Novel microporous titanium–niobium–silicates with the structure of nenadkevichite

Abstract

A series of synthetic microporous analogues of the mineral nenadkevichite are prepared; Raman spectroscopy shows the isomorphous substitution of titanium for niobium in octahedral framework sites.

Synthesis, Swelling, and Exfoliation of Microporous Lamellar Titanosilicate AM‐4

“…The exfoliation and the band at lower displacement increases, which will have been generated from the exchange of Na + by protons as observed for nenadkevichite and ETS-4, [27] in agreement with other observations on AM-4 material. [28] This effect could also be attributed to the breaking of X-O-X bonds (X = Si and Ti), which is consistent with the fine, high length/width ratio particles observed by TEM.…”

Structure and photocatalytic properties of Nb-doped Bi12TiO20 prepared by the oxidant peroxide method (OPM)

“…2) showed a homogeneous distribution of the elements in the crystalline samples, independently of the amount of niobium, confirming that it was incorporated into the crystalline lattice of the sellenite structure. The amounts of niobium measured Perhaps Raman spectroscopy provides the best evidence for the isomorphous substitution of titanium by niobium (Rocha et al 1996). Most of the niobium oxide compounds contain an octahedral NbO 6 cluster with different distortion extents, probable because Nb(V) is too small to form regular octahedra (Jehng and Wachs 1991).…”

Microporous Titanosilicates and other Novel Mixed Octahedral-Tetrahedral Framework Oxides

“…The structure of nenadkevichite (from Saint-Hilaire, Quebec, Canada) consists of square rings of silicon tetrahedra Si 4 O 12 in the (100) plane joined together by chains of (Nb,Ti)O 6 octahedra in the [100] direction (Figure 7d and 7e). [44,45] Many porous framework titanosilicates contain Ti-O-Ti linkages that often form infinite chains. Rocha and Anderson and co-workers have been able to prepare a series of synthetic analogues of nenadkevichite with Ti/Nb molar ratios ranging from 0.8 to 17.1 and a purely titaneous sample.…”

“…[44,45] The Raman spectra of a sample with Ti/ Nb ϭ 0.8 ( Figure 13) displays two main bands at 668 and 226 cm -1 associated with the NbO 6 octahedra. [44,45] The Raman spectra of a sample with Ti/ Nb ϭ 0.8 ( Figure 13) displays two main bands at 668 and 226 cm -1 associated with the NbO 6 octahedra.…”