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The GK-12 program involves students doing a masters or a Ph.D. in science and engineering working with a science teacher to develop demonstrations and laboratories which will bring the excitement of science into the schools. They work for an entire semester with the same group in school. We expect that the teachers will be able to carry on these demonstrations after the GK-12 students have left. Another aspect we want to bring to the students is the excitement of doing research in the field, and that what they are learning may be helpful in doing this research. As part of their work, we ask the GK-12 participants to prepare a research presentation for their schools. They have to present it in language that the students will understand, and with the material that the students have learned. In doing this, the students learn how to explain their research in much better terms and the K-12 students are exposed to real research and new approaches that nonetheless are based in the lessons they are learning.

Since its establishment in 1997, the undergraduate program at the University of Maryland has successfully established laboratories where new findings are introduced and used to teach the basic concepts and basic experimental methods in Materials Science and Engineering. This presents the challenge of changing the materials, keeping in mind that the students are being introduced for the first time to many of the concepts. In the junior laboratory of materials, we have successfully changed three laboratories (optical microscopy, rectifying components and X-ray) and a demonstration (TEM) in order to introduce nanomaterials and biomaterials. These laboratories show that currently used techniques can aid in studying the new developments in materials and that most, if not all, the basic concepts can be applied in studying them. They also help the students look at the effects of the structure – processing – properties relationship that is basic to Materials Science and Engineering. We relate all laboratories to experiments and studies currently happening in materials science, even if we have not had the opportunity or the facilities to change it. The laboratory has been approved by ABET 2000.

We have integrated recent research results in the curriculum of the University of Maryland, while leaving the basics intact. This allows us to teach the fundamental laws and to show the students how these help us to answer questions that are of importance today. This can be done as part of a laboratory and as part of a class. In the laboratory classes, we emphasize what is measured (the main topic), then measure samples recently done in the literature. If available, we measure two samples and have a discussion on what are the differences. These are then related to the manner the samples have been grown. In the classes, we show the basic equation or relation, and introduce how it can answer a question that is pertinent to today's research.

We have performed depth profile analyses of the lattice parameters in epitaxial thin films of La1−xCaxMno3 (LCMO), where x = 0.33 or 0.3, to understand the evolution of strain relaxation processes in these materials. The analyses were done using Grazing Incidence X-ray Scattering (GIXS) on films of different thicnesses on two different substrates, (100) oriented LaAlO3 (LAO), with a lattice mismatch of ∼2% and (110) oriented NGO, with a lattice mismatch of less than 0.1%. Films grown on LAO can exhibit up to three in-plane strained lattice constants, corresponding to a slight orthorhombic distortion of the crystal, as well as near-surface and columnar lattice relaxation. As a function of film thickness, a crossover from a strained film to a mixture of strained and relaxed regions in the film occurs in the range of 700 Å. The structural evolution at this thickness coincides with a change in the resistivity curve near the metalinsulator transition. The in-plane compressive strain has a range of 0.2 – 1.5%, depending on the film thickness for filsm in the range of 400 - 1500 A.

We have used the intensity and tunability of a synchrotron x-ray source in order to access the buried interface between a glass substrate and a liquid crystal thin film. We find that for energy of 9.4kev, the x-rays can penetrate a 0.22mm substrate. Grazing Incidence x-ray Scattering has been used to study the alignment of the films as a function of depth and temperature. Our results indicate the presence of both a chevron structure and a structure similar to the helical twist-grainboundary (TGB) phase. Some films have a disordered interfacial layer. This technique can be applied in the study of semiconductor devices as well as surfactant film interfaces.

We have used Grazing Incidence X-ray Scattering to study the depth dependence of the interfacial structure of smectic liquid crystal (8CB) hybrid films. These films are bounded by a grated glass substrate and air, and have been studied as a function of both temperature and thickness. Our measurements indicate the presence of both a chevron structure and a structure similar to the helical twist-grain-boundary (TGB) phase. Our measurements constitute the first to show that this structure can also be observed in hybrid smectic liquid crystal films. The twisted structure is the result of anchoring at two dissimilar competing confining surfaces.

An overview of our work on the synthesis of nanostructured powders and coatings using the polyol process is presented.

Thin films of light atomic weight elements in amorphous, partially-crystalline, or crystalline forms have applications in a broad range of technologies. For example, amorphous tetrahedral carbon (a-tC) and polymeric thin films impact electronic materials technology as electron- and light-emitting device elements, respectively. A lack of crystallinity introduces complexity in the experimental and theoretical characterization of these materials but is not necessarily a limiting factor in their performance. While the growth process is clearly a major factor governing the physical properties of a film, interactions with the substrate are also important, so surface and interface analysis provides an important complement to bulk measurements. Currently, the fundamental and applied aspects of the atomic, electronic and vibrational structure of these complex materials are being elucidated by novel approaches combining several experimental techniques with theoretical calculations. This paper focuses on several approaches in the characterization and modification of thin films made possible by recent experimental advances. The structural and electronic properties of two model systems are considered as examples: a-tC thin films grown by pulsed laser deposition (PLD) and poly aniline thin films grown by vapor deposition. First, scanning probe microscopies and x-ray scattering are used to investigate the structural aspects of a-tC films as a function of PLD growth conditions. The possible connection of nanoscale surface modification and characterization with electron emission properties will be discussed. Second, the results of inelastic scattering spectroscopy and other surface techniques will be discussed to obtain information on both interfacial aspects of the growth of polyaniline thin films and microscopic and macroscopic aspects of electrical conductivity upon doping. Comparisons will be made with other studies that address properties of analogous crystalline systems as appropriate. A brief assessment of the broader problem of analyzing these systems will be given.

We present the results of a post-deposition annealing structural study on amorphous tetrahedrally-coordinated carbon (a-tC) films on Si(100) prepared by pulsed-laser deposition. Films as-deposited and post-annealed at 200, 300, 400, 500 and 600 °C, respectively, are studied using combined x-ray reflectivity and low-angle scattering measurements. The scans are fit to the Fresnel equations to obtain values for average film density, film and interface thickness, and film and interface roughness. We observe a correlation between the evolution of film density, roughness and the spacing of quasi-periodic structures in the films as a function of annealing temperature. We relate the evolution of these structural features with previous measurements of the resistivity and the observed stress release in these films.

We present the results of an X-ray scattering study on partially confined smectic-A (layered) LC films. This partial confinement is achieved by placing the LC material inside the open grooves of a glass grating. Samples prepared in this manner are confined in the direction perpendicular to the gratings. Samples in which the LC is contained entirely inside the grooves develop an induced molecular tilt, which results in a compression of the smectic layers. The molecular tilt varies as the amount of the LC material increases, eventually forming a thin overlayer film above the gratings. As the thickness varies, a second region develops in the films. The layer spacing in this region is close to the bulk layer spacing. This structural evolution is coupled to a variation in the nematic-to-smectic-A phase transition temperature of the samples from the bulk. In addition, the nature of the phase transition is driven first order. The effects of partial confinement on a sm-C* LC film is discussed briefly.

We compare the microstructure of highly tetrahedrally-coordinated-amorphous carbon (atC) films prepared by pulsed laser deposition (PLD), measured using both small angle x-ray scattering (SAXS) and x-ray reflectivity, with other physical properties such as film stress and electrical resistivity. These properties are controlled by the film growth conditions and film thicknesses. Films prepared under vacuum conditions exhibit a shift in the measured mass density, as a function of laser energy density. The density for films approximately 600Å thick approach that of crystalline diamond. The measured densities for thicker, approximately 1000Å films, exhibit a smaller shift, and a lower density value. This shift correlates to observed changes in film stress and electrical resistivity. The small angle signal of the reflectivity spectra suggests the presence of layering, or in-plane density variations or a combination of both within the films.

Scanning Tunneling and Atomic Force Microscopy (STM, AFM) of amorphous tetrahedral carbon films (a-tC) film surfaces grown by pulsed laser deposition indicate extreme flatness and uniform electronic properties.1 This is consistent with the observed predominance of sp3 (diamond-like) bonding in these materials.2 Potential applications of a-tC films may be enhanced with the ability to modify their surfaces on the nanoscale. Exploiting the metastable nature of the sp3 hybridized state of carbon, the high flux electron beam from an STM tip was used to modify ˜100 nm regions; processing in air or in vacuum produces similar results. STM and AFM maps of the modified regions indicate stable morphologic and electronic structures consistent with a local transformation to sp2 (graphitic) hybridization. Surface potentiometric mapping of these regions indicates a correlation between electron dose and a lowering of the surface potential. In addition, spatially-resolved electron energy loss spectroscopy of the modified areas performed with a Scanning Auger Microscope shows plasmon energy shifts that confirm an elevated sp2 content in the modified regions.3

The structure and composition of tetrahedral-coordinated amorphous diamondlike carbon films (a-tC) grown by pulsed laser deposition (PLD) of graphite has been studied with atomic force microscopy (AFM). The nanometer-scale surface structure has been studied as a function of growth parameters (e.g., laser energy density and film thickness) using contact-mode and tapping-mode AFM. Although the surfaces were found to be generally smooth, they exhibited reproducible structural features on several size scales which correlate with the variation of laser energy and the effects of excited ion etching.

We performed an X-ray diffraction study of amorphous-tetrahedrally-coordinated carbon (a-tC) films prepared by pulsed laser deposition (PLD). The samples' properties were analyzed as a function of laser energy and thickness. For all thicknesses and laser energies, films were made up of clusters with a basic unit size of 7 -11 nm. Thicker films, as well as films prepared at higher laser densities exhibit larger clusters, in the tens of nanometers. The clusters are not readily observable by AFM, which may indicate the presence of a flat (graphitized) top film surface.

We have performed high resolution x-ray diffraction measurements of the strain field in UHV deposited Ag(111) films on a 7×7 reconstructed Si(111) surfaces shows a faulted epitaxial layer with a 0.4% out-of-plane strain, and a -1% in-plane strain. The strain field anisotropy is similar to that observed on epitaxial YSi2-x on Si(111), and is an unexpected result for the present system, due to the lack of a lattice match between the silver and silicon unit cells. The out-of-plane diffraction peaks have an angular distribution of 1.23°, full width at half maximum (FWHM), as determined from rocking curve measurements.

The development of integrated electronic devices has resulted in an increased interest in the study of ferroelectric ceramic films on silicon prepared by diverse methods. Some of these studies aim at the development of films whose ferroelectric properties equal or approximate those of the bulk ceramic. It is therefore important to attain a better understanding of the microstructure of these films and the relationship between the microstructure and the different film preparation methods. This study examines the strain field in such a film as a function of annealing time. The technique chosen was grazing incidence x-ray scattering (GIXS), and the material, thin films of BaTiO3 deposited on silicon (111) single crystals by metallo-organic deposition (MOD). The BaTiO3 {110} and {101} reflections were monitored. A substantial relaxation of the d-spacing of planes parallel to the surface was measured after a 64 hour annealing. The d-spacing of planes perpendicular to the surface remained essentially unchanged.

We have used high resolution grazing incidence x-ray scattering (GIXS) to study the in-plane and out-of-plane structure of epitaxial YSi2-x films grown on Si (111), with thicknesses ranging from 85Å to 510Å. Our results indicate that the films are strained, and that film strain increases as a function of thickness, with lattice parameters varying from a = 3.846Å/c = 4.142Å for the 85Å film to a = 3.877Å/c = 4.121Å for the 510Å film. We correlate these results with an increase in pinhole areal coverage as a function of thickness. In addition, our measurements show no evidence for the existence of ordered silicon vacancies in the films.