Calorimetric and related studies of disorder in solid electrolyte and similar materials
described. The calorimeter is of traditional design but the
control system is new, based around a Commodore PET microcomputer.
The first heat capacity measurements made, on a sample of
Calorimetry Conference Sapphire between 77 and 315 K, indicated
an accuracy within 1%. Since that time substantial improvements
to the control system have been made. For most samples studied
experimental precision is considerably better than 1%. Even with
drift periods as long as 5-6 h, precision is better than 2%.
The first heat capacity studies by adiabatic calorimetry
are reported for crystalline Ag614W04 and AgI3IgW20S. Both
exhibit three transitions, two first order near 19S and 246 K
and a continuous transition with a maximum near 275 K. These
findings are discussed in relation to previous studies of these
electrolytes. The glassy electrolyte Ag13IgW20S shows no evidence
of these transitions, and non-equilibrium behaviour is apparent.
The heat capacity differs significantly from the literature data
for the glass Ag
A continuous transition has been found in [NMe4]2Ag13115
near 155 K.
To allow a comparison of the electrolyte heat capacities
with those of their components, a heat capacity study of Ag
was carried out. Three samples were used: finely divided
precipitate; crushed pellets formed from the powder; and a
crushed cooled melt. Equilibration times for the first two were
long, 1-2 h and 5-6 h respectively. This is in line with published
data for another powdered solid. The behaviour of the crushed
cooled melt was normal. A small heat capacity anomaly is apparent
at 277 K though this may result from slight breakdown of Ag
during melting or from impurity phases present in the
Some results of an extended x-ray absorption fine structure
study of a copper(I) electrolyte are presented which suggest
that in these systems electrolyte modification occurs during