MILD HYDROTHERMAL SYNTHESIS OF TITANATE FILMS - FROM POLYCRYSTALLINE BATIO3 TO EPITAXIAL PBTIO3

Titanate films, a technological important dielectric, have found signi ficant applications ranging from materials science to ferroelectronics . A vacuum-intensive method is traditionally employed to fabricate the se films, but it is condition stringent and so relatively expensive, w hile a high-temperature process is needed for crystallization during o r after film formation, which may be incompatible with the underlying monolithic circuits. Fortunately, the hydrothermal method, which was a traditional way for producing ceramic micropowders, has now been newl y developed as a non-traditional way and is increasingly being used to prepare perovskite oxide films. Here we report that films of two clas sic examples of ferroelectric perovskites, BaTiO3 and PbTiO3, can be f ormed under mild hydrothermal conditions of temperatures lower than 20 0 degrees C and pressures lower than 1.0 MPa. The BaTiO3 films formed on Ti-coated Si substrates are well crystallized submicrocrystallites. A better understanding of the growth mechanisms of these films sugges ts a possible route to hydrothermal epitaxy of PbTiO3 on SrTiO3. As th e result, our trials on SrTiO3(100) substrates proved that an epitaxia l film of PbTiO3 was successfully obtained.