Synthesis and Electrical Characterization of Thin Films of PT and PZT Made from a Diol‐Based Sol‐Gel Route

Abstract

Lead titanate (PT) sols were prepared using propanediol, butanediol, or pentanediol solutions of lead acetate trihydrate and titanium diisopropoxide bis(acetylacetonate). Precursor sols for PbZr0.53Ti0.47O3 (PZT) films were prepared from propanediol solutions, with zirconium tetrapropoxide being used as the zirconium source. Films were formed by spin‐coating the sols onto silicon and platinized silicon substrates; the resulting gel layers were converted to ceramic films by adopting a two‐stage heating schedule with final firing temperatures of 600–700°C. Information on film crystallization, microstructure development, and electrical properties is presented for both compositions. The limiting thickness of surface‐smooth crack‐free single‐layer films was ∼1 μm. The PT films exhibited a “linear” polarization‐electric field (P‐E) response, while the PZT films gave rise to characteristic ferroelectric P‐E hysteresis loops. A 0.5 μm thick single‐layer PZT film exhibited remanent polarization (Pr) values of ∼34 μC·Cm−2, with a coercive field (Ec) of ∼45 kV·Cm−2; the relative permittivity (ɛr) and the dissipation factor (D) were ∼1250 and 0.07. For a 1 μm single‐layer PZT film, the respective values were Pr∼19 μC∼Cm−2, Ec∼40 kV∼Cm−2, ɛr∼750, and D= 0.03.

Barium titanate sols prepared by a diol-based sol–gel route

“…The sols were prepared using 1,3 propanediol, barium acetate, and titanium isopropoxide, modified by acetylacetonate. Previously this chemical approach has proved to be successful in preparing lead zirconate titanate (PZT) precursor sols [16,17].…”

“…To make it more stable to air, the titanium alkoxide can be modified by reaction with acetylacetone [14]. One of the modified titanium alkoxides, titanium diisopropoxide bisacetylacetonate (TIAA), has been used to prepare lead titanate and lead zirconate titanate sols for thin film deposition [15,16].…”

PZT thick films by diol chemical solution deposition

“…Precursor sols for PbZr 0.53 Ti 0.47 O 3 films were prepared using 1-3 propanediol solutions with lead acetate trihydrate, titanium diisopropoxide bis(acetylacetonate) and a zirconium acetate solution, according to diol-based solution synthesis [14,15] and modified lead zirconate titanate (PZT) film preparation. The route is schematically shown in Fig.…”

Sol–gel derived Pb(Zr,Ti)O3 thin films: Residual stress and electrical properties

“…Unfortunately, a common observation during the development of PZT technology was that thin films, whether deposited by sputtering, CVD, PLD, or chemicalsolution deposition processes, did not have the same properties as their bulk counterparts. [3][4][5][6][7] These observations have since led to increased activity in the field in an attempt to elucidate the fundamental differences between bulk and thin film ferroelectric perovskites. Potential mechanisms for the observed differences in PZT materials include: thickness, grain size, interface, crystal orientation, and residual stress.…”