ゾル-ゲル法による酸化物結晶薄膜の成長 : KTNエピタキシー膜(<小特集>酸化物のエピタキシー)

抄録

The sol-gel method is one of the promissing methods to synthesize the well-defined films. In this article, the key processing parameters are introduced to prepare the epitaxial oxide film of K(Ta, Nb)O_3 as an example Epitaxial potassium tantalate-niobate (KTa_xNb_<1-x>O_3, KTN) thin films could be synthesized through reaction control of metal alkoxide solution. The structure of KTN precursors in solution was analyzed by NMR spectroscopy. The KTN precursor consists of K[Nb(OEt)_6]and K[Ta(OEt)_6]with a molecular level interaction in ethanol. Staring metal alkoxides including metal-oxygen-carbon bonds were found to undergo bond rearrangement, yielding KTN precursors under the controlled reaction conditions. Perovskite KTN films crystallized on MgO(100) substrates using H_20/0_2 vapor treatment at 300℃ followed by crystallization at 675℃. KTN films on Pt(100)/MgO(100) of perovskite phase also crystallized at 700℃. KTN films were confirmed to have an epitaxy on Pt(100)/MgO(100) substrates by X-ray pole figure analysis. KTa_<0.65>Nb_<0.35>0_3 films on Pt(100)/MgO(100) substrates showed P-E hysteresis at 225K. The Curie temperature of the KTa_<0.65>Nb_<0.35>0_3 film was 310 K.