A Comparative Rietveld Refinement Study of Natisite Prepared in Different Morphology

Vibrational Spectral Analysis of Natisite (Na2TiSiO5) and its Structure Evolution in Water and Sulfuric Acid Solutions

“…As shown in Figure 3 , the distances between O a and the surrounding Ti and Si are too large to form chemical bonds. Furthermore, unlike the rarely observed TiO 5 trigonal bipyramids in γ- Na 2 TiO 3 , and TiO 5 asymmetric square pyramids are formed here, a common form for Ti(IV) of five-fold coordination [ 23 , 38 ]. Six-coordinated sodium ions are located in the layer built by TiO 5 and SiO 4 units, and they may be extracted from natisite via migrating through the layer space or breaking down the layered structure.…”

“…Although the synthesis of natisite has been studied [ 22 , 23 , 24 ], the effects of temperature and NaOH concentration remain unclear. Figure 1 shows the XRD patterns of the hydrothermal products obtained from different temperatures and NaOH concentrations.…”

“…Natisite can be prepared by both solid-state reaction and hydrothermal methods [ 11 ]. By adjusting the molar ratios of Na 2 O/TiO 2 and TiO 2 /SiO 2 in the hydrothermal process, Stanislav Ferdov selectively synthesized natisite with truncated bipyramidal, disk-shaped, and pillowlike microstructures [ 22 , 23 ], in which SiO 2 was used as the silicon source [ 23 , 24 ]. A double-walled natisite nanotube was prepared by an alkaline hydrothermal process with cetyltrimethylammonium bromide as an assistant [ 2 ].…”

Refinement of the crystal structure of fresnoite, Ba2TiSi2O8, from Löhley (Eifel district, Germany); Gladstone–Dale compatibility, electronic polarizability and vibrational spectroscopy of minerals and inorganic compounds with pentacoordinated TiIVand a titanyl bond

“…Among numerous titanosilicates, only in a very limited number of naturally occurring mineral species [namely, fresnoite (Moore & Louisnathan, 1967), natisite (Ferdov, 2013), paranatisite (Sokolova & Hawthorne, 2002), yoshimuraite (McDonald et al, 2000), bornemanite (Ca ´mara & Sokolova, 2007), kazanskyite (Ca ´mara et al, 2012), nechelyustovite (Ne `meth et al, 2009), innelite (Sokolova et al, 2011), phosphoinnelite (Pekov et al, 2007) and titanium members of the lamprophyllite group (Aksenov et al, 2021;Rastsvetaeva et al, 2017)] and several synthetic compounds does Ti have fivefold coordination. Most of these compounds contain barium or strontium.…”