THE JUNIOR LABORATORY: A PLACE TO INTRODUCE BASICS AS WELL AS NEW FINDINGS Luz J. Martínez-Miranda, O. C. Wilson, Jr. and L. G. Salamanca-Riba Dept. of Materials Science and Engineering, University of Maryland Dept. of Materials Science and Engineering, University of Maryland College Park, MD College Park, MD

GOALS TO FAMILIARIZE STUDENTS WITH THE BASIC TECHNIQUES OF MATERIALS SCIENCE WHILE GIVING THEM A TASTE OF WHAT WE DO IN THE RESEARCH OF MATERIALS. -TO TEACH STUDENTS HOW TO COMMUNICATE THEIR RESULTS IN WRITING, AND ORALLY. -TO TEACH STUDENTS HOW TO DESIGN AN EXPERIMENT.

CHALLENGES: -HOW TO BE ABLE TO CHANGE SAMPLES, ADD TECHNIQUES, WITHOUT BURDENING THE STUDENTS -HOW TO DO THE ABOVE AND STILL TEACH THEM WHAT THEY NEED TO LEARN. -HOW TO KEEP THIS AS AN UNDERGRADUATE COURSE AND NOT A GRADUATE RESEARCH COURSE.

WHAT WE HAVE DONE… WE HAVE CHANGED THE SAMPLES OR THE APPROACH TO TEACHING IN THREE OF THE ~14 EXPERIMENTS WE OFFERWE HAVE CHANGED THE SAMPLES OR THE APPROACH TO TEACHING IN THREE OF THE ~14 EXPERIMENTS WE OFFER WE HAVE INTRODUCED AN ORAL PRESENTATION COMPONENT WHERE THE STUDENTS ARE ASKED TO RELATE A PARTICULAR EXPERIMENT WITH A RESEARCH RESULT AND HOW THEY WOULD GO USING THE TECHNIQUE TO STUDY IT.WE HAVE INTRODUCED AN ORAL PRESENTATION COMPONENT WHERE THE STUDENTS ARE ASKED TO RELATE A PARTICULAR EXPERIMENT WITH A RESEARCH RESULT AND HOW THEY WOULD GO USING THE TECHNIQUE TO STUDY IT. STUDENTS CAN SEE:STUDENTS CAN SEE: -THE IMPORTANCE OF THE TECHNIQUE IN THE PRESENT RESEARCH -THE MATERIALS THAT ARE STUDIED NOWADAYS -THE IMPORTANCE OF THE PROCESSING – STRUCTURE – PROPERTIES WHICH WE EMPHASIZE

Experiment Purpose: a.The relation between the processing and the structure observed. b.A dark field vs. a bright field image c. They determine the lattice parameters of the film and the islands, and learn how to determine it from the pictures and the diffraction pattern d.What is the error in their measurement. e. Observe defects, grain boundaries Before: Done with a semiconductor film Now: Done with an La 0.67 Sr 0.33 MnO 3 (LSMO) film that under certain growth conditions develops MnO columns Discussion: Effects on magnetic properties; observation of grain boundaries, defects Ref: Y. Li, et al., JMR, 15, 1524 (2000) TEM Prof. L. G. Salamanca-Riba

The students look at a transverse view of the sample (here shown from the reference) and a plan view (here shown from the pictures taken during their experiment). The plan view is a dark field showing the MnO particles

Optical microscopy Profs. Otto C. Wilson, Jr., R. Briber and L. J. Martinez-Miranda Experiment purpose: To learn to use optical microscopy to study phase transitions in different materials; to use birefringence to determine the phase change or the structure of a sample; how to associate the birefringence with the difference in index of refraction, and how to determine how a sample is oriented with respect to the surface. Before: Done with polymers and liquid crystals. Now: The polymer part stays. We use an inorganic polymer, AlFeOOH, which acts as a liquid crystal and also like collagen. Discussion: To begin to understand how the different alignments can lead to the different body parts. Ref: L. J. Martínez-Miranda, A. J. Douglas and O. C. Wilson, Jr., accepted in Molec. Cryst. Liq. Cryst. (2002).

a b c d e f Students observe the phase change from the isotropic (a) to the homoetropic phase (c-d) to the striped domain structure. They time the changes with the help of a video system.

RECTIFYING COMPONENTS : A NEW TWIST TO AN OLD PROBLEM (L. J. Martínez-Miranda) The students look at a p-n junction and at LED’s to observe the turn-on voltage. In addition, students study various rectifying components that have been prepared such that the density varies between 2.5 (samples 411 and 413) and 3.4 (sample 412). They observe the effect of the density on the turn-on voltage. Samples donated by Dr. J. Sullivan and Dr. M. P. Siegal, SNL

Rectifying components We also show them that the properties of the C films are changed not by changing the entire film but by the creation of nano islands of higher density, even at room temperature. Ref: M. P. Siegal, et al, Appl. Phys. Lett. 76, 2047 (2000); M. P. Siegal, et al. Appl Phys. Lett., 76, 3052 (2000); L. J. Martínez-Miranda, et al. Appl. Phys. Lett., 79, (2001).

X-ray diffraction L. J. Martínez-Miranda Experiment Purpose: to become familiar with the structural analysis of powders, textured samples and single crystals In the future: add crystals prepared using different chemical routes, some of them nanocrystalline. (This is done to a certain extent with the Cu samples, but we don’t explore the nanorange.) Discussion: See how the way it is processed affects the structure (including nanostructure), comparing the signal at low angle with the signal at high angle. Samples donated: Dr. Lynn Kurihara, NRL

The students get together and discuss their results, comparing how their samples were prepared, and how that is reflected on the samples’ structure or in its properties. This gives them an opportunity to practice their oral skills with their colleagues.

Conclusions We have shown, through the examples above, that we can change the material in various experiments without altering the basics we are teaching. We make the students aware that these techniques are used in our research to look into the properties of the materials. We have noticed that after the experiment the students ask us questions regarding the materials, or any other type of materials related to the experiments. We hope that the fact that they will also retain part of the basic lessons we want to teach them.

The TEM research was supported by the NSF-MRSEC grant No. DMR The TEM research was supported by the NSF-MRSEC grant No. DMR The rectifying components research was supported by the US DOE under contract No. DE-ACO4-94AL85000The rectifying components research was supported by the US DOE under contract No. DE-ACO4-94AL85000 The AlFeOOH microscope work was supported in part by an internal UMCP-GRB fund (for L. J. M. M.).The AlFeOOH microscope work was supported in part by an internal UMCP-GRB fund (for L. J. M. M.). We are very grateful to Dr. Lynn K. Kurihara, from NRL, Dr. Michael Siegal from SNL and Dr. J. P Sullivan from SNL for their interest and willingness to let us use some of their samples.We are very grateful to Dr. Lynn K. Kurihara, from NRL, Dr. Michael Siegal from SNL and Dr. J. P Sullivan from SNL for their interest and willingness to let us use some of their samples.