Molten salt synthesis of A-site disordered niobate microcrystals with tetragonal tungsten bronze structure

Abstract

The anisometric templates with the same composition as the matrix is the key to the preparation of textured high entropy or multi-element doped ferroelectric ceramics. Here, we designed the A-site disordered niobate ((Na0.5K0.5)(Sr0.4Ba0.3Ca0.3)2Nb5O15) with tetragonal tungsten bronze structure and fabricated the needle-like microcrystals with a high aspect ratio by molten salt synthesis. The effects of process parameters (calcination temperature and molten salt content) on the morphology and chemical composition of products were investigated. It was found that a single tetragonal tungsten bronze structure phase could be obtained at calcination temperatures up to 1200 ℃. With the increase of molten salt content, the size of product particles become more uniform. The TEM results suggested that the obtained needle-like particle was a single crystal and had a uniform distribution of elements. In addition, the photocatalytic properties of the microcrystals were evaluated by degrading the organic dye methylene blue (MB) under simulated sunlight conditions. The present work shows the potential of the A-site disordered niobate microcrystals with tetragonal tungsten bronze structure for the solar-driven remediation of polluted water.