Morphological analysis and photoluminescence properties of hydrophilic porous anodic alumina formed in oxalic acid

Reddy, P. Ramana; Ajith, K M; Udayashankar, N.K.

doi:10.1007/s10854-016-4432-6

Cited by 10 publications

(9 citation statements)

References 31 publications

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“…It is to be noted that obtained values are in satisfactory agreement with each other in shown ± 0.05 eV scatter. It is known that luminescence centers of AAO synthesized in (COOH) 2 are complexes based on oxygen vacancies and/or oxalate-ions impurities formed during oxidation process [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22]. Electrolyte composition in current work excluded presence of oxalate-ions.…”

Section: Discussionmentioning

confidence: 99%

“…Numerous studies considering luminescent properties of anodic aluminum oxide synthesized in electrolytes of various type and composition have been conducted up to date [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22]. The most intensive emission with maximum in 430 -500 nm range was demonstrated by amorphous as-grown nanostructures anodized in oxalic acid based solutions [6][7][8][9].…”

Section: Introductionmentioning

confidence: 99%

“…The most intensive emission with maximum in 430 -500 nm range was demonstrated by amorphous as-grown nanostructures anodized in oxalic acid based solutions [6][7][8][9]. A major contribution in mechanisms of observed luminescence were made by defects attributed to oxygen vacancies in different charge state [7,[10][11][12][13][14][15][16][17][18] and/or oxalate-ions impurities [8,9,[19][20][21][22]. Therefore, it is of current interest to search for optimal anodizing modes and electrolytes composition in order to obtain nanostructured oxide layers with high concentration of optically active defects formed due to developed surface with big specific area.…”

Section: Introductionmentioning

confidence: 99%

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Blue photoluminescence of sponge-like highly porous alumina synthesized in hydrofluoric acid based electrolytes

Ilin

Вохминцев

Martemyanov

et al. 2017

J. Phys.: Conf. Ser.

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Abstract. For the first time nanostructures of anodized aluminum oxide (AAO) were synthesized using hydrofluoric acid based electrolytes under potentiostatic mode with varied oxidation conditions. As-grown oxide layers were amorphous and had sponge-like disordered structure with ramified pores system of 50 to 300 nm diameters. All samples under daylight demonstrated blue emission with power up to 10 µW that was seen by naked eye. It was shown that integral intensity of photoluminescence (PL) emission band in 350 -650 range increases up to 7 -60 times depending on synthesis details. Observed PL spectra were approximated by superposition of two components with E max = 2.74 and 2.44 eV, FWHM = 0.63 and 0.53 eV. It was substantiated that studied emission have intrinsic origin and can be attributed to F 2 2+ -and F 2 -centers.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Blue photoluminescence of sponge-like highly porous alumina synthesized in hydrofluoric acid based electrolytes

Ilin

Вохминцев

Martemyanov

et al. 2017

J. Phys.: Conf. Ser.

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“…The smoothed PL spectra are adduced in works [6][7][8], however information about the way of this smoothing is absent. The works [9][10] perform the decomposition of PL spectra on elementary bands by means of mathematical packages, but smoothing is not shown in details and even the used way of it is not mentioned. There is an opinion in the book [11], which is considered as one of basic sources on the problem of smoothing, that luminescent spectra must be smoothed by Savitzky-Golay method, using the window width that equals 11 or 25 points, and polynomials from quadratic to quintic inclusive.…”

Section: Literature Reviewmentioning

confidence: 99%

Method of smoothing photoluminescence spectra

2018

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The smoothing method for experimental photoluminescence spectra, which uses Tikhonov regularization method, is proposed. Smoothing problem statement is performed as a statement of the minimization problem based on the least squares criterion. The functional to be minimized is a compound of two terms. The first one is the basic term, which determines the quality of data approximation provided by smooth function. The second one is the regularization term, which sets a constraint on the energy by smooth function derivative of a given order. A solution of the smoothing problem is obtained in the closed form analytically. The solution can be implemented by a simple array of matrix operations; one of those is an operation of matrix inversion. The necessity of matrix inversion imposes constraints on the order of derivative used in the proposed method and on noise level. It is related to the increase of either the order of derivative at the given noise level in data or the noise level at the given order of derivative, that deteriorates the conditionality of a matrix to be inverted and limits the scope of the proposed method, accordingly. Efficiency comparison of the proposed smoothing method, the Savitzky-Golay method, and the moving average method was performed by the numerical simulation of two models of photoluminescence spectra. Their advantages, disadvantages, and also the scopes of applicability are noted. The best values of operating parameters of these methods for the different noise levels in data were obtained. The conditions, under which the potential capabilities of the proposed smoothing method excel the potential possibilities of Savitzky-Golay method, were indicated. The results of smoothing the experimental photoluminescence spectra obtained for ZnO:Mn nanocrystals and ZnS:Mn crystals are provided.

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“…Nano-porous anodic alumina membranes were prepared using electro-chemical anodization method since the last two decades onward [1][2][3]. The formation mechanism of porous structure is still controversial [4], even though there is a lot of reports on applications of PAA in optical [5,6], mechanical [7,8] and structural [9][10][11] properties. Anodization to be derived by direct in situ methods is too difficult process [12], neither the scanning electron microscope nor the optical microscope can observe the process.…”

Section: Introductionmentioning

confidence: 99%

Morphology and photoluminescence of nano-porous anodic alumina membranes obtained in oxalic acid at different anodization potentials

2020

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Porous Anodic alumina (PAA) with highly ordered pore geometry serves as an ideal template for future development of nanodevices. In the present work, PAA was prepared by varying anodization potential from 10 to 50 V in oxalic acid at 8°C with a constant electrolyte concentration of 0.3 M. The influence of anodization potential on the structural and photoluminescence (PL) properties of PAA has been studied. The effect of anodization potential on the main pore characteristics of PAA such as pore diameter, interpore distance, pore density, porosity and circularity was studied. It was observed that circularity of PAA was nearly equal to one in the case of anodization potential of 40 V. Highest regularity ratio (RR) obtained for PAA formed in 40 V and it was calculated by WSxM software. It was noticed that with increasing anodization potential there is a slight change in PL spectra of PAA and shows a strong PL peak in blue region.

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Morphological analysis and photoluminescence properties of hydrophilic porous anodic alumina formed in oxalic acid

Cited by 10 publications

References 31 publications

Blue photoluminescence of sponge-like highly porous alumina synthesized in hydrofluoric acid based electrolytes

Blue photoluminescence of sponge-like highly porous alumina synthesized in hydrofluoric acid based electrolytes

Method of smoothing photoluminescence spectra

Morphology and photoluminescence of nano-porous anodic alumina membranes obtained in oxalic acid at different anodization potentials

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