Jinhao Qiu

A general and simple method to synthesize well-crystallized nanostructured vanadium oxides for high performance Li-ion batteries

A remarkably simple and effective high-temperature mixing method under hydrothermal conditions was applied to synthesize well-crystallized V3O7·H2O nanobelts, VO2 (B) nanosheets and VO2 (A) nanorods with good performances for Li-ion batteries. In particular, V3O7·H2O exhibited an excellent electrochemical performance. The outstanding electrochemical properties were explained through analysis of the crystal structures.

Rod-like NaNbO3: mechanisms for stable solvothermal synthesis, temperature-mediated phase transitions and morphological evolution

One dimensional (1D) NaNbO3 powders have attracted increasing attention for their excellent photo-catalytic and piezoelectric properties, and the stable, moderate and low-energy synthesis of the targets is highly desirable. Herein, a facial solvothermal strategy is adapted to synthesize the one-dimensional (1D) rod-like precursors Na7(H3O)Nb6O19·14H2O by using isopropanol as the reaction medium. When the precursor is subjected to post-heating treatments, rod-like orthorhombic as well as approximate ellipsoid-like monoclinic NaNbO3 powders are obtained. Corresponding mechanisms for the stable solvothermal synthesis, morphological evolution and phase transition are further proposed and discussed.

Annealing temperature effects on the electrical properties of (K, Na) NbO3 thin film fabricated by a sol-gel process with a citrate precursor solution

ABSTRACT Utilizing the comparatively low cost niobium pentoxide (Nb2O5) as raw material, (K,Na)NbO3(KNN) thin films were deposited onto Ti substrate by a sol–gel non-alkoxide process. The effects of annealing temperature on the phase, morphology, dielectric, and ferroelectric properties of KNN thin films were investigated. KNN thin films without impurities were obtained above 700°C, and the microstructure of all films were dense and uniform. A maximum dielectric constant of 480 was obtained in the film annealed at 700°C, which is comparable to the film prepared from niobium ethoxide.

Synthesis and photoluminescence properties of single-crystal ZnO hexagonal pyramids by PEG400-assisted thermal decomposition route

Abstract Large-scale synthesis of ZnO hexagonal pyramids was achieved by a simple thermal decomposition route of precursor at 240 °C in the presence of PEG400. The precursor was obtained by room-temperature solid-state grinding reaction between Zn(CH 3 COO) 2 ·2H 2 O and Na 2 CO 3 . Crystal structure and morphology of the products were analyzed and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM). The results of further experiments show that PEG400 has an important role in the formation of ZnO hexagonal pyramids. Difference between the single and double hexagonal pyramid structure may come from the special thermal decomposition reaction. The photoluminescence (PL) spectra of ZnO hexagonal pyramids exhibit strong near-band-edge emission at about 386 nm and weak green emission at about 550 nm. The Raman-active vibration at about 435 cm −1 suggests that the ZnO hexagonal pyramids have high crystallinity.