Topological Photoluminescence and Slow Magnetic Relaxation in a Quasi One-Dimensional Stoichiometric Ternary Tb(III) Cyanamide

Abstract

Technological advances are intangibly linked to the preparation and description of new solid-state materials. Recently, low-dimensional lanthanide-based systems have received particular attention for their interesting magnetic and luminescent properties. Thus, motivated by the emergence of such “NCN” chemistry, we present the synthesis of the stoichiometric Tb(III) cyanamide Li_xNa_1–xTb(NCN)₂, which crystallizes in an orthorhombic structure where the magnetic Tb³⁺ ions are arranged in well-separated one-dimensional chains parallel to the c axis. Luminescence studies show phosphor-like behavior with a process of energy migration probed to be one-dimensional due to the large difference in the size of the intra- and interchain transfer probabilities. As a consequence, a long luminescent lifetime of 1.22 ms was observed at 100 K. In contrast, AC magnetic susceptibility studies reveal a slow magnetic relaxation process, with a relaxation time of 4.03 μs, thus establishing a good correlation between the compound’s 1D structure and its luminescent and magnetic properties. This work represents a fine example of a Tb(III)-based solid-state cyanamide compound exhibiting slow magnetic relaxation and slow radiative decay.