the phase transition method under high temperature and high pressure (HTHP) conditions.…”