Single crystal grown in larger, charged drops of soln. - suspended with less deformation by electrostatic field and ultrasonic standing wave field

摘要

The single crystal growth, by evapn of solvent from a drop of the dissolved material, is carried out while the drop is held motionless in an ultrasonic standing wave field. The feature is that the drop has been charged electrically and that an electrostatic field is : superimposed. Initially the drop is suspended by just the ultrasonic field, and later the electrostatic field is added. The magniture of both fields is adjustable. The equipment used to carry out the process includes an ultrasonic transducer and a non-conductive reflector at some distance from it, which also contains a convex electrode embedded in it or a ringshaped one surrounding it. The reflector also features a central cavity to improve the stability of positioning. The chamber in which the evapn takes place pref contains a quantity of the solvent in order to control the vapour pressure using temp difference or concn difference of a dissolved salt, for a controlled evapn rate. This sovlent is pref available on the open bottom plane of the chamber. USE/ADVANTAGE - The addn of the electrostatic field allows larger drops to be suspended without causing deformation. It also makes the positioning of the droplet easier. The process consists of bringing a droplet into the ultrasonic field through an injection needle. Then the charge is applied and the electrostatic field adjusted.