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Thermal conductivity and diffusivity of KH2PO4 and NH4H2PO4 polycrystalline samples near their phase transitions

Published online by Cambridge University Press:  03 March 2011

B.M. Suleiman ,
E. Karawacki  and
S.E. Gustafsson
B.M. Suleiman
Affiliation:
Department of Physics, Chalmers University of Technology, S-412 96 Gothenburg, Sweden
E. Karawacki
Affiliation:
Department of Physics, Chalmers University of Technology, S-412 96 Gothenburg, Sweden
S.E. Gustafsson
Affiliation:
Department of Physics, Chalmers University of Technology, S-412 96 Gothenburg, Sweden
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Abstract

Simultaneous measurements of thermal conductivity and diffusivity of ferroelectric polycrystalline samples of the KDP family type have been performed with the transient plane source (TPS) technique over the temperature range 88-300 K. The thermal conductivity behavior resembles that of the corresponding single crystals, but with values a factor of three lower. This decrease in thermal conductivity of the polycrystalline form is attributed to scattering mechanisms due to microstructural imperfections such as point defects, grain boundaries, etc. Values of porosity have been estimated using the dimensions of the unit cell deduced from the x-ray analysis and the apparent densities. The data indicate that the phase transition mechanisms (displacement type and order-disorder type) still dominate the conduction processes in spite of the presence of other scattering mechanisms due to the imperfection of the microstructure in the polycrystalline form of these materials.

Type
Articles
Information
Journal of Materials Research , Volume 9 , Issue 7 , July 1994 , pp. 1895 - 1898
Copyright
Copyright © Materials Research Society 1994

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References

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