posted on 2024-02-22, 18:43authored byZhen Song, P. A. Tanner, Quanlin Liu
Cr3+ doped near-infrared phosphors hold significant
applications and generate considerable research interest. The critical
parameter for assessing the strength of the crystal field for Cr3+ in the Tanabe–Sugano diagram is the boundary value
of Dq/B, representing the ratio of crystal field splitting to the
Racah parameter B. Nevertheless, there are conflicting values for
this parameter, as reported in various studies, such as 2.1, 2.2,
and 2.3 for C/B = 4.5–4.8. Moreover, some Cr3+ doped
phosphors with wide-band emissions exhibit a Dq/B value that falls
within the region of a contradictory strong field. In this study,
we numerically determine the boundary value of Dq/B, which distinguishes
between strong and weak fields. The results then demonstrate a dependence
on the host material and are correlated with the values of Racah parameters
B and C. This work resolves the inconsistency between the boundary
values of Dq/B and the emission profile of Cr3+, providing
researchers with a more profound comprehension of Cr3+ luminescence.