Armin Anwar Qualifier Exam

Abstract: Praseodymium Nickelate (PrNiO₃), part of the broader RNiO₃ (R = rare earth) perovskite family,

could be a benchmark for studying the interplay between structure, electronic correlations, and

emergent quantum phases. RNiO₃ (R≠La) compounds exhibit a temperature-driven metal-insulator

(M–I) transition, which systematically shifts with the size of the rare-earth ion due to lanthanide

contraction, directly affecting the Ni–O–Ni bond angles and bandwidth. Among these, PrNiO₃ lies

near the boundary of metallic and insulating behavior, making it highly susceptible to external

tuning via doping or strain. Furthermore, these nickelates are characterized by strong Ni 3d–O 2p

hybridization, resulting in a mixed-valence ground state that includes both Ni³⁺O2- (3d⁷2P6) and

Ni²⁺O- (3d⁸L) configurations. In this study, we aim to investigate the effects of isoelectronic- and

hole- doped series of Pr1-xAxNiO3 (where A: Ca2+, Sr2+, Ba2+, La3+, Y3+, Eu3+) to probe how

different dopants influence the electronic, magnetic, and potentially superconducting properties.

Motivated by the recent discovery of superconductivity in infinite-layer nickelate thin films (e.g.,

Nd₀.₈Sr₀.₂NiO₂), this work aims to understand how chemical doping alters the electronic phase

diagram of PrNiO₃. Polycrystalline bulk samples were prepared using a sol-gel citrate/nitrate

precursor that was then subjected to high oxygen pressure (150-200 bar), high temperature (950◦C

− 1050◦C) conditions, enabling precise control over phase formation and oxygen stoichiometry.

Throughout the investigation, special emphasis will be placed on the roles of lattice strain, Ni–O

covalency, and carrier concentration in suppressing the metal-insulator transition and enabling new

quantum ground states.