Albanese Elisa, Ruiz Puigdollers Antonio, Pacchioni Gianfranco
Dipartimento di Scienza dei Materiali, Università di Milano-Bicocca, via R. Cozzi 55, 20125 Milano, Italy.
ACS Omega. 2018 May 17;3(5):5301-5307. doi: 10.1021/acsomega.8b00667. eCollection 2018 May 31.
Bulk ZrO is both nonreducible and nonmagnetic. Recent experimental results show that dopant-free, oxygen-deficient ZrO nanostructures exhibit a ferromagnetic behavior at room temperature (RT). Here, we provide a comprehensive theoretical foundation for the observed RT ferromagnetism of zirconia nanostructures. ZrO nanoparticles containing up to 700 atoms (3 nm) have been studied with the help of density functional theory. Oxygen vacancies in ZrO nanoparticles form more easily than in bulk zirconia and result in electrons trapped in 4d levels of low-coordinated Zr ions. Provided the number of these sites exceeds that of excess electrons, the resulting ground state is high spin and the ordering is ferromagnetic. The work provides a general basis to explain magnetism in intrinsically nonmagnetic oxides without the help of dopants.
块状氧化锆既不可还原也无磁性。最近的实验结果表明，无掺杂、缺氧的氧化锆纳米结构在室温下表现出铁磁行为。在此，我们为观察到的氧化锆纳米结构的室温铁磁性提供了全面的理论基础。借助密度泛函理论研究了含有多达700个原子（3纳米）的氧化锆纳米颗粒。氧化锆纳米颗粒中的氧空位比块状氧化锆中更容易形成，并导致电子被困在低配位锆离子的4d能级。如果这些位点的数量超过多余电子的数量，所产生的基态就是高自旋的，且有序排列是铁磁性的。这项工作为解释本征非磁性氧化物中的磁性提供了一个通用的基础，而无需掺杂剂的帮助。
