Fine ammonium paratungstate was prepared by microwave-ultrasonic cooperative evaporation crystallization without external force or any surfactant. The effects of temperature, ammonium tungstate concentration, power of microwave and ultrasonic, as well as cooperative time on the particle size and morphology of ammonium paratungstate were investigated. Under the optimum conditions, the fine single-crystal ammonium paratungstate with an average particle size of 7.6 μm, uniform size distribution, perfect crystal, and five crystal water could be prepared.

 

Ultrasound is sound waves with frequencies which are higher than those audible to humans. Ultrasonic images also known as sonograms are made by sending pulses of ultrasound into tissue using a probe. The sound echoes off the tissue; with different tissues reflecting varying degrees of sound. These echoes are recorded and displayed as an image to the operator.

 

Microwave technology is extensively used for point-to-point telecommunications (i.e. non-broadcast uses). Microwaves are especially suitable for this use since they are more easily focused into narrower beams than radio waves, allowing frequency reuse; their comparatively higher frequencies allow broad bandwidth and high data transmission rates, and antenna sizes are smaller than at lower frequencies because antenna size is inversely proportional to transmitted frequency. Microwaves are used in spacecraft communication, and much of the world's data, TV, and telephone communications are transmitted long distances by microwaves between ground stations and communications satellites. Microwaves are also employed in microwave ovens and in radar technology.