The delafossites are a class of layered metal oxides that are notable for being able to exhibit optical transparency alongside an in-plane electrical conductivity, making them promising platforms for the development of transparent conductive oxides. Pressure-induced polymorphism offers a direct method for altering the electrical and optical properties in this class, and although the copper delafossites have been studied extensively under pressure, the silver delafossites remain only partially studied. We report two new high-pressure polymorphs of silver ferrite delafossite, AgFeO₂, that are stabilized above ∼6 and ∼14 GPa. In situ X-ray diffraction and vibrational spectroscopy measurements are used to examine the structural changes across the two phase transitions. The high-pressure structure between 6 and 14 GPa is assigned as a monoclinic C2/c structure that is analogous to the high-pressure phase reported for AgGaO₂. Nuclear resonant forward scattering reveals no change in the spin state or valence state at the Fe³⁺ site up to 15.3(5) GPa.

中文翻译：

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银铁氧体铜铁矿 (AgFeO2) 的高压多晶现象


铜铁矿是一类层状金属氧化物，以能够表现出光学透明性和面内导电性而著称，这使其成为开发透明导电氧化物的有希望的平台。压力诱导的多晶型现象提供了改变此类电学和光学性质的直接方法，尽管铜铜铁矿在压力下已得到广泛研究，但银铜铁矿仍仅得到部分研究。我们报告了两种新的银铁氧体铜铁矿高压多晶型物 AgFeO ₂ ，它们稳定在 ~6 和 ~14 GPa 以上。原位 X 射线衍射和振动光谱测量用于检查两个相变期间的结构变化。 6 至 14 GPa 之间的高压结构被指定为单斜 C2/c 结构，类似于 AgGaO ₂ 报道的高压相。核共振前向散射显示 Fe ³⁺ 位点的自旋态或价态在高达 15.3(5) GPa 时没有变化。