The vibrational properties of one-dimensional ZnO:Ce nanostructures

Cheng, Baochang; Xiao, Yanhe; Wu, Guosheng; Zhang, Lide

doi:10.1063/1.1639131

Cited by 130 publications

(91 citation statements)

References 21 publications

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“…5 shows that the relative intensity of LO and AM mode with respect to the E 2 ͑H͒ intensity increases almost linearly with effective Co concentration. Similar features around 500-600 cm −1 were observed in several works on TM, 18,[23][24][25] Ce, 26 and Sb-doped ZnO samples. 27 In those works the main peak of the broad band is, however, at ϳ530 cm −1 , and it has been attributed to complexes involving intrinsic defects, such as oxygen vacancies ͑V O ͒ and Zn interstitials ͑Zn i ͒.…”

Section: Resultssupporting

confidence: 64%

Absence of ferromagnetic order in high quality bulk Co-doped ZnO samples

Carvalho

Godoy

Paes

et al. 2010

Journal of Applied Physics

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Bulk Zn1−xCoxO samples were synthesized via standard solid-state reaction route with different Co molar concentrations up to 21%. A detailed microstructural analysis was carried out to investigate alternative sources of ferromagnetism, such as secondary phases and nanocrystals embedded in the bulk material. Conjugating different techniques we confirmed the Zn replacement by Co ions in the wurtzite ZnO structure, which retains, however, a high crystalline quality. No segregated secondary phases neither Co-rich nanocrystals were detected. Superconducting quantum interference device magnetometry demonstrates a paramagnetic Curie–Weiss behavior with antiferromagnetic interactions. We discuss the observed room temperature paramagnetism of our samples considering the current models for the magnetic properties of diluted magnetic semiconductors.

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Section: Resultssupporting

confidence: 64%

Absence of ferromagnetic order in high quality bulk Co-doped ZnO samples

Carvalho

Godoy

Paes

et al. 2010

Journal of Applied Physics

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“…The small shifting of E 2 phonon mode can be related to a strain induced by Fe dopant. Same phenomenon occurred in Ce and Tb doped ZnO samples reported in literature [19,20]. When the size of particles reduces to nanoscale, the k = 0 selection rule for the first order Raman scattering is relaxed and the phonon scattering will not be limited to the centre of Brillouin zone.…”

Section: Raman Spectroscopymentioning

confidence: 53%

Structural, EPR, photo and thermoluminescence properties of ZnO:Fe nanoparticles

Reddy

Kokila

Nagabhushana

et al. 2012

Materials Chemistry and Physics

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a b s t r a c tZn (1−x) Fe (x) O (1+0.5x) (x = 0.5-5 mol%) nanoparticles were synthesized by a low temperature solution combustion route. The structural characterization of these nanoparticles by PXRD, SEM and TEM confirmed the phase purity of the samples and indicated a reduction in the particle size with increase in Fe content. A small increase in micro strain in the Fe doped nanocrystals is observed from W-H plots. EPR spectrum exhibits an intense resonance signal with effective g values at g ≈ 2.0 with a sextet hyperfine structure (hfs) besides a weak signal at g ≈ 4.13. The signal at g ≈ 2.0 with a sextet hyperfine structure might be due to manganese impurity where as the resonance signal at g ≈ 4.13 is due to iron. The optical band gap E g was found to decrease with increase of Fe content. Raman spectra exhibit two non-polar optical phonon (E 2 ) modes at low and high frequencies at 100 and 435 cm −1 in Fe doped samples. These modes broaden and disappear with increase of Fe dopant concentration. TL measurements of ␥-irradiated (1-5 kGy) samples show a main glow peak at 368• C at a warming rate of 6.7• Cs −1 . The thermal activation parameters were estimated from Glow peak shape method. The average activation energy was found to be in the range 0.34-2.81 eV.

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“…It has been reported that the interaction between electromagnetic ͑EM͒ radiation and the particles depends on the size, shape, and state of aggregation of the crystal. 21 Since the particle size in this study is much lower than the EM radiation, surface phonon modes ͑SPM͒ can be observed in the IR spectra as well. For spherical particles, the value of the first order ͑n =1͒ SPM is given by 25 …”

Section: Ftir Spectroscopy Studymentioning

confidence: 98%

“…The IR active optical phonon modes of ZnO show a characteristic broad reststrahlen band in the spectral range of 300-600 cm −1 . 21 Higher wave number peaks correspond to vibration modes of various impurities such as hydroxyl, carboxylate, and alkane in the materials. 22 In this work, within the displayed frequency range, phase segregated ZnMgO and ZnCdO alloy nanostructures show two impurity bands near 600-1000 cm −1 due to C-OH bond.…”

Section: Ftir Spectroscopy Studymentioning

confidence: 99%

Phonon dynamics of Zn(Mg,Cd)O alloy nanostructures and their phase segregation

Ghosh¹,

Dilawar²,

Bandyopadhyay³

et al. 2009

Journal of Applied Physics

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Effective medium formulation for phonon transport analysis of nanograined polycrystals J. Appl. Phys. 111, 014307 (2012) Negative refraction of elastic waves in 2D phononic crystals: Contribution of resonant transmissions to the construction of the image of a point source AIP Advances 1, 041405 (2011) Thermal energy transport model for macro-to-nanograin polycrystalline semiconductors J. Appl. Phys. 110, 114310 (2011) Nanostructure model of thermal conductivity for high thermoelectric performance J. Appl. Phys. 110, 114306 (2011) Additional information on J. Appl. Phys. In this paper we report phonon dynamics in chemically synthesized Zn 1−x Mg x O ͑0 Յ x Յ 0.07͒ and Zn 1−y Cd y O ͑0 Յ y Յ 0.03͒ alloy nanostructures of sizes ϳ10 nm using nonresonant Raman and Fourier transformed infrared spectroscopy. Substitution by Mg makes the unit cell compact while Cd substitution leads to unit cell expansion. On alloying, both A 1 ͑LO͒ and E 1 ͑LO͒ mode of wurtzite ZnO show blueshift for Zn 1−x Mg x O and redshift for Zn 1−y Cd y O alloy nanostructures due to mass defect and volume change induced by the impurity atoms. Significant shift has been observed in E 1 ͑LO͒ mode for Zn 1−x Mg x O ͑73 cm −1 for x = 0.07͒ and Zn 1−y Cd y O ͑17 cm −1 for y = 0.03͒ nanostructures. The variation in Zn͑Mg,Cd͒-O bond length determined from the blue-͑red-͒ shift of IR bands on alloying with Mg ͑Cd͒ is consistent with their respective ionic sizes and the structural changes predicted by x-ray diffraction study. However, on progressive alloying one can detect phase segregation ͑due to presence of interstitial Mg and Cd ions͒ in the alloy nanostructures for relatively higher Mg and Cd concentrations. This is confirmed by the gradual absence of the characteristic IR and Raman bands of wurtzite ZnO near 400-600 cm −1 as well as by x-ray and TEM studies.

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The vibrational properties of one-dimensional ZnO:Ce nanostructures

Cited by 130 publications

References 21 publications

Absence of ferromagnetic order in high quality bulk Co-doped ZnO samples

Absence of ferromagnetic order in high quality bulk Co-doped ZnO samples

Structural, EPR, photo and thermoluminescence properties of ZnO:Fe nanoparticles

Phonon dynamics of Zn(Mg,Cd)O alloy nanostructures and their phase segregation

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