Structural phase transitions in niobium oxide nanocrystals

Abstract

Niobium oxide nanocrystals were successfully synthesized employing the green synthesis method. Phase formation, microstructure and compositional properties of 1, 4 and 7 days incubation treated samples after calcinations at 450 C were examined using X-ray diffraction, Raman, photoluminescence (PL), infrared, X-ray photoelectron spectra and transmission electron microscopic characterizations. It was observed that phase formation of Nb 2 O 5 nanocrystals was dependent upon the incubation period required to form stable metal oxides. The characteristic results clearly revealed that with increasing incubation and aging, the transformation of cubic, orthorhombic and monoclinic phases were observed. The uniform heating at room temperature (32 C) and the ligation of niobium atoms due to higher phenolic constituents of utilized rambutan during aging processing plays a vital role in structural phase transitions in niobium oxide nanocrystals. The defects over a period of incubation and the intensities of the PL spectra changing over a period of aging were related to the amount of the defects induced by the phase transition. IntroductionNiobium oxide (Nb 2 O 5 ) has been used to develop electrical,[1,2] superconducting,[3] relaxor,[4À6] optical, thermal and structural,[7À10] resistance switching,[11] dielectric and pyroelectric,[12] and phase transition [13] properties. In recent years, Bafrooei and his co-workers [14] investigated the microwave sintering effect on densification, microstructure and microwave dielectric properties of ZnNb 2 O 6 nanopowders. Jeong and his co-workers [15] studied the fabrication of super hydrophobic niobium pentoxide thin films employing anodization. Yang and his co-workers [16] explored the sensing and pH imaging properties of niobium oxide prepared employing rapid thermal annealing for electrolyte insulator semiconductor structure and light-addressable potentiometric sensor applications. Kadir and his co-workers [17] studied Nb 2 O 5 Schottky-based ethanol vapour sensors effect of metallic catalysts. Kong and his co-workers [18] revealed ultra high intercalation pseudocapacitance of mesoporous orthorhombic niobium pentoxide from a novel cellulose nanocrystal template. Wang and his co-workers [19] investigated orthorhombic niobium oxide nanowires for next generation hybrid supercapacitor device. Zhou and his co-workers [20] studied photoluminescence (PL) of amorphous niobium oxide films synthesized by solid state reaction. In a separate study, Karlinsey [21] investigated the preparation of self-organized niobium oxide microstructures via potentiostatic anodization.However, the above preparation methods involve either two chemical precursors or high temperature, solvents, reductants and stabilizing agents as well as high costs for the

Synthesis and structural characterization of gallium oxide powders

“…In the present study, the inorganic complex intermediate green ligation from natural waste resources has been adopted to synthesis gallium oxide powders [13][14][15][16][17][18][19][20][21]. Among many synthetic methods, metal-ellagate square planar complex method is the simple technique to prepare bio inspired transition metal oxide powders.…”

Structural characterization of beryllium and indium oxide powders

“…In the present study, we report on the structural properties of beryllium and indium oxide powders using a sustainable green synthesis method without surfactant and template at room temperature incubation and aging over a period of 7 days for sustainable materials development. Therefore, in the present study, metal-ellagate square planar complex method is employed to prepare metal oxide powders [36][37][38][39][40][41][42][43][44]. The obtained metal-ellagate complex has been decomposed into BeO and In 2 O 3 powders by calcinating in static air atmosphere at 350, 500 and 650°C for 1 h.…”