A new family of magnetic semiconductors, K
2Cd
3(1-x)Mn
3xS
4, prepared from molten K
2S
xis reported. For
x ![](/images/entities/le.gif)
0.6, the compounds crystallize in the K
2Cd
3S
4 structure type. The cellvolumes of the series obey Vegard's Law for solid solutions. The compounds range in colorfrom yellow through orange brown to red and possess platelike morphologies. A structuraltransformation occurs between
x = 0.7 and
x = 0.9. Red plates of K
2Cd
0.4Mn
2.6S
4 (
x = 0.87)crystallize in the space group
Ccca with
a = 5.9217(8) Å,
b = 13.531(1) Å,
c = 11.0696(8) Å,and
V = 887.0(1) Å
3. The end member, K
2Mn
3S
4, crystallizes in the space group
Ccca with
a = 11.0637(7) Å,
b = 26.830(2) Å
c = 5.8180(4) Å, and
V = 1727 Å
3. For
x ![](/images/entities/le.gif)
0.6, thecompounds form as (M
3S
4)
n2n- layers, interspersed by K
+ cations. These layers are composedonly of M
3S
42- units shaped like truncated cubes. When
x = 0.87, a new structure related tothat of Cs
2Mn
3S
4 is observed. The end member of the series (i.e.,
x = 1) K
2Mn
3S
4 is revealedto have a related yet surprising structure. The compounds display room-temperature bandgaps ranging from 2.79 to 2.92 eV. Absorptions in the mid-gap region, due to Mn
2+-basedd-d transitions, are also observed. The compounds are strongly emissive in the visiblespectrum at room temperature, with the light emission shifted to the red immediately uponthe introduction of small amounts of manganese. The magnetic properties of these compoundsevolve from classical paramagnetic to spin glass as a function of
x. For
x ![](/images/entities/ge.gif)
0.05, thecompounds deviate from Curie-Weiss behavior. Antiferromagnetic coupling is observed inall cases. With very high Mn content transitions to magnetically complex phases are observedwith possible spin-glass-like behavior.