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The industrial applications of luminescent coatings for temperature sensing and high‐security QR codes have multiple inherent problems in their application (speed, cost, industrial feasibility) or properties (poor adhesion, chemical, thermal stability, or thermal contact). Luminescent coatings created by the electrochemical Plasma Electrolytic Oxidation (PEO) process have superior properties and can be grown directly within minutes, but are limited to the number of possible luminescent dopants. Having the unlimited possibility for doping on the PEO coatings would provide for superior coatings in all industrially appealing features. Herein, it is shown that adding any luminescent powder results in its partial dissociation and incorporation of its constituents, while it also gets incorporated as a whole. In this manner, alumina coatings are grown with various combinations and concentrations of divalent samarium and europium, and yttrium oxide with trivalent europium ions. These polycrystalline coatings whose microhardness is next to that of the diamond produce intense luminescence in the blue and red regions. Al2O3:Eu2+/Sm2+/3+ + Y2O3:Eu3+ coatings show an excellent temperature sensing performance from the cryogenic up to the high temperatures. Ultimately, the proof‐of‐concept of the luminescent QR code by the electrochemical process is realized creating a highly secure code with unprecedented environmental stability. [ABSTRACT FROM AUTHOR]

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) thermometers (transitions from the three thermalized levels, 4F9/2, 4I15/2, and 4G11/2 to the ground level). Reduced matrix elements of these three transitions are calculated from the Slater integrals and spin‐orbit coupling parameters and they are compared to the most frequently used values from Carnall's tables. The comparison of JO parameters shows the smaller variation of the Ω6, related to rigidity, in crystal hosts than in glasses, and the opposite was observed for the Ω2,4 parameters. LIR performances are simulated by the JO thermometric model for each material by the conventional LIR and the LIR that exploits the third thermalized level. The comparison of the predicted figures of merit in luminescence thermometry reveals the most promising thermometric Dy3+ doped crystals and glasses. [ABSTRACT FROM AUTHOR]

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 strong interaction of low‐lying Pr3+ 4f5d energy levels with the 4f levels. Here, the straightforward JO parametrization method that uses the emission spectrum and the excited state lifetime of the Pr3+ 3P0 level which does not require any fitting procedure are shown. In addition, the theory and software for calculations of JO parameters from Pr3+ emission are explained. The method requirements are low‐temperature photoluminescence measurements of Pr3+ introduced in low phonon energy hosts with a relatively high lying 4f5d energy level. The method is demonstrated on emissions of YF3:Pr3+ and LaF3:Pr3+ powders. [ABSTRACT FROM AUTHOR]

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 strong interaction of low‐lying Pr3+ 4f5d energy levels with the 4f levels. Here, the straightforward JO parametrization method that uses the emission spectrum and the excited state lifetime of the Pr3+ 3P0 level which does not require any fitting procedure are shown. In addition, the theory and software for calculations of JO parameters from Pr3+ emission are explained. The method requirements are low‐temperature photoluminescence measurements of Pr3+ introduced in low phonon energy hosts with a relatively high lying 4f5d energy level. The method is demonstrated on emissions of YF3:Pr3+ and LaF3:Pr3+ powders. [ABSTRACT FROM AUTHOR]

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 widely used aluminum alloys, 6061 and 7075, are also coated. For this purpose, plasma electrolytic oxidation (PEO), an effective technique for producing hard ceramic coatings on various metal surfaces, is used. It is shown that thermometric coatings can be produced on aluminum in one‐step process by adding the raw precursor to the electrolyte. The valence reduction of Ln3+ to Ln2+ is achieved during the PEO process. The intense and broad (orange to deep red) emission from the coating shows supersensitivity to temperature changes over the 100–648 K range. The temperature is obtained from the coating emission using i) the emission intensity ratio method, ii) emission lifetime, and iii) emission band position with sensitivities of 4.8% K−1, 1.2% K−1, and 8 cm−1 K−1, respectively. Several applications would benefit from the thermometric coating's excellent temperature resolution of 0.04 K and the choice of three temperature read‐outs that facilitate the coating's use in different luminescence thermometry setups. [ABSTRACT FROM AUTHOR]

The red phosphor Y2Mo4O15:Eu3+ calcined at different temperatures is obtained by a solid‐state method, and is investigated in this article. Usage of solid‐state method with the combination of five different calcination temperatures (500, 550, 600, 650, and 700 °C) leads to the formation of pure monoclinic phase in all samples apart from the one calcined at the lowest temperature. Crystallite size obtained by Rietveld refinement is in the range of 38–55 nm. Scanning electron microscopy analysis confirms the presence of agglomerates. Luminescence emission spectra and emission decay curves are measured for all pure samples, and parameters derived from these measurements are used for Judd–Ofelt analysis. International commission on illumination (CIE) chromaticity diagram confirms the presence of pure red emission and high quantum efficiency. [ABSTRACT FROM AUTHOR]