Complex palladium oxides are rare examples of oxides that can be easily hole-doped to drive insulator to metal transitions. However, the amount of dopant required to drive these transitions can vary widely. PdO will become metallic with as little as 1 mol % Li doping. Other palladium compounds require upwards of 20 mol % hole dopant to become metallic.<sup> </sup>In this work, the local structures of various complex palladium oxides are explored to inform the nature of these insulator-metal transitions and explain observed differences between structurally similar compounds. <sup>23</sup>Na solid state magic angle spinning nuclear magnetic resonance (MAS-NMR) allows for a direct probe of the chemical environment of the hole dopant throughout the course of the insulator-metal transition. Pair distribution function (PDF) analysis of neutron and x-ray total scattering data is used to observe differences in the local structure with increasing doping. Fitting of the PDF data reveals a relationship between the tendency to remain insulating with local deviations from the average crystal structure. Similar electronic structures calculated using density functional theory further emphasize the role of the local structure in the observed electronic properties. The relationships between electrical transport measurements, doping level, and local structure will be discussed.

Local structure influence on the insulator-metal transition in complex palladium oxides

251st National Meeting (2016)

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