Russell Lipeles

This report has been reviewed by the Public Affairs Office (PAS) and is releasable to the National Technical Information Service (NTIS). At NTIS, it will be available to the general public, including foreign nationals. This technical report has been reviewed and is appiuvcd foi publication. Publication of this report does not constitute Air Force approval of the report's findings or conclusions. It is published only for the exchange and stimulation of ideas.

Zambrana was the project officer for the Mission-Oriented Investigation and Experimentation (MOIE) program. This report has been reviewed by the Public Affairs Office (PAS) and is releasable to the National Technical Information Service (NTIS). At NTIS, it will be available to the general public, including foreign nationals. This technical report has been reviewed and is approved for publication. Publication of this report does not constitute Air Force approval of the report's findings or conclusions. It is published only for the exchange and stimulation of ideas.

The effects of hydrolysis on the degree of polymerization during metallo-organic solution deposition of lead zirconate titanate (PZT) films have been investigated. The reaction of lead 2-ethylhexanoate, zirconium n-tetrapropoxide, and titanium tetrabutoxide in isopropanol with water were studied using thermogravimetry, specular reflectance Fourier transform infrared spectroscopy (FTIR), and optical and electron microscopy. Films prepared from coating solutions having varying amounts of water exhibited dramatic differences in morphology. The films were spin-coated on platinum coated fused silica substrates and annealed at 525/sup 0/C for 30 minutes. Unhydrolyzed coating solutions and solutions with a mole ratio of water to total metal of 0.5 yielded perovskite films with 0.5 to 5 ..mu..m grains. A mole ratio of 1.5 (the amount of water required to completely hydrolyze the metallo-organics in the solution) formed amorphous, porous films. The stability of the prepolymerized films inhib...

An aqueous, metallo-organic precursor for PbTiO3 (PT), Pb(Zr, Ti)O3 (PZT), and (Pb1−x, Lax) (Zry, Ti1−y)1−x/4O3 (PLZT) ceramic powders has been developed employing the acetate complexes of Pb2+, La3+, Zr4+, and Ti4+. The crystallization behavior (e.g., degree of crystallization and crystallite size) was examined over the temperature range of 400–700 °C with concentrations of excess lead varying from 0–5% using x-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy techniques. It was found that PT, PZT, and PLZT crystallize at temperatures as low as 450 °C, 500 °C, and 500 °C, respectively, and the excess lead required for crystallization of the perovskite phase is ⋚1%. Intermolecular mixing among acetate precursors via chelating and bridging structures was evident and appeared to be responsible for the low crystallization temperatures. The process is compared to the current sol-gel methods for its possible use in thin film ferroelectric manufacture.

Deposition by the aqueous acetate solution (DAAS) technique was used to synthesize highly crystalline thin films of undoped and 2% iron-doped Pb(Zr{sub 0.53}Ti{sub 0.47})O{sub 3} [PZT (53,47)] perovskites on sapphire and Pt substrates at 600 C. Fe ions were added either at the precursor stage or diffused thermally. The crystallization of the films was measured by X-ray diffraction. The ferroelectric activity was examined by polarization-voltage hysteresis (P-E) loops. The electro-optical properties of ferroelectric/photoconductive PZT thin films were investigated by excitation photocurrent spectroscopy (EPS) and 77 K emission spectroscopy. The photoconductivity measured at visible wavelengths was enhanced for the thermally diffused, but not the precursor-processed doped materials. This, together with lattice parameters obtained from X-ray data and P-E hysteresis loop measurements, suggested that the precursor-processed doped ions are strongly bonded in the perovskite lattice, wherea...

The effects of hydrolysis on the degree of polymerization during metallo-organic solution deposition of lead zirconate titanate (PZT) films have been investigated. The reaction of lead 2-ethylhexanoate, zirconium n-tetrapropoxide, and titanium tetrabutoxide in isopropanol with water were studied using thermogravimetry, specular reflectance Fourier transform infrared spectroscopy (FTIR) and optical and electron microscopy.Films prepared from coating solutions having varying amounts of water exhibited dramatic differences in morphology. The films were spin-coated on platinum coated fused silica substrates and annealed at 525°C for 30 minutes. Unhydrolyzed coating solutions and solutions with a mole ratio of water to total metal of 0.5 yielded perovskite films with 0.5–5μm grains. A mole ratio of 1.5 (the amount of water required to completely hydrolyze the metallo–organics in the solution) formed amorphous, porous films. The stability of the prepolymerized films inhibits crystallizati...

Impregnant manufacturing procedures were evaluated as part of a program to develop guidelines for producing reliable dispenser cathodes. Such procedures must be controlled in order to eliminate variations in impregnant composition that can give rise to unpredictable cathode performance. Experiments revealed that variations in impregnant composition result primarily from contamination by moisture, incomplete mixing, and incomplete reaction. Procedures developed to overcome these problems are discussed. The following recommendations are made: (1) Alumina must be dried prior to weighing to avoid inaccurate formulation due to moisture. (2) Multiple dry and wet mixing steps are nedded to thoroughly homogenize the starting materials. (3) Calcination temperatures of 1300 + or - 60 C are required to form thoroughly reacted barium calcium aluminates. (4) Thermogravimetry is useful for testing impregnants and starting materials for moisture contamination.

The deposition by aqueous acetate solution (DAAS) technique has been developed for the preparation of 5% Fe-doped Pb (Zr 0.53 Ti 0.47) O 3 (PZT) and (Pb 0.93 La 0.07)(Zr 0.65 Ti 0.35) 0.983 O 3 (PLZT) thin films on Pt〈 111〉/Ti/SiO 2/Si substrates. PZT films, ...