Raman spectroscopy and characterisation of α‐gallium oxyhydroxide and β‐gallium oxide nanorods

Abstract

Raman spectroscopy complemented by infrared spectroscopy was used to characterise both gallium oxyhydroxide (a-GaO(OH)) and gallium oxide (b-Ga 2 O 3 ) nanorods synthesised with and without the surfactants using a soft chemical methodology at low temperatures. Nano-to micro-sized gallium oxyhydroxide and gallium oxide materials were characterised and analysed by both X-ray diffraction and Raman spectroscopy. Rod-like GaO(OH) crystals with average length of ∼2.5 µm and width of 1.5 µm were obtained. Upon thermally treating gallium oxyhydroxide GaO(OH) to 900°C, b-Ga 2 O 3 was synthesised retaining the initial GaO(OH) morphology. Raman spectroscopy has been used to study the structure of nanorods of GaO(OH) and Ga 2 O 3 crystals. Raman spectroscopy shows bands characteristic of GaO(OH) at 950 and ∼1000 cm−1 attributed to Ga-OH deformation modes. Bands at 261, 275, 433 and 522 cm −1 are assigned to vibrational modes involving Ga-OH units. Bands observed at 320, 346, 418 and 472 cm −1 are assigned to the deformation modes of Ga 2 O 6 octahedra. Two sharp infrared bands at 2948 and 2916 cm −1 are attributed to the GaO(OH) symmetric stretching vibrations. Raman spectroscopy of Ga 2 O 3 provides bands at 630, 656 and 767 cm −1 which are assigned to the bending and stretching of GaO 4 units. Raman bands at 417 and 475 cm −1 are attributed to the symmetric stretching modes of GaO 2 units. The Raman bands at 319 and 347 cm −1 are assigned to the bending modes of GaO 2 units.

Structural and optical properties of GaN and InGaN nanoparticles by chemical co-precipitation method

“…In addition to the above modes, the five other peaks at 125, 195, 247, 302 and 407 cm À1 were also observed. The presence of peaks at 195 and 407 cm À1 are corresponds to downshift of A g symmetry modes of Ga 2 O 3 [37] due to unavoidable surface oxidation states in InGaN nanopowders as it has a strong affinity to oxidation. Although, the Ga 2 O 3 phase is not observed in XRD, a very small amount of oxygen is present in the EDS measurement.…”

Raman spectroscopic study of the hydrogen‐arsenate mineral pharmacolite Ca(AsO3OH)·2H2O—implications for aquifer and sediment remediation

“…Alignment of all crystals in a similar orientation has been attempted and achieved. However, the differences in intensity observed may be due to minor differences in the crystal orientation 23–32, 36–41…”

Silver centers luminescence in phosphate glasses subjected to X‐Rays or combined X‐rays and femtosecond laser exposure

“…Meanwhile, the GPN o glass exhibits low band intensities related to asymmetric (PO 3 2− ) vibrations of Q 1 entities as well as symmetric and asymmetric stretching of the Q 2 phosphate tetrahedron respectively peaking at 1100 cm −1 , 1170 cm −1 and 1200 cm −1 . While the main contributions at 640 cm −1 and 980 cm −1 are respectively assigned to [GaO 4 ] − stretching vibrations and symmetric (PO 4 3− ) stretching in Q 0 phosphate entity. These both main contributions emphasizes a majority of Q 0 phosphate entities surrounded by sodium ions or gallium in tetrahedral sites [GaO 4 ] − .…”

“…,28 as well as symmetric and asymmetric stretching of the Q 2 phosphate tetrahedron22,24,26,28 respectively peaking at 1100 cm −1 , 1170 cm −1 and 1200 cm −1 . While the main contributions at 640 cm −1 and 980 cm −1 are respectively assigned to [GaO 4 ] − stretching vibrations[24][25][26][29][30][31] and sym-…”