Comments on the effects of solution precursor characteristics and thermal processing conditions on the crystallization behavior of sol-gel derived lead zirconate titanate thin films

Abstract

Lead zirconate titanate (PZT 40/60) thin films were fabricated on electroded silicon wafers using chemical solution deposition. Two different chelating agents, acetic acid and acetylacetone, were used in the synthesis of the precursor solutions. The microstructure of the acetylacetone-derived film was characterized by nucleation at the platinum electrode and a columnar growth morphology (˜100−200 nm lateral grain size). In contrast, the acetic acid-derived film was characterized by both columnar grains nucleated at the electrode, and larger (˜1 μm) grains nucleated at the surface of the film. Using Fourier transform infrared (FTIR) diffuse reflectance spectroscopy, we also noted that the pyrolysis behavior of the films was dependent on the chelating agent employed. The acetylacetone-derived films, which displayed only one nucleation event, were also characterized by a higher pyrolysis temperature than the acetic acid-derived films. Previously, microstructural differences of this nature were attributed to variations in “precursor structure.” In this paper, we discuss an alternative mechanism for the observed microstructural variations in films prepared from different solution precursors. In the model proposed, we discuss how changes in film pyrolysis temperature result in a change in film crystallization temperature, and hence, a change in the effective driving force for crystallization. We show how the change in crystallization driving force is expected to impact the thin film microstructure due to the accompanying variations that occur in the barrier heights for interface (lower electrode) and surface nucleation. A standard approach to nucleation in glasses is used as the basis of the proposed model. Finally, we also discuss how the model can be used to understand the observed effects of heating rate and thickness on the microstructure of solution-derived thin films.

Preparation and Characterization of Nano-Cadmium Ferrite

“…The very small band at 2300 cm −1 is due to adsorbed or atmospheric CO 2 [2,21]. The characteristic small bands at 1716 and 1338 cm −1 are assigned to both asymmetric and symmetric C-O, respectively [2,19,21].…”

“…The characteristic small bands at 1716 and 1338 cm −1 are assigned to both asymmetric and symmetric C-O, respectively [2,19,21]. The C-O bands region is an indicative of the presence of organic residues due to acetylacetone species [21].…”

Influencia de los parámetros de procesado y del substrato en la orientación preferente de láminas delgadas de titanato de plomo modificado con calcio preparadas por Sol-Gel

“…La existencia de esa fase coebica de Pt 3 Ti inducir'a la nucleaci-n de cristales de perovskita orientados en <111>, siempre que esta primera capa de Pb 0.76 Ca 0.24 TiO 3 fuese lo suficientemente fina como para que la nucleaci-n fuese heterogŽnea (3). Efectivamente, como se ha indicado en la parte experimental para la obtenci-n de l ‡minas con espesores de ~300 nm, se han depositado y cristalizado cuatro monocapas de ferroelŽctrico, lo que indica que el espesor promedio de cada monocapa es dẽ 75 nm, espesor suficientemente peque-o como para que la perovskita nuclee mayoritariamente de forma heterogŽnea (8). El dep-sito de capas tan finas tambiŽn disminuye el grado de tensiones desarrolladas en las l ‡minas (9), haciendo posible que en este caso sea peque-a la contribuci-n de este factor al grado de orientaci-n de la pel'cula.…”

Processing and properties of ferroelectric relaxor lead scandium tantalate Pb(Sc1/2Ta1/2)O3 thin films

“…17 In addition, in chemical solution derived films, the pathway from an amorphous to a final crystalline state passes through an intermediate phase whose structure and stoichiometry is often different than the desired final phase. [18][19][20] Theoretical work has recently revealed that inhomogeneities and concentration gradients may act as an effective internal field that smears out the phase transition 21 and reduces the permittivity. The low temperatures used in thin film annealing coupled with point defect formation may significantly affect the local structure and properties of the final crystalline phase.response in PST showed that the small film permittivity is truly a property of the film, and not the result of a surface passive layer.…”