I. S. Molchan

Visible luminescence from europium-doped alumina sol–gel-derived films confined in porous anodic alumina

Abstract In this work, we report on strong photoluminescence (PL) of europium-doped alumina sol–gel-derived films fabricated onto porous anodic alumina of 30 μm thickness. The PL spectra represent a set of peaks typical for Eu 3+ ions with the maximum at 617 nm. PL intensity was found to increase with increase of Eu content in xerogel. Cooling the samples from 300 to 10 K leads to an increase in PL intensity. Eu PL increases nearly linearly with the excitation power within a range up to 25 mW/cm 2 . Red Eu-related PL from all of the samples is visible to the naked eye even at room temperature.

Comparison of terbium photoluminescence from ion implanted and sol–gel-derived films

Abstract In this work, we investigate the photoluminescence (PL) of terbium-doped films fabricated by ion implantation and sol–gel synthesis. Terbium implantation was carried out into SiO 2 , ZrO 2 and Al 2 O 3 thin film fabricated by dry processes onto silicon substrates followed by heat treatment in vacuum at a temperature ranging from 473 to 873 K during 30 min. Sol–gel-derived films were fabricated onto monocrystalline silicon or porous anodic alumina substrates by spin-on deposition of titania or alumina-based sol containing aqueous-alcohol solution of terbium nitrate. PL measurements were carried out at temperatures from 10 to 300 K. Comparison of PL data obtained from Tb-implanted SiO 2 , ZrO 2 and Al 2 O 3 films allows the conclusion that ZrO 2 is the best host material for Tb 3+ ions, revealing a set of sharp well resolved bands corresponding to 5 D 4 – 7 F J electron transitions of Tb 3+ ions with the maximum at 546 nm. Tb PL was found to be 15–20 times stronger for xerogels fabricated onto porous anodic alumina 30-μm-thick in comparison with ion implanted thin films.

Photoluminescence investigation of porous anodic alumina with spin-on europium-containing titania sol–gel films

Abstract In this work, we investigate europium-containing sol–gel derived films fabricated onto porous anodic alumina (PAA) of thickness ranging from 0.5 to 5 μm. The sols were prepared from Ti(OC 2 H 5 ) 4 precursor mixed with aqueous-alcohol solution of europium nitrate and deposited onto PAA. The concentration of europium oxide in xerogel was 40 wt.%. The PL spectra exhibit bands typical for Eu 3+ corresponding to 5 D 0 → 7 F j ( j =1–4) electron transitions with the maximum at 617 nm ( 5 D 0 → 7 F 2 ). The PL intensity of all the bands increases with the thickness of PAA. The samples exhibit a red light emission visible to the naked eye within the investigated temperature range from 10 to 300 K.

High‐efficiency luminescent sources fabricated in mesoporous anodic alumina by sol‐gel synthesis

This paper summarizes our recent results on the synthesis and investigation of photoluminescence (PL) from lanthanide-doped microporous xerogel solids mesoscopically confined in porous anodic alumina (PAA). It was demonstrated, for Tb-doped samples, that the PL intensity is strongly enhanced in comparison to thin xerogel films processed onto flat surfaces and increased with the thickness of the PAA layer. It was revealed for both Tb- and Eu-doped PAA-based structures that maximum emission is achieved at a excitation wavelength near 285 nm for the employed TiO 2 and Al 2 O 3 xerogels. Strong Eu- and Tb-related PL visible to the naked eye was demonstrated, and a method for the fabrication of luminescent images based on anodizing, photolithography, and sol-gel processes is proposed.

Luminescence of Eu3+ and Tb3+ Ions in the Structure Microporous Xerogel/Mesoporous Anodic Aluminum Oxide

We have investigated the luminescence, luminescence excitation, and transmittance of europium- and terbium-doped xerogel films formed on smooth, nanotextured surfaces and in the pores of anodic aluminum oxide. Some factors responsible for enhancement of luminescence in the structure lanthanide-doped xerogel/mesoporous anodic aluminum oxide have been analyzed. It is assumed that the optical excitation of lanthanide ions can be realized directly, through a xerogel matrix, and due to the multiple scattering of exciting radiation by the matrix of mesoporous anodic aluminum oxide.

Lanthanide‐doped sol‐gel‐derived films fabricated in mesoporous anodic alumina

— Porous anodic alumina films with controllable morphology were fabricated under varied anodizing conditions and examined by scanning electron microscopy and photoluminescence analysis. Erbium-, terbium-, and europium-doped xerogel films were formed inside the porous layer. Strong visible and infrared photoluminescence from the erbium-doped xerogel/porous anodic alumina structure was observed. An electroluminescent cell based on xerogel/porous anodic alumina structure was also developed, with terbium- and europium-related electroluminescence investigated.

Optoelectronic applications of lanthanide-doped sol-gel products and porous anodic alumina

— Recent studies on structures, comprising lanthanide-doped xerogels embedded in porous anodic alumina, are presented. It is shown that a terbium and europium co-doped sol-gel film embedded in porous anodic alumina allows a change in the color of the photoluminescence, from red to green, with a change in the excitation wavelength. The possibility of strong erbium-related 1.53-μm emission from yttrium-aluminium garnets in porous anodic alumina is also demonstrated. Visually, it is revealed that the blue alumina-related emission is predominant over the red europium-related emission from the structure xerogel/porous anodic alumina structure. Finally, the birefringence effect of a porous anodic alumina membrane is discussed.

P-81: Lanthanide-Doped Xerogel/Porous Anodic Alumina Structures for Image Formation

We report on the developed fabrication method of lanthanide-doped xerogel/porous anodic alumina structures for an image formation via the aluminum anodization, the sol-gel synthesis, and the photolithography process. The mechanisms responsible for strong lanthanide luminescence in the structures are discussed. It is speculated that exploiting porous anodic alumina causes significant change in the excitation conditions of lanthanides, probably due to multiple scattering and interference of the exciting light. The structures of europium- or terbium-doped xerogel/porous anodic alumina are also considered in view of application in electroluminescent devices.