Current Research

  My materials science research includes developing both new materials and new, more efficient materials production processes for deposition of thin films, microfibers (10 µm) and microparticles of commercial importance in advanced semiconductor and electronics devices, corrosion and wear resistant coatings, and catalytic support systems, with product morphology controlled by process parameters. Current investigations are ongoing in three areas: supercritical processing, boron carbide devices, and polymers for harsh environments.
Supercritical processing. Oxides and diamond-like carbon (DLC) films have been grown from a clean, environmentally-friendly process, using only ultra-pure supercritical water and inorganic precursors, such as graphite as the raw materials in a free-jet expansion deposition system. This deposition system is one of the few facilities in the world where solutions of high-temperature, high-pressure water and inorganic materials are studied, and it is unique in its capacity for varying both the electrochemical and physical environments to explore fundamental electrochemical phenomena in flowing deposition processes. Electrochemical effects and manipulating the electrochemical environment have recently been shown to be important. [1, 2]. Resulting films have been robust, adhered well to a variety of substrates (metals, polymers, and silicon), and have definitely undergone a dissolution and subsequent precipitation, as shown by mass spectrometry [3] and by FTIR and electron diffraction of the deposited films [2]. Particles and microfibers have been produced in the same system by careful control of processing conditions. To predict and control product morphology as a necessary step to commercialization, we have developed a detailed process model, relating the thermodynamics, fluid mechanics, mass transport, electrokinetics and reaction and condensation kinetics to film and particle morphology, crystallinity, and uniformity.
The fundamental knowledge of electrochemical effects in flowing systems has broader applications than the processing of high quality electronic materials. Results of this research on the electrochemical behavior of the high-temperature, high-pressure flowing aqueous solutions can be applied to the prevention of corrosion in power plants, and to geochemical processes, both for the understanding of natural mineral formation and for evaluating feasibility of geothermal energy recovery.
Boron carbide devices. Boron carbide is a refractory material which, in its semiconducting form, has great potential for electronic and magnetic devices in specialized environments, such as space vehicles. It also functions as a solid state neutron detector when the naturally occurring ¹⁰B fissions upon collision with a thermal neutron [4]. By exploiting the isomeric differences in compound with the same elemental make-up but in different arrangements, (similar to the differences between polyethylene and polypropylene) unique and exciting new devices have been fabricated and are being tested, including a diode made from only boron and carbon [5]. In this area, the Nebraska method of processing is used to produce the devices, but fundamental studies include spectroscopic characterization performed at UNL and at the UNL Synchrotron Beamline at CAMD, LSU campus, Baton Rouge, LA.[6]
Results of this research have space, nuclear industry, and high-temperature semiconductor applications, as well as the fundamental understanding of the III-IV compounds. [7]
Polymer for harsh environments. Novel polymer materials for harsh environments are also being investigated. In addition to predicting and evaluating performance in harsh environments and specialized applications, novel polymers, including bio-based polymers, are being developed and fabricated [8].

References

(Group members: graduate students, undergraduates students)
J. I. Brand and A. O. Sezer, "Electrochemical Aspects of Inorganic film deposition from Supercritical Aqueous Solutions", Proc. of the GVC-Fachausschuss Hochdruckverfahren-technik High Pressure Chemical Engineering Karlsruhe, Germany, N. Dahmen ed., p. 97-99, 1999.

Ali O. Sezer, Ph. D. Dissertation, UNL August 2003 “The Effect of Electrochemical Phenomena on the Deposition of Carbon Containing Inorganic Thin Films from Supersonic Expansion of Aqueous Supercritical Solutions” (J. I. Brand, advisor).

Lonne Blecha, M.S.December 2000. “Direct-Sampling Mass Spectroscopy of a Free Jet Expansion of a Supercritical Water Solution” (J. I. Brand, advisor).

B.W. Robertson, S. Adenwalla, A. Harken, P. Welsch, J.I. Brand, P.A. Dowben, and J.P. Claassen, "A Class of Boron Based Solid State Neutron Detectors", Appl. Phys. Lett. 80, 3644-3646 (2002).

Anthony N. Caruso, Ravi B. Billa, Jennifer I. Brand, and P.A. Dowben, “The Heteroisomeric Diode”, J. Phys.: Condens. Matter 16, L139-146 (2004).

A.N. Caruso, Snjezana Balaz, Bo Xu, P.A. Dowben, A.S. McMullen, J.I. Brand, Y.B. Losovyj, and D.N. McIlroy, “The Surface Photovoltage Effects on the Isomeric Semiconductors of Boron-Carbide”, Appl. Phys. Lett. 84, 1302-1304 (2004).

Ravi Billa, A. N. Caruso, and J. I. Brand, “A New Class of Solar Cells: Isomeric Boron Carbide Semiconductors with Fourth Quadrant Conductivity”, Proc. of MRS, 2004.

J. Akerlund, S. Harmeier, J. Pumphrey, D. C. Timm, and J. I. Brand, "High-Performance Plastics from Diketopiperazines Derived from Amino Acids", J. Appl. Polymer Science 78 (12), 2213-2218 (2000).

Ph.D. Degrees Supervised to Completion

Ali O. Sezer. Ph. D. August 2003 “The Effect of Electrochemical Phenomena on the Deposition of Carbon Containing Inorganic Thin Films from Supersonic Expansion of Aqueous Supercritical Solutions”. Faculty. Chemical Engineering Department, Bucknell University.

M.S. Degrees Supervised to Completion

John W. Guerry, M. S. May 1996, "The Deposition of Aluminum Oxide and Diamond Films through the Rapid Expansion of Supercritical Solutions. Now electronics processing engineer, Motorola, Texas.
Ali O. Sezer, M. S. December 1997, "The Effect of Oxygenated Compounds on the Vapor Pressure of Hydrocarbons." Completed a PhD.
Stacey D. Uden, M. S. December 1998, “Process Control of a Batch Distillation with Rectification in an Undergraduate Laboratory”. (Co-advisor with D. C. Timm.) Now a systems analyst, Chicago.
Darlene Larson Hug, M. S. December 1999, “Modelling and Moiré Deflectometry Analysis of the Free-jet Expansion Flow Profile of Supercritical Water”. Employed as systems engineer, New Jersey.
Lonne Blecha, M. S. December 2000, “Direct-Sampling Mass Spectroscopy of a Free Jet Expansion of a Supercritical Water Solution”. Electronics processing engineer, Arizona.
Ravi Babu Billa, M. S. January 2004, “Semiconducting Boron Carbide Heteroisomeric Diode: Fabrication and Characterization.” Currently seeking employment.