ISSN 0018-151X, High Temperature, 2018, Vol. 56, No. 1, pp. 33–37. © Pleiades Publishing, Ltd., 2018.
Original Russian Text © S.V. Stankus, I.V. Savchenko, O.S. Yatsuk, 2018, published in Teplofizika Vysokikh Temperatur, 2018, Vol. 56, No. 1, pp. 30–34.
The Caloric Properties of Liquid Bismuth
S. V. Stankus*, I. V. Savchenko, and O. S. Yatsuk
Kutateladze Institute of Thermophysics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090 Russia
Received March 14, 2017
Abstract—We investigated the enthalpy of liquid bismuth within the temperature range of 580–1325 K in a
massive isothermal drop calorimeter using the mixture method. We obtained the approximation equations
and determined the isobaric heat capacity. The estimated errors of the data on the enthalpy and the heat
capacity are equal to 0.2% and 0.5%, respectively. The results are compared with the literature data. We con-
firmed the existence of a heat-capacity minimum of liquid bismuth of approximately 800 K. We show that
above 940 K the heat capacity depends linearly on the temperature. We developed tables of the recommended
values of the caloric properties within the range from the melting point to 1325 K.
Recently, heavy metals such as lead and bismuth
and their reciprocal eutectic alloy have been consid-
ered as prospective liquid-metal heat carriers
(LMHCs) for fast nuclear reactors [1, 2]. Thus, for
many practical applications in nuclear-power engi-
neering, reliable information on the thermophysical
properties of heavy LMHCs in the condensed state at
technically important temperatures is necessary. As
well, bismuth is a component in numerous fusible
compounds that are applied in technology in a very
The caloric properties of bismuth have been mea-
sured in numerous experiments. Reviews of the works
in this field up to 1960 are found in many authoritative
handbooks [3, 4]. The values of the caloric properties
of liquid bismuth in  are based on the results of the
heat-capacity measurements  performed within the
range from the melting point up to 802 K. The charac-
ter of the C
variation with temperature was similar to
the heat-capacity variation in the well-studied tin: a
sharp decrease after melting with a subsequent
approach to the constant value. However, in 1975, a
paper  was published where very careful measure-
ments of the heat capacity of liquid bismuth up to
950 K using the adiabatic calorimetry method were
presented; the authors showed that above 800 K a C
increase began and did not end at the maximum tem-
perature of the experiments. We note that a similar
(T) dependence occurs for the majority of the liquid
alkali metals .
The present work is aimed at obtaining new exper-
imental data on the caloric properties of liquid bis-
muth within a wider temperature range in order to
confirm the results of  and to determine the tem-
perature dependence of the heat capacity above 950 K.
We performed experiments using a massive iso-
thermal drop calorimeter; its design and initial data-
processing technique were described in  in detail.
The calorimeter includes a high-temperature oven
with a tubular molybdenum heater, a calorimetric
unit, a system for ampoule ejection and a locking
device. The 10 kW electric oven allows measurements
in a vacuum or in an inert atmosphere at up to 2300 K.
The thick-wall molybdenum leveling unit is equipped
with two protecting heaters, making it possible to
maintain the preset (including zero) temperature gra-
dient over the unit. The quick-disconnecting vacuum
coupling and the cooling chamber with the rod are
installed on the upper oven lid; they receive the sample
and to deliver it into the oven without its depressuriza-
tion. A mechanical lock is mounted at the rod end that
holds the ampoule; it is opened by an electromagnet.
The ampoule is protected from both ends by thermo-
radiation shield modules; the lower one automatically
opens during ejection. We measured the sample tem-
perature using an S-type platinum–platinum–rho-
dium thermocouple, which is inserted in the protec-
tion cartridge directly into the ampoule. When the
lock opens (during sample ejection) the ampoule
slides off the thermocouple. The cold thermojunc-
tions of all the thermocouples are kept at a tempera-
ture by running water, with an error within 0.1 K.
The calorimetric unit design includes a 24 kg chro-
mium-plated copper cylinder that hangs hermetically
on a thin-wall tube inside the isothermal envelope.
The gap between the unit and the envelope is placed
under a vacuum of up to 0.1 mPa by a turbo-molecular
pump. Two copper lids grounded in the spline hous-
ings are opened by electromagnets only during sample
ejection; they prevent the heating of the unit by the