This study addresses a perennial problem in the synthesis of copper vanadates, namely, that of phase purity. A time-efficient solution combustion synthesis (SCS) was employed for obtaining α-CuV2O6 in a polycrystalline powder form in a matter of minutes. Admixture of the final product with α-Cu2V2O7 or V2O5 was avoided by a combination of careful pH control of the SCS precursor mixture and by a postsynthesis NaOH wash. The phase purity of the resultant product was demonstrated by Rietveld refinement of the X-ray diffraction data, energy-dispersive X-ray analyses, and laser Raman spectroscopy. Photoelectrochemical (PEC) measurements showed the material to be an n-type semiconductor. Possible applicability of α-CuV2O6 in PEC devices designed for solar water splitting hinges on a comprehensive study of its structural, optical, magnetic, and optoelectronic attributes; this was done by a combination of theory and experiment. Intensity-modulated photocurrent spectroscopy on thin film samples permitted an assessment of the balance between charge transfer and surface recombination, underlining that the charge separation efficiency determined the photocurrent magnitude. Finally, experiments on the PEC stability of this material on prolonged (∼4 h) irradiation revealed self-healing behavior induced by incipient photocorrosion product layer formation on the oxide semiconductor surface.

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Eu-based compounds often exhibit unusual magnetism, which is critical for nontrivial topological properties seen in materials such as EuCd 2 As 2 . The authors investigate the structure and physical properties of EuZn 2 As 2 through measurements of the electrical resistivity, Hall effect, magnetization, and neutron diffraction. Their data show that EuZn 2 As 2 orders antiferromagnetically with an A-type spin configuration below T N = 19 K. Surprisingly, there is strong evidence for dominant ferromagnetic fluctuations above T N , as reflected by positive Curie-Weiss temperature and extremely large negative magnetoresistance (MR) between T N and T fl ≈200 K. Furthermore, the angle dependence of the MR ab indicates field-induced spin reorientation from the ab-plane to a direction ≈45°from the ab plane. Compared to EuCd 2 As 2 , the doubled T N and T fl make EuZn 2 As 2 a better platform for exploring nontrivial magnetic and electronic properties in both magnetic fluctuation (T N < T < T fl ) and ordered (T < T N ) regimes.

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