Valency of YbB6

Towards a Single Chemical Model for Understanding Lanthanide Hexaborides

“…This picture signals the existence of a single bonding mode within YbB6, with Yb not switching valency through phonons and remaining either single valent, or divalent but such that some Yb atoms are Yb(II) and others are Yb(III), as suggested by some authors. 7,18 To the best of our knowledge, no Schottky anomalies have been reported for YbB6, in agreement with the model. 33,34 However, it has been noted that the heat capacity increases more rapidly than expected at 15 K, 34 and that at p >18 GPa a transition to a mixed-valent state occurs with an anomaly in the T2g mode for the B.…”

“…YbB6 has been proposed to be both Yb(II/III) mixed valent, and Yb(II) single valent. 7,17,18 The ELF in the YbB6 solid shows the same pattern as for EuB6 and SmB6 ( Figure S4A). The electron population in the B-B bond is 2.58 e -, very similar to that in EuB6 (2.54 e -).…”

“…Another unusual LnB 6 is YbB 6 , proposed to be a moderately correlated topological insulator, similar to SmB 6 , but with a larger bulk band gap [7] . There is a disagreement whether YbB 6 is single‐valent, Yb II , [17] or mixed‐valent, Yb II /Yb III [7, 18] …”

“…7 There is a disagreement whether YbB6 is single-valent, Yb(II), 17 or mixedvalent, Yb(II)/Yb(III). 7,18 Despite much theoretical research, [19][20][21] many features of LnB6 remain a mystery, and there is no unifying molecular-level framework that would simultaneously explain all their more and less exotic behaviors, and predict new ones. Here, we expect to advance in such unifying model of LnB6, and pave the way towards the rational discovery of new quantum phases with selected properties.…”

Pressure-induced quantum phase transitions in aYbB6single crystal

“…For the valence state of YbB 6 , we note that previous ARPES measurements and X-ray photoelectron experimentsat ambient pressure have established that the divalent Yb component is dominant in the bulk YbB 6 [43]. To know the pressure dependent valence state of Yb ions and especially clarify whether the high-pressure gapped phase is in a mixed valence state, we performed high-pressure X-ray absorption measurements at beamline 14W1 at Shanghai Synchrotron Radiation Facilities.…”