2026-09-22T11:40:50Z https://www.ideals.illinois.edu/oai-pmh

oai:www.ideals.illinois.edu:2142/122107 2024-03-02 col_2142_5131 col_2142_13836 com_2142_5130 com_2142_13835 com_2142_234

Shoemaker, Daniel P Shoemaker, Daniel P Goldschmidt, Elizabeth A Schleife, André Shim, Moonsub 2023-12 application/pdf en text Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2025-12-01 The student, Zachary Riedel, accepted the attached license on 2023-11-10 at 10:34. The student, Zachary Riedel, submitted this Dissertation for approval on 2023-11-10 at 10:37. This Dissertation was approved for publication on 2023-11-16 at 10:16. DSpace SAF Submission Ingestion Package generated from Vireo submission #19901 on 2024-03-01 at 13:29:35 Designing stoichiometric Eu3+ materials for dense, optically addressable quantum memory Riedel, Zachary W. Quantum Memory Lanthanides Rare-earths Crystal Growth Materials Design Photoluminescence Diffraction Density Functional Theory 2023-11-16 Rare-earth elements are well suited for building long-lived quantum memory. Their filled 5s and 5p orbitals shield their 4f-4f orbital optical transitions from external influences, leading to long, millisecond-scale optical transition coherence times. Here, we diverge from typical rare-earth doping approaches by using stoichiometric rare-earth compounds for quantum memory systems. Instead of containing low concentrations of randomly dispersed rare-earth cations, stoichiometric systems drastically increase the rare-earth density while improving homogeneity by reducing local strain and point defects. Improved homogeneity then narrows the inhomogeneous linewidth of the optical transitions. For a stoichiometric Eu3+ compound with an ultra-narrow inhomogeneous linewidth, we can resolve optically addressable transitions between nuclear spin states, which have up to hours-long coherence times. But the only compound reported to have the necessary linewidth, Eu35Cl3·6H2O, has practical limitations. To search for new candidates, I began by looking for known Eu3+ compounds with large distances between Eu3+ cations in the crystal lattice. I grew single crystals of the metal-organic frameworks Eu(HCOO)3·(HCONH2)2 and Eu(HCOO)3 from heated solutions. Both have optical lifetimes >1.4 ms at 1.4 K, but only Eu(HCOO)3 is stable in air. I then improved the Eu(HCOO)3 synthesis procedure, producing transparent, well-faceted crystals at room temperature. The second system from my initial search was the layered oxide EuAl3(BO3)4. Growing EuAl3(BO3)4 crystals from two flux systems, I showed that coherent polymorph domains shift the Eu3+ site symmetry within a single crystal. I also used a flux growth procedure to isolate the material’s C2/c polymorph and helped develop a new procedure for synthesizing polycrystalline EuAl3(BO3)4 in a conventional microwave. To limit linewidth broadening from isotopes, I next proposed unrealized stoichiometric Eu3+ candidates containing mononuclidic ions and used DFT to predict their stability, navigating the computational challenges posed by 4f electrons. I then synthesized the new, DFT-predicted double perovskite Cs2NaEuF6. From my DFT calculations and a search of the Materials Project database, I identified phosphates and iodates as the next chemical spaces to search for narrow linewidth compounds. I synthesized crystals of two iodates, NaEu(IO3)4 and Eu(IO3)3, both of which have a high intensity 5D0→7F0 transition at room temperature. My synthesized candidates span a variety of chemical spaces and are platforms for studying the influence of structural motifs and defect chemistry on the inhomogeneous linewidth, providing a pathway to discovering ultra-narrow linewidth compounds. Text eng https://hdl.handle.net/2142/122107 Copyright 2023 Zachary W. Riedel Ph.D. Dissertation Materials Science & Engr University of Illinois at Urbana-Champaign Materials Science & Engineerng