Alex’s co-authored paper was published at Physical Review Materials. Congrats!

Juan Schmidt, Alexander Horvath, Seok-Woo Lee, Sergey Bud’ko, Paul C. Canfield, “Room-temperature shape-memory effect in Sr(Ni1-xCux)2P2, Physical Review Materials (2026) – ACCEPTED [web]

Abstract: The compound SrNi2P2 can exhibit multiple crystal structures with no P-P pairs bonded (uncollapsed tetragonal, or ucT, state), with one-third of the P-P pairs bonded (one-third collapsed orthorhombic, or tcO, state), or with all P-P pairs bonded (collapsed tetragonal, or cT, state) across the Sr layers. The system can be tuned into its different states by changing temperature, mechanical stress, or chemical composition. Changes in bonding may manifest in changes of macroscopic properties of the material, such as its shape, electrical conductivity, or magnetism. In this work, we show that SrNi2P2 can be tuned among the three states by changing Cu substitution and temperature. We present temperature-dependent resistance and single-crystal x-ray diffraction results in Sr(Ni1−Cu)2P2 single-crystals that show that Cu substitution favors the P-P bonding, stabilizing the cT state at ambient pressure. We construct a T − x phase diagram that shows how all of these transition temperatures increase with increasing Cu fraction, x. The transition between the tcO state and the cT state exhibits a very large thermal hysteresis, which can be tuned to temperatures close to room temperature. In particular, the properties of Sr(Ni0.963Cu0.037)2P2 may make it suitable for applications as a shape memory material at room temperature.

Alex’s co-authored paper was published at Materials & Design. Congrats!

Lily Behnke, Ethen T Lund, Abinish K. Dutta, Joanna De LaTorre, Sungwoo Sohn, Alexander J. Horvath, Seok-Woo Lee, Jan Schroers  “Metallic glass wire-based springs,” Materials & Design 269 116626 (2006) [PDF] [web]

Abstract: We present the manufacturing, demonstration, and characterization of metallic glass (MG) springs. MG springs are manufactured by thermoplastically shaping MG wires, demonstrating exceptional performance in quality factor and elastic displacement. These springs are manufactured using two processes with differing resultant properties. The first is a single-step process that elastically and plastically deforms the MG wire at room temperature into a helical spring geometry, resulting in the formation of substantial shear band density where the remaining elastic stresses are then released upon heating. The second is a two-step process that incrementally deforms the MG wire entirely within the elastic regime at room temperature then applies heating and cooling cycles to realize a final shear-band-free geometry. The quality factor, spring constant, and maximum elastic force and displacement of these fabricated MG springs are compared to state-of-the-art spring steel and stainless-steel springs of the same geometry. We found that the elastically formed MG spring exhibits a higher quality factor (35%) and higher elastic displacement (2x) than state-of-the-art springs. The scalable, fast, and precise manufacturing processes presented in this work combined with the superior performance compared to state-of-the-art materials makes a strong case for the widespread use of MG springs.