Density of Molten Terbium Chloride

Anhydrous (99.99%) TbCl3 was obtained from Aldrich (Milwaukee, WI, USA) and used without further purifications. It was handled in an argon-filled dry box with a water content < 2 ppm and an oxygen content < 1 ppm. A 166Ho radiation source (2.27 MBq) was used because of its desirable decay characteristics (t1/2 = 1200y, up to 8 photons per disintegration, more than 10% branching ratio). A multi-channel pulse height analyzer, coupled with a Ge-detector (1.7 keV FWHM at 1332.5 keV, 23% relative efficiency) was used to obtain the γ-ray spectrum of the 166Ho. A schematic diagram of the experimental set-up is shown in Figure 1. The radiation source was placed in a lead shield. A tungsten alloy and lead were used as collimator. The sample in a quartz cell was set in a furnace. Nickel foils and cupper plates were used to prevent thermal effects on the radiation source and the Ge-detector. Gamma-ray spectra were first taken with an empty quartz cell and the cell filled with water. After the cell was charged with anhydrous Terbium chloride, it