Hydrolysis of titanium tetrafluoride

Buslaev, Yu. A.; Dyer, Daniel S.; Ragsdale, Ronald O.

doi:10.1021/ic50058a017

Cited by 46 publications

(28 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Nevertheless, within the rising edge region, the curve of the milled sample is closer to that of pure TiO 2 than that of Ti 2 O 3 . Experiments performed by Buslaev et al 42 would exclude TiO 2 as a product of the hydrolysis reaction of TiF 4 . The combination of the observations reported for the milled sample, at the pre-edge region, at the rising edge region, and at the absorption edge allows concluding that Ti has an oxidation state of IV (TiO 2 or TiF 4 ).…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Chemical State, Distribution, and Role of Ti- and Nb-Based Additives on the Ca(BH₄)₂ System

et al. 2013

View full text Add to dashboard Cite

Light metal tetrahydroborates are regarded as promising materials for solid state hydrogen storage. Due to both a high gravimetric hydrogen capacity of 11.5 wt % and an ideal dehydrogenation enthalpy of 32 kJ mol −1 H 2 , Ca(BH 4 ) 2 is considered to be one of the most interesting compounds in this class of materials. In this work, a comprehensive investigation of the effect of different selected additives (TiF 4 , NbF 5 , Ti-isopropoxide, and CaF 2 ) on the reversible hydrogenation reaction of calcium borohydride is presented combining different investigation techniques. The chemical state of the Nb-and Ti-based additives is studied by Xray absorption spectroscopy (e.g., XANES). Transmission electron microscopy (TEM) coupled with selected area electron diffraction (SAED) and energy-dispersive X-ray spectroscopy (EDX) was used to show the local structure, size, and distribution of the additive/catalyst.11 B{ 1 H} solid state magic angle spinning-nuclear magnetic resonance (MAS NMR) was carried out to detect possible amorphous phases. The formation of TiB 2 and NbB 2 nanoparticles was observed after milling or upon sorption reactions of the Nb-and Ti-based Ca(BH 4 ) 2 doped systems. The formation of transition-metal boride nanoparticles is proposed to support the heterogeneous nucleation of CaB 6 . The {111}CaB 6 /{1011}NbB 2 , {111}CaB 6 / {1010}NbB 2 , as well as {111}CaB 6 /{1011}TiB 2 plane pairs have the potential to be the matching planes because the d-value mismatch is well below the d-critical mismatch value (6%). Transition-metal boride nanoparticles act as heterogeneous nucleation sites for CaB 6 , refine the microstructure thus improving the sorption kinetics, and, as a consequence, lead to the reversible formation of Ca(BH 4 ) 2 . ■ INTRODUCTIONHydrogen is considered a promising future energy carrier due to its high abundance and its weight. In addition, its chemical energy per mass is the highest among all the chemical fuels. Solid state hydrogen storage is advantageous concerning safety and suitability compared to the liquid and compressed gas technology.1 Alkaline and alkaline earth metal tetrahydroborates offer high gravimetric and volumetric hydrogen densities which could satisfy the requirements set by the DoE (U.S. Department of Energy).2 Among light metal tetrahydroborates, Ca(BH 4 ) 2 is regarded as a potential candidate for solid state hydrogen storage due to its high gravimetric (11.5 wt %) and volumetric (∼130 kg m −3 ) hydrogen content. 3 In addition, the dehydrogenation enthalpy was calculated to be 32 kJ mol4,5 provided that CaH 2 and CaB 6 are the decomposition products, which is within the optimal range for mobile applications.4,5 As a consequence, a decomposition temperature lower than 100°C at 1 bar H 2 pressure is estimated. However, several decomposition paths for pure Ca (BH 4 H 2 ). 8 Formations of CaB 2 H x (x = 2) (reaction 3) and of the CaB m H n phase were recently observed.12,13 By calculations, Zhang et al.9 found that the CaB 2 H x (x = 2) phase is too unstabl...

show abstract

Section: ■ Results and Discussionmentioning

confidence: 99%

Chemical State, Distribution, and Role of Ti- and Nb-Based Additives on the Ca(BH₄)₂ System

et al. 2013

View full text Add to dashboard Cite

show abstract

“…Only approximately 5~o of the H2TiF6 in 30ml of solution is consumed by 1 g of kaolinite, with the formation of SiF4 (gas), HzSiF6, H3A1F6, HzFeF5 and complexes such as HTiFsH20 (Buslaev et al, 1967), but not titanyl ions (Cotton and Wilkinson, 1972, p. 84). The large excess of H2TiF6 is required to prevent further oxygenation and consequent precipitation of TiO2 through reversal of equation (1).…”

Section: Resultsmentioning

confidence: 99%

Anatase and Rutile Determination in Kaolinite Deposits

Sayin

Jackson

1975

Clays and clay miner.

View full text Add to dashboard Cite

Abstract--Hexafluorotitanic acid (H2TiF6) selectively dissolves kaolinite and most other phyllosilicate minerals of soils and sediments, concentrating free crystalline (Ti, Fe)O2 minerals (partially substituted anatase and rutile) in the residue. A series of H2TiF6 reagents was standardized by analysis of the Ti content and by tests with pure anatase and commercial kaolinites. The Ti in the H2TiF6 solution selected (made from 49% HF + reagent TiO2) was 16.5% by weight as analyzed by the Tiron method. Treatment of pure anatase with the reagent H2TiF6 resulted in a 98% by weight recovery of TiO2 in the residue. The fraction of TiO2 recovered in the residue of commercial Georgia kaolinites was 88-101}/o after treatment with the selected H2TiF6 reagent. Isolates from nine Georgia kaolinite samples with varying amounts of TiOz and Fe203 were examined by X-ray powder diffraction, scanning electron microscopy and elemental analysis. The main constituent of the (Ti,Fe)O2 isolates was anatase for all samples, with minor amounts of coarser rutile and mica from coarser kaolinite. The anatase and rutile isolates contained 74-93% (Ti,Fe)O~ with 0-5-3-1% Fe. The other constituents of the isolates were muscovite of mica (0"3-7~o), quartz (0-9~o) and amorphous relics of vermiculite and/or kaolinite (6-19%). Rutile, muscovite and quartz appear to be detrital but the anatase and relics are probably authigenic. Fine anatase appears to stick on the muscovite flakes as revealed by scanning electron microscopy and heavy liquid data for separation of these two minerals. The (Ti,Fe)Oz isolates from kaolinites which passed with the first magnetic concentrate of anatase were coarse, on the order of a few microns dia., as revealed by the scanning electron microscopy. Those passed with subsequent extensive magnetic concentrates from the same samples were finer. The anatase isolated from kaolinite purified by removal of as much of the impurities as possible by magnetic means was extremely fine, most of the particles being on the order of 0.1 #m dia. More than one third of the total FezO 3 in kaolinites magnetically separated in the first pass was extracted by the citrate-bicarbonate-dithionite treatment after hot NaOH dissolution of 5~74% of the kaolinite, showing that the Fe203 had been mainly associated within the kaolinite. Only 2-6% of the total Fe203 was extracted from magnetically purified kaolinite after 40-50~o of this kaolinite had been dissolved, indicating that most of the Fe is in the anatase and futile fraction.

show abstract

“…23 Nóbrega et al 15 show the capacity of this TiF 4 varnish to form reaction products such as FA and CaF 2 . Probably due to the mineral exchange process that occurs between the tooth and the biofilm, 18 loss of fluoride may have occurred on the biofilm, not allowing its measurement on the surface of the dental element after 14 days.…”

Section: Discussionmentioning

confidence: 99%

In situ effect of titanium tetrafluoride varnish on enamel demineralization

et al. 2017

View full text Add to dashboard Cite

The effect of a 4% titanium tetrafluoride (TiF 4 ) varnish on enamel demineralization was evaluated. Twelve volunteers participated in this double-blind, randomized crossover study. Six enamel specimens were positioned in intraoral appliances throughout four treatment stages: 4% TiF 4 varnish (experimental varnish), 5% sodium fluoride (NaF) varnish (Duraphat ® ), placebo varnish, and negative control (deionized water). After 24 h, the varnishes were removed and plaques were allowed to accumulate. A 20% sucrose solution was dripped onto enamel blocks (10x/day). Enamel alterations were analyzed by surface microhardness (SMH), percentage of surface loss (%SML), cross-sectional microhardness (CSMH), scanning electron microscopy (SEM), and energy dispersive X-ray spectrometry (EDS). Student's paired t-test was used for SMH analysis and repeated-measures analysis of variance (ANOVA) for %SML and CSMH (∆Z) analyses (p-value=0.05). The TiF 4 varnish group had lower %SML than the placebo and control groups (p=0.044 and p=0.003, respectively), thus showing its capacity to inhibit surface demineralization. TiF 4 and NaF varnishes demonstrated a protective effect against mineral loss on the enamel subsurface. Both were statistically different from the control group when CSMH was analyzed (p=0.000). A titanium dioxide film was observed on enamel surfaces of the TiF 4 group SEM images. EDS confirmed the presence of titanium in all TiF 4 samples. The 4% TiF 4 varnish is a promising compound capable of reacting with enamel to protect it against surface and subsurface demineralization.

show abstract

Hydrolysis of titanium tetrafluoride

Cited by 46 publications

References 0 publications

Chemical State, Distribution, and Role of Ti- and Nb-Based Additives on the Ca(BH₄)₂ System

Chemical State, Distribution, and Role of Ti- and Nb-Based Additives on the Ca(BH₄)₂ System

Anatase and Rutile Determination in Kaolinite Deposits

In situ effect of titanium tetrafluoride varnish on enamel demineralization

Contact Info

Product

Resources

About

Hydrolysis of titanium tetrafluoride

Cited by 46 publications

References 0 publications

Chemical State, Distribution, and Role of Ti- and Nb-Based Additives on the Ca(BH4)2 System

Chemical State, Distribution, and Role of Ti- and Nb-Based Additives on the Ca(BH4)2 System

Anatase and Rutile Determination in Kaolinite Deposits

In situ effect of titanium tetrafluoride varnish on enamel demineralization

Contact Info

Product

Resources

About

Chemical State, Distribution, and Role of Ti- and Nb-Based Additives on the Ca(BH₄)₂ System

Chemical State, Distribution, and Role of Ti- and Nb-Based Additives on the Ca(BH₄)₂ System