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The method of measuring temperature using luminescence by analyzing the emission spectra of Pr3+-doped YF3 using principal component analysis is presented. The Pr3+-doped YF3 is synthesized using a solid-state technique, and its single-phase orthorhombic crystal structure is confirmed using X-ray diffraction. The emission spectra measured within the 93–473 K temperature range displays characteristic Pr3+ f-f electronic transitions. The red emission from the 3P0,1→3H6,3F2 electronic transition mostly dominates the spectra. However, at low temperatures, the intensity of the green emissions from the 3P0,1→3H5, deep-red 3P0,1→3F4, and the deep-red emissions from the 3P0,1→3F4 transitions are considerably lower compared to the intensity of the red emissions. Temperature variations directly impact the photoluminescent spectra, causing a notable increase in the green and deep-red emissions from the 3P1 excited state. We utilized the entire spectrum as an input for principal component analysis, considering each temperature as an independent group of data. The first principal component explained 99.3% of the variance in emission spectra caused by temperature and we further used it as a reliable temperature indicator for luminescence thermometry. The approach has a maximum absolute sensitivity of around 0.012 K−1. The average accuracy and precision values are 0.7 K and 0.5 K, respectively.

first_pagesettingsOrder Article Reprints Open AccessArticle Structure–Dopant Concentration Relations in Europium-Doped Yttrium Molybdate and Peak-Sharpening for Luminescence Temperature Sensing by Tamara Gavrilović *,Aleksandar Ćirić *,Mina Medić,Zoran RistićORCID,Jovana Periša,Željka AntićORCID andMiroslav D. Dramićanin Center of Excellence for Photoconversion, Vinča Institute of Nuclear Sciences-National Institute of the Republic of Serbia, University of Belgrade, 11001 Belgrade, Serbia * Authors to whom correspondence should be addressed. Materials 2024, 17(17), 4267; https://doi.org/10.3390/ma17174267 Submission received: 23 July 2024 / Revised: 12 August 2024 / Accepted: 20 August 2024 / Published: 28 August 2024 (This article belongs to the Special Issue Exploring the Versatility of Piezoelectric and Dielectric Electroceramics: Synthesis, Characterization, and Applications) Downloadkeyboard_arrow_down Browse Figures Versions Notes Abstract A set of Eu3+-doped molybdates, Y2−xEuxMo3O12 (x = 0.04; 0.16; 0.2; 0.4; 0.8; 1; 1.6; 2), was synthesized using a solid-state technique and their properties studied as a function of Eu3+ concentration. X-ray diffraction showed that the replacement of Y3+ with larger Eu3+ resulted in a transformation from orthorhombic (low doping concentrations) through tetragonal (high doping concentrations), reaching monoclinic structure for full replacement in Eu2Mo3O12. The intensity of typical Eu3+ red emission slightly increases in the orthorhombic structure then rises significantly with dopant concentration and has the highest value for the tetragonal Y2Mo3O12:80mol% Eu3+. Further, the complete substitution of Y3+ with Eu3+ in the case of monoclinic Eu2Mo3O12 leads to decreased emission intensity. Lifetime follows a similar trend; it is lower in the orthorhombic structure, reaching slightly higher values for the tetragonal structure and showing a strong decrease for monoclinic Eu2Mo3O12. Temperature-sensing properties of the sample wit

Herein, we demonstrate the photoluminescence properties of Dy3+-activated YNbO4, LuNbO4, and mixed YxLu1−xNbO4:Dy3+ (x=0.25, 0.5, 0.75) phosphors. For this purpose, fve samples with a fxed Dy3+ concentration (2 mol%) were prepared by the solid-state reaction method. X-ray difraction measurements showed that all phosphors crystallize in a monoclinic fergusonite-beta-(Y) structure with a C2/c space group. Scanning electron microscopy clearly shows that samples are composed of dense, well-developed micron-sized, cube-shaped grains with rounded edges. The photoluminescent emission spectra feature Dy3+ peaks at standard positions corresponding to transitions from the 4 F9/2 excited emitting level to the 6 HJ (J=15/2; 13/2; 11/2 and 9/2) lower levels with two dominant emission bands placed in the blue (~479 nm, B) and yellow (~576 nm, Y) spectral region. It is observed that with Lu increase in the host lattice Y/B ratio decreases toward the desired ratio of unity to obtain white light. To evaluate the suitability of these phosphors for use in solid-state lighting, their photoluminescence emission was analyzed in detail by calculating CIE coordinates, correlated color temperature (CCT) and Delta u,v (DUV). It is shown that CIE chromaticity coordinates of all Dy3+-activated YxLu1−xNbO4 samples (x=0, 0.25, 0.5, 0.75, and 1) fall into the white portion of the diagram and that with the increase of Lu in the host lattice color becomes whiter. CCT values for all samples are in the cooler 4000–4500 K range with positive DUVs indicating that color points are placed above the black body curve. The average lifetime of 4 F9/2 level is calculated to be~0.2 ms for all Dy3+-activated YxLu1−xNbO4 samples, indicating that there is no infuence of the Y-to-Lu ratio in the host niobate material on the luminescence kinetics.

Photonics applications based on rare-earth (RE)-doped crystals are developing in many different fields, such as photovoltaic, laser technology, optical data storage, sensing, bioimaging, diagnosis and therapy. RE-doped inorganic bulk materials have long been known to cause luminescence emissions that are spectrally distributed throughout the whole optical range, from the ultraviolet (UV) to the mid-infrared region, with unique features which have made these materials very important, especially for laser applications. Moreover, when grown in nanometric size, these materials exhibit peculiar behaviors for their efficiency, lifetimes, energy transfer processes, interaction with the environment, etc., which have stimulated new research devoted, on the one hand, to the physical understanding of these phenomena, and on the other hand, to the development of many new applications. This book is dedicated to studying RE-doped bulk and nanocrystalline materials from a scientific point of view and to presenting their possible applications in any field. This book is intended to serve as a unique multidisciplinary forum covering all aspects of science, technology and applications of RE-doped crystals, starting from the growth techniques with specific attention to the emission features of these materials and their applications.

Materials matter: any breakthrough that changes society owes its success to the molecular building blocks used to create it. Advanced materials are essential to economic security and human well-being, with applications in industries aimed at addressing challenges in clean energy, national security, and human welfare. Therefore, speeding up the pace of development and implementation of advanced material systems is critical for achieving global competetiveness in the 21st century. In recent decades, significant progress has been evident in the processing and properties of materials intended for use in various biotechnologies, biomedicine, and dentistry. This volume specifically introduces new materials based on natural and synthetic substances with improved properties relevant to applications in biomedicine and biotechnologies., Materijali su važni: svaki napredak koji menja društvo duguje svoj uspeh molekularnim gradivnim blokovima koji se koriste za njegovo stvaranje. Napredni materijali su od suštinskog značaja za ekonomsku bezbednost i ljudsko blagostanje, sa primenom u industrijama usmerenim na rešavanje izazova u pogledu čiste energije, nacionalne bezbednosti i ljudskog blagostanja. Stoga je ubrzanje tempa razvoja i implementacije naprednih materijalnih sistema kritično za postizanje globalne konkurentnosti u 21. veku. Poslednjih decenija evidentan je značajan napredak u obradi i svojstvima materijala namenjenih upotrebi u različitim biotehnologijama, biomedicini i stomatologiji. Ova tematska sveska posebno predstavlja nove materijale zasnovane na prirodnim i sintetičkim supstancama sa poboljšanim svojstvima relevantnim za primenu u biomedicini i biotehnologiji.

Luminescent Eu3+-doped SrF2 nanoparticles were synthesized using microwave-assisted synthesis. Their surfaces were modified either by polyethylene glycol or mercaptopropionic acid to enhance their dispersibility in aqueous media and colloidal formation. X-ray diffraction analysis confirmed single-phase cubic structure in both types of hydrophilic-modified Sr0.9Eu0.1F2 luminescent powders. The average crystallite size of nanoparticles is found to be ∼13 nm. Scanning electron microscopy of the representative PEG2000-modified sample revealed that particles form agglomerates composed of densely packed nanoparticles. The microstructure at a local level was investigated by transmission electron microscopy showing the presence of sphere-like nanoparticles with an average particle size of 12.5 nm and 14 nm for PEG-modified and MPA-modified Sr0.9Eu0.1F2, respectively. Both PEG2000 and MPA-modified Sr0.9Eu0.1F2 water dispersions show strong red Eu3+ emission under 405 nm excitation that is quenched in the presence of the primary NP fertilizer, ammonium dihydrogen phosphate, NH4H2PO4. The limit of detection was calculated to be ∼19 mM for both hydrophilic-modified Sr0.9Eu0.1F2 luminescent nanoparticles.

The sensitivity of luminescent Boltzmann thermometers is restricted by the energy difference between the thermally coupled excitement levels of trivalent lanthanides, and their values further decrease with increases in temperature, rendering their use at high temperatures difficult. Here, we demonstrate how to overcome this sensitivity limitation by employing multiparameter and multilevel cascade temperature readings. For this purpose, we synthesized Dy3+:Y2SiO5, a phosphor whose emission is known to begin quenching at very high temperatures. Its photoluminescence-emission features, later used for thermometry, consisted of two blue emission bands centered around 486 nm and 458 nm, and two bands centered around 430 nm and 398 nm, which were only visible at elevated temperatures. Next, we performed thermometry using the standard luminescence-intensity ratio (LIR) method, which employs the 4F9/2 and 4I15/2 Dy3+ levels’ emissions and the multilevel cascade method, which additionally uses the 4G11/2 level and overlapping intensities of 4I13/2, 4M21/2, 4K17/2, and 4F7/2 levels to create two LIRs with a larger energy difference than the standard LIR. This approach yielded a sensitivity that was 3.14 times greater than the standard method. Finally, we simultaneously exploited all the LIRs in the multiparameter temperature readings and found a relative sensitivity that was 30 times greater than that of the standard approach.

We report the procedure for hydrothermal synthesis of ultrasmall Yb3+/Tm3+ co-doped Sr2LaF7 (SLF) upconversion phosphors. These phosphors were synthesized by varying the concentrations of Yb3+ (x = 10, 15, 20, and 25 mol%) and Tm3+ (y = 0.75, 1, 2, and 3 mol%) with the aim to analyze their emissions in the near IR spectral range. According to the detailed structural analysis, Yb3+ and Tm3+ occupy the La3+ sites in the SLF host. The addition of Yb3+/Tm3+ ions has a huge impact on the lattice constant, particle size, and PL emission properties of the synthesized SLF nanophosphor. The results show that the optimal dopant concentrations for upconversion luminescence of Yb3+/Tm3+ co-doped SLF are 20 mol% Yb3+ and 1 mol% Tm3+ with EDTA as the chelating agent. Under 980 nm light excitation, a strong upconversion emission of Tm3+ ions around 800 nm was achieved. In addition, the experimental photoluminescence lifetime of Tm3+ emission in the SLF host is reported. This study discovered that efficient near IR emission from ultrasmall Yb3+/Tm3+ co-doped SLF phosphors may have potential applications in the fields of fluorescent labels in bioimaging and security applications.