Table 1. Comparison of Parameters Extracted for Pr⁴⁺ from This Work with Other 4f-Based RE Ions^a.

RE ion	host lattice	excited state (cm–1)	AJ (MHz)	gav	T (K)	T1 (ms)	Tm (μs)	T* (K)	ref
Pr4+	BaSnO3	∼2000	∼1800	∼0.58	5	∼33	∼18	∼60	this work
Ce3+	CaWO4	53–135	N/A	∼1.4	5	∼24.7	∼14.2	∼18	(42)
Nd3+	Y2SiO5	∼77	∼530	∼2.6	5	∼30	∼106	∼7	(16)
Gd3+	CaWO4	∼33,000d	∼15	∼2	6	∼8	∼5.4	∼70	(43)
Gd3+	trensalb	∼33,000d		∼2	5	∼0.03	∼12	>30	(44)
Gd3+	sTPATCN	∼33,000d		∼2	7	∼0.36	∼18.3	>50	(45)
Er3+	CaWO4	∼19	∼125	∼5	3.5		∼7 (50)e		(11)
Yb3+c	Y2SiO5	∼115	∼500	∼4	5	∼7	∼10 (73)e	∼9	(18)
Yb3+c	trensalb	∼500	∼600	∼3.8	5	∼0.4	∼0.5	20	(46)

^aT* corresponds to the temperature at which T_m is limited by T₁ given by T_m/T₁ = 1.

^bMolecular complex.

^cValue reported for ¹⁷¹Yb.

^dFor Gd³⁺, the excited state corresponds to the SOC multiplet and not a CF excited state. Given the ⁸S_7/2 GS, the CF splitting is usually very small. This minimizes mixing from the excited ⁶P_7/2 and ⁶D_7/2 SOC multiplets and has been proposed to suppress decoherence due to the vanishing orbital angular momentum.

^eThe values in the parenthesis correspond to the maximum value reported but measured at a lower temperature of 2–3 K. For a more direct comparison, the table is constructed with values reported at the base temperature of this study at T = 5 K.