The Study of New Electronic Materials: Organometallic Chemical Vapor Deposition of High-Temperature Superconducting Thin Films and Synthesis and Characterization of Phthalocyanine Molecular Metals

High-temperature superconducting YBa_2 Cu_3O_{7 -delta} and Tl-Ba-Ca-Cu-O thin films have been prepared by low-pressure organometallic chemical vapor deposition (OMCVD) using the volatile precursors Y(dipivaloylmethanate)_3, Ba(heptafluorodimethyloctanedionate) _2, Cu(acetylacetonate)_2 , Ca(dipivaloylmethanate)_2 and thallium(cyclopentadienide). YBa_2 Cu_3O_{7 -delta} films were prepared using argon as the carrier gas and water vapor as a reactant. After annealing under oxygen, the films had good compositional and dimensional uniformity and were preferentially oriented with the crystallite c axes perpendicular to the substrate surface. Zero resistances as high as 86 K were observed. Films of Tl-Ba-Ca-Cu-O have been prepared by two complimentary OMCVD routes. Ba-Ca-Cu-O films were first prepared by OMCVD. Thallium was next incorporated into these films either by vapor diffusion using bulk Tl-Ba -Ca-Cu-O as the source or by OMCVD using Tl(cyclopentadienide). Both types of films consist primarily of the TlBa_2 Ca_2Cu_3O _{rm x} phase, have preferential orientation of the CuO planes parallel to the substrate surface, and exhibit zero resistance by 100 K. Tl-Ba-Ca-Cu-O films have also been prepared by an unique hybrid technique that combines electron beam evaporation with OMCVD. Multi-layer thin films of Ba-Ca -Cu were prepared by sequential evaporation of BaF _2, CaF_2, and Cu sources onto a substrate followed by annealing in water vapor saturated oxygen. Thallium was then incorporated into these films utilizing the same techniques used in the all OMCVD process. The resultant films consist of highly oriented single phase TlBa_2Ca _2Cu_3O _{rm x} with zero resistances of 104 K. The phthalocyanine molecular metal Ni(Pc)(ClO _4)_{rm y}, y = 0.39-0.47, has been synthesized using high-temperature electrocrystallization techniques. The structure of a crystal with y = 0.42 consists of staggered (39.5^circ) Ni(Pc) ^{+0.42} units separated by 3.233(1) A with disordered, off axis ClO_4^ - ions. At lower temperatures there is diffractometric evidence for anion ordering. At 300 K, the conductivity of Ni(Pc)(ClO _4)_{rm y} is 700 +/- 200 Scm ^{-1}. Variable-temperature conductivity data exhibits metal-like behavior on cooling with discontinuous behavior below ca. 150 K which may reflect the anion ordering. Thermoelectric power and optical reflectivity data are characteristic of a low-dimensional molecular metal and agree with sample -dependent y values. Both measurements yield a tight-binding bandwidth of ca. 1.5(1) eV.