TITLE: X-ray Photoelectron Spectroscopy Studies of Metallic Diborides

J. Amer. Ceram. Soc. 75 [10]2849-2856, 1992.

W.A. Zdaniewski and N.L. Brungard

The binding energies of core electrons in d-type stoichiometric diborides of several transition metals were measured by X-ray photoelectron spectroscopy. Metal core lines in the diborides shifted either to higher or to lower binding energies compared with those appertaining to corresponding elemental states and varied with the metal. The shifts were < 0.6 eV. Carbides, oxides and oxycarbides of variable stoichiometries were the major impurities detected in the diborides. The binding energy shifts showed a progressive change as the electronegativity difference between the metal and the metalloid (boron, carbon, nitrogen, oxygen) increased. This indicated that the bond in boro-oxycarbides may be partially ionic.

TITLE: Preparation and Characterization of Sputtered TiB₂ Films

J. Mater. Res. 6 [5] 1066-1072, 1991.

By W.A. Zdaniewski, J.H. Wu, S.C. Gujrathi and K. Oxhorn.

Smooth, continuous TiB₂ films were deposited on TiB₂-AlN composites and Si substrates by sputtering in high vaccum. Excellent adhesion between films and substrates was indicated; no film delamination was induced by Vickers indentation at high loads. Analyses by secondary ion mass and x-ray photoelectron spectroscopies showed that the films were of high purity and contained H, C, O, N, and Na elements as trace impurities. Quantitative depth profile by the elastic recoil detection (ERD) nuclear scattering technique using 30 MeV ³⁵Cl beam revealed that the Ti/B atomic ratio was very close to 0.5, while the ¹⁰B/¹¹B isotopic ratio was 0.25.

TITLE: Ceramic Coating on Ceramic Substrates by Liquid Metal Transfer

J. Amer. Ceram. Soc. 73 [9] 2753- 2756, 1990.

By L.D. Silverman, W.A. Zdaniewski, and N.L. Brungard

A variety of ceramic coatings have been put on ceramic substrates by the molten metal transfer technique. In the diffusion coating process a reactant metal dissolved in a molten "transfer agent" metal reacts with a substrate to form the coating. Titanium dissolved in molten tin has been reacted with silicon carbide, aluminium nitride and silicon nitride substrates to produce titanium carbide and titanium nitride coatings, respectively. Similarly, tantalum metal hass been reacted to form carbide or nitride coatings. The unreacted tin is finally removed by decantation followed by acid leaching.

TITLE: Characterization of Au-AlN and Au-SiC Interfaces

J. Amer. Ceram. Soc. 72 [11] 2084-2087, 1989.

Aluminium nitride and silicon carbide substrates were screen printed with fritless gold and fired at 850^o C in air. Interfacial diffusion zones up to 7 micrometers thick were observed, in which the concentrations of Au, Na impurities, and combined O varied together. Secondary ion mass and photoelectron spectroscopy revealed oxidized Al in the gold conductor supported by AlN. It is suggested that enhanced oxidation accompanies the diffusion of Au into the ceramic.

By W.A. Zdaniewski and C.H. Houser.



Title: Effect of Surface Roughness on Dielectric Strength of Thick Film Dielectrics

Amer. Ceram. Soc. Bull. 66 [8] 1270-1272, 1987.

By W.A. Zdaniewski and J.P. Maher.



Title: Effect of Localized Redox Equilibria on Adhesion Between Gold and Thick Film Dielectrics

J. Mater. Sci. 25, 3155-3158, 1990.

By W.A. Zdaniewski and L.D. Silverman.

The effect of processing atmospheres with decreasing partial pressure of oxygen on the stability of dielectric glass formers, and on the wetting between gold and dielectrics was studied. Thermodynamic calculations, contrasted with experimental results, suggest that localized redox conditions may differ from ideal thermodynamic equilibria. As the redox quilibrium shifts towards reducing conditions, a compositional change occurs and affects the interfacial energies. Screen-printed gold combined with a lead-borosilicate glass dielectric becames non-wetting when fired in nitrogen gass.