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Constructing acid–base pairs is one of the efficient strategies for the design of proton conductors with high conductivity, due to the ultrafast proton-hopping with a low energy barrier between a proton donor (acid group) and an acceptor (base group). In this study, an acid–base adduct polyamine–P2Mo5 model system was established, including adducts [C6N4H22][H2P2Mo5O23]·H2O (P2Mo5-TETA), [C4N3H16]2[P2Mo5O23]·H2O (P2Mo5-DETA), and [C2N2H10]2[H2P2Mo5O23] (P2Mo5-EN), (TETA = triethylenetetramine, DETA = diethylenetriamine, EN = ethanediamine). Proton conductivity analyses showed that adduct P2Mo5-EN exhibited the highest proton conductivity 1.13 × 10−2 S cm−1 at 65 °C and 95% RH, which was one and three orders of magnitude greater than those of P2Mo5-DETA and P2Mo5-TETA under the same conditions. Ea values of all three adducts are lower than 0.4 eV, which indicates that their proton transfer is attributed to the Grotthuss mechanism. Combined with visual structure analysis, the proton transport pathways of three adducts are highlighted. Moreover, we use this model system to discuss in detail the effect of pKa, proton density and size of polyamine molecules on the proton conductivity of organic amine-POM adducts. [ABSTRACT FROM AUTHOR]

A diphosphine-protected 18-gold-atom nanocluster was isolated via a facile reduction of an AuI precursor by NaBH4. Its composition was identified as {[Au18(dppm)6Cl4]·C6H6·3Cl·PF6} (SD/Au18, SD = SunDi; dppm = bis-(diphenylphosphino)methane) by X-ray single crystal structural analysis. This nanocluster possesses a prolate shape and is built from an Au10 kernel (bi-octahedral Au6 units sharing one edge) fused with two Au7 caps via sharing six gold atoms. The identity of the Au18 cluster is further demonstrated by ESI-MS. The number of valence electrons of [Au18(dppm)6Cl4]4+ is 10 (n* = 18–4–4), which does not match with the known magic numbers according to the spherical jellium model, and elongated models must be considered. The special stability of the Au18 cluster likely arises from geometrical factors in the metallic core. Two charge states are reported for this system. This work not only presents the structure elucidation of a diphosphine-protected Au18 nanocluster, but also provides an important insight into the growth pattern of gold nanoclusters and the charge states they can achieve. [ABSTRACT FROM AUTHOR]

In this work, we report on the first successful deposition of Vernier phase yttrium oxyfluoride (V-YOF) thin films on Si (100) wafers using pulsed liquid injection metal organic chemical vapor deposition (PLI-MOCVD). The formation of V-YOF has been confirmed by X-ray diffraction measurements and electron probe microanalysis. The infrared phonon modes of V-YOF thin films and their corresponding optical constants as inferred from spectroscopic ellipsometry are reported here for the first time. The V-YOF thin films are featured by a broad absorption band centering around 370–373 cm−1; their refractive index is located between those of YF3 and Y2O3, and which shows an intimate relationship with the oxygen content in the film. The luminescence properties of Er3+ doped V-YOF thin films are finally examined and compared with that of YF3. Our results highlight that the as-deposited V-YOF thin films by PLI-MOCVD serve as promising candidates as efficient host material for spectral conversion for photovoltaic applications. [ABSTRACT FROM AUTHOR]

By changing the pH values and solvents of reaction systems, four polyoxomolybdate-based compounds, [CoL(H2O)2][β-Mo8O26]0.5 (1), {[Co2L2(H2O)3][Mo7O23]}·3H2O (2), [Co2L3][δ-Mo8O26]0.5[β-Mo8O26]0.5·10H2O (3), [Co2L3][H4Mo8O28]·4DMA·2H2O (4), (L = 1,3-bis(1H-imidazole-4-carboxamido)metaphenylene, DMA = N,N‘-dimethylacetamide), have been synthesized in the presence of the Co2+ ion, L ligand and Mo7O246−. Compounds 1 and 2 were obtained under hydrothermal conditions; the different pH values result in two kinds of polyoxomolybdate anions, [β-Mo8O26]4− in 1 and [Mo14O46]8− in 2, and the similar [CoL(H2O)2]2+ or [Co2L2(H2O)3]4+ metal–organic chains. Compounds 3 and 4 were synthesized under mixed-solvent conditions. There are two kinds of octamolybdate isomers in 3, [β-Mo8O26]4− and [δ-Mo8O26]4− anions, but only one kind of [Mo8O28]8− anion in 4, but the two compounds have a similar metal–organic cage [Co2L3]4+. The results reveal that the pH values and different solvents play key roles in tuning the diverse architectures of polyoxomolybdate anions and metal–organic motifs. The adsorption activities for organic dyes, crystal violet (CV), methylene blue (MB) and Congo red (CR), and the electrocatalytic properties of hydrogen peroxide (H2O2) and ascorbic acid (AA) of compounds 1–4 are reported here. [ABSTRACT FROM AUTHOR]

Various yellowish-green persistent phosphors of Y2.95−x−yLuxGdyAl5−zGazO12:0.05Ce3+ (x = 0–1, y = 0–1, z = 1–4) were successfully synthesized by the one-step high-temperature solid-state reaction method in air. The effects of simultaneous doping of Lu3+, Gd3+ and Ga3+ on the luminescence properties of the phosphors were investigated in detail for the first time. Herein, the microstructure, morphology, afterglow performance, luminescence properties, thermoluminescence, thermal quenching and flicker index of the efficient blue-light-activated Y2.95−x−yLuxGdyAl5−zGazO12:0.05Ce3+ phosphors were tested. The τ90 and τ80 values of Y1.45LuGd0.5Al2.5Ga2.5O12:0.05Ce3+ are 10.8 ms and 33.2 ms, respectively. These parameters are important in terms of effectiveness in reducing flicker in alternating current (AC) LEDs. Compared with the conventional Y3Al2Ga3O12:Ce3+ phosphor, the Y1.45LuGd0.5Al2.5Ga2.5O12:0.05Ce3+ phosphor has a better luminescence performance, stronger afterglow performance, and lower flicker index. The quantum yield of the Y1.45LuGd0.5Al2.5Ga2.5O12:0.05Ce3+ phosphor was 86.42% and the luminous efficiency of the LED devices prepared with it reached 92.12 lm W−1 when operated at 100 mA. Integrating sphere and spectroradiometer tests as well as CIE chromaticity diagrams indicate that the AC-WLEDs assembled by mixing the Y1.45LuGd0.5Al2.5Ga2.5O12:0.05Ce3+ phosphor and a commercial red phosphor in an appropriate ratio could obtain ideal white light with a high color-rendering index (87.9) and the flickering index was successfully reduced from 100% to 61.4%. [ABSTRACT FROM AUTHOR]

Developing an efficient strategy for obtaining proton conductors with wide working temperature domains is of great significance for the wide application of proton conductors. To date, proton conductors that have high proton conductivity from subzero temperatures to high temperatures above 100 °C have been very rare. Herein, we prepared two composites, H3PO4@MIL-101-SO3H(Cr) (1) and H2SO4@MIL-101-NH2(Al) (2) by applying a dual-modification strategy to functionalize MOF MIL-101, that is, incorporating acidic guest molecules into the channels of MIL-101 while modifying the MIL-101 backbone with functional groups. Both composites have high proton conductivity over a broad temperature domain (−40 °C to above 150 °C) due to the complementary conduction or synthetic conduction of the backbone functional group and acidic guest molecules in different temperature ranges. The proton conductivities of 1 are 0.9 × 10−1 S cm−1 at 65 °C and 95% RH, 7.5 × 10−5 S cm−1 at −40 °C and 1.4 × 10−2 S cm−1 at 150 °C. Further, the proton conductivities of 2 are 5.8 × 10−2 S cm−1 at 65 °C and 95% RH, 7.1 × 10−4 S cm−1 at −40 °C and 2.5 × 10−4 S cm−1 at 170 °C. All the proton conductivities of the two composites in three temperature domains (low, moderate and high temperature) are at a high level among those of reported proton conductors. Moreover, their proton conductivities have good stability and durability in the broad temperature region from subzero temperatures to high temperatures above 100 °C. [ABSTRACT FROM AUTHOR]

Three novel cicada-like nickel(II) clusters, formulated as [Ni6(bdped)2(mba)6(Hdmpz)2(NO3)2(H2O)2]·4MeCN (SD/Ni6b), [Ni5(bdped)2(tca)6(Hdmpz)(MeOH)2(H2O)]·MeOH (SD/Ni5a) and [Ni4(Hbdped)2(ba)4(Hdmpz)2]·2NO3·2MeCN (SD/Ni4a), were obtained by tuning the auxiliary carboxylic acids, where H2bdped = 1,2-bis-(3,5-dimethylpyrazol-1-yl)-ethane-1,2-diol; Hmba = 2-methylbenzoic acid; Hdmpz = 3,5-dimethyl-1H-pyrazole; Htca = 3-thiophenecarboxylic acid; and Hba = benzoic acid. The structures of SD/Ni6b, SD/Ni5a and SD/Ni4a are built from a central Ni4O4 opened cube, appending two to zero NiNO5 octahedra. The solution behaviours of SD/Ni6b, SD/Ni5a and SD/Ni4a were studied in detail via an ESI-MS technique and their solution stabilities were confirmed. Magnetic analysis indicated the presence of Ising-type anisotropy: D = −13, −10, and −11 cm−1 for SD/Ni6b, SD/Ni5a, and SD/Ni4a, respectively; moreover, dominantly ferromagnetic interactions were found between magnetic centers: J1 = 6.5 cm−1, J2 = −0.44 cm−1 and J1 = 5.9 cm−1, J2 = 2.6 cm−1 for SD/Ni5a and SD/Ni4a, respectively. Besides, the photocurrent signals were observed and they reached the maximum very quickly for these three nickel(II) clusters and then their current intensities remained almost constant, which provide a possibility to be used for light-harvesting and photo-related catalysis. [ABSTRACT FROM AUTHOR]

We report a robust room temperature ferroelectric (FE) state in (1 − x)Pb0.99Nb0.02[(Zr0.57Sn0.43)0.933Ti0.067]0.98O3–xZnO ((1 − x)PNZST–xZnO) composites, where PNZST shows a predominant antiferroelectric (AFE) nature due to ZnO-induced internal strain. Upon heating, a FE-AFE transition occurs and generates high pyroelectric performance. The composite with x = 0.1 shows a peak pyroelectric coefficient of p = 2450.7 × 10−4 C m−2 K−1 and figures of merit of current responsivity Fi = 926.9 × 10−10 m V−1, voltage responsivity Fv = 1334.3 × 10−2 m2 C−1, and detectivity Fd = 1194.8 × 10−5 Pa−1/2, which are about two orders of magnitude higher than those of most perovskite pyroelectric oxides. More interestingly, the FE-AFE transition temperature, i.e., the temperature corresponding to peak pyroelectric performance, is tunable in a wide temperature range from 30 °C to 65 °C. This work not only provides a promising material candidate for high performance pyroelectric devices, but also an alternative idea to develop ferroelectric and pyroelectric properties based on antiferroelectric materials. [ABSTRACT FROM AUTHOR]

The thermal depolarization around 100 °C of the Bi0.5Na0.5TiO3-based piezoelectric solid solutions leads to the disappearance of macroscopic ferroelectric/piezoelectric properties and remains a long-standing obstacle for their actual applications. In this communication, we report lead-free piezoelectric composites of 0.94Bi0.5Na0.5TiO3-0.06BaTiO3:0.5ZnO (BNT-6BT:0.5ZnO, where 0.5 is the mole ratio of ZnO to BNT-6BT) with deferred thermal depolarization, which is experimentally confirmed by systematic temperature dependent dielectric, ferroelectric, piezoelectric measurements. Especially, based on temperature dependent X-ray diffraction measurements on unpoled and poled samples, thermal depolarization is confirmed to have no relationship with the structural phase transition, the possible mechanism for the deferred thermal depolarization is correlated with the ZnO-induced local electric field which can suppress the depolarization field. We believe our results may be helpful for understanding the origin of thermal depolarization in BNT-based piezoelectric materials, and thus provide an effective way to overcoming this obstacle. [ABSTRACT FROM AUTHOR]