Viscosities of molten alkali-metal bromides and iodides

Viscosities of molten alkali-metal bromides and iodides, whose reported values are scattered, have been measured by the use of a capillary viscometer made of quartz which is newly designed to obtain a high precision. The viscometer consists of the quartz capillary with a funnel of the suspended level type, and the melt is sealed in it t, nder vacuum. The total error in the measurement is estimated to be within 0.7% at high temperatures. Viscosities of all tile alkali metal bromides and iodides show similar values at a constant temperature. Viscot, s flow behaviors of all the alkali-metal halides are discussed based on the activation energy and the hard sphere model. The apparent activation energy increases with tin increase in the melting temperature of the salt. The viscosity of the alkali metal halide melt at the melting temperature increases as the ratio of bard sphere volume to hole volume calculated from the surface tension.