Layered K2Ti4O9 and the open metastable TiO2(B) structure

Tournoux, M.; Marchand, R.; Brohan, Luc

doi:10.1016/0079-6786(86)90003-8

Cited by 129 publications

(101 citation statements)

References 57 publications

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“…4. For the TiO 2 (B) phase, each nanowire was basically composed of a single crystal (or a bundle of single crystal wires), however, a large number of defects and mosaic-like structure were observed, which can be attributed to the facetted internal voids (negative crystal) formed by the dehydration, as reported earlier in the literatures [16,45]. In contrast, TiO 2 anatase nanowires contained fewer defects and no mosaic-like structure.…”

Section: Characterization Of Tio 2 Nanowiresmentioning

confidence: 67%

“…TiO 2 (B) is a metastable polymorph of titanium dioxide, first synthesized by Marchand et al in 1980 [14], which is formed by the dehydration of layered or tunnel-structured hydrogen titanates (H 2 Ti n O 2n+1 ) [15][16][17][18]. Later, in 1991, naturally occurring TiO 2 (B) was also identified in a natural anatase crystal by Banfield et al [19][20][21].…”

Section: Introductionmentioning

confidence: 99%

“…Thus, this phase is also called "the fourth TiO 2 mineral", or more simply "monoclinic TiO 2 [22]." Since TiO 2 (B) contains a relatively large channel structure, it was studied for hydrogen [23] and Li-ion storages [16,[24][25][26]. TiO 2 (B) usually forms a fibrous or rod-like structure [27], and as reported by Sugimoto et al in 2002, a preferentially oriented TiO 2 (B) thin-film can be also prepared [28].…”

Section: Introductionmentioning

confidence: 99%

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Addition of TiO2 nanowires in different polymorphs for dye-sensitized solar cells

2007

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TiO 2 (B) and TiO 2 anatase nanowires were prepared at 150• C for 120 h by a hydrothermal method followed by calcination in air at 400• C for 2 h and at 700 • C for 2 h for TiO 2 (B) and TiO 2 anatase, respectively. Although dye-sensitized solar cells (DSC) with fully nanowire electrodes showed a rather low light-to-electricity conversion efficiency of 1.33 % for TiO 2 (B) and 2.42% for TiO 2 anatase, 10 wt % nanowire-dispersed electrodes in a P-25 TiO 2 -nanoparticle matrix demonstrated improved efficiency of 6.17 % for TiO 2 (B) and 6.53% for TiO 2 anatase, these exceeding that of pure P-25 electrodes in this work (η=5.59%). The dominant mechanisms of the improvement at 10 wt% for the two different polymorphs are thought to be different, i.e., a light-scattering and film-thickness increment for the TiO 2 (B) system, whereas there is an improved conduction path through the matrix for the TiO 2 anatase system.

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Section: Characterization Of Tio 2 Nanowiresmentioning

confidence: 67%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Addition of TiO2 nanowires in different polymorphs for dye-sensitized solar cells

2007

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“…This is rather surprising, since with the ultimate removal of K20 from the structure, approximately 32% of the volume is lost, as calculated from the unit cell parameters and cell content. The measured density has previously been found to be substantially lower than the expected value [3].…”

mentioning

confidence: 88%

On the transformation mechanism of K2Ti4O9 to TiO2(B) and formation of microvoids

Wallenberg

Sanati

Andersson

1990

Microsc. Microanal. Microstruct.

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“…12) Further, it is rare that consideration is given to other titania phases including brookite, TiO 2 (B), TiO 2 (II), TiO 2 (H) amongst others, although these can be present as transient, or nanoencapsulated structures within the commonly recognized polytypes. 13) For the past two decades, sol-gel routes have been an important source of nanocrystalline titania. 14,15) The critical amorphous to anatase phase transition is controlled fundamentally by preparative conditions, that in turn, dictate photocatalytic efficiency.…”

Section: Introductionmentioning

confidence: 99%

Controlled Nanophase Development in Photocatalytic Titania

Hon

White

et al. 2003

Mater. Trans.

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Acid catalyzed hydrolysis of titanium butoxide was used to synthesize homogenous titania gels, which were converted to the anatase and rutile polytypes through controlled firing. The mechanism of this phase transformation was investigated by quantitative powder X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM). Condensation to titania is a function of annealing time, temperature and atmosphere. In air, calcinations below 600 C favored the formation of anatase, with rutile only appearing at >600 C. However, in situ transformation where titania nanoparticles were treated under vacuum in the TEM required heating at higher temperatures up to 900 C. This is may be due to the formation of surface layers of reduced titanium oxide that passivate and retard the anatase to rutile transformation. Grain growth and specific surface area varied inversely, with especially rapid crystallization observed at and beyond the transformation temperature. Potential photocatalytic activity was identified with ultraviolet-visible (UV-Vis) spectroscopy. A red shift of the absorption edge for nano-titania was observed due to quantum size effects.

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Layered K2Ti4O9 and the open metastable TiO2(B) structure

Cited by 129 publications

References 57 publications

Addition of TiO2 nanowires in different polymorphs for dye-sensitized solar cells

Addition of TiO2 nanowires in different polymorphs for dye-sensitized solar cells

On the transformation mechanism of K2Ti4O9 to TiO2(B) and formation of microvoids

Controlled Nanophase Development in Photocatalytic Titania

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