Sodium Titanates: Stoichiometry and Raman Spectra

Bamberger, C.E.; Begun, G. M.

doi:10.1111/j.1151-2916.1987.tb04963.x

Cited by 98 publications

(76 citation statements)

References 11 publications

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“…The Raman spectrum of bulk Na 2 Ti 3 O 7 (curve c) and Na 2 Ti 6 O 13 (curve d) are similar to those reported in the literature. [33][34][35] Again the relative number of modes observed for Na 2 Ti 3 O 7 and Na 2 Ti 6 O 13 are in agreement with group theory predictions. We observed that both NTTiOx and NRTiOx have different Raman spectra with respect to the number of bands, but they are similar with regard to location of energy bands.…”

Section: Vibrational Propertiessupporting

confidence: 84%

Structural, morphological and vibrational properties of titanate nanotubes and nanoribbons

Viana¹,

Ferreira²,

Filho³

et al. 2009

J. Braz. Chem. Soc.

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Este trabalho relata o estudo das propriedades estruturais, morfológicas e vibracionais dos nanotubos e das nanofitas de titanato obtidos a partir de estruturas bidimensionais por meio de tratamento hidrotérmico do TiO 2 em solução aquosa de NaOH. As propriedades físicas destas nanoestruturas, como preparadas e tratadas termicamente, são discutidas e comparadas com seus similares "bulks" (Na 2 Ti 3 O 7 e Na 2 Ti 6 O 13 ). Os resultados obtidos por várias técnicas de caracterização nos permitem concluir que as paredes dos nanotubos e das nanofitas, como preparados, são isoestruturais ao composto Na 2 Ti 3 O 7 . Contudo, nos nanotubos as ligações químicas são deformadas por causa da curvatura das paredes, enquanto nas nanofitas as camadas apresentam apenas uma desordem estrutural provocada pelo efeito de tamanho. As características térmicas das nanofitas são similares àquelas observadas para os nanotubos, nos quais as mudanças estruturais e morfológicas levam para a formação de grandes bastões (bulks) com uma mistura de fase Na 2 Ti 3 O 7 e Na 2 Ti 6 O 13 . Concluímos que os nanotubos e as nanofitas de titanato têm a mesma composição química, igual a Na 2-x H x Ti 3 O 7• nH 2 O (0 ≤ x ≤ 2). Também podemos sugerir que a espectroscopia Raman pode ser usada para uma fácil e rápida identificação das mudanças morfológicas e estruturais das nanoestruturas de titanato.This work reports the structural, morphological and vibrational properties of titanate nanotubes and nanoribbons obtained from bidimensional structures by hydrothermal treatment of TiO 2 in aqueous NaOH solutions. The physical properties of these as-synthesized and heat-treated nanostructures are discussed in comparison with their bulk (Na 2 Ti 3 O 7 and Na 2 Ti 6 O 13 ) counterparts. The results obtained from several characterization techniques allowed to conclude that the layers of both as-synthesized nanotubes and nanoribbons are isostructural to the Na 2 Ti 3 O 7 compound. However, in the nanotubes, the chemical bonds are deformed because of the curvature of walls while in the nanoribbons the layers present structural disorder due only the size effects. The thermal behavior of titanate nanoribbons is similar to those observed for titanate nanotubes. When thermally treated titanate nanoribbons change to bulk with a phase mixing of Na 2 Ti 3 O 7 and Na 2 Ti 6 O 13 . We conclude in this work that the chemical composition of both the titanate nanotubes and the nanoribbons is the same, Na 2-x H x Ti 3 O 7•nH 2 O (0 ≤ x ≤ 2) and Raman spectroscopy can be used for an easy and quick identification of both morphology and structure changes of the nanosized titanates.Keywords: titanium oxide, titanate nanostructures, thermal treatment, phase transformation, spectroscopy IntroductionIntensive investigations have been carried out on the physical and chemical properties of inorganic nanosized materials in the recent years. 1 Researchers are realizing that one-dimensional nanostructures made from inorganic materials have intriguing properties different from those of c...

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Section: Vibrational Propertiessupporting

confidence: 84%

Structural, morphological and vibrational properties of titanate nanotubes and nanoribbons

Viana¹,

Ferreira²,

Filho³

et al. 2009

J. Braz. Chem. Soc.

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“…According to the Raman spectra in the literature [27], the sharp peaks labeled with numbers in Fig. 2 belong to K 2 Ti 6 O 13 , which is sensitive to Raman spectroscopy [28,29]. However, the corresponding peaks in Fig.…”

Section: Resultsmentioning

confidence: 99%

Corrosion behavior of Ti3AlC2 in molten KOH at 700 °C

Sun

Zhou

et al. 2013

J Adv Ceram

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This paper investigated the corrosion behaviors of Ti 3 AlC 2 at 700 ℃ in molten KOH with various mass ratios. If the mass ratio of KOH:Ti 3 AlC 2 ≤2, Ti 3 AlC 2 can resist KOH hot corrosion in 2 h. Ti 3 AlC 2 suffered serious corrosion attack if the mass ratio≥3. The main compositions of corroded samples were amorphous graphite and potassium titanates (K 2 O·nTiO 2 ). If the samples were washed by acid and dried, potassium titanates could decompose to K 2 O and amorphous rutile. Based on the experimental results, a corrosion mechanism of Ti 3 AlC 2 in molten KOH was proposed.

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“…The peak at high frequency is attributed to the short Ti-O stretching vibration with non-bridging oxygen atoms coordinated to the interlayer cation. 25 This peak is located at higher frequencies for the sodium form compared to the potassium one, shifting from 880 to 900 cm -1 , meaning that the bond has become shorter. In addition, the peak at 235 cm -1 which corresponds to the Ti-O-K vibration 26 in K 0.8 Ti 1.73 Li 0.27 O 4 changed after the ion exchange and split into several overlapping peaks in the Na ion-exchanged sample.…”

Section: Chemical and Structural Characterizationmentioning

confidence: 99%

Lepidocrocite-type Layered Titanate Structures: New Lithium and Sodium Ion Intercalation Anode Materials

2014

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The electrochemical characteristics of lepidocrocite-type titanates derived from K 0.8 Ti 1.73 Li 0.27 O 4 are presented for the first time. By exchanging sodium ions for potassium, the practical specific capacity of the titanate in both sodium and lithium half cells is considerably enhanced. Although the gross structural features of the titanate framework are maintained during the ion exchange process, the symmetry changes because sodium occupies different sites from potassium. The smaller size of the sodium ion compared to potassium and the change in site symmetry allow more alkali metal cations to be inserted reversibly into the structure during discharge in sodium and lithium cells than in the parent compound. Insertion of lithium cations takes place at an average of about 0.8V vs. Li + /Li while sodium intercalation occurs at 0.5V vs. Na + /Na, with sloping voltage profiles exhibited for both cell configurations, implying singlephase processes. Ex situ synchrotron X-ray diffraction measurements show that a lithiated 2 lepidocrocite is formed during discharge in lithium cells, which undergoes further lithium insertion with almost no volume change. In sodium cells, insertion of sodium initially causes an overall expansion of about 12% in the b lattice parameter but reversible uptake of solvent minimizes changes upon further cycling. In the case of the sodium cells, both the practical capacity and the cyclability are improved when a more compliant binder (polyacrylic acid) that can accommodate volume changes associated with insertion processes is used in place of the more common polyvinylidene fluoride. The ability to tune the electrochemical properties of lepidocrocite titanate structures by varying compositions and utilizing ion exchange processes make them especially versatile anode materials for both lithium and sodium ion battery configurations.

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Sodium Titanates: Stoichiometry and Raman Spectra

Cited by 98 publications

References 11 publications

Structural, morphological and vibrational properties of titanate nanotubes and nanoribbons

Structural, morphological and vibrational properties of titanate nanotubes and nanoribbons

Corrosion behavior of Ti3AlC2 in molten KOH at 700 °C

Lepidocrocite-type Layered Titanate Structures: New Lithium and Sodium Ion Intercalation Anode Materials

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