ISSN 1070-4272, Russian Journal of Applied Chemistry, 2008, Vol. 81, No. 11, pp. 2043–2044. © Pleiades Publishing, Ltd., 2008.
Original Russian Text © O.D. Chimitova, B.G. Bazarov, K.N. Fedorov, Zh.G. Bazarova, 2008, published in Zhurnal Prikladnoi Khimii, 2008, Vol. 81,
No. 11, pp. 1928–1929.
Electrical Properties of Triple Molybdates Rb
O. D. Chimitova, B. G. Bazarov, K. N. Fedorov, and Zh. G. Bazarova
Baikal Institute of Nature Management, Siberian Division, Russian Academy of Sciences, Ulan-Ude, Buryatia, Russia
Received January 21, 2008
Abstract—Triple molybdates of the compositions Rb
(5 : 1 : 2) and Rb
(2 : 1 : 4),
Ln = Се–Lu, were prepared by solid-phase reactions. The temperature dependence of the electrical conductivity
of the compounds Rb
(5 : 1 : 2) at 200–500°C was studied.
Increased interest in complex molybdenum oxide
compounds is caused by their diverse physicochemical
(piezoelectric, ferroelectric, optical, and catalytic)
The aim of this study was to synthesize triple mo-
, Ln = Ce–Lu, and to exam-
ine their electrical conductivity.
Е6-13А teraohmmeter at fixed voltages of 30 and
60 mV. The quantity t
was determined as the ratio of
the electronic conductivity measured on direct current
to the total conductivity measured on alternating cur-
We have studied the temperature dependence of the
conductivity of triple molybdates in the temperature
range 200–500°C. The dependence of the total conduc-
tivity of triple molybdates on reciprocal temperature in
the coordinates log
/T is shown in the figure.
Triple molybdates of these compositions were pre-
pared from neutral molybdates (except for cerium) by
solid-phase reactions in the temperature range 500–
600°С within 70–100 h. Attainment of the equilibrium
was monitored by X-ray diffraction with a Bruker D8
Advance diffractometer (CuK
monochromator, interval of angles 10°–40° with a
Samples for measuring electric properties were pel-
lets approximately 1 mm thick and 10 mm in diameter.
The pellets were prepared by pressing powder samples
with the subsequent annealing at a temperature of
of the corresponding compound.
The temperature dependences of the conductivity σ,
permittivity ε, and dielectric loss tangent tan
studied on a pilot installation according to the Vest–
Tallan procedure . The quantity σ was measured on
alternating current with an E8-4 capacitance meter
with the connection of a Р-5025 capacitor box allow-
ing the interval of measuring tan
δ in the samples to be
increased. The direct current was measured with an
Temperature dependence of the electrical conductivity σ of
, (2) Rb
, (3) Rb
, and (5) Rb
The ordinate values give the conductivity at a cer-
tain temperature. We determined the activation ener-
gies of ionic and electronic conductivity E
(i) and Е
from the line slopes. The calculated activation energies
of the conductivity E
(i) and Е
(e) and the conductivi-
ties σ of triple molybdates are given in the table.