The iron selenide compound BaFe2Se3 was synthesized by a two-step high-temperature solid state method. The single-crystal X-ray determination of the prepared compound revealed a three-dimensional structure consisting of double chains of edge-sharing FeSe4 tetrahedra separated by Ba2+. In contrast to the case for alkali metal intercalated iron-based chalcogenides (like KxFe2−ySe2), the double chains of BaFe2Se3 were cut out of the two-dimension layers. X-ray photoelectron spectroscopy measurements indicated that there existed two valence states of iron: Fe2+ and Fe3+, which proved there were vacancies in the iron sites. In addition, the magnetic measurements demonstrated that BaFe2Se3 was antiferromagnetic and the Neel temperature of the sample was related to the average electronic spin of iron sites.

•Hierarchical CoMoO4@MnO2 core–shell nanosheet arrays were prepared for the first time.•The hierarchical core–shell nanostructure largely enhanced pseudocapacitive properties.•Good cyclability with only 7% loss after 3000 cycles at 20 mA cm−2 was obtained.•The electrode displays high specific capacitance of 2159.4 F g−1 at 3 mA cm−2.In this work, the hierarchical CoMoO4@MnO2 core–shell nanosheet arrays have been synthesized, which are grown directly on Ni foam as an integrated electrode for supercapacitors. Nanosheet arrays of cobalt-molybdenum precursors are synthesized first by a mild hydrothermal reaction and used as the “core”. After the second facile hydrothermal process with a successive annealing, the Co–Mo precursors are transformed into the 3D hierarchical CoMoO4@MnO2 core–shell nanostructure. This core–shell heterostructure exhibits desirable electrochemical properties. It shows a high specific capacitance of 2159.4 F g−1 (2.27 F cm−2) at 3 mA cm−2 and high cycle stability with 93% retention of its initial specific capacitance at 20 mA cm−2 after 3000 cycles in 1 M KOH solution. In conclusion, the CoMoO4@MnO2 composites could be used as promising electrode materials for electrochemical energy storage due to their remarkable electrochemical properties.

A series of hexagonal perovskite-type compounds Yb1−xDyxMnO3 (0.1 ≤ x ≤ 0.5) have been prepared by the traditional solid-state reaction method at 1573 K, and a single crystal orthorhombic perovskite-type compound Yb0.5Dy0.5MnO3 has also been obtained by a high-pressure flux method at 1273 K under 5 GPa high pressure. Final products are fully characterized by XRD and XPS analyses, and then subject to magnetic measurements. It appears that the hexagonal Yb1−xDyxMnO3 (0.1 ≤ x ≤ 0.5) compounds have shown antiferromagnetic properties with a Néel temperature of 10 K, and canted antiferromagnetic behaviour is clearly evident at a lower temperature. Also, it is found that the magnetization of Yb1−xDyxMnO3 increases with the increase of Dy content. The orthorhombic Yb0.5Dy0.5MnO3 single crystal has been found to be paramagnetic, differing from RMnO3 reported in the literature, which is antiferromagnetic due to subtle structural difference.

A series of Sr-substituted Gd1-xSrxMnO3(0.1≤x≤0.3) materials was prepared via a standard method involving solid-state reaction. Their crystal structure within the entire doping region was determined to be orthorhombic perovskite type. The magnetic properties of the perovskite Gd1-xSrxMnO3(0.1≤x≤0.3) were thoroughly investigated. It appears that Mn ions with high valence state can induce stronger magnetization, and negative magnetization is evident in the manganites with x=0.1 and x=0.2, suggesting that valence fluctuation plays an important role in such systems. The result of XPS analysis indicates that the valence state of Mn ions is 3.25 and there seems to be excess amounts of oxygen in the structure of Gd0.8Sr0.2MnO3+δ. In addition, the results of magnetization measurements demonstrate that spin reversal occurs only when the applied field is less than 1.99×105 A/m, which presumably could be due to the negative exchange interaction between Mn sub-lattice and Gd sites.

SrWO4:Eu3+ nanowires were synthesized at 160 °C within 10 min via a microwave-assisted hydrothermal method. In examining the influences of synthesis temperature and reaction time on the morphology of nanowires, it was found that any temperatures and reaction time except 160 °C and 10 min gave rise to poorer morphologies under otherwise equal conditions. The synthesized nanowires were characterized by means of X-ray diffraction(XRD), scanning electron microscopy(SEM), transmission electron microscopy(TEM), high-resolution transmission electron microscopy(HRTEM), energy dispersive X-ray(EDX) and Raman spectrometry, respectively. The results suggest that the samples are homogenous and dispersive single phase nanowires. The photoluminescence properties of the nanowires were determined with a spectrofluorometer. Two obviously sharp peaks at 395 and 464 nm and a broad peak centered at 290 nm were found in their excitation spectrum. Under excitation at 395 and 464 nm, the 5D0→7F2 transition is the dominant process which means Eu3+ ion is located at a low symmetry site, while the 5D0→7F1 transition dominates under the excitation at 290 nm, showing a highly symmetric field around the Eu3+ ion, which indicates the presence of the two local Eu3+ environments.

An integrated electrode of hierarchical ZnCo2O4@ZnCo2O4 core–shell nanosheet arrays/nickel foam has been successfully synthesized, via a one-step hydrothermal method followed by calcination treatment. The hierarchical ZnCo2O4@ZnCo2O4 nanosheet arrays seem to possess mesoporous characteristics with ultrathin thickness. Due to its novel, hybrid nanoarchitecture, such an electrode system has exhibited remarkable areal specific capacitance along with excellent cycling life, even under fairly high current density conditions.

Single crystal GdNbO4:Ln3+ (Ln = Dy, Eu) phosphors were prepared via a high-temperature high-pressure hydrothermal procedure at 650 °C under autogenous pressure. X-ray diffraction, field emission scanning electron microscopy, photoluminescence, Raman and XPS were utilized to characterize the as-synthesized phosphors. XRD reveals that the samples begin to crystallize at 550 °C and a pure GdNbO4 phase can be obtained at 650 °C. FE-SEM images indicate that GdNbO4:Ln3+ (Ln = Dy, Eu) samples consist of fine sheets with a size of 50–100 μm. Under UV excitation, the GdNbO4:Eu3+ and GdNbO4:Dy3+ phosphors showed the characteristic emissions of Eu3+ are 5D0 → 7FJ (J = 0, 1, 2, 3, 4), and Dy3+ (4F9/2 → 6H15/2 and 4F9/2 → 6H13/2 transitions), respectively. The preparation method presented here dramatically lowered the traditional temperature of 2300 °C or above in the Czochralski method. The GdNbO4:Dy3+ single crystals showed a bright white emission under different excitation wavelengths with a relatively high quantum yield of 21.7%. The GdNbO4:0.05Eu3+ exhibited excellent bright red luminescence at 612 nm under near-UV excitation, narrowed emission spectra, room temperature luminescence lifetimes of milliseconds and maximum quantum efficiencies of 43.2%.

High-purity zirconium trisulfide (ZrS3) and hafnium trisulfide (HfS3) nanobelts with maximal length of 2–5 mm have been successfully synthesized through a chemical vapor transport (CVT) process. XRD results show that ZrS3 and HfS3 crystallize in the monoclinic system. SEM images reveal that ZrS3 and HfS3 nanobelts have thickness ranging from 60 to 120 nm, and HRTEM images and ED patterns confirm that [100] is the dilated direction and [010] is the elongated direction for both the trisulfide nanobelts. The formation of these trisulfide nanobelts is interpreted by a vapor-solid mechanism. The results of Raman scattering show that a slight red shift and peak broadening are observed relative to those of large crystals, which may be induced by the phonon confinement effect.Highlights► High-purity ZrS3 and HfS3 nanobelts with maximal length of 2–5 mm ► The optimum reaction conditions were confirmed. ► Raman spectra red shift and broaden induced by the phonon confinement effect.

Cuprous oxide (Cu2O) was synthesized via reactions between cupric oxide (CuO) and copper metal (Cu) at a low temperature of 300 °C. This progress is green, environmentally friendly and energy efficient. Cu2O crystals with truncated octahedra morphology were grown under high pressure using sodium hydroxide (NaOH) and potassium hydroxide (KOH) with a molar ratio of 1:1 as a flux. The growth mechanism of Cu2O polyhedral microcrystals are proposed and discussed.Graphical AbstractThe Cu2O crystals with truncated octahedral shape were one-step synthesized in high yield via high pressure flux method for the first time, which is green and environmentally friendly. The mechanisms of synthesis and crystal growth were discussed in this paper.Highlights► Cuprous oxide was one-step green synthesized by high pressure flux method. ► The approach was based on the reverse dismutation reactions between cupric oxide and copper metal. ► This progress is green, environmentally friendly and energy efficient. ► The synthesized Cu2O crystals were of truncated octahedra morphology.