Structural and Spectroscopic Investigations of Blue, Vanadium-Doped ZrSiO₄ Pigments Prepared by a Sol−Gel Route

Abstract

A sol-gel reaction starting from silicon and zirconium alkoxides, in water-ethanol mixtures, was employed to obtain vanadium-doped zirconium silicate powders (zircon). The reactions were performed by modulating both (a) the amount of the vanadium salt in the starting mixture and also (b) the amount of mineralizer (NaF). The products of the sol-gel reaction were calcined at 600, 800, 1000, and 1200 degrees C. The samples were characterized by X-ray powder diffraction (XRPD), electron paramagnetic resonance spectroscopy (EPR), scanning electron microscopy (SEM), X-ray absorption near-edge spectroscopy (XANES), and diffuse UV-vis-near-IR reflectance spectroscopy. Results from the structural, morphological, and optical characterization are examined and cross-compared to produce a consistent picture of the key factors leading to the formation, growth, and optical properties of the reaction products.

V–Al–O catalysts prepared by flame pyrolysis for the oxidative dehydrogenation of propane to propylene

“…The actual location of V 4+ ions in host lattices has been the subject of controversial debates for many systems [28][29][30][31][32][33][34][35][36][37] including V2O5 supported on inert oxides like Al2O3 and SiO2 [27,38,39]. Small hyperfine parameters [30], by far smaller than those given in Table 3, are typical of a tetrahedral site (low co-ordination number), whereas large hyperfine parameters were attributed to a dodecahedral site (high co-ordination number), i.e.…”

Ni‐Ti Codoped Hibonite Ceramic Pigments by Combustion Synthesis: Crystal Structure and Optical Properties

“…The design of new pigments is simpler for crystal structures having a single cationic site, e.g., corundum or rutile, circumstance that prevents order–disorder phenomena in the partition of dopant and main component. Similarly, the control is easier for crystalline phases which exhibit two polyhedra with distinct volume and coordination number, and therefore host cations with different radii and valence states, as in the case of the cubic and octahedral sites of perovskite, or the cubic and tetrahedral sites of zircon . However, the pigment design turns to be challenging as far as complex structures are concerned, i.e., those where three or more cationic sites are present, particularly if ions partition over different polyhedra can occur.…”

Fully densified zircon co-doped with iron and aluminium prepared by sol–gel processing

“…ability to control dopant levels more accurately. Several research groups have tried to incorporate metal ions such as iron, 1-3,10,11 vanadium [12][13][14][15][16][17][18] and praseodymium [19][20][21] into the structure of zircon during its synthesis. This has primarily been done in order to study the effect of dopants on pigmentation.…”