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Designing a "rewritable paper" is an effective and feasible method to solve the environmental problems caused by paper consumption. Inorganic ferroelectrics and robust oxide photochromic materials exhibit excellent reversible print/erase responses, a fast response time, and outstanding physical and chemical stability, which are vital for the implementation of a rewritable paper. However, the application of "rewritable paper" based on these inorganic photochromic materials is limited by its low color contrast. In this study, an ultra-high color contrast of 77.1% is obtained through inducing oxygen vacancy defects in Ba3MgSi2O8:0.5%Pr3+ by ion doping and sintering in a reducing atmosphere. The rewritable paper fabricated with Ba3MgSi2O8:0.5%Pr3+ shows a reversible write and erase response under UV illumination and thermal stimulus and also shows the advantages of a fast response time and excellent color reversibility. Furthermore, due to a good overlap between the absorption peak of Ba3MgSi2O8 and the excitation/emission peak of Pr3+, a large luminescence modulation of 97.9% can be obtained in Ba3MgSi2O8:0.5%Pr3+, which has a wide application prospect in anti-counterfeiting displays and easy-readout/erasable photo-memorizers. The insights provided will support fellow researchers to design high-performance inorganic photochromic systems by inducing oxygen vacancies. [ABSTRACT FROM AUTHOR]

Colloidal all‐inorganic lead halide perovskite nanocrystals (LHP NCs) feature with tunable high‐efficiency photoluminescence from blue to red for optoelectronic applications but suffer from instability under water moisture, UV light illumination, high‐temperature shock, as well as oxygen erosion. Previous work to improve LHP NCs stability was mainly focused on either glass bulk sealed LHP quantum dots (QDs) with low quantum efficiency, or mesoporous silica matrixes confined LHP QDs with organic ligands still existing. Here, a facile, noncolloidal, ligand‐free LHP QDs growth with physical confinement is proposed by integrating the growth of perovskite QDs with the fabrication process of hydrophobic silica‐aerogel powders (SAPs). As a result, the as‐synthesized mono‐ and mixed‐cesium‐lead‐halide QDs @ SAPs composites show tunable photoluminescence from purple to deep red. Besides, the Pr3+ ions doped CsPbBr3 QDs @ SAPs composites exhibit moderate quantum efficiency, excellent stability under UV illumination, water moisture as well as temperature variation. Furthermore, performances of white LED device encapsulated Pr3+ doped composite with blue GaN chip and commercial red (Sr, Ca)AlSiN3:Eu2+ phosphor are evaluated. This work demonstrates a facile and general strategy for synthesizing high‐stable all‐inorganic cesium‐lead‐halide QDs for applications in white LED and display devices. [ABSTRACT FROM AUTHOR]

Bifunctional luminescence materials have aroused considerable concern due to their wide application and high utilization. In this study, we have successfully integrated bright green up-conversion luminescence of K0.5Bi0.5TiO3 (KBT): Er/In ceramics with potential applications on cryogenic optical thermometry and photomemory. By employing the fluorescence intensity ratio based on thermally coupled levels of Er3+: 2H11/2/4S3/2, the splendid low-temperature sensing properties were demonstrated as the maximum relative sensitivities were 7.14% K−1 and 8.73% K−1 at 137 K for KBT: Er and KBT: Er/In ceramics, respectively. Moreover, the reversible photochromism performance could be triggered by the 365 nm irradiation and vanished by thermal stimulation at 150 °C. Remarkably, the coupling of up-conversion luminescence and photochromism performance has a promising application on rewritable photomemory. For the KBT: Er/In ceramic, the emission intensity could be reduced by 76.59% after coloration, and restored to its original value after bleaching. In order to evaluate the practicability of applying on photomemory, a reversible experiment was designed and successfully executed. It is believed that the KBT: Er/In bifunctional ceramic can be a great candidate for low-temperature sensing and optical information storage devices. [ABSTRACT FROM AUTHOR]

The thermal quenching of phosphors seems to be inevitable, which severely limits their applications related to high temperature. Therefore, the development of thermally stable phosphors and the exploration of anti-thermal quenching mechanism is still a pivotal need. Herein, an internal self-regulation anti-thermal quenching strategy has been proposed to develop Pr3+-activated GdNbO4 red phosphor, whose loss of red emission intensity can be compensated at the expense of blue emission during the heating process. The integrated photoluminescence intensity of GdNbO4:x%Pr3+ (x = 0.1–2.5) is maintained or even continuously enhanced from 300 K to 620 K based on the metal-to-metal charge transfer between Pr3+ ions and Nb5+ ions. For the GdNbO4:0.1%Pr3+ sample, the integrated intensity of its red emission remarkably reaches 290% at 540 K compared to that at 300 K. As expected, the opposite temperature response of Pr3+ 3P0 → 3H4 and 1D2 → 3H4 indicates that GdNbO4:0.1%Pr3+ has advantage in optical thermometry based on MMCT (Sr = 0.7% K−1 at 430 K and Sa = 18% K−1 at 620 K). Our work could open a new gateway to design phosphors with anti-thermal quenching performance for high-temperature applications and develop high-performance optical temperature sensing in Pr3+-activated oxide phosphors. [ABSTRACT FROM AUTHOR]

Owing to the impact of robust thermal quenching, lanthanide-based luminescence thermometer operation can usually only be achieved within a comparatively small temperature scope (ambient temperature to 800 K). Here, this study presents a method for addressing the mentioned limits, and a luminescence thermometer with an ultra-wide temperature range has been achieved, which adopted Pr3+-doped Ba(Zr0.16Mg0.28Ta0.56)O3 transparent ceramic to be the optical temperature probe. Based on the high luminescence intensity and excellent thermal stability of the 3P0–3F2 hypersensitive transition of Pr3+ in Ba(Zr0.16Mg0.28Ta0.56)O3 transparent ceramic, the intensity ratio of the emissions at 624 nm and 649 nm was employed for temperature sensing in an ultra-wide range (293–873 K), and the maximal relative sensitivity reached 1.05% K−1, outperforming most existing luminescence temperature measurement transparent ceramics. Furthermore, in Pr3+-doped Ba(Zr0.16Mg0.28Ta0.56)O3 transparent ceramic, the lifetime of the 3P0–3H4 transition also exhibits prominent optical thermometry performance (303–873 K). The results presented in this work may be of high significance for the design of novel ratiometric/lifetime dual-mode optical temperature sensors in the high-temperature measurement field. [ABSTRACT FROM AUTHOR]

In this study, various Na0.5Bi0.5TiO3:0.5 at% Ho3+ (NBT:Ho) ceramics with different Yb3+ ion doping concentrations were synthesized by a conventional solid-state reaction method. Under the irradiation of a 980 nm laser, the NBT:Ho sample exhibited four distinguished emission bands centered at 525, 548, 656, and 753 nm. By co-doping Yb3+ ions into NBT as the sensitizers, the up-conversion luminescence of Ho3+ ions was greatly enhanced. The mechanism for up-conversion luminescence was determined to be a two-photon absorption process. The DFT simulations revealed that the Ho3+ 4f orbitals pass through the Fermi level and thus f–f transitions could be highly sensitive to temperature variation. Green emissions at 525 and 548 nm were ascribed to the two thermally coupled excited states 5F4 and 5S2 transferring to the ground state 5I8, respectively. The temperature-dependent population between 5F4 and 5S2 could be interpreted by Boltzmann's distribution in the range of 167–377 K. The relative sensitivities were calculated to be 6.14% K−1 at 167 K and 1.03% K−1 at 377 K, and the corresponding absolute sensitivities were estimated to be 0.09 × 10−3 K−1 and 2.11 × 10−3 K−1, respectively. The temperature resolution was calculated to be about 0.053 K at 167 K and 0.319 K at 377 K. The excellent repeatability of the NBT:Ho3+ ceramics was demonstrated by means of successive heating–cooling cycles in the range of 167–377 K. The above investigation results demonstrate the promising application of NBT:Ho in cryogenic optical thermometers. [ABSTRACT FROM AUTHOR]

Disk transparent ceramics with multilayer composite structure serves well as laser gain medium because of its excellent thermal and optical properties. For such a type of material, the preparation of corresponding outstanding slurry is the first yet most essential step, and it may determine the quality of both subsequent green tape and the sintered ceramics. In this work, the tape‐casting slurry with typically pseudoplastic behavior was carefully modulated in the mixture solvent of anhydrous ethanol and ethyl acetate, and its rheological property was systematically investigated using fine‐controlled rotary rheometer. The obtained result reveals 4wt.% fish oil to be the best dispersed agent. With the obtained slurry for tape‐casting followed by lamination and warm isostatic‐pressing, the multilayer ultrathin TCs was successfully fabricated via high‐temperature vacuum sintering technology. The obtained full‐dense microstructure with high optical quality may endow the studied ceramic with great potential for highly efficient solid‐state laser gain medium. [ABSTRACT FROM AUTHOR]

The optical gain and radiative current density of GaInNAs/GaAs/AlGaAs separate confinement heterostructure quantum well (QW) lasers with an emission wavelength of 1.3 μm have been theoretically investigated. The effect of carrier leakage from the GaInNAs QW to the GaAs waveguide layer is studied, and its influence on the optical gain and radiative current density is identified. The hole filling caused by an injected carrier has a strong impact on the optical gain and radiative current density, while the effect of electron filling is negligible, reflecting the smaller band-gap discontinuity in the valence band than in the conduction band. Hole occupation in the waveguide layer decreases the optical gain, and increases the radiative and threshold current densities of the laser. Our calculated threshold current density (659.6 A/cm2) at T=300 K is in good agreement with the experimental value (650.9 A/cm2) reported in literature [R. Fehse et al., IEEE J. Sel. Top. Quantum Electron. 8, 801 (2002)]. [ABSTRACT FROM AUTHOR]