Synthesis and characterization of rare earth‐doped silica nanoparticles for optimizing vapor phase doping technique

Abstract

The synthesis of rare earth‐doped aluminosilicate soot particles through vapor phase doping technique has been systematically investigated to achieve better control of rare earth homogeneity in silica glass. The experiments were designed to establish the correlation of process conditions with the physicochemical properties of the formed soot particles. Attained results depict that the characteristics of soot particles are much dependent on vapor phase compositions as well as the deposition temperature. Doping of alumina/rare earth oxide into silica matrix lowers the viscosity of the glass material at a level where size of soot particles becomes independent of deposition temperature. But dopant concentration in the formed soot samples moderately depends on the main burner temperature and by altering it appropriately one can eliminate soot layer sintering step. The paper also reports on the optimum conditions which are necessary to produce rare earth‐doped preforms of better homogeneity and thus, assist in achieving greater control over the process technology of vapor phase doping. As per the authors’ knowledge, this investigation presents completely new findings which have not been reported by any other research group earlier.

Regulable surface hydroxyl group content in disperse ultrafine amorphous SiO2 nanoparticles

“…[1][2][3][4][5][6] SiO 2 NPs show a stable structure, environmental friendliness, high acid resistance, and high specific surface area and are ideal materials for applications in environmental pollutant remediation, element removal, and water purification. [7][8][9][10][11] Dispersity, morphology, size, and surface silanol group content are key factors governing the characteristics of amorphous SiO 2 NPs. The content, allocation, and reactivity of surface OH groups in SiO 2 NPs are of scientific and technological significance.…”

“…Amorphous silica (SiO 2 ) in forms of SiO 2 nanoparticles (NPs), SiO 2 gels, aerosils (pyrogenic silicas), aerosilogels, porous SiO 2 glasses, and so on is a kind of silica material that has been the subject of scientific research and applied in a wide variety of high technologies 1–6 . SiO 2 NPs show a stable structure, environmental friendliness, high acid resistance, and high specific surface area and are ideal materials for applications in environmental pollutant remediation, element removal, and water purification 7–11 . Dispersity, morphology, size, and surface silanol group content are key factors governing the characteristics of amorphous SiO 2 NPs.…”

“…The highest value of the boundary temperatures for the complete removal of physically adsorbed water (T B ) is 190 ± 10 • C. 2 A broad region of weight loss above T B in the thermogravimetric (TG) curve should F I G U R E 1 X-ray diffraction (XRD) patterns of the samples calcinated at various temperatures for 4 h. result from the removal of silanol groups. 15,20,21 It should be made clear that only vicinal silanols, germinal silanols, and isolated silanols as well as physically adsorbed water molecules on SiO 2 NPs can significantly affect their pertinent reaction processes, such as surface modification reactions, [6][7][8][9] environmental pollutant remediation, [22][23][24][25][26][27][28][29] self-assembly processes, 30 and the preparation and properties of quartz glasses. 31 For example, the isolated silanols, germinal silanols, and vicinal silanols on the surface of SiO 2 materials are the adsorption sites for naphthalene.…”