National University of Singapore

Junmin Xue

John Wang

Leong Chew Lim

Leong Ming Gan

Anthony Zhaohui Zhou

Dongmei Wan

Ser Choon Ng

Heterolayered thin films having ferroelectric/piezoelectric layers of alternating crystal structures and methods of their preparation are provided. In the ferroelectric/piezoelectric thin film, a first layer has a rhombohedral crystal structure and a second layer adjacent the first layer has a tetragonal crystal structure. The layers have a (100) preferred orientation with &#x3b1;-axis normal to the surface of the film. The first layer can be a Zr-rich lead ziroconate titanate layer (e.g., PbZrTiO) and the second layer can be a Ti-rich PZT layer (e.g., PbZrTiO). Heterolayered ferroelectric/piezoelectric thin film comprising a plurality of such first and second layers in alternating sequence exhibits particularly improved electrical properties.

Heterolayered ferroelectric thin films and methods of forming same

Mechanochemical fabrication produces electroceramics using oxides as starting materials. The fabrication starts with mixing industrial ceramic oxide powders. Electroceramic phases are formed by reacting the oxide powders in a mechanochemical chamber, which is a wear-resistant cylindrical vial with one or more solid balls inside. The formation of electroceramic phases of pervoskite structure and fine crystallinity are activated by mechanical energy or a combination of mechanical energy and thermal energy. Sintered electroceramic materials and components are fabricated when compacts or green bodies made of the resulting ceramic powders are densified at the sintering temperature. The technique can fabricate a wide range of PbO-based ceramics such as Pb(Mg Nb )O (PMN), Pb(Mg Nb ) O -PbTiO (PMN-PT), Pb(Mg Nb ) O -Pb(Zn Nb )O -PbTiO (PMN-PZN-PT), and other PMN-based relaxor ferroelectrics, Pb(Zr Ti )O (PZT) and PZT-based piezoelectrics at sintering temperatures as low as 900&deg; C.

Mechanochemical fabrication of electroceramics

A method for producing electroceramic materials of high sintered density from hydroxide and/or oxalate precursors is disclosed. In this method the precursor(s) are compacted to form a preform, thermally treated, recompacted and then sintered to form finished products.

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Singapore, Singapore

Junmin Xue