Publications

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Transforming lignin into a water-soluble polymer.

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The impact on the final morphology of yttria (Y2O3) nanoparticles from different ratios (100/0, 90/10, 65/35, and 50/50) of oleylamine (ON) and oleic acid (OA) via a solution precipitation route has been determined. In all instances, powder X-ray diffraction indicated that the cubic Y2O3 phase (PDF #00-025-1200) with the space group I-3a (206) had been formed. Analysis of the collected FTIR data revealed the presence of stretches and bends consistent with ON and OA, for all ratios investigated, except the 100/0. Transmission electron microscopy images revealed regular and elongated hexagons were produced for the ON (100/0) sample. As OA was added, the nanoparticle morphology changed to lamellar pillars (90/10), then irregular particles (65/35), and finally plates (50/50). The formation of the hexagonal-shaped nanoparticles was determined to be due to the preferential adsorption of ON onto the {101} planes. As OA was added to the reaction mixture, it was found that the {111} planes were preferentially coated, replacing ON from the surface, resulting in the various morphologies noted. The roles of the ratio of ON/OA in the synthesis of the nanocrystals were elucidated in the formation of the various Y2O3 morphologies, as well as a possible growth mechanism based on the experimental data.

The synthesis of a series of lanthanide trifluoroacetic acid (H-TFA) derivatives which contain only the TFA and its conjugate acid has been developed. From the reaction of Ln(N(SiMe3)2)3 with an excess amount of H-TFA, the products were identified as: [Ln(μ-TFA)3(H-TFA)2]n (Ln = Y, Ce, Sm, Eu, Gd, Tb, Dy), [Ln(μ-TFA)3(μ-H-TFA)]n·solv (Ln·solv = Pr·2 H-TFA, H3O+, Ho·2py, Er·py, Yb·py, H-TFA), 3[H][(TFA)La(μ-TFA)3La(TFA)(μ-TFA)2(μc-TFA)2]n ½(H2O) ½(H2O, H-TFA) (La·½(H2O) ½(H2O, H-TFA)), [(k2-TFA)Nd(μ-TFA)3]n·H-py+ (Nd·H-py+), [(py)2Tm(μ-TFA)3]n (Tm), or [Lu(μ-TFA)4Lu(μ-TFA)3·H3O+]n (Lu·H3O+). The majority of samples formed long chain polymers with 3 or 4 μ-TFA ligands. Tm was isolated with py coordinated to the metal, whereas Ho, Er, and Yb were isolated with py located within the lattice. Select samples from this set of compounds were used to generate nanomaterials under solvothermal (SOLVO) conditions using pyridine (py) or octylamine at 185 °C for 24 h. The SOLVO products were isolated as: (i) from py: La – fluocerite (LaF3, PDF 98-000-0214, R = 9.64%, 35(0) nm), Tb – terbium fluoride (TbF3, PDF 00-037-1487, R = 4.76%, 21(2) nm), Lu lutetium oxy fluoride (LuOF, PDF 00-052-0779, R = 8.24%, 8(2) nm); (ii) from octylamine: La – fluocerite/lanthanum oxide carbonate (LaF3, PDF 98-000-0214, R = 7.47%, 5(0) nm; La2O2(CO3), PDF 01-070-5539, R = 12.32%, 12(0) nm), Tb – terbium oxy fluoride (TbOF, PDF 00-008-0230, R = 7.01%, 5(0) nm); Lu – lutetium oxide (Lu2O3, PDF 00-012-0728, R = 6.52%, 6(1) nm).

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There is a rising interest in developing functional electronics using additively manufactured components. Considerations in materials selection and pathways to forming hybrid circuits and devices must demonstrate useful electronic function; must enable integration; and must complement the complex shape, low cost, high volume, and high functionality of structural but generally electronically passive additively manufactured components. This article reviews several emerging technologies being used in industry and research/development to provide integration advantages of fabricating multilayer hybrid circuits or devices. First, we review a maskless, noncontact, direct write (DW) technology that excels in the deposition of metallic colloid inks for electrical interconnects. Second, we review a complementary technology, aerosol deposition (AD), which excels in the deposition of metallic and ceramic powder as consolidated, thick conformal coatings and is additionally patternable through masking. As a result, we show examples of hybrid circuits/devices integrated beyond 2-D planes, using combinations of DW or AD processes and conventional, established processes.

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The use of colloidal processing principles in the formation of ceramic materials is well appreciated for developing homogeneous material properties in sintered products, enabling novel forming techniques for porous ceramics or 3D printing, and controlling microstructure to enable optimized material properties. The solution processing of electronic ceramic materials often involves multiple cationic elements or dopants to affect microstructure and properties. Material stability must be considered through the steps of colloidal processing to optimize desired component properties. This review provides strategies for preventing material degradation in particle synthesis, milling processes, and dispersion, with case studies of consolidation using spark plasma sintering of these systems. The prevention of multication corrosion in colloidal dispersions can be achieved by utilizing conditions similar to the synthesis environment or by the development of surface passivation layers. The choice of dispersing surfactants can be related to these surface states, which are of special importance for nanoparticle systems. A survey of dispersant chemistries related to some common synthesis conditions is provided for perovskite systems as an example. Furthermore, these principles can be applied to many colloidal systems related to electronic and optical applications.

In this study, the use of maltodextrin supramolecular structures (MD SMS) as a reducing agent and colloidal stabilizing agent for the synthesis of Ag nanoparticles (Ag NPs) identified three key points. First, the maltodextrin (MD) solutions are effective in the formation of well-dispersed Ag NPs utilizing alkaline solution conditions, with the resulting Ag NPs ranging in size from 5 to 50 nm diameter. Second, in situ characterization by Raman spectroscopy and small angle X-ray scattering (SAXS) are consistent with initial nucleation of Ag NPs within the MD SMS up to a critical size of ca. 1 nm, followed by a transition to more rapid growth by aggregation and fusion between MD SMS, similar to micelle aggregation reactions. Third, the stabilization of larger Ag NPs by adsorbed MD SMS is similar to hemi-micelle stabilization, and monomodal size distributions are proposed to relate to integer surface coverage of the Ag NPs. Conditions were identified for preparing Ag NPs with monomodal distributions centered at 30–35 nm Ag NPs.

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High temperature solid state sodium (23Na) magic angle spinning (MAS) NMR spin lattice relaxation times (T1) were evaluated for a series of NASICON (Na3Zr2PS12O12) materials to directly determine Na jump rates. Simulations of the Ti temperature variations that incorporated distributions in Na jump activation energies, or distribution of jump rates, improved the agreement with experiment. The 23Na NMR T1 relaxation results revealed that distributions in the Na dynamics were present for all of the NASICON materials investigated here. The 23Na relaxation experiments also showed that small differences in material composition and/or changes in the processing conditions impacted the distributions in the Na dynamics. The extent of the distribution was related to the presence of a disordered or glassy phosphate phase present in these different sol-gel processed materials. The 23Na NMR T1 relaxation experiments are a powerful tool to directly probing Na jump dynamics and provide additional molecular level details that could impact transport phenomena.

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