Synthesis,
Structural Characterization, and Physical
Properties of the New Transition Metal Oxyselenide Ce<sub>2</sub>O<sub>2</sub>ZnSe<sub>2</sub>
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Abstract
The
quaternary transition metal oxyselenide Ce<sub>2</sub>O<sub>2</sub>ZnSe<sub>2</sub> has been shown to adopt a ZrCuSiAs-related
structure with Zn<sup>2+</sup> cations in a new ordered arrangement
within [ZnSe<sub>2</sub>]<sup>2–</sup> layers. The color of
the compound changes as a function of cell volume, which can vary
by ∼0.4% under different synthetic conditions. At the highest,
intermediate, and lowest cell volumes, the color is yellow-ochre,
brown, and black, respectively. The decreased volume is attributed
to oxidation of Ce from 3+ to 4+, the extent of which can be controlled
by synthetic conditions. Ce<sub>2</sub>O<sub>2</sub>ZnSe<sub>2</sub> is a semiconductor at all cell volumes with experimental optical
band gaps of 2.2, 1.4, and 1.3 eV for high, intermediate, and low
cell volume samples, respectively. SQUID measurements show Ce<sub>2</sub>O<sub>2</sub>ZnSe<sub>2</sub> to be paramagnetic from 2 to
300 K with a negative Weiss temperature of θ = −10 K,
suggesting weak antiferromagnetic interactions
