SHORT COMMUNICATION Thermal properties of 15-mol% gadolinia doped ceria thin films prepared by pulsed laser ablation K. Muthukkumaran & P. Kuppusami & R. Srinivasan & K. Ramachandran & E. Mohandas & S. Selladurai Received: 13 December 2006 / Accepted: 13 December 2006 / Published online: 17 February 2007 # Springer-Verlag 2007 Abstract Thermal properties of 15-mol% gadolinia doped ceria thin films (Ce 0.85 Gd 0.15 O 1.925 ) prepared by pulsed laser ablation on silicon substrates in the temperature range 473–973 K are presented. Thermal diffusivities and thermal conductivities were evaluated using photoacoustic spec- troscopy. The influence of grain size on thermal properties of the films as a function of deposition temperature is studied. It is observed that the thermal diffusivity and the conductivity of these films decreases up to 873 K and then increases with substrate temperatures. The thermal proper- ties obtained in these films are discussed on the basis of influence of grain size on phonon scattering. Keywords Thin films . Ceria . Thermal analyses Introduction Solid electrolytes based on doped ceria are of considerable interest for potential use in solid oxide fuel cells (SOFCs) due to a higher ionic conductivity with respect to stabilized zirconia and a lower cost in comparison with lanthanum gallate-based electrolytes. High oxide ion conduction in doped ceria makes it possible to decrease SOFC operation temperature, thus reducing numerous technological prob- lems. In addition, doped ceria is in great demand as a topcoat material for thermal barrier coatings (TBCs) used in gas turbine engines. The important selection criterion is that the material must have the potential for having low thermal conductivity. More recent increase in operating temperatures of gas turbines have been enabled by deposition of TBCs on high-temperature gas turbine components [1, 2]. TBCs are complex, multifunctional thick films (typically 100 μm to 2 mm thick) of a refractory material that protects the metal part from the extreme temperatures in the gas. Indeed, in the hottest part of many gas turbine engines, the coatings enable metallic materials to be used at gas temperatures above their melting points [4, 5]. Under such heat flux conditions, it is the thermal conductivity of the coating that dictates the temperature drop across the TBC [6]. Although the primary function of TBCs is as a thermal barrier, the extremely aggressive thermo-mechanical envi- ronment in which they must function demands that they also meet other severe performance constraints. In particular, to withstand the thermal expansion stresses associated with heating and cooling, either as a result of normal operation or as a consequence of a ‘flame-out’, the coatings must be able to undergo large strains without failure. This ‘strain compliance’ is typically conferred through the incorporation of porosity in the microstructure by, for example, forming the coating by pulsed laser deposition (PLD) or plasma spraying. It is apparent that the thermal conductivity of the oxide materials strongly depends on microstructural features such as surface finish, grain size, and porosity introduced as a result of the chosen method of deposition. Ionics (2007) 13:47–50 DOI 10.1007/s11581-007-0068-0 K. Muthukkumaran (*) : S. Selladurai Department of Physics, Anna University, Chennai 600 025, India e-mail: muthuk24@yahoo.co.in P. Kuppusami : E. Mohandas Physical Metallurgy Section, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, India R. Srinivasan Department of Physics, Thiagarajar College, Madurai 625 009, India K. Ramachandran School of Physics, Madurai Kamaraj University, Madurai 625 021, India