Synthesis of Bulk Superconducting LiNbO$_2$ Crystals through CaH$_2$ Reduction

Ryan Paxson; Stephanie J. Hong; Bicky S. Moirangthem; Parham Kabirifar; Saya Takeuchi; Tianyu Li; Chih-Yu Lee; Haotong Liang; Keenan Avers; Kamal R. Joshi; Amlan Datta; Makariy A. Tanatar; Shanta Saha; Joseph A. Dura; Peter Zavalij; Johnpierre Paglione; Ruslan Prozorov; Alexander J. Grutter; Efrain E. Rodriguez; Ichiro Takeuchi

arXiv · 2607.06819

Synthesis of Bulk Superconducting LiNbO$_2$ Crystals through CaH$_2$ Reduction

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Abstract

We have synthesized layered superconducting LiNbO$_2$ crystals through a bulk phase transformation from LiNbO$_3$ single crystals via CaH$_2$ reduction. As the Nb valence is reduced from 5+ to 3+, the material undergoes a structural transformation to the resulting product, LiNbO$_2$, which is accompanied by metallic behavior and a superconducting transition, Tc onset, as high as 14.4 K. Secondary ion mass spectroscopy (SIMS) and X-ray photoelectron spectroscopy (XPS) show that the resulting phase is hole-doped through de-lithiation during the reduction. Magnetization and AC susceptibility measurements from a tunnel diode resonator confirm the bulk nature of superconductivity with a superconducting volume fraction of approximately 77% and an upper critical field approaching 26 T. Our study demonstrates extreme hydride reduction as an effective method to induce phase transformations with non-topotactic pathways and can be used to synthesize bulk materials with exotic properties.

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Ryan Paxson, Stephanie J. Hong, Bicky S. Moirangthem, Parham Kabirifar, Saya Takeuchi, Tianyu Li, Chih-Yu Lee, Haotong Liang, Keenan Avers, Kamal R. Joshi, Amlan Datta, Makariy A. Tanatar, Shanta Saha, Joseph A. Dura, Peter Zavalij, Johnpierre Paglione, Ruslan Prozorov, Alexander J. Grutter, Efrain E. Rodriguez, Ichiro Takeuchi. 2026-07-07. Synthesis of Bulk Superconducting LiNbO$_2$ Crystals through CaH$_2$ Reduction. https://arxiv.org/abs/2607.06819

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