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Vezzoli, G. C.

doi:10.1103/physrevb.26.3954

Cited by 30 publications

(18 citation statements)

References 11 publications

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“…The X-ray diffractograms of Figure Figure 3 shows the SEM images of niobium pentoxide synthesized at T = 650 • C using NH 4 OH through (a) sol-gel and (b) Pechini methods. The bar in Figure 3a represents 1 µm, while the bar in Figure 3b represents 100 nm.…”

Section: Methodsmentioning

confidence: 99%

“…The most efficient luminescence occurs in niobyl groups as in the Nb-O group with a short bond distance, of approximately 0.17 nm [17]. Structurally isolated NbO 6 octahedra are not efficient luminescent centers [18], whereas isolated distorted niobate groups, such as in LaNbO 4 , where the Nb(V) has a 4 + 2 coordination, provide very efficient centers. The closer the Nb-O-Nb angles are to 180 the more pronounced the effects of the NbO 6 condensation become [16,17,[19][20][21].…”

Section: Introductionmentioning

confidence: 99%

“…Regarding these phases, many studies have demonstrated how it is possible to obtain a certain phase from a previous one. For instance, it is known that the trigonal L-Nb 2 O 5 Nb phase turns into a monoclinic high-temperature phase H-Nb 2 O 5 close to 900 • C [4]. Also, by heating niobium pentoxide at constant pressure, the sequence of phase transitions H-Nb 2 O 5 → B-Nb 2 O 5 → T-Nb 2 O 5 is observed [5] and, at a constant temperature, it was demonstrated that B-Nb 2 O 5 and T-Nb 2 O 5 constitute high pressure polymorphs of Nb 2 O 5 [6].…”

Section: Introductionmentioning

confidence: 99%

“…From the technological point of view, the niobium pentoxide is of remarkable importance because it presents energy absorption in the ultraviolet region, whereby this semiconductor can be used to protect materials from that radiation. Nb 2 O 5 presents a series of structural phases (trigonal, hexagonal, monoclinic or orthorhombic) [4] and consequently, it can present different physical characteristics such as a semiconductor or as a dielectric material, depending on the symmetry. Regarding these phases, many studies have demonstrated how it is possible to obtain a certain phase from a previous one.…”

Section: Introductionmentioning

confidence: 99%

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Synthesis and Characterization of Nano-Particles of Niobium Pentoxide with Orthorhombic Symmetry

Joya

Barba-Ortega

Raba-Páez

et al. 2017

Metals

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Abstract:In this work, a set of nanoparticles of Nb 2 O 5 nanoparticles were grown by both the Pechini and the sol-gel methods. The amorphous materials were calcined at 650 • C or at 750 • C. X-ray diffraction, scanning electron microscopy, luminescence and Raman spectroscopy were used in order to characterize the materials. From the study, it is possible to state that the method of production of nanoparticles, beyond the temperature of synthesis, has a great influence on whether the phase produced is hexagonal or orthorhombic. Additionally, compared to de Sol-gel method, the Pechini method produced samples with smaller particle sizes. The photoluminescence spectra of niobium pentoxide nanostructure materials show that the emission peaks are positioned between 334 to 809 nm and there is a change of intensity which varies depending on the synthesis route used. High pressure Raman spectra at room temperature were obtained from two samples grown by the sol-gel method. Up to 6 GPa, where it is possible to observe the Raman bands, no modification other than the increase of disorder was observed, and this can be associated with a change of phase.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Synthesis and Characterization of Nano-Particles of Niobium Pentoxide with Orthorhombic Symmetry

Joya

Barba-Ortega

Raba-Páez

et al. 2017

Metals

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show abstract

“…It has abundant polymorphic shapes which give height to a pleasant series of structural phases [3] that rely on composition mechanisms, pressure and temperature. Thus, it enables existent various physical characteristics like a semiconductor or as a dielectric material, relying on the similarity.…”

Section: Introductionmentioning

confidence: 99%

Niobium Pentoxide thin films employ simple colloidal suspension at low preparation temperature

et al. 2017

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Abstract. In this work a nano-colloidal suspension is used to prepare Nb 2 O 5 thin films. The effect of different substrates on structural properties of niobium pentoxide thin film deposited by spin coating technique on silicon and quartz substrates are presented. We observed that the obtained structure is monocline in both substrates. The diffraction peaks in both substrates ensured the successful formation of Nb 2 O 5 thin films with a clear polymorphous structure. However, the structure became more crystalline with additional distinguished peaks on silicon substrate comparing to quartz substrate. The extracted structural parameters from X-Ray diffraction show that the grain size of the thin films on quartz is smaller than silicon with the values of 16.47 nm and 20.98 nm respectively. The stress measurement records the values of 0.19 and 0.00719 for the thin films deposited on silicon and quartz substrates respectively. Effects of film thickness depicted increment in the absorbance and reduction in the band gap. Energy gaps of 2.7, 2.58 and, 2.5 eV are measured as a result of increasing the film thicknesses of 325, 420 and 450 nm respectively.

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Electronic Structures and Catalytic Activities of Niobium Oxides as Electrocatalysts in Liquid‐Junction Photovoltaic Devices

Yun

Shi

et al. 2019

Solar RRL

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Two types of nanosized niobium oxides and their composites, pseudohexagonal Nb2O5 (TT‐Nb2O5), monoclinic NbO2 (M‐NbO2), and the coexistence of TT‐Nb2O5 and M‐NbO2 (TT‐Nb2O5/M‐NbO2), are successfully synthesized through the urea‐metal chloride route, and they exhibit excellent catalytic activity and photovoltaic performance in dye‐sensitized solar cells (DSSCs). First‐principles density function theory (DFT) calculations show that their catalytic activity is significantly influenced by their intrinsic electronic structures and properties. The lone‐pair 4d1 electrons of Nb4+ in M‐NbO2 enhance the Nb–I interaction and promote electron transfer from the M‐NbO2 counter electrode (CE) to I, thus resulting in superior catalytic properties in M‐NbO2‐based DSSCs. In addition, the adsorption energy of I on the M‐NbO2 surface is in the optimal energy range of 0.3—1.2 eV, and the Fermi level of M‐NbO2 is 0.6 eV, which is higher than the I3− reduction reaction potential, and I3− can be spontaneously reduced to 3I−. Herein, a general strategy for understanding the electronic structures and catalytic activities of transition metal compounds as CE catalysts for DSSCs is provided.

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Electrical properties of NbO2andNb2
G. C. Vezzoli
¹

Cited by 30 publications

References 11 publications

Synthesis and Characterization of Nano-Particles of Niobium Pentoxide with Orthorhombic Symmetry

Synthesis and Characterization of Nano-Particles of Niobium Pentoxide with Orthorhombic Symmetry

Niobium Pentoxide thin films employ simple colloidal suspension at low preparation temperature

Electronic Structures and Catalytic Activities of Niobium Oxides as Electrocatalysts in Liquid‐Junction Photovoltaic Devices

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Electrical properties of NbO2andNb2G. C. Vezzoli1

Cited by 30 publications

References 11 publications

Synthesis and Characterization of Nano-Particles of Niobium Pentoxide with Orthorhombic Symmetry

Synthesis and Characterization of Nano-Particles of Niobium Pentoxide with Orthorhombic Symmetry

Niobium Pentoxide thin films employ simple colloidal suspension at low preparation temperature

Electronic Structures and Catalytic Activities of Niobium Oxides as Electrocatalysts in Liquid‐Junction Photovoltaic Devices

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Electrical properties of NbO2andNb2
G. C. Vezzoli
¹