We demonstrate ferroelectricity in Mg-substituted ZnO thin films with the wurtzite structure. Zn_1−xMg_xO films are grown by dual-cathode reactive magnetron sputtering on (111)-Pt // (0001)-Al₂O₃ substrates at temperatures ranging from 26 to 200 °C for compositions spanning from x = 0 to x = 0.37. X-ray diffraction indicates a decrease in the c-lattice parameter and an increase in the a-lattice parameter with increasing Mg content, resulting in a nearly constant c/a axial ratio of 1.595 over this composition range. Transmission electron microscopy studies show abrupt interfaces between Zn_1−xMg_xO films and the Pt electrode. When prepared at pO₂ = 0.025, film surfaces are populated by abnormally oriented grains as measured by atomic force microscopy for Mg concentrations >29%. Raising pO₂ to 0.25 eliminates the misoriented grains. Optical measurements show increasing bandgap values with increasing Mg content. When prepared on a 200 °C substrate, films display ferroelectric switching with remanent polarizations exceeding 100 μC cm⁻² and coercive fields below 3 MV cm⁻¹ when the Mg content is between ∼30% and ∼37%. Substrate temperature can be lowered to ambient conditions, and when doing so, capacitor stacks show only minor sacrifices to crystal orientation and nearly identical remanent polarization values; however, coercive fields drop below 2 MV/cm. Using ambient temperature deposition, we demonstrate ferroelectric capacitor stacks integrated directly with polymer substrate surfaces.

Two-dimensional CuFeSe₂ nanosheets have been successfully obtained via solution-phase synthesis using a sacrificial template method. The high purity was confirmed by X-ray diffraction and the two-dimensional morphology was validated by transmission electron microscopy. The intense absorption in the 400–1400 nm region has been the basis for the CuFeSe₂ nanosheets’ photothermal capabilities testing. The colloidal CuFeSe₂ (CFS) nanosheets capped with S²⁻ short ligands (CFS-S) exhibit excellent biocompatibility in cell culture studies and strong photothermal effects upon 808 nm laser irradiation. The nanosheets were further loaded with the cancer drug doxorubicin and exposed to laser irradiation, which accelerated the release of doxorubicin, achieving synergy in the therapeutic effect.