Quasicrystalline phase-change memory

Abstract

phase-change memory utilizing amorphous-to-crystalline phase-change processes for reset-to-set operation as a nonvolatile memory has been recently commercialized as a storage class memory. Unfortunately, designing new phase-change materials (PCMs) with low phase-change energy and sufficient thermal stability is difficult because phase-change energy and thermal stability decrease simultaneously as the amorphous phase destabilizes. This issue arising from the tradeoff relationship between stability and energy consumption can be solved by reducing the entropic loss of phase-change energy as apparent in crystalline-to-crystalline phase-change process of a Gete/Sb 2 te 3 superlattice structure. A paradigm shift in atomic crystallography has been recently produced using a quasi-crystal, which is a new type of atomic ordering symmetry without any linear translational symmetry. This paper introduces a novel class of PCMs based on a quasicrystalline-toapproximant crystalline phase-change process, whose phase-change energy and thermal stability are simultaneously enhanced compared to those of the Gete/Sb 2 te 3 superlattice structure. This report includes a new concept that reduces entropic loss using a quasicrystalline state and takes the first step in the development of new PCMs with significantly low phase-change energy and considerably high thermal stability.

Emerging role of air pollution and meteorological parameters in COVID‐19

“…Many studies have examined the association between NO 2 and COVID‐19 66 , 10–74 . NO 2 , an endogenously generated oxidant, has a potential impact on COV19 epidemic transmission 75 .…”

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