Zoran Ristic

Zoran Ristic
Vinča Institute of Nuclear Sciences | VIN

Dr.

About

69
Publications
9,438
Reads
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1,118
Citations
Additional affiliations
August 2010 - April 2013
University of Geneva
Position
  • PostDoc Position
February 2007 - December 2009
University of Naples Federico II
Position
  • PhD Student

Publications

Publications (69)
Article
We demonstrate the thermal history forensic measurements founded on the emission intensity ratio of Eu³⁺-doped yttrium vanadate. An increase in phosphor’s crystallite size with annealing temperature is observed, causing a significant and permanent increase in the emission intensity and symmetry ratio (ratio of Eu3+ 5D0 → ⁷F1 and ⁵D0 → ⁷F2 emissions...
Article
Full-text available
The near-infrared luminescence of Ca6Ba(PO4)4O:Mn5+ is demonstrated and explained. When excited into the broad and strong absorption band that spans the 500–1000 nm spectral range, this phosphor provides an ultranarrow (FWHM = 5 nm) emission centered at 1140 nm that originates from a spin-forbidden 1E → 3A2 transition with a 37.5% internal quantum...
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
Luminescence thermometry exploiting luminescence kinetics as a thermometric parameter is regarded as one of the most reliable temperature readout techniques. Transition metal ions are of particular interest in this application which is due to the possibility of modulating their spectroscopic properties by changing the strength of the crystal field...
Article
Full-text available
Studies on oxide quasi-two-dimensional electron gas (q2DEG) have been a playground for the discovery of novel and sometimes unexpected phenomena, like the reported magnetism at the surface of SrTiO3 (001) and at the interface between nonmagnetic LaAlO3 and SrTiO3 band insulators. However, magnetism in this system is weak and there is evidence of a...
Article
Potential of Eu³⁺, Mn⁴⁺ co-doped YAG for dual-activated luminescence intensity ratio thermometry is investigated. The samples were prepared by modified Pechini method and cubic structure confirmed by X-ray diffraction with average crystallite size of ∼ 20 nm. Scanning electron microscopy revealed different sized chunks composed of ellipsoidal-shape...
Article
This paper presents the Cr³⁺-activated Mg2TiO4 phosphor temperature dependance of its near infrared luminescence and its potential in the optical thermometry applications. In this respect, temperature dependences of three emission features were tested over the broad temperature range (10–500 K): (i) the luminescence intensity ratio (LIR) between em...
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...
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
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 multiparametric luminescence thermometry with Dy³⁺, Cr³⁺ double activated yttrium aluminium garnet – YAG is demonstrated. Phospors were synthesized via Pechini method and their structure is confirmed by X-ray diffraction analysis. Mean crystallite size of powders was calculated to be ~22 nm. Morphology was investigated using scanning electron m...
Article
Full-text available
This paper presents four new temperature readout approaches to luminescence nanothermometry in spectral regions of biological transparency demonstrated on Yb3+/Er3+-doped yttrium aluminum garnet nanoparticles. Under the 10 638 cm-1 excitation, down-shifting near infrared emissions (>10 000 cm-1) are identified as those originating from Yb3+ ions' 2...
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
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
Cr ³⁺ -doped Mg 2 SiO 4 orthorhombic nanoparticles are synthesized by a combustion method. The 3d ³ electron configuration of the Cr ³⁺ ion results in the deep-red emission from optical transitions between d–d orbitals. Two overlapping emissions from the Cr ³⁺ spin-forbidden ² E g → ⁴ A 2g and the spin-allowed ⁴ T 2g → ⁴ A 2g electronic transitions...
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
This work demonstrates the luminescence of Mn4+ activated cubic spinel Li4Ti5O12 (LTO) powders. One-step solid-state method was used to obtain eleven samples with different quantities of Mn4+. The deep red emission centered at around 696 nm originates from 2Eg → 4A2g spin forbidden electronic transitions from 3 d3 electron configuration of Mn4+ ion...
Article
Full-text available
A strategy for optical nanothermometry using the negative thermal quenching behavior of intrinsic BiFeO3 semiconductor nanoparticles has been reported here. X-ray diffraction measurement shows polycrystalline BiFeO3 nanoparticles with a rhombohedral distorted perovskite structure. Transmission electron microscopy shows agglomerated crystalline nano...
Article
When activated by Dy3+, Na0.25K0.25Bi0.50TiO3 (NKBT), piezoelectric powders show strong luminescence in the blue and yellow spectral range. Emissions of this material can be effectively utilized for both luminescence intensity ratio and lifetime-based readouts of temperature. Photoluminescence measurements over a temperature range of 293–483 K show...
Preprint
Full-text available
The discovery of a surface/interfacial quasi 2-dimensional electron gas (q2DEG) in SrTiO$_{3}$ boosted expectations for novel oxide electronics due the intriguing and rich physics uncovered, including multiband and possibly unconventional superconductivity, large Rashba-like spin-orbit coupling and large spin to charge conversion efficiency. While...
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
In this work, the potential of Li1.8Na0.2TiO3:Mn4+ for the lifetime-based luminescence thermometry is assessed. The material is prepared by the solid-state reaction of Li2CO3, Na2CO3, and nanostructured TiO2 at 800 °C, and its monoclinic structure (space group C2/c) is confirmed by X-ray diffraction analysis. In this host, Mn4+ provides strong abso...
Article
Luminescence of monoclinic lithium metatitanate (Li2TiO3) powders activated with different quantities of Mn4+ is studied in detail. Its strong deep‐red emission arising from the Mn4+ 2Eg → 4A2g spin forbidden transition is centered at around 688 nm and is suitable for luminescence thermometry. Structural and electron paramagnetic resonance analyses...
Article
Full-text available
Material properties can be controlled via strain, pressure, chemical composition, or dimensionality. Nickelates are particularly susceptible due to their strong variations of the electronic and magnetic properties on such external stimuli. Here, we analyze the photoinduced dynamics in a single crystalline NdNiO3 film upon excitation across the elec...
Preprint
Full-text available
The control of materials properties with light is a promising approach towards the realization of faster and smaller electronic devices. With phases that can be controlled via strain, pressure, chemical composition or dimensionality, nickelates are good candidates for the development of a new generation of high performance and low consumption devic...
Preprint
Full-text available
Many complex electronic systems exhibit so-called pseudogaps, which are poorly-understood suppression of low-energy spectral intensity in the absence of an obvious gap-inducing symmetry. Here we investigate the superconductor $Ba_{1-x}K_{x}BiO_{3}$ near optimal doping, where unconventional transport behavior and evidence of pseudogap(s) have been o...
Article
Full-text available
The electronic structure of in situ grown ferroelectric BaTiO3(001) films is studied by angle-resolved photoemission spectroscopy. A two-dimensional state is found at the film-vacuum interface with an unexpected checkerboardlike Fermi surface. The observed absence of in-plane dispersion of the states is attributed to the influence of the strong ele...
Article
The binary luminescence thermometry probe is prepared from Y2O3:Ho3+ and Mg2TiO4:Mn4+ powders. This probe facilitates self‐referencing temperature readouts with excellent repeatability from both emission intensity ratio and excited state lifetimes. The ratio of intensities of Mn4+ deep red emission from 2E, 4T2→4A2 electronic transitions, and Ho3+...
Article
Full-text available
Observation of Bloch oscillations and Wannier-Stark localization of charge carriers is typically impossible in single-crystals, because an electric field higher than the breakdown voltage is required. In BaTiO$_3$ however, high intrinsic electric fields are present due to its ferroelectric properties. With angle-resolved photoemission we directly p...
Article
The two-dimensional electron gas at the surface of titanates gathered attention due to its potential to replace conventional silicon based semiconductors in the future. In this study, we investigated films of the parent perovskite CaTiO$_3$, grown by pulsed laser deposition, by means of angular-resolved photoelectron spectroscopy. The films show a...
Article
Engineering the electronic band structure of two-dimensional electron liquids (2DELs) confined at the surface or interface of transition metal oxides is key to unlocking their full potential. Here we describe a new approach to tailoring the electronic structure of an oxide surface 2DEL demonstrating the lateral modulation of electronic states with...
Article
We investigate the band structure of BaBiO3, an insulating parent compound of doped high-Tc superconductors, using in situ angle-resolved photoemission spectroscopy on thin films. The data compare favorably overall with density functional theory calculations within the local density approximation, demonstrating that electron correlations are weak....
Article
Full-text available
The observation by scanning tunnelling spectroscopy of Abrikosov vortex cores in the high-temperature superconductor YBa2Cu3O7-δ (Y123) has revealed a robust pair of electron-hole symmetric states at finite subgap energy. Their interpretation remains an open question because theory predicts a different signature in the vortex cores, characterized b...
Data
Supplementary Figures 1-2, Supplementary Note 1
Article
Full-text available
We present a combined angle-resolved photoemission spectroscopy (ARPES) and first-principles calculations study of the electronic structure of LaAgSb$_2$ in the entire first Brillouin zone. We observe a Dirac-cone-like structure in the vicinity of the Fermi level formed by the crossing of two linear energy bands, as well as the nested segments of F...
Article
Full-text available
Surfaces and interfaces offer new possibilities for tailoring the many-body interactions that dominate the electrical and thermal properties of transition metal oxides [1–3]. Here, we use the prototypical two-dimensional electron liquid (2DEL) at the SrTiO 3 (001) surface [4–7] to reveal a remarkably complex evolution of electron-phonon coupling wi...
Article
Full-text available
We employed {\it in-situ} pulsed laser deposition (PLD) and angle-resolved photoemission spectroscopy (ARPES) to investigate the mechanism of the metal-insulator transition (MIT) in NdNiO$_3$ (NNO) thin films, grown on NdGaO$_3$(110) and LaAlO$_3$(100) substrates. In the metallic phase, we observe three dimensional hole and electron Fermi surface (...
Article
Full-text available
We study the structural, magnetic, and transport properties of ${\mathrm{LaAlO}}_{3}$/${\mathrm{EuTiO}}_{3}$/${\mathrm{SrTiO}}_{3}$ heterostructures grown by pulsed laser deposition. The samples are characterized in situ by electron diffraction and scanning probe microscopy and ex situ by transport measurements and x-ray absorption spectroscopy. ${...
Article
Full-text available
We studied the structural, magnetic and transport properties of LaAlO3/EuTiO3/SrTiO3 heterostructures grown by Pulsed Laser Deposition. The samples have been characterized in-situ by electron diffraction and scanning probe mi-croscopy and ex-situ by transport measurements and x-ray absorption spectroscopy. LaAlO3/EuTiO3/SrTiO3 films show a ferromag...
Article
A full understanding of the mechanism of the formation of a two-dimensional electron gas (2DEG) at the interface between insulating LaAlO(3) (LAO) thin films and bulk SrTiO(3) (STO) crystals is a prerequisite for the full exploitation of this class of materials. Here, by using a combination of advanced X-ray synchrotron-based spectroscopic and stru...
Article
Illustration of a synchrotron-radiation X-ray experiment on a LaAlO3 /SrTiO3 heterostructure: Absorption of linear polarized photons is used to determine the orbital splitting of 3d orbitals (upper-right) of titanium ions (red spheres); surface X-ray-diffraction allows a structural refinement of the systems. M. Salluzzo and co-workers combine these...
Chapter
The origin of a high-mobility two-dimensional electron system (2DES) at the interface of LaAlO3/SrTiO3 (LAO/STO) heterostructures is still subject of intense research activities in both theory and experiment. The 2DES is expected to be formed by Ti 3d electrons, as Ti is the only multivalent ion in LAO/STO to accommodate the extra interface charge,...
Article
By using scanning tunneling microscopy/spectroscopy we show that the interface between LaAlO3 and SrTiO3 band insulators is characterized by in-gap interface states. These features were observed in insulating as well as conducting LaAlO3/SrTiO3 bilayers. The data show how the interface density of states evolves across the insulating to metal transi...
Article
Full-text available
Scanning tunneling spectroscopy suggests the formation of a two dimensional electron gas (2DEG) on the TiO2 terminated surface of undoped SrTiO3 single crystals annealed at temperature lower than 400 {\deg}C in ultra high vacuum conditions. Low energy electron diffraction indicates that the 2D metallic SrTiO3 surface is not structurally reconstruct...
Article
Full-text available
We report on a systematic study of the growth of epitaxial TiO(2) films deposited by pulsed laser deposition on Ti-terminated SrTiO(3) (001) single crystals. By using in situ reflection high energy electron diffraction, low energy electron diffraction, x-ray photoemission spectroscopy, and scanning probe microscopy, we show that the stabilization o...
Article
Full-text available
The appearance of high-mobility electrons at the LaAlO3/SrTiO3 interface has raised strong interest in the material science community and a lively debate on the origin of the phenomenon. A possible explanation is an electronic reconstruction, realizing a transfer of electrons to SrTiO3 at the interface, thereby avoiding the build-up of excessive Co...
Article
Today, treatment of human calculi, and particularly those of gallbladder, is, to a large extent, less invasive procedure due to numerous non-invasive methods that have been developed. CO2 laser of pulse (output 5W)(W-watt, SI unit system) and continual mode (output 15W) and diode laser (808 nm-nanometer, SI) were used for tests of fragmentation of...
Article
Full-text available
The physics of high critical temperature superconductors (HTS) remains a fascinating but undisclosed issue in condensed matter. One of the most interesting topics is the transition from the insulating phase of the parent compound, having long range antiferromagnetic order, to the superconducting phase. A method to investigate in detail the supercon...
Article
Full-text available
The so-called “polar catastrophe,” a sudden electronic reconstruction taking place to compensate for the interfacial ionic polar discontinuity, is currently considered as a likely factor to explain the surprising conductivity of the interface between the insulators LaAlO3 and SrTiO3. We applied optical second harmonic generation, a technique that a...
Article
A simple technique for the growth of SrO-terminated SrTiO3 surfaces is reported. High quality SrTiO3 epitaxial films were grown by reflection high energy electron diffraction assisted pulsed laser deposition on suitably prepared NdGaO3 (110) substrates. The surface properties, analyzed within a growth/characterization multichamber ultrahigh vacuum...
Article
Full-text available
We report a detailed study of the transport properties of Nd1+xBa2−xCu3O7−δ thin films with doping changed by field effect. The data cover the whole superconducting to insulating transition and show remarkable similarities with the effect of chemical doping in high critical temperature superconductors. The results suggest that the add-on of carrier...
Article
Full-text available
Commonly implemented nickel and titanium alloys are nowadays alloyed with many new elements. Obtained in this way, new Ti-alloys are of great practical significance in aircraft industry, while Ni-alloys are important in energetic and nuclear technique. Selected alloys of titanium and nickel have been treated in vacuum by various thermo-mechanical r...
Article
Nichrome coatings have been deposited using the d.c. sputtering of the target (80% Ni–20% Cr wt.) by Ar+ ions at a working pressure of 10−1 Pa and at room temperature. After the air exposure of samples at room temperature, their phase composition and structure was studied by X-ray diffraction, while the surface elemental composition was determined...
Article
The inelastic energy losses of He+ ions singly scattered from polycrystalline chromium (Cr) surface in the 0.7–2.0keV energy range were experimentally investigated in this work. The energy spectra of ions scattered to 90° were measured. The peak corresponding to singly scattered ions is resolved into two Gaussians. The one at higher energies (elast...
Article
Quantitative surface composition analysis using low energy ion scattering (LEIS) can be obstructed by the deviations introduced by the primary beam profile and the analyzer optics. A novel procedure is presented for excluding these deviations in LEIS measurements. The LEIS spectra were calculated from the assumed energy distribution, primary beam p...
Article
Full-text available
Thin films of nichrome were deposited by d.c. sputtering of a target (80%Ni 20%Cr w.t) by Ar+ions at a working pressure of 10-1 Pa and at room temperature. The phase composition and grain size were studied by X-ray Diffraction (XRD), while the surface chemical composition was determined by Low Energy Ion Scattering (LEIS). Analysis of phase composi...
Article
Ta2O5 is a material with good perspectives for many applications in modern electronics and information technologies. Several deposition techniques of thin Ta2O5 films have been suggested. Reliable information is still needed, however, on structural, electrical and optical parameters of the films, and their dependence on the deposition technique. We...
Article
We present a mathematical algorithm for the analysis of electrophoretic patterns resulting from arbitrarily primed PCR profiling. The algorithm is based on the established mathematical procedures applied to the analysis of digital images of gel patterns. The algorithm includes (a) transformation of the image into a matrix form, (b) identification o...