Preparation Method of Spherical Barium Tungstate

Tungstate nanomaterial has a good application prospects in scintillation materials, optical fibers, photoluminescent materials, microwave applications, humidity sensors, magnetic devices, catalysts and corrosion inhibitors, and have become a hot research topic in recent years. In addition to the above-mentioned application potential, barium tungstate nanomaterial is also a good photocatalyst for the degradation of organic pollutants under light irradiation.

Compared with the conventional photocatalyst titanium dioxide (TiO₂), barium tungstate has a narrow band gap (about 2.4-2.7 eV) and possess high catalytic activity under visible light. In recent years, many literatures have reported the preparation of barium tungstate (Bi₂WO₆). The crystal form of barium tungstate is mostly in the form of flakes, or a fluffy ball, flower or other morphological assembly assembled from bismuth tungstate nanosheets. It is known that barium tungstate has at least six crystal forms, and the flower-like and flake-shaped barium tungstate has a prominent defect of easy agglomeration. The spherical strontium tungstate with high dispersibility is less reported.

In order to study the photocatalytic properties of spherical barium tungstate, the researchers used the following steps to prepare:

1) 1.2 g of barium sulfate was added to 0.6 ml of concentrated nitric acid, and after initial stirring, 15 ml of deionized water was added, and the mixture was dissolved and diluted, and recorded as solution A. Further, 0.55 g of ammonium paratungstate decahydrate was added to 30 ml of deionized water, stirred and dissolved, and recorded as solution B.

2）Solution A was added dropwise to Solution B, and stirred while stirring to form a uniform suspension. The pH of the solution was adjusted to approximately 8 with 20% aqueous ammonia. Then, it was aged at a temperature of 368 K in a sealed state for 24 hours. At the end of the aging, the precipitated product was washed with a large amount of deionized water, and after drying, cerium tungstate nanocrystals were obtained.

3) The crystal form of the prepared barium tungstate is consistent with the standard powder diffraction card (JCPDS: 43‐0447), which is a spherical nano-grain with a diameter of about 150 nm, uniform size, and a purity of more than 99%.

The shape of strontium tungstate prepared by the above method is spherical nanocrystal. Its diameter is between 100 and 200 nanometers, the size is uniform, the dispersion is high, and it is not easy to agglomerate, in photocatalysis, scintillation materials, gas sensing materials, magnetic devices, optical fibers and other fields have higher application value.

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