. 2012 May 28;2:426. doi: 10.1038/srep00426

Table 2. Nominal compositions, masses of starting materials, and synthetic conditions for A_xFe₂Se₂ (A = Li, Na, K, Ba, Sr, Ca, Yb, and Eu).

	Masses used
Nominal composition	Metal (g)	FeSe (g)	LA (ml)	Reaction duration (days)	T_c^onset(K)	Superconductive shielding fraction (10 K)	Composition characterized by ICP-AES
LiFe₂Se₂	0.0077	0.3001	15	8	44	32%	-
Na_0.5Fe₂Se₂	0.0175	0.4001	15	3	45	∼34%	Na_0.42Fe₂Se_1.88
NaFe₂Se₂	0.0272	0.3002	15	6	46	50%	Na_0.61Fe₂ Se_1.9
NaFe₂Se₂	0.0258	0.3002	15	3	46	40%	Na_0.69Fe₂ Se_1.96
NaFe₂Se₂	0.0259	0.3006	15	4	46	27%	Na_0.8Fe₂ Se₂
K_0.5Fe₂Se₂	0.0220	0.3000	10	13	29	1.5%	-
KFe₂Se₂	0.0290	0.3999	15	2.5	40	11%	-
KFe₂Se₂	0.0290	0.3999	15	2.5	30	2.5%	-
Ca_0.5Fe₂Se₂	0.0226	0.3000	10	2	∼40	4%	-
Sr_0.5Fe₂Se₂	0.0491	0.3010	15	8	∼35	10%	-
Sr_0.8Fe₂Se₂	0.0814	0.3131	15	13	38	60%
Ba_0.5Fe₂Se₂	0.0509	0.2000	10	8	40	25%	Ba_0.48Fe₂Se_1.16
Ba_0.8Fe₂Se₂	0.1219	0.3000	10	4	39	62%	Ba_0.64Fe₂Se_1.62
EuFe₂Se₂	0.0843	0.3001	15	10	40	8%	-
Yb_0.5Fe₂Se₂	0.0963	0.3000	15	10	42	7%	-
Yb_0.8Fe₂Se₂	0.1365	0.2658	10	10	42	5%	-
FeSe (soaked in LA)	-	0.2000	10	17	8.5^◊	-	-

The superconductive shielding fraction was estimated at 10 K from ZFC curve. ICP-AES, inductively coupled plasma atomic emission spectrometer.

Samples synthesized without shaking.

Same sample measured before and after 1 hour's exposure to air (see Supplementary Fig. S3).

◊ SC due to β-FeSe.

Table 2. Nominal compositions, masses of starting materials, and synthetic conditions for AxFe2Se2 (A = Li, Na, K, Ba, Sr, Ca, Yb, and Eu).