Aleksandar Ćirić

Aleksandar Ćirić
Vinča Institute of Nuclear Sciences | VIN · Department of Radiation Chemistry and Physics

Doctor of Philosophy

About

51
Publications
11,864
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546
Citations
Introduction
Current research interests: *Judd-Ofelt theory *Photoluminescence *Lantanides *Temperature measuring techniques Methods and techniques: *Programming: Java, PHP, Wolfram CDF *Thermometry: Luminescence intensity ratio, time and *frequency domain *Judd-Ofelt: from emission spectra of europium, diffuse-reflectance spectra of all lantanides. *Plasma electrolytic oxidation. *CIE Working on: *Creation of better temperature sensors. *Improving temperature measurement techniques. *Material analysis for temperature sensing. *Plasma electrolytic oxidation on various transition metals, doped with various rare-earth elements. *Extension of Judd-Ofelt theory to the field of thermometry and colorimetry. *Finding better phosphors for LED and lasing purposes.
Additional affiliations
December 2019 - August 2020
Vinča Institute of Nuclear Sciences
Position
  • Professor (Assistant)
February 2008 - December 2009
Microsoft
Position
  • Engineer
Education
November 2015 - May 2019
University of Belgrade
Field of study
  • Applied Physics
October 2003 - April 2015
University of Belgrade
Field of study
  • Theoretical and Experimental Physics

Publications

Publications (51)
Article
Full-text available
Y3NbO7:xEu3+ powders (x = 0.25, 0.5, 0.75, 2, 3, 5, 10 at%) were synthesized by a two-step vibrational milling, alternating with annealing. All the samples crystallize as fluorite-type structure, with crystallite size 50–60 nm and show a strong orange/red luminescence with an excited state lifetime around 1.2 ms. Photoluminescence excitation and em...
Article
A series of LaGa1–xO3:Cr³⁺x phosphors (x = 0.002, 0.005, 0.01, 0.02, 0.04) were synthesised by solid-state reaction and structurally characterised by Rietveld refinement from powder X-ray diffraction data. Amongst the five compounds, that with x = 0.01 exhibited the highest photoluminescence quantum yield at room temperature, those with higher dopi...
Article
Full-text available
Temperature-induced bandshift of luminescence peaks is frequently described with McCumber-Sturge relation which is difficult for fitting or practical applications due to its mathematical complexity. Here for the first time, we give its exact solution in terms of polylogarithms, and an excellent approximation that is better at lower temperatures tha...
Article
In response to the sensitivity limitation of ratiometric luminescence thermometers, herein we propose a novel temperature readout, which exploits two pairs of thermalized energy levels in trivalent lanthanide ion-activated phosphors, to provide significantly enhanced sensitivity. This method is called the luminescence intensity ratio squared (LIR ²...
Article
Full-text available
Eu3+-doped YxLu1−xNbO4 (x = 0, 0.25, 0.5, 0.75, 1) were prepared by the solid-state reaction method. YNbO4:Eu3+ and LuNbO4:Eu3+ crystallize as beta-Fergusonite (SG no. 15) in 1–10 μm diameter particles. Photoluminescence emission spectra show a slight linear variation of emission energies and intensities with the solid-solution composition in terms...
Article
We report on overcoming the sensitivity limit of Boltzmann's thermometers by utilization of seven thermalized Dy³⁺ excited states in the Lu1.5Y1·5Al5O12 host. Emission spectra recorded from room temperature to 938 K show transitions originating from seven ⁴F9/2, ⁴I15/2, ⁴G11/2, ⁴I13/2, ⁴M21/2, ⁴K17/2, and ⁴F7/2 excited levels to the ⁶H15/2 ground s...
Article
Energy level positions, refractive index values, Judd–Ofelt (JO) intensity parameters, Slater integrals, and spin‐orbit coupling parameters are taken from the literature for 27 Dy3+‐doped materials (five crystals and 22 glasses). Investigated are only the transitions that are used for the Boltzmann‐type luminescence intensity ratio (LIR) thermomete...
Article
Full-text available
Judd–Ofelt theory is a cornerstone of lanthanides’ spectroscopy given that it describes 4fn emissions and absorptions of lanthanide ions using only three intensity parameters. A self-referenced technique for computing Judd–Ofelt intensity parameters from the excitation spectra of Eu3+-activated luminescent materials is presented in this study along...
Article
Phosphors for luminescence thermometry La 1− x Ga 0.99 O 3 :Cr 0.01 , Nd x were synthesised by the solid-state method, structurally characterised using powder X-ray diffraction data, and investigated by ambient and variable-temperature optical measurements.
Article
15 μm thick Ti-Sapphire coatings were synthesized at room temperature by the plasma electrolytic oxidation (PEO) method for 20 min from the pure aluminium substrate and with the addition of the TiO2 particles in various concentrations in the supporting electrolyte. The coatings are featured by microscopic pores typical for PEO surfaces. The dominan...
Chapter
The highly-efficient upconversion photoluminescent ZrO2:Ln³⁺/Yb³⁺ (Ln = Er, Ho, Tm) films were prepared by the plasma electrolytic oxidation method from the pure zirconium foil, by adding Ln2O3 and Yb2O3 particles to the supporting electrolyte, in various concentrations. The method of synthesis, morphology, chemical, and phase composition of formed...
Article
Upconversion sub-micron particles are one of the most perspective materials due to their wide application range, the most important being in the bio-medicinal field where they can be used for labeling, sensing, treatment or drug delivery. Chemically stable upconversion sub-micron particles of La2O2S co-doped with Yb³⁺/Ho³⁺ and Yb³⁺/Tm³⁺ were synthe...
Article
Two experimental practices in luminescence intensity ratio (LIR) thermometry based on the spectral deconvolution (SD) and separation at chosen wavelength (WS) were analyzed for the case when sharp emission is overlapping with a broad one, which is frequently the case for Cr³⁺ and Mn⁴⁺ in the intermediate or strong crystal fields. Their performances...
Preprint
Full-text available
Judd-Ofelt theory presents a centrepiece in spectroscopy of lanthanides since it explains and predicts 4f absorptions and emissions from only 3 intensity parameters. A self-referenced method for calculating Judd–Ofelt intensity parameters from the excitation spectra of Eu3+-activated luminescent materials is proposed in this study along with a desc...
Article
Full-text available
Mn2+ single doped as well as Mn2+/Eu2+ and Mn2+/Ce3+ co-doped Al2O3 coatings were synthesized by plasma electrolytic oxidation process of aluminum and their structural, morphological, and above all, photoluminescence (PL) properties were investigated in deep. Al2O3:Mn2+ coatings exhibit a weak green PL emission centered at about 525 nm attributed t...
Article
The luminescence thermometry based on the intensity ratio of Cr³⁺ and host emissions in the Cr³⁺ activated MgTiO3 phosphor powder is demonstrated over the 100–350 K temperature range. Phosphor was prepared by a two-step procedure based on the sol-gel and molten salt methods. Rhombohedral crystal structure of the material is confirmed by X-ray diffr...
Article
Thermographic properties of Cr³⁺-doped Al2O3 coatings created by plasma electrolytic oxidation (PEO) are investigated. Scanning electron microscopy revealed dense coatings uniformly distributed over the aluminum surface with uniform elemental maps, confirming homogeneous distribution of chromium ions. X-ray diffraction analysis shows that created c...
Article
Multifunctional coatings of Al2O3 co-doped Tb³⁺ or Tb³⁺/Eu²⁺ were synthesized by the rapid and facile plasma electrolytic oxidation method on pure aluminium substrate. SEM & EDS analysis revealed porous structure independent on the doping concentration, with uniform distribution of co-doped rare-earth elements and incorporated concentrations propor...
Article
Nanoparticles of less than 100 nm of La2O2S co-doped with Er³⁺ and Yb³⁺ in 2% and 12% concentrations, respectively, were synthesized by the improved furnace combustion technique that limits the precursor usage and without the hazardous chemicals. The lanthanum oxysulfide was identified in hexagonal crystal phase. Under 980 nm excitation the sample...
Article
Temperature sensing from the photoluminescence of MgAl2O4:Cr³⁺ ceramic powder is systematically investigated. Material was prepared by self-propagating high temperature synthesis method. In this host, Cr³⁺ experiences the strong crystal field, so the overlapping emissions from ²E and ⁴T2 energy levels are observed. Emission and excitation spectra w...
Article
The COVID-19 infectious disease in 2020 caused a global and subsequent lockdown policies imposed by various governments. Public libraries were affected as well. For many public libraries, the only one that remained active and available to users was access to their digital content. The Njegoš public library in Knjaževac, Serbia, responded by improvi...
Article
Judd–Ofelt (JO) theory explains the optical properties of trivalent lanthanides using only three intensity parameters. The JO parametrization is a complicated procedure of absorption spectra analysis, especially cumbersome for powders and non‐transparent materials. For the Pr3+ activated materials, the procedure is additionally complicated due to s...
Article
Eu³⁺ and Tb³⁺ doped ZnO optical coatings were formed by the Plasma Electrolytic Oxidation (PEO) method from the pure Zn sheet, with various dopant concentrations. The morphologies show no significant change with the introduced dopant or their concentrations, with typical appearance of PEO formed coatings. All elements are uniformly distributed, and...
Article
Full-text available
This paper is devoted to the study of the photoluminescent (PL) characteristics of blue-emitting Al2O3:Tm3+ and Al2O3:Tm3+/Ce3+ coatings. The presented coatings were synthesized by plasma electrolytic oxidation process of aluminum in electrolyte containing Tm2O3 and Tm2O3/CeO2 particles, and characterized by SEM/EDS, XRD, and PL emission and excita...
Article
The introduction of additional functionalities to materials is exceptionally important as it opens new applications for them. Aluminum, one of the most abundant and important materials, is coated with luminescent Sm2+‐doped γ‐aluminium oxide to impart thermometric functionality. Considering the potential industrial applications, two of the most wid...
Article
Full-text available
The figures of merit of luminescence intensity ratio (LIR) thermometry for Er3+ in 40 different crystals and glasses have been calculated and compared. For calculations, the relevant data has been collected from the literature while the missing data were derived from available absorption and emission spectra. The calculated parameters include Judd–...
Preprint
Full-text available
The figures of merit of luminescence intensity ratio (LIR) thermometry for Er3+ in 40 different crystals and glasses have been calculated and compared. For calculations, the relevant data has been collected from the literature while the missing data were derived from available absorption and emission spectra. The calculated parameters include Judd-...
Article
A series of new red phosphors based on apatite-type gadolinium silicate host, Gd 9.33−x Eu x (SiO 4 ) 6 O 2 (0.03 < x < 1.87), have been synthesised and analysed.
Article
Nano-crystallite Lanthanum oxysulfide (La2O2S), a versatile compound with a wide range of applications, has been synthesized by the Solid State, Hydrothermal, and a novel Furnace Combustion technique. The last one limits the precursors, thus minimizing the resource usage, does not require passing of the H2S, CS2, or any of the hazardous gasses duri...
Article
The steady-state luminescence thermometry analysis was performed on thin-films of undoped Gd2O3 and Gd2O3 doped with Ho³⁺, Eu³⁺ and Er³⁺, created by the plasma electrolytic oxidation process. The experimental setup for luminescent measurements closely resembles the practical luminescent fiber-optic thermometer. The visible PL from Gd³⁺ was utilized...
Article
The Judd-Ofelt model, already verified for the luminescence intensity ratio (also called fluorescence intensity ratio, FIR) thermometry from the emission spectra, is modified and tested for the double-excitation (also called ground-state-absorption, GSA) thermometry. The adapted model has been tested on Lu2O3:Eu³⁺, with a 99.9% match of the tempera...
Article
In this paper, photoluminescence (PL) properties of Pr³⁺ single doped and Pr³⁺/Eu²⁺ co-doped Al2O3 coatings formed by plasma electrolytic oxidation of aluminum were investigated. The PL spectra of Al2O3:Pr³⁺ coatings feature bands ascribed to 4f-4f transitions of Pr³⁺. PL excitation spectra contain three broad bands in the violet and blue regions w...
Article
In this paper, Dy³⁺ and Dy³⁺/Ce³⁺ doped Al2O3 coatings were synthesized by plasma electrolytic oxidation process of aluminum. Structural and photoluminescence (PL) properties of obtained coatings as well as energy transfer mechanism from Ce³⁺ to Dy³⁺ were studied. The PL excitation and emission spectra of Al2O3:Dy³⁺ featured weak bands attributed t...
Article
Full-text available
The emission of Er 3+ provides three combinations of emission bands suitable for ratiometric luminescence thermometry. Two combinations utilize ratios of visible emissions (2 H 11/2 → 4 I 15/2 at 523 nm/ 4 S 3/2 → 4 I 15/2 at 542 nm and 4 F 7/2 → 4 I 15/2 at 485 nm/ 4 S 3/2 → 4 I 15/2 at 545 nm), while emissions from the third combination are locat...
Article
Zirconia (ZrO2) coatings, doped with Gd³⁺ and Dy³⁺ in various concentrations, were created by the plasma electrolytic oxidation (PEO) process of zirconium by the addition of Gd2O3 and Dy2O3 particles to the supporting electrolyte, respectively. Their morphological, chemical, phase, and above all, photoluminescent (PL) properties were examined. Morp...
Article
Full-text available
Plasma electrolytic oxidation (PEO) of aluminum in electrolytes containing CeO2 and Eu2O3 powders in various concentrations was used for creating Al2O3 coatings doped with Ce3+ and Eu2+ ions. Phase and chemical composition, surface morphology, photoluminescence (PL) properties and energy transfer from Ce3+ to Eu2+ were investigated. When excited by...
Article
Judd-Ofelt analysis has been performed from the photoluminescence emission spectra of Y2O3:Eu3+ with 3%, 1% and 0.1% doping concentration and YVO4:Eu3+ with 1% doping concentration, in temperature range from 40 °C to 460 °C. For precise calculation, an extended Sellmeier equation that accounts for the doping concentration and temperature dependence...
Article
Gd2O3 and Gd2O3:Ln³⁺ (Ln = Eu, Er, Ho) coatings were formed by the fast and cheap plasma electrolytic oxidation (PEO) process, from the pure gadolinium plate and an addition of appropriate Ln2O3 particles to the supporting electrolyte. Monoclinic phase of Gd2O3 is identified in all samples. Gd2O3 absorbs in the UV region and the photoluminescence i...
Article
The red phosphor Y2Mo4O15: Eu3+ calcined at different temperatures is obtained by a solid‐state method, and is investigated in this paper. Usage of solid state method with combination of five different calcined temperatures (500, 550, 600, 650 and 700 °C) led to the formation of pure monoclinic phase in all samples apart from the one calcined at th...
Article
An extension of the Judd-Ofelt theory, a theoretical model to the field of Luminescence intensity ratio method in phosphor thermometry has been presented, that enables a calculation of thermometric figures of merit: sensitivity, maximum sensitivity and temperature resolution, by the Judd-Ofelt intensity parameters. The model is applicable for 7 out...
Article
Plasma electrolytic oxidation (PEO) of yttrium is performed for the first time and is shown that Y2O3 and trivalent rare-earth ions (Eu³⁺, Er³⁺ or Ho³⁺) doped Y2O3 films can be formed by PEO in alkaline electrolyte without or with addition of rare-earth oxide particles (Eu2O3, Er2O3 or Ho2O3), respectively. The elements present in PEO micro-dischar...
Article
Full-text available
Traditional applications of the Judd-Ofelt (JO) theory to the analysis of the Eu³⁺ optical spectra make use of the emission transitions originating from the ⁵D0 manifold. In the present paper, we report an alternative method of evaluating the JO intensity parameters from the Eu³⁺ emission spectra based on the ⁵D1 → ⁷F0,1 transitions. The reduced ma...
Article
Full-text available
Photoluminescence spectra of bulk YVO4 doped with 1 mol% of Eu³⁺ and Dy³⁺ were recorded on the range from room temperature to 733 K, in 20 K steps. The temperature sensing performances were estimated by the luminescence intensity ratio, line-broadening and line-shift methods. The luminescence intensity ratio was tested by the ratio of intensities o...
Article
Zirconia coatings doped with various contents of Tm³⁺ and Yb³⁺ were formed by the plasma electrolytic oxidation process of zirconium foils for 15 min in alkaline electrolyte containing Tm2O3 and Yb2O3 powders in different concentrations. The coatings were composed of monoclinic and tetragonal ZrO2 phases, but Tm and Yb incorporated into ZrO2 coatin...
Article
Pr³⁺ doped ZrO2 coatings were formed by the plasma electrolytic oxidation (PEO) of zirconium in electrolyte containing Pr2O3 powder. The concentration of a uniformly distributed Pr³⁺ in the coatings increases with time of the PEO process or the concentration of added Pr2O3 powder, causing the stabilization of the tetragonal ZrO2 at the expense of t...
Article
A theoretical model for approximate evaluation of CIE chromaticity coordinates from the Judd-Ofelt intensity parameters has been presented. By reviewing the photoluminescence properties of all the lanthanides, the model's applicability was restricted to Nd³⁺, Sm³⁺, Eu³⁺, Tb³⁺ and Dy³⁺. Explicit equations for calculation of CIE coordinates for each...
Article
Judd-Ofelt analysis of HfO2:Eu³⁺ with various europium doping concentrations, formed by plasma electrolytic oxidation, had been investigated. Ω2 parameter is increasing, while Ω4 parameter shows no concentration dependence. For the highest europium doping concentration of 0.62 at% Ω2 = 4.03·10⁻²⁰ cm² and Ω4 = 2.26·10⁻²⁰ cm². Radiative transition pr...
Article
Full-text available
A complete apparatus for luminescence thermometry has been built comprising a programmable hot-plate up to 400 °C, a hot/cold plate 0 °C-80 °C, a control circuit with thermocouple feedback, a platinum resistance thermometer and an oven for calibration. An original design allowed us to build the apparatus for under 100 $, considerably less than for...
Article
Luminescence thermometry on europium doped TiO2 films, prepared by the plasma electrolytic oxidation, was investigated by the Luminescence Intensity Ratio method. The performance of the material for temperature sensing was tested from room temperature to 260 °C. The theoretical fit of the emission intensity ratio of Eu³⁺⁵D1→⁷F1 and ⁵D0→⁷F2 transiti...
Article
In this paper we will be presenting JOES (Judd-Ofelt from Emission Spectra), an application software for calculation of the Judd-Ofelt intensity parameters and derived quantities from the emission spectra of Eu³⁺ doped materials. The program is written to be user friendly and it requires no previous experience in the field of study. This Free and O...
Article
Plasma electrolytic oxidation was used for synthesis of Eu³⁺ doped monoclinic HfO2 coatings on hafnium substrate. Results of photoluminescence (PL) measurements show the existence of two distinct regions: one that is related to the blue emission originating from oxygen vacancy defects in HfO2 and the other one characterized with a series of sharp o...

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