A simple hydrothermal route to the eulytite phase of bismuth germanium oxide (E-BGO: Bi4(GeO4)3) that required no post-processing has been developed. The E-BGO material was isolated from a mixture of bismuth nitrate pentahydrate and a slight excess of germanium oxide in water under hydrothermal conditions (185 °C for 24 h). The resultant materials were characterized by powder x-ray diffraction, scanning electron microscopy, transmission electron microscopy, and luminescence measurements to verify the particle's phase (eulytite), morphology, size, and response to a variety of excitation energy sources, respectively. Photoluminescence spectroscopic response from E-BGO pellets indicated that the samples exhibited a strong emission peak consistent with an x-ray induced luminescence of a E-BGO single crystal (500 nm excited at 285 nm). Cathodoluminescent properties of the E-BGO displayed a broadband spectrum with a maximum at 487 nm. The growth process was consistent with a standard Oswald ripening and LaMer growth processes.

A specially designed specimen holder employing a beryllium dome has been fabricated for collection of X-ray diffraction (XRD) data from highly reactive materials. The specimen holder has a robust O-ring type seal (<10−9Torr) and no observed intensity artifacts in the 1° to 150° 2θ range. The design also minimizes specimen displacement errors and allows for analysis of both powders and bulk specimens (i.e., pellets). The simple design makes for straightforward assembly of the holder within the confines of a glove box. XRD analysis of hygroscopic LaBr3 powders collected with this holder are suitable for Rietveld structure refinement, yielding unit cell lattice parameters of a=7.9703(6) Å and c=4.5122(6) Å; cell volume=248.44(6) Å3; Rp=7.70%.

Ultraviolet irradiation (λ = 248 nm) was used to photocatalyze a solution of the heteroleptic titanium alkoxide (OPy)2Ti(TAP)2 [where OPy = pyridine carbinoxide and TAP = 2,4,6 tris(dimethylamino)phenoxide], leading to the deposition of a titania-based thin film only in the exposed region. The effect of water addition to the (OPy)2Ti(TAP)2 pyridine solution on the properties of the final photodeposited film structure was examined by using vibrational spectroscopy and electron microscopy. Under consistent optical exposure conditions, the amount of water added altered the nanoscale porosity of the final material produced. Films deposited from a solution with a 1:1 H2O/Ti content exhibited surface pores ∼100 nm in diameter, whereas a 4:1 ratio yielded 10-nm pores, and material produced from a 8:1 solution appeared fully condensed. In addition, the effect of postdeposition thermal treatments on the nanostructure and chemistry of the photodeposited films was examined.

The formation of 10-nm ZnO nanopyramids using a simple synthetic route has been isolated from the reaction of Zn(OAc)2·2H2O in 1,4-butanediol followed by ripening at 90 °C. This was accomplished by establishing control over the Ostwald ripening process through the use of a carboxylic acid specific adsorbate. Using a variety of analytical methods, it is proposed that the carboxylate groups in the acetate precursor stabilize the {101} habit planes, creating septahedral shapes or nanopyramids. Particle assembly into crystallographically oriented dimers was observed with high specificity, and the association mechanism is suggested to relate to the crystal polarity and the variation in specific adsorption of the carboxylic acid to the surface facets. These materials are a candidate for biological labeling applications in living cells.

Photodeposited physical relief structures have been formed via the UV-irradiation of solutions of the heteroleptic titanium alkoxide, (OPy)2Ti(TAP)2. Raman studies of the films produced confirm the photoinitiation of hydrolysis and condensation reactions in the molecular structure, leading to the development of an insoluble solid phase. Using a shadow mask technique, these films were deposited directly from solution with microscale patterning and their structure and properties were studied as a function of both irradiation conditions (UV-fluence and intensity) as well as precursor solution chemistry (water content). Variations in nanostructure are visible in scanning electron micrographs, with a higher solution water content producing a more condensed, i.e. less porous, film.

The response of a mononuclear, heteroleptic titanium alkoxide [(OPy)2Ti(4MP)2, where OPy = pyridinecarbinol; NC5H4(CH2O) and 4MP = 4-mercaptophenol; OC6H4(SH)] to ultraviolet (UV) irradiation in dilute solution and in solid-state samples has been measured. Vibrational spectroscopy [Fourier transform infrared (FTIR) absorption and Raman scattering] was used to monitor changes in molecular structure upon exposure to 337.1- and 365-nm light. Assignment of spectral features to vibrational modes of the molecule was aided by a normal-mode analysis of the energy-minimized molecular structure within a density-functional theory framework. Photoinduced decreases in peak areas were observed in both FTIR spectra of the precursor solutions and Raman data collected from solution-cast films of the precursor material. These changes were associated with vibrational modes localized at the 4MP ligands. Conversely, no significant modification of vibrational structure associated with the OPy moiety was observed under the excitation conditions examined. In a related study, thin films of the precursor were cast, sampled, and irradiated with UV light in scintillation vials under hydrated air (40% relative humidity) and dry Ar to evaluate the influence of local atmospheric composition on the photoresponse. An increase in the magnitude of photoinduced vibrational changes was observed in the moist-air environment, again associated primarily with the 4MP ligand. The results support an interpretation of these structural changes in terms of a preferential enhancement of hydrolysis at the 4MP site under these conditions. These findings are discussed in the context of an optically driven molecular assembly strategy based on the photoinitiation of intermolecular bonding at selected sites about the metal center.

The effects of ultraviolet irradiation on a heteroleptic titanium alkoxide ((OPy)2Ti(4MP)2) have been investigated. The molecule has been studied in solution and in thin film form using FTIR and Raman spectroscopies. Quantum computational modeling was used to associate vibrational modes with structural moieties present in the molecule. In all cases examined, a preferential photoinduced modification in vibrational resonances linked to the 4-mercaptophenol (4MP) ligand was observed. In contrast, little or no change was exhibited in the vibrational structure of the OPy ligands.

We demonstrate the functionalization of 2-D photonic crystal structures operating at ∼ 1.5 μm with colloidal PbSe quantum dots and examine the modified photoluminescence from the functionalized photonic crystal. Using spin coating and airbrushing, monodisperse PbSe quantum dots were deposited from hexanes on lithographically patterned GaAs photonic crystal substrates. The effectiveness of patterning the PbSe quantum dots via standard liftoff process was examined. The near-IR photoluminescence spectra of quantum dot-functionalized photonic crystals were studied. We found that the photoluminescence peak became attenuated by approximately a factor of five and exhibited a narrow peak width (50 nm vs. 120 nm) compared to PbSe deposited on unpatterned GaAs, suggesting that there is some coupling between the quantum dots and the photonic crystal. Future work to improve the coupling and detection efficiency is proposed.

Lanthanide (Ln) doping of lead zirconate titanate (PLnZT 4/30/70) thin films was conducted to investigate effects on structural and electrical properties. Films were spin-coat deposited from precursor solutions made using a previously reported “basic route to PZT” chemistry. The remanent polarization (Pr), dielectric constant (ε), dielectric loss (tan δ), and lattice parameter values were obtained for each of the doped PLnZT films. Films doped with amphoteric cations (Tb, Dy, Y, and Ho) displayed high Pr values, square hysteresis loops, and enhanced fatigue resistance. Smaller radius Ln-doped films display an increased tendency toward (100) orientation in otherwise (111)-oriented films.

The “aging” characteristics of an acetic acid/methanol solvent-based lead zirconate titanate (PZT) precursor solution, prepared by the Inverted Mixing Order (IMO) process, have been studied for an extended period of time. The changes in film properties were characterized using optical microscopy, optical scattering, and ferroelectric testing. Films generated from the IMO process exhibit an increase in thickness as a function of solution age due to chemical “aging” (esterification) of the precursor solution. This increased thickness results in a decrease in the microstructural uniformity, which affects the electrical and optical properties. In order to understand and eventually control this phenomenon, we have quantified the “aging” of this solution using a variety of analytical methods, including 1H NMR spectroscopy, pH measurements, and Fourier transform infrared (FTIR) spectroscopy. It is of note that we have discovered a method that circumvents this “aging” problem by removal of the volatile material, forming an IMO powder which can be redissolved to produce high quality PZT thin films whenever desired.

We have developed a simple and rapid method for the synthesis of a precursor solution used in the production of SBT powders and thin films of the layered-perovskite phase SrBi2Ta2O9 (SBT). Precursor solution preparation takes less than 30 min and involves the generation of two solutions: (a) Bi(O2CMe)3 dissolved in pyridine and (b) Ta(OCH2Me)5 added to Sr(O2CMe)2 and then solubilized by HO2CMe. After stirring separately for 10 min, these solutions are combined, stirred for an additional 10 min, and used without any further modifications. The individual solutions and ternary mixture were studied using a variety of analytical techniques. Films of the layered-perovskite phase were formed at temperatures as low as 700 °C. Ferroelectric testing of SBT films, fired at 750 °C, reveals standard hysteresis loops with no fatigue for up to 4 × 109 cycles.

A bismuth-deficient pyrochlore phase has been observed in both powder and film samples fired at 775 °C. The estimated stoichiometry of this pyrochlore (based on calculated diffraction patterns) was Sr0.2(Sr0.5Bi0.7)Ta2O6.75. This bismuth-deficient pyrochlore phase may be considered deleterious to the formation of the SrBi2Ta2O9“SBT” ferroelectric compound since a significant presence of this pyrochlore compound implies a large deviation from the desired cation ratios. Additionally, films prepared on platinized silicon substrates indicate the SBT phase formation may be encouraged by the substrate; there appears to be some 00l preferential orientation for stoichiometric SBT thin films.

In attempt to ultimately control the characteristics of the PZT films, we have decided to investigate some of the basic chemistry associated with these solutions. Frequently, these solutions have been generated from Group IV metal alkoxides in acetic acid (HOAc). Therefore, studies of the simple reactivity between M(OCHMe2)4 (M = Ti, Zr) and HOAc have been undertaken. These reactions were monitored by 1H, 13C, 17O NMR, FT-IR, TGA/DTA, and single crystal X‐ray studies. Films were produced from spin‐coat deposition of crystalline material (from the titanium reaction) in toluene and aged solutions as well.