Nanosized Eu-Doped NaYSiO Oxyapatite Phosphor: A Comprehensive Insight into Its Hydrothermal Synthesis and Structural, Morphological, Electronic, and Optical Properties.

Detailed analysis covered the optical and structural properties of Eu-doped NaYSiO oxyapatite phosphors, which were obtained via hydrothermal synthesis. X-ray diffraction patterns of NaYSiO:xEu (x = 0, 1, 5, 7, 10 mol% Eu) samples proved a single-phase hexagonal structure ( (176) space group). Differential thermal analysis showed an exothermic peak at 995 °C attributed to the amorphous to crystalline transformation of NaYSiO.

Tuneable Red and Blue Emission of Bi-Co-Doped SrF:Eu Nanophosphors for LEDs in Agricultural Applications.

Tunable blue/red dual-emitting Eu-doped, Bi-sensitized SrF phosphors were synthesized utilizing a solvothermal-microwave method. All phosphors have cubic structure (- (225) space group) and well-distinct sphere-like particles with a size of ~20 nm, as examined by X-ray diffraction and transmission electron microscopy. The diffuse reflectance spectra reveal a redshift of the absorption band in the UV region as the Bi concentration in SrF: Eu phosphor increases.

Antimicrobial Activity of Amino-Modified Cellulose Nanofibrils Decorated with Silver Nanoparticles.

Silver nanoparticles (Ag NPs) conjugated with amino-functionalized cellulose nanofibrils (NH-CNFs) were in situ-prepared by reducing silver ions with free amino groups from NH-CNFs. The spectroscopy and transmission electron microscopy measurements confirmed the presence of non-agglomerated nanometer-in-size Ag NPs within micrometer-large NH-CNFs of high (20 wt.-%) content.

Thermal Quenching Mechanism of Mn in NaSiF, NaKSiF, and KSiF Phosphors: Insights from the First-Principles Analysis.

This study aims to identify the key factors governing the thermal quenching of Mn ion luminescence in fluoride-based phosphor materials used as red emitters in modern-day phosphor-converted LED devices. Here, we employ first-principles calculations for Mn-doped NaSiF, NaKSiF, and KSiF hosts to explore how host properties and local coordination environments influence thermal quenching behavior. The ΔSCF method was used to model the geometric structures of the MnA (ground) and E, T (excited) states and the energies of the optical transitions between these states.

First-Principles Linear Combination of Atomic Orbitals Calculations of KSiF Crystal: Structural, Electronic, Elastic, Vibrational and Dielectric Properties.

The results of first-principles calculations of the structural, electronic, elastic, vibrational, dielectric and optical properties, as well as the Raman and infrared (IR) spectra, of potassium hexafluorosilicate (KSiF; KSF) crystal are discussed. KSF doped with manganese atoms (KSF:Mn) is known for its ability to function as a phosphor in white LED applications due to the efficient red emission from Mn⁴⁺ activator ions. The simulations were performed using the CRYSTAL23 computer code within the linear combination of atomic orbitals (LCAO) approximation of the density functional theory (DFT).

Unraveling Broadband Near-Infrared Luminescence in Cr-Doped CaYGeO Garnets: Insights from First-Principles Analysis.

In this study, we conducted an extensive investigation into broadband near-infrared luminescence of Cr-doped CaYGeO garnet, employing first-principles calculations within the density functional theory framework. Our initial focus involved determining the site occupancy of Cr activator ions, which revealed a pronounced preference for the Y sites over the Ca and Ge sites, as evidenced by the formation energy calculations. Subsequently, the geometric structures of the excited states E and T, along with their optical transition energies relative to the ground state A in CaYGeO:Cr, were successfully modeled using the ΔSCF method.

Frontiers of Deep-Red Emission of Mn Ions with Ruddlesden-Popper Perovskites.

It is well-known that the chemical composition of the host material significantly affects the spectroscopic performance of transition metal ions. However, it is worth noting that also the structure and symmetry of crystallographic sites play significant roles in transition metal ion luminescence. In this study, we demonstrate three perovskite structures of strontium titanate forming so-called Ruddlesden-Popper phases doped with Mn ions.

Electronic, Optical, and Vibrational Properties of an AgAlS Crystal in a High-Pressure Phase.

The aim of this study is to comprehensively examine the structural composition and properties of the AgAlS crystal during its high-pressure phase. This analysis delves into the second coordination environment of the crystal structure and elucidates the distinct transformations it undergoes during the phase transition. The band energy structure was calculated, and the origin of electronic levels was clarified.

Luminescence Thermometry with Nanoparticles: A Review.

Luminescence thermometry has emerged as a very versatile optical technique for remote temperature measurements, exhibiting a wide range of applicability spanning from cryogenic temperatures to 2000 K. This technology has found extensive utilization across many disciplines. In the last thirty years, there has been significant growth in the field of luminous thermometry.

Isolated Coordination Polyhedron Confinement in ABPO:Mn (A = Ba/Sr; B = Mg/Zn).

Many research efforts have focused on designing new inorganic phosphors to meet different application requirements. The structure-photoluminescence relationship between activator ions and the matrix lattice plays an irreparable role in designing target phosphors. Herein, a series of ABPO:Mn (A = Ba/Sr; B = Mg/Zn) phosphors are prepared for a detailed study on the relationship between the luminescence performance and spatial structure and symmetry of the doping site of Mn.

Study on Local-Structure Symmetrization of KXF Crystals Doped with Mn Ions by First-Principles Calculations.

The crystals of Mn-activated fluorides, such as those of the hexafluorometallate family, are widely known for their luminescence properties. The most commonly reported red phosphors are AXF: Mn and BXF: Mn fluorides, where A represents alkali metal ions such as Li, Na, K, Rb, Cs; X=Ti, Si, Ge, Zr, Sn, B = Ba and Zn; and X = Si, Ge, Zr, Sn, and Ti. Their performance is heavily influenced by the local structure around dopant ions.

Comparative analysis of Ag NPs functionalized with olive leaf extract and oleuropein and toxicity in human trophoblast cells and peripheral blood lymphocytes.

Dry olive leaf extract (DOLE) and its active component oleuropein (OLE) were applied as reducing and stabilizing agents to prepare colloidal 20-25 nm silver nanoparticles (Ag NPs). The Ag NPs were characterized using transmission electron microscopy, X-ray diffraction analysis, and absorption spectroscopy. The cytotoxic actions of coated Ag NPs, and their inorganic and organic components, were examined against trophoblast cells and human peripheral blood lymphocytes (PBLs), Gram-positive, Gram-negative bacteria, and yeast.

Comparison of Performance between Single- and Multiparameter Luminescence Thermometry Methods Based on the Mn Near-Infrared Emission.

Herein, we investigate the performance of single- and multiparametric luminescence thermometry founded on the temperature-dependent spectral features of CaBaPO:Mn near-infrared emission. The material was prepared by a conventional steady-state synthesis, and its photoluminescence emission was measured from 7500 to 10,000 cm over the 293-373 K temperature range in 5 K increments. The spectra are composed of the emissions from E → A and T → A electronic transitions and Stokes and anti-Stokes vibronic sidebands at 320 cm and 800 cm from the maximum of E → A emission.

Understanding the power of luminescence ratiometric thermal history indicators driven by phase transitions: the case of Eu doped LaVO.

Finding thermal history phosphors with high sensitivity and a consistent readout is required for reliable thermal history determination with high temperature resolution. This work presents a new thermal history phosphor based on the luminescence of Eu ions in LaVO to meet these requirements. As demonstrated, raising the annealing temperature causes a structural phase transition from a low-temperature tetragonal phase to a high-temperature single-stranded phase.

Barium hexaferrite nanoplatelets with polyphenol coatings for versatile applications as a stable, magnetic, and antimicrobial colloid.

Colloidal stabilization of magnetic nanoparticles is one of the most important steps in the preparation of magnetic nanoparticles for potential biomedical applications. A special kind of magnetic nanoparticle are barium hexaferrite nanoplatelets (BSHF NPLs) with a hexagonal shape and a permanent magnetic moment. One strategy for the stabilization of BHF in aqueous media is to use coatings.

Hydrothermal Synthesis and Properties of Yb/Tm Doped SrLaF Upconversion Nanoparticles.

We report the procedure for hydrothermal synthesis of ultrasmall Yb/Tm co-doped SrLaF (SLF) upconversion phosphors. These phosphors were synthesized by varying the concentrations of Yb (x = 10, 15, 20, and 25 mol%) and Tm (y = 0.75, 1, 2, and 3 mol%) with the aim to analyze their emissions in the near IR spectral range.

Exploiting High-Energy Emissions of YAlO:Dy for Sensitivity Improvement of Ratiometric Luminescence Thermometry.

The sensitivity of luminescence thermometry is enhanced at high temperatures when using a three-level luminescence intensity ratio approach with Dy- activated yttrium aluminum perovskite. This material was synthesized via the Pechini method, and the structure was verified using X-ray diffraction analysis. The average crystallite size was calculated to be around 46 nm.

Toxicity of Silver Nanoparticles Supported by Surface-Modified Zirconium Dioxide with Dihydroquercetin.

The antibacterial performance and cytotoxic examination of in situ prepared silver nanoparticles (Ag NPs), on inorganic-organic hybrid nanopowder consisting of zirconium dioxide nanoparticles (ZrO NPs) and dihydroquercetin (DHQ), was performed against Gram (-) bacteria and Gram (+) bacteria , as well as against human cervical cancer cells HeLa and healthy MRC-5 human cells. The surface modification of ZrO NPs, synthesized by the sol-gel method, with DHQ leads to the interfacial charge transfer (ICT) complex formation indicated by the appearance of absorption in the visible spectral range. The prepared samples were thoroughly characterized (TEM, XRD, reflection spectroscopy), and, in addition, the spectroscopic observations are supported by the density functional theory (DFT) calculations using a cluster model.

Mn-activated CaBa(PO)O near-infrared phosphor and its application in luminescence thermometry.

The near-infrared luminescence of CaBa(PO)O:Mn 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 E → A transition with a 37.5% internal quantum efficiency and an excited-state lifetime of about 350 μs.

Interfacial charge transfer complex formation between silver nanoparticles and aromatic amino acids.

The optical properties of surface-modified silver nanoparticles (Ag NPs) with aromatic amino acids tryptophan (Trp) and histidine (His) were examined using the cluster model for density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations. Also, the redistribution of electronic charges upon chemisorption of ligand molecules onto silver's surfaces is determined. The obtained theoretical data, on one side, undoubtedly indicate the the formation of an interfacial charge transfer (ICT) complex between silver and this type of ligand, and, on the other side, partial oxidation of surface silver atoms accompanied by an increase of electron density in ligand molecules.

New Insights into Amino-Functionalization of Magnetic Nanoplatelets with Silanes and Phosphonates.

Magnetic nanoplatelets (NPLs) based on barium hexaferrite (BaFeO) are suitable for many applications because of their uniaxial magneto-crystalline anisotropy. Novel materials, such as ferroic liquids, magneto-optic composites, and contrast agents for medical diagnostics, were developed by specific surface functionalization of the barium hexaferrite NPLs. Our aim was to amino-functionalize the NPLs' surfaces towards new materials and applications.