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In the present work, a series of low-temperature firing scheelite structured microwave dielectric in water-insoluble LaO-NbO-VO system was prepared via the traditional solid-state reaction method. Backscattering electron diffraction, X-ray diffraction (XRD), energy-dispersive analysis, and Rietveld refinements were performed to study the phase evolution and crystal structure. In the full composition range of (1 - x)LaNbO-xLaVO (0 ≤ x ≤ 0.9) ceramics, at least four typical phase regions including monoclinic fergusonite, tetragonal sheelite, B-site ordered sheelite, and composite of monoclinic LaVO and tetragonal sheelite phases can be detected according to XRD analysis. The variations of relative dielectric constant ε, quality factor Q × f, and resonant frequency τ could be attributed to Nb/V-O bond ionicity, lattice energy, and the coefficient of thermal expansion. Infrared reflectivity spectra analysis revealed that ion polarization contributed mainly to the permittivity in microwave frequencies ranges. Furthermore, the 0.7LaNbO-0.3LaVO ceramic sintered at 1160 °C possessed excellent microwave dielectric properties with an ε of ∼17.78, a Q × f of ∼75 940 GHz, and a τ of ca. -36.8 ppm/°C. This series of materials might be good candidate for microwave devices.

Industry has been seeking a thin-film capacitor that can work at high temperature in a harsh environment, where cooling systems are not desired. Up to now, the working temperature of the thin-film capacitor is still limited up to 200 °C. Herein, we design a multilayer structure with layers of paraferroelectric (Ba 0.3 Sr 0.7 TiO 3 , BST) and relaxor ferroelectric (0.85BaTiO 3 −0.15Bi(Mg 0.5 Zr 0.5 )O 3 , BT−BMZ) to realize optimum properties with a flat platform of dielectric constant and high breakdown strength for excellent energy storage performance at high temperature. Through optimizing the multilayer structure, a highly stable relaxor ferroelectric state is obtained for the BST/ BT−BMZ multilayer thin-film capacitor with a total thickness of 230 nm, a period number N = 8, and a layer thickness ratio of BST/ BT−BMZ = 3/7. The optimized multilayer film shows significantly improved energy storage density (up to 30.64 J/cm 3 ) and energy storage efficiency (over 70.93%) in an ultrawide temperature range from room temperature to 250 °C. Moreover, the multilayer system also exhibits excellent thermal stability in such an ultrawide temperature range with a change of 5.15 and 12.75% for the recoverable energy density and energy storage efficiency, respectively. Our results demonstrate that the designed thin-film capacitor is promising for the application in a harsh environment and open a way to tailor a thin-film capacitor toward higher working temperature with enhanced energy storage performance.

Superwettable (by water or oil) materials have been used in oil/water separation to cope with the growing oily industrial sewage discharge and oil spill accidents. The artificial superwetting materials for oil/water separation that have been previously reported are expensive, and using them usually causes secondary pollution, so practical, large-scale uses of those materials are limited. Here, we find that wood sheet shows underwater superoleophobicity and low oil adhesion in water, resulting from its strong capacity of absorbing water. A through-microhole array was created on the wood sheet surface by a simple mechanical drilling process. The prewetted porous sheet had great ability to separate the mixtures of water and oil with high separation efficiency. Wood is a low cost, green, and natural eco-friendly material; therefore, we believe that such a simple, low-cost, efficient, and green route of large-scale oil/water separation has great potential to practically solve the pollution problems caused by oil spill and oily industrial wastewater.

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