Bridgmantechniek

Bridgmantechniek, in English the Bridgman technique, is a crystal growth method used to obtain single crystals from the melt by moving the material through a controlled temperature gradient. It was developed by the American physicist Percy Williams Bridgman in the early 20th century and is closely related to the Bridgman-Stockbarger variant. The method relies on directional solidification: a crucible containing the melt is translated or pulled through a furnace where a steep temperature gradient promotes solidification starting from a seed crystal.

In practice, a sealed crucible or ampoule, often made of quartz, holds the material. The ampoule is placed in a furnace that provides a high-temperature zone and a colder zone along its length. During growth, the crucible is slowly moved so that the solid–liquid interface advances in a controlled manner, ideally producing a single crystal with a chosen crystallographic orientation. By adjusting the gradient, pulling rate, and seed placement, researchers attempt to suppress multiple nucleation events and obtain a coherent crystal.

Materials grown by Bridgman techniques include metals and alloys, oxides, and certain semiconductors such as silicon, germanium, GaAs, and CdTe. There are vertical and horizontal configurations, and the distinct Stockbarger variant emphasizes a well-defined temperature gradient along the growth axis. The method is valued for its simplicity and ability to handle high-melting-point or volatile materials, but it can be slow and prone to thermal stress or impurity incorporation from the crucible.

Today, Bridgman techniques are often used in niche applications and research settings, particularly when alternative crystal growth methods are unsuitable or when small to medium-sized single crystals are required.