Approach for enhanced polarization of polycrystalline bismuth titanate films by Nd3+/V5+ cosubstitution

• Published in: Applied physics letters 2002-09, Vol.81 (12), p.2229-2231
• Main Authors: Uchida, Hiroshi, Yoshikawa, Hiroki, Okada, Isao, Matsuda, Hirofumi, Iijima, Takashi, Watanabe, Takayuki, Kojima, Takashi, Funakubo, Hiroshi
• Format: Article
• Language: English
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/1.1507839

Thin films of Nd3+-substituted bismuth titanate, (Bi4.00−y,Ndy)Ti3.00O12 (BNT), Nd3+/V5+-cosubstituted bismuth titanate, (Bi4.00−y,Ndy)(Ti3.00−xVx)O12 (BNTV), and La3+-substituted bismuth titanate, (Bi3.25,La0.75)Ti3.00O12 (BLT) were fabricated on the (111)Pt/Ti/SiO2/(100)Si substrates by a chemical solution deposition technique. These films possessed random-oriented polycrystalline structure. The BNT film had larger remnant polarization (Pr) than the BLT film; Pr and coercive field (Ec) of the BNT film with y=0.50 were 32 μC/cm2 and 126 kV/cm, respectively. Furthermore, V5+ substitution improved the Pr value of the BNT film up to 37 μC/cm2 (BNTV film; y=0.50, x=0.02), while the BNTV film had an Ec value of approximately 119 kV/cm which was similar to that of the BNT film. Ferroelectric properties of the Pb-free polycrystalline BNT and BNTV films are comparable with those of conventional Pb-based ferroelectric films like a lead zirconate titanate.