Ring depression technique for measuring surface tension of molten germanium

A convenient ring technique (ring depression technique, hereafter) has been newly developed for measuring the surface tension of molten germanium. The validity of this technique is demonstrated through comparison with the results of the sessile drop technique. The temperature gradient of germanium surface tension K = d gamma/dT of -0.08 x 10(-3) N/mK obtained using the ring depression technique showed a good agreement with the result obtained by using the sessile drop technique. Moreover, in relation to maximum surface tension, the difference was within 13% between the results obtained by using the two techniques. Our newly developed technique provides a method for measuring surface tension which excludes reaction between the probe and the molten germanium. This paper describes the ring depression technique for the first time. (C) 1998 Elsevier Science B.V. All rights reserved.