350

300

250

150

Pressure (GPa)

Ref. [18]

1.54

1.82

2.38

2.05 (this work)

λ_opt

Ref. [18]

1428

1373

1270

1160 (this work)

ϖ (K)

Equation (7)

119

144

164

133

$T_c^{°}$ (K)

Equation (9)

151

195

266

250

T_c(K)

Equation (8)

0.447

0.460

0.480

0.442

α

Equation (11)

0.35

0.35

0.36

0.35

α