Synthesis of (Pb,La) (Zr,Ti)O3 films using a diol based sol-gel route

• Published in: Journal of materials science 1998, Vol.33 (3), p.659-667
• Main Authors: KURCHANIA, R, MILNE, S. J
• Format: Article
• Language: English
• Subjects: Composition; Cross-disciplinary physics: materials science; rheology; Dielectric strength; Exact sciences and technology; Ferroelectric materials; Ferroelectricity; Lanthanum; Lead lanthanum zirconate titanate; Lead zirconate titanates; Leakage current; Liquid phase epitaxy; deposition from liquid phases (melts, solutions, and surface layers on liquids); Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Physics; Polarization; Silicon substrates; Sol-gel processes; Spin coating; Thin films; Zirconium
• ISSN: 0022-2461; 1573-4803
• DOI: 10.1023/A:1004377409565

Morphotropic phase boundary compositions of lead zirconate titanate (PZT) modified with 2, 5 and 10 mol% lanthanum (PLZT) have been prepared using a diol based sol–gel route. Thin films of these PLZT compositions were fabricated on platinized silicon substrates by a spin coating technique. The effects of firing temperature and lanthanum modifications were investigated with regard to phase development, microstructure, and ferroelectric and dielectric characteristics. A strong 〈1 1 1〉 orientation developed as the amount of lanthanum doping increased. The results indicate that the values of remanent polarization, Pr, and dielectric constant, εr, decrease, relative to unmodified PZT, for films modified with 2 and 5 mol% lanthanum. The 5 mol% La films for example had a Pr of 14 μC cm−2 and an εr value of 700 compared to 31 μC cm−2 and 1480 for undoped PZT films. At these La concentrations there was also an improvement in the leakage current density by two orders of magnitude compared with unmodified PZT. The 10 mol% La sample did not exhibit any switchable polarization behaviour.