Sajan D, George; Rajesh, K; Warrier, K G K; Radhakrishnan, P; Nampoori, V P N; Vallabhan, C P G(October 29, 2011)
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Abstract:
The laser induced non-destructive photoacoustic technique has been employed
to measure the thermal diffusivity of lanthanum phosphate ceramics prepared
by the sol–gel route. The thermal diffusivity value was evaluated by knowing
the transition frequency between the thermally thin to thermally thick region
from the log–log plot of photoacoustic amplitude versus chopping frequency.
Analysis of the data was carried out on the basis of the one-dimensional
model of Rosencwaig and Gersho. The present investigation reveals that the
sintering temperature has great influence on the propagation of heat carriers
and hence on the thermal diffusivity value. The results were interpreted
in terms of variations in porosity with sintering temperature as well as with
changes in grain size.
Sajan D, George; Rajesh, Komban; Warrier, K G K; Radhakrishnan, P; Nampoori, V P N; Vallabhan, C P G(Taylor & Francis, February , 2010)
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Abstract:
A laser-induced photoacoustic technique was employed to investigate
thermal transport through nanocrystalline CePO4 samples prepared via the
sol–gel route. Evaluation of thermal diffusivity was carried out using the
one-dimensional model of Rosencwaig and Gersho for the reflection
configuration of the photoacoustic method. Structural analyses of samples
revealed that they are nanoporous in nature, possessing micron-sized
grains. Analysis of results shows that thermal diffusivity value varies with
sintering temperature. Results are explained in terms of the variation in
porosity with sintering temperature and the effects of various scattering
mechanisms on the propagation of phonons through the nanoporous
ceramic matrix. Further analyses confirm that apart from porosity, grain
boundary resistance and interface thermal resistance influence the effective
value of thermal diffusivity of the samples under investigation.