NON-TECHNICAL DESCRIPTION: With the exponential growth of information technologies, the ability to store huge amounts of data is becoming a major societal need. Phase-change materials are some of the most promising materials for future data-storage applications. They are the key component enabling high density optical data storage such as rewritable DVD (digital versatile disc) and nonvolatile computer memories (phase-change random access memory (PC-RAM)). However, they currently suffer from aging issues that lead to degradation over time and eventually to data loss. This research aims at developing a new generation of phase-change materials that are immune to this data-loss phenomenon. Moreover, such materials can enable emerging technologies (high density multilevel memories and ultrafast, artificial neuron-like processors) that rely on highly stable phase-change materials. Through the process of conducting this research, graduate students are being trained in the field of materials science and engineering. Materials expertise is in high demand in high technology sectors such as the microelectronic industry. TECHNICAL DETAILS: The discovery of phase-change materials exhibiting a pronounced fragile-to-strong transition is key to the development of memory devices that are immune to the data-loss phenomenon currently plaguing memory technologies. The discovery of these new materials is achieved by characterizing the thermodynamic and structural behavior of families of phase change materials. The goal is to identify materials that are immune to structural relaxation. These materials are key in enabling emerging technologies that rely on fractional changes in physical properties and are particularly sensitive to drift. This research therefore supports the development of transformational new technologies such as artificial neural-network processor for ultra-fast computing. From a fundamental point of view, this research provides key insight into the origin of fragile-to-strong transitions and answers outstanding related questions in glass science such as the origin of beta-relaxation and polyamorphism. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.