A highly sensitive ratiometric optical thermometer based on a SrMgWO double perovskite doped with Dy exploiting thermally coupled and uncoupled levels.

The increasing demand for highly sensitive optical thermometers operating within a wide temperature range necessitates the development of new phosphors. In this work, the potential temperature sensing performance of a novel yellow-emitting phosphor, SrMgWO double perovskite, doped with varying concentrations of Dy was investigated for the first time. Increasing the concentration of Dy from 0% to 7% shifted the color of luminescence from blue to yellowish-orange within the CIE1931 color space.

Discovering the Potential of High Phonon Energy Hosts in the Field of Visible-to-Ultraviolet C Upconversion.

The recent pandemic has intensified the search for new ultraviolet C (UVC) phosphors excited by low-intensity visible light that can be used for disinfection or therapeutic purposes. Currently, the most promising phosphor with efficient upconversion was thus far YSiO (YSO) doped with Pr. However, we have studied a new material Sr(BO):Pr (SBO), whose upconversion emission is 10 times stronger than YSO, despite the high phonon energy possessed by SBO and despite the lack of optimization of synthesis and dopant concentration and the absence of co-dopant that should be added to compensate for the charge.

UVC Stokes and Anti-Stokes Emission of CaY(PO) Polycrystals Doped with Pr Ions.

The recent COVID-19 pandemic has made everyone aware of the threat of viruses and the growing number of antibiotic-resistant bacteria. It has become necessary to find new methods to combat these hazards. One tool that could be used is UVC radiation, i.

Highly Sensitive Temperature Sensors Resulting from the Luminescent Behavior of Sm-Doped BaMgMoO High-Symmetry Double-Perovskite Molybdate Phosphors.

We present double-perovskite molybdate with the formula of BaMgMoO doped with Sm ions as a potential red phosphor to improve the color characteristics of white-light-emitting dioded (wLEDs). The new orange-red phosphor was synthesized using the co-precipitation (CP) method, and then its structural and spectroscopic properties were determined. Red emission at 642.

UVC Up-Conversion and Vis-NIR Luminescence Examined in SrO-CaO-MgO-SiO Glasses Doped with Pr.

The application of ultraviolet-C light in the field of surface treatment or photodynamic therapy is highly prospective. In this regard, the stable fluorescent silicate SrO-CaO-MgO-SiO-PrO glasses able to effectively convert visible excitation on the ultraviolet praseodymium emission were fabricated and examined. An unusual wide-range visible-to-UVC up-conversion within 240-410 nm has been achieved in Pr-doped glasses, revealing their potential advantage in different sophisticated disinfection technologies.

Luminescence Properties of an Orthorhombic KLaF Phosphor Doped with Pr Ions under Vacuum Ultraviolet and Visible Excitation.

Fluorides have a wide bandgap and therefore, when doped with the appropriate ions, exhibit emissions in the ultraviolet C (UVC) region. Some of them can emit two photons in the visible region for one excitation photon, having a quantum efficiency greater than 100%. In a novel exploration, praseodymium (Pr) ions were introduced into KLaF crystals for the first time.

Upconversion Luminescence Properties of Pr-Doped BaYF Nanoparticles Prepared by Microwave Hydrothermal Method.

Pure and Pr-doped BaYF nanoparticles were synthesized by the microwave hydrothermal method. The nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and optical spectroscopy. The XRD and TEM confirm that the average size of nanoparticles is in the range of 26-37 nm.

Effect of A-Cation Radius on the Structure, Luminescence, and Temperature Sensing of Double Perovskites AMgWO Doped with Dy (A = Ca, Sr, Ba).

Herein, we report a case of AMgWO (A = Ca, Sr, Ba) doped with 2%Dy, 2%Li, in which the influences of the cation substitution are exhibited through the crystal structure, the charge transfer band (O-W), the emission spectrum, the color of the luminescence, and the luminescent decay time. The substitution of Ca and Sr ions for larger ions (Ba) led to the crystal structure alteration from cubic to monoclinic and tetragonal, respectively. These structure changes also lowered the crystallography symmetry site of Dy, tuned the color of the emitted light from the whitish to yellowish region, and caused a blue shift of the CTB.

Highly Stable White Light Emission from III-Nitride Nanowire LEDs Utilizing Nanostructured Alumina-Doped Mn and Mg.

In this report, red-emitting alumina nanophosphors doped with Mn and Mg (AlO:Mn, Mg) are synthesized by a hydrothermal method using a Pluronic surfactant. The prepared samples are ceramic-sintered at various temperatures. X-ray diffraction shows that AlO:Mn, Mg annealed at 500 °C exhibits a cubic γ-AlO phase with the space group 3-227.

Influence of Sintering Parameters on Spectroscopic Properties of BMW: Eu Ceramic Materials Prepared by HPLT Technique.

In this work, BaMgWO: Eu (BMW: Eu) ceramic materials with a double perovskite structure were sintered using the High-Pressure Low-Temperature sintering (HPLT) technique. As part of the research, the influence of pressure (CP), sintering temperature (CT), and sintering time (CTS) on the structure and luminescence of the doped BMW were determined. Structural analysis via XRD and SEM + EDS and spectroscopic analysis via emission and excitation spectra, decay time, and absorption spectra of the obtained ceramics were performed.

Passive radiant cooling without sacrificing the aesthetics of objects.

Photonic-engineered passive radiative cooling built into decorative climate-controlled enclosures reduces the active power consumption of the existing enclosure without sacrificing its aesthetics.

On how the mechanochemical and co-precipitation synthesis method changes the sensitivity and operating range of the BaMgEuWO optical thermometer.

The suitability of BaMgWO (BMW) double perovskite doped with Eu for the construction of an optical thermometer was tested. It has been shown that by controlling the conditions of BMW synthesis, the sensitivity of the optical thermometer and the useful range of its work can be changed. Pure BMW and doped with Eu samples were prepared using the mechano-chemical and co-precipitation methods.

Effect of Ceramic Formation on the Emission of Eu and Nd Ions in Double Perovskites.

Herein, the structure, morphology, as well as optical properties of the powder and ceramic samples of BaMgWO are presented. Powder samples were obtained by high temperature solid-state reaction, while, for the ceramics, the SPS technique under 50-MPa pressure was applied. The morphology of the investigated samples showed some agglomeration and grains with a submicron size of 490-492 µm.

Exploration of the Temperature Sensing Ability of LaMgTiO:Er Double Perovskites Using Thermally Coupled and Uncoupled Energy Levels.

This work aimed to explore the temperature-sensing performance of LaMgTiO:Er double perovskites based on thermally coupled and uncoupled energy levels. Furthermore, the crystal structure, chemical composition, and morphology of the samples were investigated by powder X-ray diffraction, energy-dispersive X-ray spectroscopy, and scanning electron microscopy, respectively. The most intense luminescence was observed for the sample doped with 5% Er.

Temperature sensitivity modulation through changing the vanadium concentration in a LaMgTiO:V,Cr double perovskite optical thermometer.

To fulfil the requirements of operating at low temperature in a harsh environment, the investigation on optical thermometers plays an increasingly important role. In this work, the influence of vanadium concentration on the capability of temperature readout by La2MgTiO6:V5+,Cr3+ luminescent thermometers was investigated for the first time. The presence of V3+ and V5+ was verified by XPS and absorption measurements.

Deep red fluoride dots-in-nanoparticles for high color quality micro white light-emitting diodes.

In this study, a novel nanostructure of fluoride red emitting phosphor is synthesized via soft templates. KSiF:Mn nanocrystals in the range of 3-5 nm diameter are found inside the porous KSiF:Mn nanoparticle hosts, forming unique dots-in-nanoparticles (d-NPs) structures with controlled optical properties. The porous KSiF:Mn d-NPs exhibit a sharp and deep red emission with an excellent quantum yield of ∼95.

Synthesis, Structure, Morphology, and Luminescent Properties of BaMgWO: Eu Double Perovskite Obtained by a Novel Co-Precipitation Method.

Eu doped BaMgWO (BMW) double-perovskite was successfully synthesized for the first time by the co-precipitation method. The synthesis procedure, crystal structure, as well as morphology of obtained samples are presented. Domination of the D-F magnetic-dipole over forced electric-dipole transitions in the emission spectra indicates that Eu ions are located in the high symmetry site with inversion center.

The effect of K cations on the phase transitions, and structural, dielectric and luminescence properties of [cat][KCr(HCOO)], where cat is protonated dimethylamine or ethylamine.

We report the synthesis, crystal structure, and dielectric, vibrational and emission spectra of two novel heterometallic perovskite-type metal-organic frameworks (MOFs) of the following formula: [(CH)NH][KCr(HCOO)] (DMAKCr) and [CHNH][KCr(HCOO)] (EtAKCr). DMAKCr crystallizes in a trigonal structure (R3[combining macron] space group) and undergoes an order-disorder phase transition to the monoclinic system (P1[combining macron] space group) at about 190 K. The dielectric studies confirm the presence of first-order relaxor-like structural transformation.

Phase transitions and chromium(iii) luminescence in perovskite-type [CHNH][NaCrAl(HCOO)] (x = 0, 0.025, 0.5), correlated with structural, dielectric and phonon properties.

We report the synthesis, crystal structure, dielectric, vibrational and emission spectra of heterometallic MOFs, [CHNH][NaCr(HCOO)] (EtANaCr), [CHNH][NaAl(HCOO)] (EtANaAl) and [CHNH][NaAlCr(HCOO)] (EtANaAlCr). These compounds crystallize in non-centrosymmetric monoclinic polar structures (space group Pn) and undergo order-disorder phase transitions upon heating to the monoclinic centrosymmetric structure (space group P2/n) at 369 (EtANaAl) and 373 K (EtANaCr). In principle, they are ferroelectric below these temperatures.

Synthesis and characterization of [(CH3)2NH2][Na0.5Cr0.5(HCOO)3]: a rare example of luminescent metal-organic frameworks based on Cr(III) ions.

A novel formate [(CH3)2NH2][Na0.5Cr0.5(HCOO)3] (DMNaCr) was prepared by a solvothermal method.