ISSN:
1551-2916
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
,
Physics
Notes:
The alternating-current electrical properties of polycrystalline CaMnO3 were investigated by alternating current complex-impedance analysis, and the dielectric properties were analyzed over the temperature and frequency ranges of 10 to 130 K and 20 Hz to 1 MHz, respectively. Direct-current conductivity and the Seebeck coefficient as a function of temperature also were analyzed. Below 120 K, a Debye-type dielectric relaxation peak was observed. Experimental results implied that the number of charge carriers, which were generated by Mn3+, were not sufficient to stabilize small polarons, although it induced lattice distortion by the Jahn—Teller effect. Therefore, the thermal motion of Mn3+ between potential minimums produced by lattice distortion in the orthorhombic structure were believed to be the source of dielectric relaxation. The temperature dependence of conductivity of the grain interior (σgi) below 120 K was believed to be due to variable range-hopping conduction, where σgi∼ exp(−T−1/4).
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1151-2916.2000.tb01277.x
Permalink