The lattice parameters, and coefficients of thermal expansion, of palladium and tungsten are measured by means of a high temperature X‐ray powder camera. The lattice constants of palladium are expressed by an analytical formula at = 3.8890 × 10− + 4.5 × 10−13 t + 1.37 × 10−16 t2 and those of tungsten by at = 3.1646 × 10−8 + 1.4398 × 10−13 t + 0.3164 × 10−16 t2. It is found that the thermal expansion coefficients can not be satisfactorily explained by Grüneisen's theory.

The thermal expansion of gold has been studled over the temperature range 25" to 878 "C by the X-ray powder technique. The experimental coefficients can be represented by the interpolation formula at = 13.99 x + 0.491 x t. The work of LAWSON, and MITRA and WTRA is discussed, and it is shown that in this temperature range it is not necessary to postulate the existence of any anomalous expansion arising from lattic defects.Die Warmeausdehnung von Gold wurde im Temperaturbereich von 25 bis 878 "C mit Hilfe des Rontgen-Pulververfahrens untersucht. Die experimentell ermittelten Koeffizienten konnen durch folgende Interpolationsformel dargestellt werden: at = 13,99 x 10 + 0,491 x t . Die Arbeiten von LAWSON sowie MITRA und MITRA werden diskutiert, und es wird gezeigt, daR es nicht notig ist, innerhalb des untersuchten Temperaturbereiches die Existenz einer anomalen Ausdehnung vorauszusetzen, die sich aus Gitterdefekten ergibt.

No abstract

The c o e f f i c i e n t s of thermal expansion d of zinc selenide have been measured dilatometrioally by Novikova (1) from 20 t o 3/40 OK and it has been found t h a t oc becomes negative a t T C 64 O K w i t h minimum value of -3.10~10-~ OC a t 36 OK, Sinoe X-ray measurement of thermal expansion i s not available, therefore, we have measured the same with a Unicam 19 om hightemperaturd powder camera.g r e a t care and temperature could be maintaned within ?2 OC. (2) and Spreadborough and Christian (3). The l a t t i c e parameter from each s e t was evaluated accurately by Cohen's (4) analyt i c a l method usfng Nelson's and Riley's ( 5 ) extrapolation function. The f i n a l value is t h e mean of the r e s u l t s of t h r e e sets. The l a t t i o e parameters at various temperature a r e given i n column two of Table 1 , and are f i t t e d i n a parabolio expreasion by a l e a s t square method The photographs were taken i n t h r e e d i f f e r e n t sets w i t h at = 5.6681~10-~ + 4016xIO-13t + 2 . 1 3~1 0 -'~t~ + 2 , 7 9~1 0 '~* t~ ? where at i s t h e l a t t i c e parameter i n cm at t OC. The thermooouple was c a l i b r a t e d by finding out t h e l a t t i o e parameters of a s i l v e r speoimen a t d i f f e r e n t temperatures and comparing them w i t h the work of Rothery and ReynoldsThe l a t t i c e parameters caloulated by the above expression a t d i f f e r e n t temper a t u r e s a r e given i n column

No abstract