"This is an example of what you don't want to see," says Luz Martínez-Miranda, holding up a slide with a squiggly, copper-colored metal squished between two pieces of glass: a liquid crystal sample had short circuited. When an experiment doesn't work, "many students feel like it's a bad thing," she says. "I tell them 'that's research: no one has shown if this works or how it works.'"
For Martínez-Miranda, the occasional short circuit is a part of discovery. She has studied liquid crystals for most of her professional life, which now centers at the Department of Materials Science and Engineering at the University of Maryland in College Park, Maryland.
"What fascinates me is the fact that you can get something with a crystal structure and still have a liquid," says Martínez-Miranda, who lives in Rockville, Maryland, with her dog Simon — a bright white, thick-coated Samoyed.
To view liquid crystals, she uses a polarizing microscope that magnifies 200 times or more; polarized lenses block out light, so she can view samples that can look a bit like ice crystals on a window, depending on the phase. If you excite the crystals and nanometer particles with changing temperature or magnetic fields, a kaleidoscopic display of colors and structures takes shape. The associate professor shares this phenomenon with her students, who peer into microscopes under her watch.
When she came to the University of Maryland in 1995, Martínez-Miranda helped design the junior materials laboratory; now, she teaches lab and materials courses, and advises undergraduates.
Her interest in nanometer particles — about five to 10 times an atom in size — began eight years ago, when Martínez-Miranda decided to see what would happen when she combined inorganic nanometer particles with the organic liquid crystals. With an X-ray machine, she tests liquid crystal films for structure, and to see how the films are affected by nanoparticles.
While many scientists are working on the interactions of disordered liquid crystals, Martínez-Miranda and her colleagues have found a niche working on the interactions of ordered liquid crystals and nanoparticles. "Our group is still at the edge," she says, riding the crest of a new research wave.
The advantage to ordered liquid crystals is that they help conduct electrons: in ordered crystals, electrons can travel smoothly through the material. In unordered liquid crystals, the electron's path is constantly interrupted, so the electron never reaches the other electrodes.
Putting this advantage to work, she and a colleague are working to create uses for ordered liquid crystals in photovoltaics.
"Solar cells made of solid state materials are expensive to fabricate because they are prepared in a clean room, where you need to prep the different layers and have them free of impurities," she says, and these materials are also less efficient. So Martínez-Miranda and her team are trying to net as much solar energy efficiency as possible using ordered liquid crystals, which don't require as much equipment for fabrication.
Martínez-Miranda's passion for science started with her chemist parents. After a childhood in Maryland, her family moved to Puerto Rico, where a high school physics teacher piqued her affinity for physics by starting the course with optics and light, instead of the customary vector sum lessons.
As she pursued physics in at the University of Puerto Rico's Río Piedras campus, she also studied music at the Conservatory of Music of Puerto Rico, earning a degree in musical performance at the same time that she finished her physics master's degree. Though she specialized in piano performance, her true musical passion became playing harpsichord with Baroque groups.
Her love of music crescendoed, but her career path clung to science. While working on her Ph.D. at the Massachusetts Institute of Technology, she found advisor Robert Birgeneau, whose zeal for liquid crystal science won her over. "He had a way of being very enthusiastic, very animated about this field," she recalls. That enthusiasm stayed with her through her work at the University of California at Berkeley, the Naval Research Laboratory, and other locations, before landing at the University of Maryland.
International conferences have lured her around the world. Last year, Martínez-Miranda and collaborators organized a National Science Foundation-sponsored physics conference in Puerto Rico for people from all over the Americas; a similar 2014 Argentina conference is in planning stages. This spring, in South Africa, she was part of the U.S. delegation at the International Union of Pure and Applied Physics' International Conference on Women in Physics.
"We have more young women going into physics and the engineering fields," Martínez-Miranda says, but change has been gradual. She recalls listening to a discussion on women in science about five years ago, and heard the same complaints of women scientists in the 1980s — including one woman scientist who reported feeling ignored by male colleagues, who assumed she had a non-leadership role. "I thought that we had crossed a threshold, but we're not quite there yet," Martínez-Miranda says.
It helps, though, when a student sees a scientist role model that looks like him or her: "They feel like they can make it," she says.