Electrical resistivity of liquid and solid sodium

Abstract

The electrical resistivity of sodium contained in a stainless-steel capillary has been determined between 19 and 300° by means of a Kelvin–Wheatstone Bridge. The resistivity of the liquid between 97·8 and 300° obeys the equation ρ_L(µΩ cm.)=a+bT+cT²+dT³–eT⁴ where T is in °C, and the constants have the values: a, 6·87; b, 2·44 × 10^–2; c, 2·67 × 10^–5; d, 1·07 × 10^–7; e, 2·67 × 10^–10. The corresponding equation for the solid over the temperature range 19–97·8° is ρ_S(µΩ cm.)=a+bT+cT²+dT³ where the constants are: a, 4·35; b, 2·13 × 10^–2; c, 6·25 × 10^–6; d, 1·04 × 10^–7. The results are compared with published values, and factors responsible for the variation in resistivity with change of phase are considered briefly. The design of apparatus whereby spurious post-melting phenomena are avoided is discussed.