Cobalt tungstate (CoWO4) is one of the representatives in the series of divalent transition metal tungstates. The crystal itself is a typical wolframite ore P2/c monoclinic space group structure. Due to its special structure, CoWO4 crystal exhibits a high dielectric constant, making it an important role in catalytic decomposition of organic pollutants, photoelectric displays, microwave dielectric ceramics, photovoltaic electrochemical cells, and magnetic memory material.
At present, the preparation method of cobalt tungstate nano material is mainly by solid phase method. Co3O4 and tungsten trioxide (WO3) are used as raw materials. The materials are uniformly mixed by a ball mill, and calcined in an air atmosphere at 900 ° C for 12 hours, and then ball milling is performed to reach the particle size smaller than 3 μm. Then, the CoWO4 ceramic powder is synthesized by sintering in an air atmosphere at 1200 ° C for 2 hours. This method is simple in operation but has a large particle size and segregation of components, which reduces the luminous efficiency of the material.
In order to overcome the high synthesis temperature existing in the conventional scheme, the problem of poor product composition and particle size uniformity. Some scholars have used the precipitation method to prepare monoclinic phase cobalt tungstate nanorod powder, which is implemented according to the following steps:
Step 1, the macroscopic size CoWO4 powder is added to the aqueous solution of triethanolamine, heated in a water bath to obtain a mixture A;
Step 2, slowly adding the aqueous solution of polyvinyl alcohol and the aqueous solution of sucrose to the mixture A heated in the water bath to obtain a uniform precursor solution, keeping it for 3-5 minutes, then heating to 190-210 ° C under constant stirring, and keeping the precursor to the precursor. Lathe Machine Cutting Tools The solution is slowly evaporated to dryness. When the solution is evaporated to dryness, a fluffy black organic block material is produced at the bottom, which is a precursor block;
Step 3, the precursor block obtained in the step 2 is subjected to pulverization, grinding, heat treatment, and then naturally cooled to room temperature to obtain a cobalt tungstate nanorod powder.
The new process utilizes a simple experimental setup and reaction steps to obtain a precursor; finally, the precursor is heat treated to obtain a monoclinic phase cobalt tungstate nanorod powder. The method has low raw material cost, simple equipment and high reaction yield. The preparation method of the invention overcomes the disadvantages of high synthesis temperature, poor product composition and uniformity of particle size in the prior preparation method.