Search

The luminous efficiency of the phosphors usually decreases as the operating temperature increases. Thermal stability is a crucial parameter for phosphors. The Ce3+/Dy3+ co-doped KCaLa(PO4)2 phosphors exhibited excellent thermal stability attributing to abnormal thermal quenching behavior. The energy exchange between trap charges and the level of Dy3+ ions may lead to this behavior. The structure of the phosphors was analyzed and studied. Under the excitation at 324 nm, the luminescence properties and energy transfer behavior were investigated in detail for Ce3+/Dy3+ co-doped KCaLa(PO4)2 phosphors. The energy transfer efficiency from Ce3+ to Dy3+ reached to 85.5% with dipole–quadrupole mode. The color coordinate points of the phosphor gradually move closer to (0.333, 0.333) as the operating temperature increased. Under the excitation at 324 nm, the internal quantum efficiency of the KCaLa0.88(PO4)2: 0.10Ce3+, 0.02Dy3+ phosphor was found to be 41.7%. Excellent thermal stability and high quantum efficiency would make the Ce3+/Dy3+ co-activated KCaLa(PO4)2 phosphor a promising application for white LEDs.

An up-conversion luminescence (UCL) transparent ferroelectric oxide (KNN) introduced by rare-earth ions (Er3+ and Bi3+) has been demonstrated to exhibit a unique, high-purity, red emitting, high tr...

A facile, green and economical preparation technique is critical for the cost-effective scale-up manufacture and optoelectronic device engineering of halide perovskites. Herein, we developed a viable solvent-free mechanochemical synthetic route to systematically prepare organic–inorganic hybrid perovskites. In this work, an enormous halide library comprising 16 zero-dimensional hybrid manganese halides with the formula of AnMnX4 (A = organic cations, X = Cl, Br, n =1, 2) was synthesized through an economically and environmentally friendly mechanical grinding solid-state reaction within a quite fast time of 40 s and 100% yield. Even without any crystallization process, these AnMnX4 display strong green light emissions with the highest photoluminescence quantum yield (PLQY) of 79.5%, which reaches up to the top rank of green-light-emitting halide perovskites. Moreover, the enormous structural library facilitates us to build up a direct correlation between intermolecular Mn⋯Mn distances and PLQY, which provides a feasibility of fine-tuning luminescence performance by reasonably managing organic species to tailor the Mn⋯Mn distance. This work not only paves a green assembly way of hybrid perovskite materials but also provides a generalized method to rationally optimize the luminescence performances of hybrid manganese halides, which is potentially extended to all emissive hybrid metal halides.

Recently, low-dimensional organic–inorganic hybrid metal halides have attracted considerable attention in solid-state optical application fields, especially in white-light emitting diodes (WLEDs) owing to intrinsic broadband luminescence performances. Herein, by selecting different types of organic cations as a structural decoration strategy, we designed a series of new 1D hybrid halides of A2Pb3Br10 (A = NPM, DMPDA, TMEN) based on same [Pb3Br10]4− chains composed of edge-shared [Pb3Br12]6− trimers. The low-dimensional crystal lattice results in the formation of self-trapped excitons, which leads to broadband light emissions covering the entire visible region for all A2Pb3Br10 homologues. Specifically, compound 1 exhibits yellowish-white light emission (0.34, 0.45) with a photoluminescence quantum efficiency of 2.51%. Both compounds 2 and 3 show bluish-white light emissions centered at 438 nm and 440 nm, respectively, with high color rendering index (CRI) of 96, which belongs to one of the highest values to date. The intrinsic broadband white light emissions enable them as promising candidates for single-component white-light emitting materials.

It remains significant to explore new types of hybrid lead halides to realize the diversifications of structural and luminescence properties due to the excellent optoelectronic performances of perovskites. Herein, by choosing various organic molecules as cationic templates, we constructed a series of new one-dimensional (1D) lead halide perovskites, namely, [DMEDA]Pb2Br6·H2O (1), [ATMPD]Pb2Br6·H2O (2) and [TMPrDA]2Pb3X10 (3: X = Br; 4: X = Cl). The crystal structures of compounds 1–4 contain 1D [Pb2Br6]2− and [Pb3X10]4− chains based on [Pb4X16] tetramer clusters as basic building units, respectively. Remarkably, compound 2 displays broadband yellow light emissions spanning the entire visible spectral range and centered at 534 nm, which can be ascribed to self-trapped excitons based on systematic characterization including time-resolved PL emission and theoretical studies. This work provides a series of new low-dimensional hybrid lead halides as prototypes to enrich the halide chemistry including crystal engineering and optoelectronic performance.

A novel photochromic (PC) ferroelectric material, Nd3+-doped K0.5Na0.5NbO3 translucent ceramic, was fabricated by a conventional solid method. The ceramic shows moderate optical transparency due to its dense microstructure, as well as good photoluminescence (PL) properties of up-conversion (UC) emission in the visible region and down-shifting (DS) emission in the near-infrared region. Simultaneously, the colors of all the ceramics turn darker after 365 nm illumination, and then recover to their initial states upon thermal stimulus (210 °C, 10 min), exhibiting a typical PC phenomenon. In particular, the effect of the PC behavior on PL lifetimes of Nd3+ was investigated. Multi-mode reversible modulations of various optical behaviors were realized based on the PC behavior, especially for the regulation of near-infrared emission. And the maximum modulation ratios of transmittances, UC or DS PL intensities and luminescence lifetimes are 43.0%, 66.7%, 66.4% and 12.8%, respectively. Owing to high-temperature sintering and Nd3+ substitution in the ceramics, cation and oxygen vacancies appear to produce F′ and V1 color centers, which are in charge of the PC behavior and corresponding modulations. These results suggest that the ceramics are a promising PC material in visible and near-infrared optical data storage, photo-switches, and optoelectronic devices. Meanwhile, they also provide insights into the applications of rare-earth Nd3+ in other inorganic PC ferroelectric materials.

Transparent Er3+/La3+ co-doped (K0.5Na0.5)NbO3 ceramic was prepared by pressureless sintering. The XRD result shows that it possesses high symmetrical pseudo-cubic perovskite structure without impurity phase. The ceramic owns fine grains with the average size of ∼350 nm, uniform grain distribution, low porosity and high density. The optical transmittance of 0.3-mm ceramic is up to ∼60% in the visible region. Additionally, the ceramic has good dielectric properties with the relaxor-like behavior. Under an excitation of 980-nm, the temperature-dependent up-conversion luminescent color of Er3+ is stable below 523 K and adjustable (changing from green to tangerine color as temperature increases) above 523 K. The ratio of red to green emission intensity with temperature can provide a non-contact luminescent route to roughly detect the phase transition of this ferroelectric ceramic. Furthermore, the fluorescence temperature sensing performance of the ceramic was investigated and the maximum sensitivity is 0.003/K at 380 K. Due to optical, PL and electrical properties, the transparent ceramic shows potential in the application of electro-optical coupling devices.

By simply doping with a certain amount of Sm3+, opaque lead-free (K0.5Na0.5)NbO3 piezoelectric ceramics were fabricated into transparent/translucent ceramics. The photochromic (PC) behavior and associated reversible transmittance/luminescence modulation were realized via physical means. Upon illumination under a xenon lamp, the maximal decreased values of optical transmittance and luminescence intensity are 36.1% and 49%, respectively. Meanwhile, the colors of all the ceramics turn darker after illumination, and subsequently return to their initial states by thermal stimulus (200 °C for 5 minutes), exhibiting a typical PC phenomenon. Combining experimental and calculation results, it can be found that the PC mechanism is closely related to the vacancy defects induced by both high-temperature sintering and Sm3+-doping. Additionally, the Sm3+ effects on phase structures, microstructures, optical transmittance and photoluminescence properties of the ceramics were systematically studied. The substitution behavior of Sm3+ and vacancy defect concentrations on the energy band gap of the material were unraveled by the first principles calculations to further clarify the corresponding mechanism. The Sm3+-doped (K0.5Na0.5)NbO3 transparent ceramics have potential for application in modulation and conversion of photoenergy, such as in optical memory and photo-switching devices. And the reversible tuning of transmittance in our material is especially attractive for exploring novel transparent PC materials.

To study the effects of carboxylates on the assembly and structures of Ni(II) coordination polymers (CPs) based on a phenyl/methylene-mixed-bridged bis-pyridyl-bis-amide [N,N′-bis(4-methylenepyridin-4-yl)-1,4-benzenedicarboxamide] (L) ligand, ten 1D → 3D Ni(II) CPs, namely [Ni(L)(2-NB)2(H2O)2] (1), [Ni(L)(4-NB)2(H2O)2] (2), [Ni(L)2(2-MOB)2] (3), [Ni(L)2(3-CB)2] (4), [Ni(L)(2-CP)(H2O)] (5), [Ni(L)(5-NIP)(H2O)2]·2H2O (6), [Ni(L)(3-NP)(H2O)2] (7), [Ni(L)(4,4′-OBA)]·H2O (8), [Ni(L)(1,4-BDC)(H2O)2]·2H2O (9) and [Ni(L)(1,4-CHDA)(H2O)2]·4H2O (10) [2-nitrobenzoic acid (2-HNB), 4-nitrobenzoic acid (4-HNB), 2-methoxybenzoic acid (2-HMOB), 3-chlorobenzoic acid (3-HCB), 2-carboxyphenylacetic acid (2-H2CP), 5-nitroisophthalic acid (5-H2NIP), 3-nitrophthalic acid (3-H2NP), 4,4′-oxybis(benzoic acid) (4,4′-H2OBA), 1,4-benzenedicarboxylic acid (1,4-H2BDC) and trans-1,4-cyclohexanedicarboxylic acid (1,4-H2CHDA)], have been hydrothermally synthesized with various carboxylates and structurally characterized by IR, PXRD and X-ray single-crystal diffraction. 1 and 2 are similar 1D coordination polymers. 3 and 4 feature similar 2D coplanar 4,4-connected networks extended by single L linkers. 5 displays a 2D wave-like 4,4-connected network based on L and 2-CP mixed linkers. 6 shows a 2D 4,4-connected structure derived from L and 5-NIP mixed spacers. 7 is a CdSO4 type 4-connected 3D framework. 8 displays a 2D → 3D parallel polycatenation array based on 2D (4,4)-connected wave-like coordinated layers. 9 and 10 feature similar 2D → 3D inclined polycatenation arrays based on 2D (4,4)-connected coplanar networks. The effects of the carboxylates on the structures of the title complexes are discussed in detail. The solid-state luminescent and fluorescent sensing properties of 1–10 for Fe3+ ions were investigated. Moreover, the effects of 1, 5 and 7 on the fluorescence properties of bovine serum albumin (BSA) and the electrocatalytic activities of carbon paste electrodes (CPEs) bulk-modified with 1, 3, 5, 7 and 9 for the reduction of hydrogen peroxide, bromate and nitrite were studied.

Recently, organic–inorganic hybrid lead halides have been explored as photoluminescent (PL) materials with flexible structural tunabilities and high photoluminescence quantum efficiencies, which can be modified by the structure regulating functions of organic cations. Here, by adopting different saturated organic cations as structure directing agents (SDAs), a series of organic–inorganic hybrid lead halides have been solvothermally synthesized and characterized with different structural types. Compound [(CH3)2NH2]2[H2DABCO]2Pb3I12 (1, DABCO = 1,4-diazabicyclo[2.2.2]-octane) features a linear zero-dimensional (0D) [Pb3I12]6− trimer, and [(Me)6-en]2Pb3I10 (2) and [H2N-Prpipz]2Pb3Br10 (3) contain two different types of one-dimensional (1D) [Pb3X10]4− chains based on the C3-symterric [Pb3X11] trimer and [PbX6] unit, respectively. In the structures of H[(Me)2-DABCO]Pb3I9 (4) and H[(Me)4-pipz]Pb3I9 (5, pipz = piperazine), the C3-symmetric [Pb3I11] trimers are interlinked to form the same two-dimensional (2D) corrugated [Pb3I9]3− layers. Under the excitation of UV irradiation, these hybrid lead halides exhibit tunable luminescence properties from yellow, orange to red emissions with the largest Stokes shift of 335 nm. The PL nature is also investigated based on temperature-dependent PL emission, time-resolved PL and theoretical calculations, etc. These hybrid lead halides provide new types of structural models to probe into the PL properties and understand the underlying structure–property relationship.

In recent years, low-dimensional lead halides have emerged as some of most attractive photoelectric materials due to their intrinsic broadband emissions with a potential application in white-light emitting diodes. To achieve the desired performance, tremendous research has emphasized the modulation of inorganic components as optical centers; however, less work has paid attention to the direct contribution of the organic components. Herein, we successfully assembled two new hybrid lead halides of [H2BPP]Pb2X6 (X = Br, 1, and Cl, 2) containing one-dimensional double [Pb2X6]2- chains using optically active 1,3-bis(4-pyridyl)-propane (BPP) as an organic cation. Under UV-light excitation, compounds 1 and 2 exhibit broadband yellowish-green emissions, which were verified by promising photoluminescence quantum efficiencies (PLQEs) of 8.10% and 4.84%, respectively. The broadband light emissions are derived from the combination of dual higher-energy blue and lower-energy yellow light spectra, which can be attributed to the individual contributions of the organic and inorganic components, respectively, according to the time-resolved and temperature-dependent emission spectra as well as theoretical calculations. This work proves the great contribution of organic components to the photophysical properties and provides a new design strategy to realize broadband light emission by rationally combining the dual-emitting properties of different assembly blocks.

Herein, by using a structural design strategy of incorporating hetrometallic halide blocks, we prepared the first 3D bimetallic halide of [H2DABCO]2Cu6PbBr12 with new topological network based on two types of 6-connected nodes. Remarkably, this 3D framework displays highly efficient thermochromic luminescence from broadband yellow to green light emissions with remarkable stability.

Recently, 2D organic-inorganic hybrid lead halide perovskites have attracted intensive attention in solid-state luminescence fields such as single-component white-light emitters, and rational optimization of the photoluminescence (PL) performance through accurate structural-design strategies is still significant. Herein, by carefully choosing homologous aliphatic amines as templates, isotypical perovskites [DMEDA]PbCl4 (1, DMEDA=N,N-dimethylethylenediamine) and [DMPDA]PbCl4 (2, DMPDA=N,N-dimethyl-1,3-diaminopropane) having tunable and stable broadband bluish white emission properties were rationally designed. The subtle regulation of organic cations leads to a higher degree of distortion of the 2D [PbCl4 ]2- layers and enhanced photoluminescence quantum efficiencies (

The BaZrx Si3 O7+2x :Eu2+ /Eu3+ (2%, molar ratio) phosphors were prepared with adding different amounts of zirconium dioxide (ZrO2 ) (x = 0, 0.2, 0.4, 0.6, 0.8, and 1) by a self-reduction method under air conditions. X-ray diffraction, photoluminescence properties, thermal quenching properties and luminescent lifetimes of the prepared samples were systematically analyzed. In BaZrx Si3 O7+2x :Eu2+ /Eu3+ , both the 4f → 5d transitions of Eu2+ and sharp emissions assigned to 5 D0 → 7 FJ (J = 0, 1, 2, 3, 4) transitions of Eu3+ were observed. In addition, the results also reveal that the amount of ZrO2 affects the crystal structure, the self-reduction process and further influences the relative intensity of Eu2+ /Eu3+ in all samples. Therefore, the diverse emission colors can be obtained and modulated by controlling the content of ZrO2 . The highlight of this work is that the white light emission is observed, when x is 0.4, 0.6, 0.8 and 1, respectively.

At present, due to the advantages of non-contact, fast response, high precision, etc., the realization of temperature sensing technology based on the fluorescence intensity ratio has become the focus of the research field of temperature measurement. Here, we successfully prepared Bi3+ and Eu3+co-doped luminescence material and studied its temperature sensing performance. The absolute sensitivity and relative sensitivity of the LaB3O6: Bi3+, Eu3+ sample reached 0.008 K−1 and 0.579% K−1 at 423 K, respectively. This work adds new candidate to the family of Bi3+ and Eu3+ co-doped temperature sensing materials.

The SrAl2O4:Eu2+, Dy3+ nanowire was successfully synthesized by means of catalyst-assisted thermal chemical vapor deposition method. Their morphology, structure, composition, luminescent properties are explored in way of SEM, TEM, XRD and PL analysis. The nanowires diameter is uniform distributed in 50∼80 nm, but orientation distribution is irregular, with the length varying from 4 μm to 20 μm. When heated up to the temperature of 1200 °C for three hours, the optimum synthesis is achieved with the alumina substrate covered by Al nanoparticles. The emission peak reaches to 517 nm with 365 nm light excitation and the luminous intensity was down to 1/10 of the initial brightness in 20 mins. The dielectric property was investigated at the room temperature, which show stronger dielectric loss ability.

A new metal-organic quadrangular macrocycle Co(III) complex was achieved via self-assembly by comprising anthracene moieties as fluorophores, while the tridentate N2O units containing amide groups as guest binding sites and communicators, for specific responses to adenosine-5′-triphosphate disodium over the other disodium 5′-ribonucleotides and inorganic phosphate anions. The M4L4 structure of macrocycle Co(III) complex was further confirmed by the crystal analysis of comparison.

The lead-free 0.985(K0.5Na0.5)NbO3-0.015ErBiO3 (KNN-EB-0.015) ceramic was fabricated by pressureless sintering. It possessed a pure perovskite phase with pseudo-cubic symmetry. Due to the fine-grains, small-sized pores, dense microstructure and relaxor-like characteristics, the ceramic was optically clear, exhibiting the highest transmittances of ∼40% and ∼71% in the visible and infrared regions, respectively. The photoluminescence (PL) properties of the ceramic were studied, including the up-conversion (UC) green and red emissions, down-conversion near infrared emission as well as the emission lifetimes. The color-tunable (from green to yellow) UC emissions were observed by increasing the temperature, based on the temperature-dependent emission spectra, which also exhibited good thermal stability (52.6% of the initial intensity at 453 K) of the ceramic. Additionally, the temperature sensing properties were investigated using the fluorescence intensity ratio technique. A maximum sensitivity of ∼0.0048 K at 603 K was obtained. Combined with the good optical and electrical properties, the KNN-EB-0.015 transparent ceramic could be a promising candidate for multifunctional optoelectronic applications.

2.5 mol% Ni2+-modified Bi0.5Na0.5TiO3 (BNT–Ni-0.025) ceramic has been fabricated based on the sol–gel method. The BNT–Ni-0.025 ceramic possesses a rhombohedral perovskite structure with denser microstructure than that of pure BNT ceramic. The introduction of certain amount of Ni2+ (e.g. 2.5 mol%) in BNT can reduce the sintering temperature (50 °C lower), effectively suppress the grain growth, greatly decrease the dielectric loss and then produce multifunctionality. The BNT–Ni-0.025 ceramic also exhibits good ferroelectric properties with a large remanent polarization of ~26 μC/cm2. The observed weak ferromagnetism of the ceramic can be ascribed to the exchange interaction between free carriers (oxygen vacancy induced delocalized electrons) and the localized Ni2+ ions. Under the excitation of 370 nm, the BNT–Ni-0.025 ceramic shows broadband NIR luminescence centered at ~1480 nm from Ni2+ with long emission lifetime (28 µs), which can cover the optical communication window and be applied in broadband optical amplifiers. The multifunctional BNT–Ni-0.025 ceramic shows potentials in the application of optical–electrical–magnetic areas.

Cr3+-Yb3+ codoped bulk glass-ceramics containing KZnF3 nanocrystals are fabricated by thermal treatment of cast glass samples and characterized by X-ray diffraction and transmission electron microscopy. The luminescent properties of the glass and glass ceramic are investigated from the measured photoluminescence spectra and fluorescent lifetime. The measurement results demonstrate that Cr3+ and Yb3+ ions are both predominantly hosted in the KZnF3 nanocrystals, and the energy absorbed by Cr3+ ions is efficiently transferred to Yb3+ ions when excited at 450 nm. Compared to the glass, the near-infrared emission in the Cr3+-Yb3+ codoped glass ceramics is significantly enhanced when the excitation wavelength lies in the range λ~400–800 nm of a solar simulator. Results indicate that the Cr3+-Yb3+ codoped KZnF3 glass ceramic provides a promising material for spectral conversion from visible sunlight to near-infrared emission and a novel gain material for solar pumped fiber laser.

With a [TM(phen)3]2+ (TM = transition metal, phen = 1,10-phenanthroline) complex and N-alkylated [(Me)2-2,2′-bipy]2+ (Me = methyl, 2,2′-bipy = 2,2′-bipyridine) as cations, a series of hybrid iodoargentates, namely [TM(phen)3]2Ag3I7 (TM = Mn (1), Fe (2)), [Mn(phen)3]Ag5I7 (3) and [(Me)2-2,2′-bipy]2Ag7I11 (4), have been solvothermally prepared and structurally characterized. Compounds 1 and 2 feature isolated windmill-shaped [Ag3I7]4− trimers based on [AgI3] triangles, whereas compound 3 contains two-dimensional (2D) microporous [Ag5I7]2− layers composed of [Ag3I7] and [Ag7I13] secondary building units (SBUs) based on [AgI4] tetrahedra. In compound 4, a 2D [Ag7I11]4− slab is formed by alternating interconnection of two different types of [Ag7I12] double chains via corner-sharing with one-dimensional (1D) large channels occupied by [(Me)2-2,2′-bipy]2+ cations. UV-vis diffuse-reflectance measurements reveal that the title compounds possess semiconducting behaviors with smaller band gaps of 1.85, 1.78, 1.89 and 2.03 eV, respectively. Sample 4 shows highly efficient photocatalytic degradation activity over organic pollutants than N-doped TiO2 (P25) under visible light irradiation. Moreover, a possible mechanism for the stable photocatalytic activity is proposed based on band structure calculation. Finally, the luminescence properties and thermal stabilities of the title compounds are also studied.

Er 3+ /Yb 3+ -codoped K 0.5 Na 0.5 NbO 3 (KNN) ceramics have been fabricated by the solid state reaction method. Under the excitation of 980 nm, Er 3+ ions exhibit visible up-conversion emissions as well as the near-infrared (NIR) and middle-infrared (MIR) emissions. Yb 3+ ions are used as the sensitizer to codope with Er 3+ in the KNN host in the purpose of improving the emission efficiency and PL intensities, i.e. significantly enhancing the blue, green, red and MIR emissions of Er 3+ . The concentration quenching effect has been discussed together with the up-conversion emissions and corresponding luminescent lifetimes. The energy transfer processes between Er 3+ and Yb 3+ have been investigated with the relationship between the Yb 3+ concentration and PL intensities. Due to the moderate ferroelectric and piezoelectric properties of the host, the ceramics show multifunctional performance and potential in the application of optoelectronic areas.

Ultraviolet light is a necessary light source for humans. As typical ultraviolet emission materials, Pb2+ doped phosphors have been widely investigated. Here, we report a Pb2+ activated silicate material. Under the excitation of 258 nm ultraviolet light, Sr2MgSi2O7:Pb2+ can emit broadband ultraviolet light with a peak at 333 nm. The luminescence intensity can be adjusted by changing the Pb2+ doping concentration, and the experiments show that the optimum concentration is 0.02. The critical distance for the corresponding concentration quenching was calculated to be 19.92 A. By gradually decreasing the Sr/Ba ratio, the luminescence wavelength is gradually shifted from 333 to 383 nm due to the increase of Pb2+-O2−covalency. The continuous replacement of Sr by Ba atoms does not change the crystal structure, and the emission wavelength adjustable range is 50 nm. Our research adds new members to the Pb2+-activated phosphor family. At the same time, the successful use of atomic substitution method provides a reference for the adjustment of the emission wavelength of Pb2+ doped materials.

The lead-free multifunctional ceramics Sm3+-doped (Ba0.85Ca0.15)(Ti0.9Zr0.1)O3 were synthesized via conventional sintering. The influences of Sm3+ concentration on phase structure, grain size, Curie temperature, ferro-/piezoelectric properties, as well as photoluminescence (PL) performances of the ceramics have been investigated. The results show that with the Sm3+ concentration of 0.4[Formula: see text]mol%, the integrated optoelectronic performances are best. In order to further study the relationship between ferroelectric and PL features, the poling effect on PL intensities of the ceramics has been focused on, giving the highest enhancement factors of 52.6% induced by both lattice distortion and phase transformation. The electric poling is an effective route to enhance the PL performance of luminescent ferroelectrics.

The BaZr

Five isostructural polymeric iodoargentates incorporating similar transition metal complex cations as structure-directing agents, – namely, [TM(2,2-bipy)3]Ag3I5 [TM = Mn (1), Fe (2), Co (3), Ni (4), Zn (5)] – have been solvothermally synthesized and structurally characterized. The title compounds contain saturated [TM(2,2-bipy)3]2+ cations and one-dimensional (1D) [Ag3I5]2– anionic chains formed by trans-interconnection of [Ag3I5] semicubes through Ag–I bonds. The optical absorption spectra indicate that compounds 1–5 are semiconductors with estimated band gaps of 2.28, 1.87, 1.95, 2.01, and 2.61 eV, respectively, which are mainly ascribed, on the basis of density functional theory (DFT) calculations, to charge transitions between the [Ag3I5]2– anionic chains and organic cationic units. We evaluated the photocatalytic efficiencies of compounds 1, 2, 4, and 5 with regard to the decomposition of crystal violet (CV) under visible irradiation, and the four compounds showed excellent photodegradation abilities in comparison with N-doped P25, with an order of 1 > 2 > 4 > 5 > P25. The luminescent properties and thermal stabilities of the title compounds were also studied.

0.93(Bi 0.5− x /0.93 Er x /0.93 Na 0.5 )TiO 3 –0.07BaTiO 3 photoluminescent ceramics have been prepared by a conventional ceramic fabrication technique and their photoluminescence, ferroelectric, dielectric and piezoelectric properties have been studied. Under an excitation of 980 nm, the ceramics exhibit visible up-conversion luminescent emissions at 532 nm (green), 540 nm (green) and 600 nm (red), as well as broadband down-conversion luminescent emissions in near-infrared (1.44–1.66 μm) and mid-infrared (2.62–2.84 μm) regions. The quenching concentration for the ceramics is high, about 6%, and both the visible and invisible emissions are very strong. Among the emissions, the photoluminescence intensity of the red emission band increases most significantly by more than 47 times as the Er-concentration increases from 0.005 to 0.07. As a result, the Commission Internationale de L’Eclairage chromaticity coordinates shift from (0.29, 0.69) to (0.49, 0.50), and the emission color changes from green to yellowish green. Owing to the establishment of a dynamic circulatory energy process at high Er-concentrations, the photoluminescence intensity of the mid-infrared emission increases significantly by more than 4 times at the expense of the near-infrared emission. Together with the good ferroelectric and piezoelectric properties, the ceramics should be promising candidates for multifunctional optoelectronic applications.

Three new organic–inorganic hybrid manganese thiogermanates and thiostannates, namely, [Mn(en)2]MnGeS4 (1, en = ethylenediamine), [Mn(dien)2]MnSnS4 (2, dien = diethylenetriamine) and [Mn(1,2-dap)]2Sn2S6 (3, 1,2-dap = 1,2-diaminopropane), have been solvothermally synthesized and structurally characterized. Compound 1 has a three-dimensional (3D) neutral framework composed of one-dimensional (1D) [MnGeS4]2− chains and unsaturated [Mn(en)2]2+ cations interconnected via Mn–S bonds, whereas compounds 2–3 feature 1D [MnSnS4]2− anionic chains and 1D neutral [Mn(1,2-dap)]2Sn2S6 chains, respectively. Investigation into the magnetic properties of the title compounds reveals antiferromagnetic and ferromagnetic coupling interactions between the Mn(II) ions for compounds 1 and 3, respectively. The optical and luminescence properties, as well as the thermal stabilities, were also studied.

Photochromic (PC) luminescent ferroelectric materials have aroused great interest because of their potential applications in optical information memories, optical switches and bio-imaging. However, those materials are basically opaque. In this work, we prepared a PC luminescent [Formula: see text][Formula: see text]NbO3-based ferroelectric transparent ceramic by modifying with [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text], which not only have good optical transmittances ([Formula: see text]60% at 900[Formula: see text]nm), moderate ferroelectric properties and down-conversion photoluminescence (PL) properties, but also exhibit reversible PC behavior. After the illumination by xenon lamp, the colors of the ceramics change from pale green to gray, and then reversibly recover to their initial state via thermal stimulus (200∘C for 10[Formula: see text]min). Interestingly, both the optical transmittances and PL intensities can be effectively tailored by controlling the PC reaction process. The results suggest that the ferroelectric transparent ceramics are promising for the modulation of photoenergy and the design of optoelectronic devices.

Er-doped K 0.5 Na 0.5 NbO 3 luminescent ceramics have been prepared using a sol–gel method. The results of X-ray diffraction show that Er 3+ diffuses into the K 0.5 Na 0.5 NbO 3 lattices, forming an orthorhombic-structured perovskite. Under an excitation of 980 nm, the ceramics exhibit luminescent emission bands at 527 nm (green), 548 nm (green), 660 nm (red) as well as 487 nm (blue), which are attributed to the transitions 2 H 11/2 → 4 I 15/2 , 4 S 3/2 → 4 I 15/2 , 4 F 9/2 → 4 I 15/2 and 4 F 7/2 → 4 I 15/2 , respectively. Our Raman results also reveal that the ceramics have low phonon energy (∼860 cm −1 ) and thus slow multi-phonon relaxation rate. The sol–gel process and Er 3+ -doping can produce ceramics with better compositional homogeneity as well as finer and uniform grains. All these are beneficial for improving both the upconversion and luminescent efficiencies of the ceramics, and thus leading to very strong green emissions even at a low quenching concentration of 2 mol%. These suggest that even without using sensitizers, the sol–gel-derived Er-doped KNN ceramics are promising candidates for multifunctional optoelectronic applications.

One new AgI complex, [Ag2(aip)(NH3)]n (H2aip = 5-aminoisophthalic acid), has been prepared and structurally and spectroscopically characterized. The title complex crystallizes in the monoclinic system P21/c (no. 14) with a = 6.975(2) A, b = 8.756(3) A, c = 16.086(6) A, β = 97.318(4)°, V = 974.4(6) A3 and Z = 4. Its structure features a three-dimensional (3D) network composed of two-dimensional (2D) flexuous layer interconnected via weak hydrogen bonds. In aqueous solution, the H2aip exhibits blue emission, while the title complex with tetranuclear silver(I) cores and weak Ag…Ag bonds shows visible intense purple luminescence.

Eu-based vanadate Ca9Eu(VO4)7 phosphor was synthesized by the solid state reaction method and was characterized by X-ray powder diffraction (XRD). The photoluminescence excitation and emission spectra, fluorescence decay curves and the dependence of luminescence intensity on temperature were investigated. The phosphor can be efficiently excited by near UV light to realize an intense red luminescence (614 nm) corresponding to the electric dipole transition 5 D0 ! 7 F2 of Eu 3+ ions. The crystallographic site-occupations of the Eu 3+ ions in Ca9Eu(VO4)7 were investigated by the site-selective excitation and emission spectra, and the fluorescence decay curves in the 5 D0 ! 7 F0 region using a pulsed, tunable, narrowband dye laser. The red luminescence together with the thermal stability was discussed on the base of the Eu 3+ site

Eu2+-doped LiCaPO4 was synthesized by the high-temperature solid-state reaction. The photoluminescence excitation and emission spectra were investigated. The results show that LiCaPO4:Eu2+ phosphor can be efficiently excited by the incident lights of 280–420 nm, which well match with the emissions of near-UV light-emitting diode (LEDs). The phosphor shows a bright blue luminescence. The temperature and concentration dependence of luminescence intensities were investigated. The phosphor has an excellent thermal stability on temperature quenching effects. The luminescence decay and the color coordinates were discussed in order to further investigate its potential applications for white LED phosphors pumped by near-UV chips.

A vanadate, Ca9Dy(VO4)7, was synthesized by the general high temperature solid-state reaction in air atmosphere. X-ray powder diffraction analysis confirmed the formation of single phase Ca9Dy(VO4)7. Photoluminescence excitation spectrum showed that the phosphor could be efficiently excited by UV–visible light from 250 to 500 nm. The characteristic emission peaks of Dy3+ were observed in the emission spectra due to the transitions of 4F9/2 → 6H15/2 at 483 nm and 4F9/2 → 6H13/2 at 573 nm. The photoluminescence measurements showed that the Ca9Dy(VO4)7 exhibited an improved chromaticity compared with YVO4:Dy3+. This was ascribed to lower site symmetry and disordered cation sites in Ca9Dy(VO4)7. The luminescence characteristics of Ca9Dy(VO4) indicated that this phosphor has a possible application for white-light-emitting diode. Luminescence mechanism and site occupancies of Dy3+ ions in Ca9Dy(VO4)7 lattices were discussed.

With different transition metal (TM) complexes as structure directing agents or building units, three new multinary chalcognidometalates based on T3 supertetrahedral nanocluster of [Mn2Ga4Sn4S20](8-) have been solvothermally synthesized and structurally characterized. In compound Mn2Ga4Sn4S20[Mn2(en)5]2·4H2O (, en = ethylenediamine), the neighboring [Mn2Ga4Sn4S20](8-) cores were bridged by two pairs of [Mn2(en)5](4+) complex cations via Mn-S bonds to form one-dimensional (1D) neutral chains. Compound Mn2Ga4Sn4S20[Mn(dien)2]4·2H2O (, dien = diethylenetriamine) contained discrete [Mn2Ga4Sn4S20](8-) cores separated by [Mn(dien)2](2+) cations. In compound Mn2Ga4Sn4S20[Mn(teta)]4 (, teta = triethylenetetramine), each [Mn2Ga4Sn4S20](8-) core was covalently attached by four [Mn(teta)](2+) complexes via terminal Mn-S bonds to form a neutral isolated cluster. The photocatalytic experiments indicate that compound was able to degrade rhodamine B (RhB) and crystal violet (CV) under visible irradiation. Furthermore, the luminescence properties and thermal stabilities of the title compounds, as well as the second-order nonlinear optical property of were also studied.

The fluorescence recognition of octahedral nanocages M-QT1 (M = Co, Zn) and metallotricycle Pd-QD, that are comprised of luminescence active quinoline groups and several kinds of amide groups, on ribonucleosides was investigated. The amide groups located on the opening windows or inner surface of the polyhedra and polygon, respectively, providing special environments for the size or shape-selective dynamic molecular recognition and amplified the guest-bonding events to produce a measurable output. While the participation of the active CH moiety in hydrogen bonding interactions corresponding to these amide groups caused the M-QT1 polyhedra to exhibit selectivity towards cytidine over other ribonucleosides, the possible two-fold hydrogen bonding interactions between the nucleosides and the amide groups in Pd-QD made the tricycle show a uridine-specific response. All these results demonstrated that these metal–organic architectures having amide groups and functionalized moieties are potential luminescence chemosensors for the selective sensing of special ribonucleosides, through modifying the hydrogen-bonding interactions.

New Ce-based Werner type tetrahedrons were achieved for size-selectively luminescent detection of natural carbohydrates through incorporating amide groups as both the multiple hydrogen bonding triggers and binding-signalling transductor.

0.93Bi0.5Na0.5TiO3-0.07BaTiO3 ceramics doped with 0.01 mol Er3+ have been prepared and their photoluminescence (PL), ferroelectric, dielectric, and piezoelectric properties have been studied. By doping Er3+ at various sites, ceramics containing oxygen or cation vacancies have been prepared and their effects have been investigated. Ceramic containing no vacancy (i.e., doping Er3+ at the Bi3+ site) has also been prepared as a reference for the study. In addition to the reduction of the up-conversion PL emissions at 532, 547, and 660 nm, our results also reveal that oxygen vacancies can enhance, at the expense of the visible emissions, the near-infrared (1.44–1.66 μm) and mid-infrared (2.62–2.84 μm) down-conversion emissions. Similar results have also been observed for the ceramics containing cation vacancies, and the enhancement in the near-infrared emission becomes much more significant, reaching about 70% for the ceramic doped with Er3+ at the Na+ site. These should be attributed to the looping mechanism ...

In order to improve SrAl2O4: Eu2+, Dy3+ luminescent properties, explore Eu2+ and Dy3+ in SrAl2O4, using a plane-wave ultrasoft pseudopotential method under the density functional theory framework, were established SrAl2O4, SrAl2O4: Eu2+ and SrAl2O4: Eu2+, Dy3+ supercell model, and calculated their population numbers, band structure and density of states. The results showed that: the luminescence center Eu2+ doping SrAl2O4 makes impurity level appearing in the forbidden band and the conduction band, and produce photoluminescence effect. On this basis, the auxiliary activator Dy3+ doping makes the luminous intensity higher, persistence time longer.