Raman Spectra of NanophaseCr2O3

Zuo, Jian‐Min; Xu, Chao; Hou, Bingzhe; Wang, Changsui; Xie, Yi; Qian, Yitai

doi:10.1002/(sici)1097-4555(199612)27:12<921::aid-jrs57>3.3.co;2-c

Cited by 16 publications

(27 citation statements)

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“…Vibrations with symmetry A 1 g and E g are Raman active, which means there are seven Raman active modes. Only five bands were found in most of the previous works of the Raman studies on chromium oxide36, 37, 40 However, six bands were revealed in this study, and another weak mode41 below 250 cm −1 was not observed. The most intense peak at 540 cm −1 was corresponding to the ν 1 ( A 1 g ) vibration mode of chromia 42.…”

Section: Resultscontrasting

confidence: 85%

“…The Raman spectrum of the Cr‐gel material heated at 550 °C in a nitrogen atmosphere is presented in Fig. 5, which is identical to a typical Raman spectrum of Cr 2 O 3 36, 37. It is understood that thermally treated product in N 2 from the Cr‐gel is crystalline Cr 2 O 3 , as confirmed by XRD (Fig.…”

Section: Resultssupporting

confidence: 59%

“…7), there are six formula units in the hexagonal unit cell. It is reported37 that chromium oxide belongs to the D 6 3 d space group, and the irreducible representations for the optical modes in the crystal are 2 A 1 g + 2 A 1 u + 3 A 2 g + 2 A 2 u + 5 E g + 4 E u . Vibrations with symmetry A 1 g and E g are Raman active, which means there are seven Raman active modes.…”

Section: Resultsmentioning

confidence: 99%

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Transition of synthetic chromium oxide gel to crystalline chromium oxide: a hot‐stage Raman spectroscopic study

Yang

Cheng

Martens

et al. 2010

J Raman Spectroscopy

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Chromium oxide gel material was synthesised and appeared to be amorphous in X-ray diffraction study. The changes in the structure of the synthetic chromium oxide gel were investigated using hot-stage Raman spectroscopy based upon the results of thermogravimetric analysis. The thermally decomposed product of the synthetic chromium oxide gel in nitrogen atmosphere was confirmed to be crystalline Cr 2 O 3 as determined by the hot-stage Raman spectra. Two bands were observed at 849 and 735 cm −1 in the Raman spectrum at 25 • C, which were attributed to the symmetric stretching modes of O-Cr III -OH and O-Cr III -O. With temperature increase, the intensity of the band at 849 cm −1 decreased, while that of the band at 735 cm −1 increased. These changes in intensity are attributed to the loss of OH groups and formation of O-Cr III -O units in the structure. A strongly hydrogen-bonded water H-O-H bending band was found at 1704 cm −1 in the Raman spectrum of the chromium oxide gel; however, this band shifted to around 1590 cm −1 due to destruction of the hydrogen bonds upon thermal treatment. Six new Raman bands were observed at 578, 540, 513, 390, 342 and 303 cm −1 attributed to the thermal decomposed product Cr 2 O 3 . The use of the hot-stage Raman spectroscopy enabled low-temperature phase changes brought about through dehydration and dehydroxylation to be studied.

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Section: Resultscontrasting

confidence: 85%

Section: Resultssupporting

confidence: 59%

Section: Resultsmentioning

confidence: 99%

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Transition of synthetic chromium oxide gel to crystalline chromium oxide: a hot‐stage Raman spectroscopic study

Yang

Cheng

Martens

et al. 2010

J Raman Spectroscopy

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“…However, the analysis of the micro-Raman spectra of the films ( fig. 2a) shows that the A 1g band is similar for the three films grown with R≥0.3 and only for the film deposited at R=0.1 is this band broader and red shifted, which is usually associated with structural disorder [27]. Therefore, the predominant factor determining the observed low intensity of the diffraction patterns for the films grown at R=0.1 and 2.9 should be the lower growth rate.…”

Section: Resultsmentioning

confidence: 95%

“…A set of bands matching the Raman active modes of Cr 2 O 3[26][27][28] can be seen infigure 2a.The diffractograms of the same films (fig. 2b) show that those deposited at R=0.3 and 1.0 are polycrystalline, exhibiting several well resolved diffraction lines that could only be indexed to the rhombohedral α-Cr 2 O 3 phase (JCPDS file nº 38-1479).…”

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confidence: 99%

Cr2O3 thin films grown at room temperature by low pressure laser chemical vapour deposition

2011

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Chromia (Cr2O3) has been extensively explored for the purpose of developing widespread industrial applications, owing to the convergence of a variety of mechanical, physical and chemical properties in one single oxide material. Various methods have been used for large area synthesis of Cr2O3 films. However, for selective area growth and growth on thermally sensitive materials, laser-assisted chemical vapour deposition (LCVD) can be applied advantageously.Here we report on the growth of single layers of pure Cr2O3 onto sapphire substrates at room temperature by low pressure photolytic LCVD, using UV laser radiation and Cr(CO)(6) as chromium precursor. The feasibility of the LCVD technique to access selective area deposition of chromia thin films is demonstrated. Best results were obtained for a laser fluence of 120 mJ cm(-2) and a partial pressure ratio of O-2 to Cr(CO)(6) of 1.0. Samples grown with these experimental parameters are polycrystalline and their microstructure is characterised by a high density of particles whose size follows a lognormal distribution. Deposition rates of 0.1 nm s(-1) and mean particle sizes of 1.85 mu m were measured for these films. (C) 2011 Elsevier B.V. All rights reserved. Document Type: ArticleLanguage: English

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Raman spectroscopy in the diagnosis of the wall painting History of Concepción, Chile

Aguayo

Clavijo

Eisner³

et al. 2011

J Raman Spectroscopy

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Pigments and fresco-related materials from the wall painting Historia de Concepción by Gregorio De La Fuente in Concepción, Chile were identified by Raman microscopy. The pigments were compared with those obtained from the artist's studio, and results allowed inference about subsequent interventions. Materials coming from processes such as salt efflorescence were also studied. The results contribute to the diagnosis of the current conservation state of the wall painting for its future restoration.

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Raman Spectra of NanophaseCr2O3

Cited by 16 publications

References 0 publications

Transition of synthetic chromium oxide gel to crystalline chromium oxide: a hot‐stage Raman spectroscopic study

Transition of synthetic chromium oxide gel to crystalline chromium oxide: a hot‐stage Raman spectroscopic study

Cr2O3 thin films grown at room temperature by low pressure laser chemical vapour deposition

Raman spectroscopy in the diagnosis of the wall painting History of Concepción, Chile

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