Infrared studies on some substituted copper chromite spinels

Basak, Dipmalya; Ghose, J.

doi:10.1016/0584-8539(94)80008-1

Cited by 21 publications

(7 citation statements)

References 13 publications

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“…Both, 1 at 665 cm -1 , and 2 at 580 cm -1 are related to bonds of the internal tetrahedra and octahedra of the structure of Cu 0.8 Ni 0.2 Cr 2 O 4 . The broadening of these bands is probably due to the presence of more than one type of cation 14 .…”

Section: Resultsmentioning

confidence: 99%

“…The relatively low values encountered are typical of Pechini synthesis, and can be attributed to the M:AC (M = Metal; AC = citric acid) molar ratio used in the synthesis, and consequently, to the chain polymer size used in pigment preparation. According to group theory, spinel type oxides should exhibit four IR bands 1 -4 [13][14] . In this investigation measurements were carried out up to 500 cm -1 , thus limiting the study to the high frequency bands ( 1 and 2 ) of the IR spectrum.…”

Section: Resultsmentioning

confidence: 99%

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Pechini synthesis and microstructure of nickel-doped copper chromites

et al. 2005

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Spinel-type solid solutions were synthesized by the Pechini method and calcined between 500 and 900 °C for 4 hours and at 900 °C for 8 hours to produce ceramic pigments. The resulting powders were characterized by thermogravimetric analysis, Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), particle size analysis and BET surface area measurements. The formation of spinel took place upon calcination at 700 °C. IR spectroscopy revealed the presence of n1 and n2 bands, typical of spinel structures, broadened by the presence of more than one cationic species in the structure. The specific area of the resulting powder decreased from 24.7 to 1.4 m² g-1 as the calcination temperature increased from 700 to 900 °C. Microstructural analyses revealed the presence of crystalline spinel as the only phase present in powders calcined at 900 °C. Colorimetric analyses using L*a*b* coordinates and UV-visible spectroscopy revealed that the pigment was predominantly black

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Pechini synthesis and microstructure of nickel-doped copper chromites

et al. 2005

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“…The origin of the T 1u modes has been the subject of controversy as two possible interpretations were proposed: In one case the two high-frequency phonon modes are related to the displacement of the Cr-X bond in the CrX 6 octahedra, while the two low-frequency phonon modes to the tetrahedra. 16,36,37 It has been shown experimentally [38][39][40] that the materials having an octahedral sublattice as one of the structural units exhibit phonon modes belonging to octahedral vibrations at higher-frequencies compared to the other lattice vibrations.…”

Section: Discussionmentioning

confidence: 99%

Evolution of the optical properties of chromium spinels CdCr2O4, HgCr2S
Rabia
¹
,
Baldassarre
²
,
Tsurkan
³

et al. 2014
Phys. Rev. B
10
2
4
0
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We report pressure-dependent reflection and transmission measurements on ZnCr2Se4, HgCr2S4, and CdCr2O4 single crystals at room temperature over a broad spectral range 200-24000 cm −1 . The pressure dependence of the phonon modes and the high-frequency electronic excitations indicates that all three compounds undergo a pressure-induced structural phase transition with the critical pressure 15 GPa, 12 GPa, and 10 GPa for CdCr2O4, HgCr2S4, and ZnCr2Se4, respectively. The eigenfrequencies of the electronic transitions are very close to the expected values for chromium crystal-field transitions. In the case of the chalcogenides pressure induces a red shift of the electronic excitation which indicates a strong hybridization of the Cr d-bands with the chalcogenide bands.

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“…According to group theory, spinel fype oxides should exlnmt four IR bands V1•V4 [Lefez et al, 1996). In the present study, however, meuutenlents were carried out up to 500 cmr 1 The powders morphologies were observed by SEM micrographs and the presence of europium in the zinc cobaltate matrix was confirmed by EDS analyses. Figure 5 shows the micrographs of ZnCo204: Eu 3 + powder calcined at 900°C.…”

Section: Resultsmentioning

confidence: 64%

PECHINI SYNTHESIS AND CHARACTERIZATION OF Eu3+ DOPED ZnCo2O4 SPINELS

Pimentel¹,

Pedrosa²,

Souza³

et al. 2005

PTQ

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Spinel oxides with the composition ZnCo2O4 and ZnCo2O4:Eu3+ have been synthesized by the Pechini method and characterized by X-ray diffraction, infrared spectroscopy, thermal analysis and scanning electron microscopy. IR spectroscopy revealed the presence of n1 and n2 bands, typical of spinel structures. The formation of monophase cubic spinel structure was confirmed by X-ray diffraction patterns. Extra lines corresponding to other phase has been observed in the powders calcined at 900 ºC. The results showed the extremely lower synthesis temperature than those presents in conventional methods.

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Infrared studies on some substituted copper chromite spinels

Cited by 21 publications

References 13 publications

Pechini synthesis and microstructure of nickel-doped copper chromites

Pechini synthesis and microstructure of nickel-doped copper chromites

Evolution of the optical properties of chromium spinels CdCr2O4, HgCr2S
Rabia
¹
,
Baldassarre
²
,
Tsurkan
³

et al. 2014
Phys. Rev. B
10
2
4
0
View full text Add to dashboard Cite

PECHINI SYNTHESIS AND CHARACTERIZATION OF Eu3+ DOPED ZnCo2O4 SPINELS

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Infrared studies on some substituted copper chromite spinels

Cited by 21 publications

References 13 publications

Pechini synthesis and microstructure of nickel-doped copper chromites

Pechini synthesis and microstructure of nickel-doped copper chromites

Evolution of the optical properties of chromium spinels CdCr2O4, HgCr2SRabia1, Baldassarre2, Tsurkan3 et al. 2014Phys. Rev. B10240View full textAdd to dashboardCite

PECHINI SYNTHESIS AND CHARACTERIZATION OF Eu3+ DOPED ZnCo2O4 SPINELS

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Product

Resources

About

Evolution of the optical properties of chromium spinels CdCr2O4, HgCr2S
Rabia
¹
,
Baldassarre
²
,
Tsurkan
³

et al. 2014
Phys. Rev. B
10
2
4
0
View full text Add to dashboard Cite