In this work, we report the low-temperature phase transition of sodium niobate (NaNbO 3 ) ceramics at the antiferroelectric-ferroelectric phase studied by the Raman scattering technique over the temperature range 10-300 K. The spectral shape indicates that the phase transition occurs at 160 K on the cooling cycle and at 260 K on heating. The recorded spectra are discussed following the separation of modes into the internal stretching modes of the NbO 6 octahedron and Na + cation translational modes. The 62 and 75 cm −1 peaks are proposed as the translational modes of Na + cation against the NbO 6 octahedron.

Raman studies of crystalline iron perchlorate hexahydrate (Fe(ClO 4 ) 2 ·6H 2 O) in the region of lattice and anion internal modes were carried out in the temperature range 80-385 K. The temperature-dependent Raman results are consistent with those from previous works, showing that two phase transitions occur around 336 and 245 K. The transition at 336 K may be considered as an order-disorder transformation, while the one at 245 K is associated with the configurational disorder of the tetrahedron of the perchlorate ions.

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The microstructure and magnetic properties of multilayer [FePt(x)/Os] n films on glass and Si substrates by dc-magnetron sputtering technique have been studied as a function of the annealing temperatures between 300 and 800 C. Here, x varied from 10, 20, 25, 50, to 100 nm with its associated n value of 10, 5, 4, 2, and 1, respectively. On glass, no diffusion evidence was found in all the samples. However, on Si, the insertion of a 10 nm Os layer into the FePt and Si interface results in better thermal stability. The Os underlayer can effectively prevent the diffusion of the intermixing between FePt layer and the Si(100) substrate for temperatures up to 800 C. The grain size of the multilayer films can be well controlled by both the annealing temperature and the thickness of the FePt layers between the Os layers. The Os layers can effectively prevent the diffusion of the intermixing among the FePt layers and the Si(100) substrate. This means that the diffusion effect can be efficiently prevent in the multilayer [FePt(x)/Os] n films by the Os layers.

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