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The Aurivillius compound PbxBi6−xFe0.5Co0.5Ti4O18 thin films were prepared via chemical solution deposition method and the influence of Pb2+ ions doping on the structure, ferroelectric and leakage properties were studied. With the increasing concentration of Pb2+ ions, the lattice distortion is increased and the growth of the films along ab plane is promoted. The calculation results show that the internal stress of the films increases with the increase of Pb2+ concentration. For the samples with low Pb2+ doping concentration (x < 0.6), the leakage current densities are also decreased, which can be attributed to the decrease in oxygen vacancy concentration. Due to the enhanced lattice distortion and decreased leakage current densities, the ferroelectric properties are improved. The film with x = 0.2 has a high saturation polarization of 42.3 µC/cm2. According to the fitting results, the leakage conduction mechanism is attributed to the combined effect of space-charge-limited conduction mechanism and ionic conduction mechanisms. [ABSTRACT FROM AUTHOR]

Different La 1-x Ba x MnO 3+δ nanopowders (with x = 0–0.20) were prepared using a traditional sol-gel method. Each sample had a size distribution between 50 and 80 nm with a single perovskite-type structure. The La 1-x Ba x MnO 3+δ based sensors showed excellent gas-sensing performance toward acetone (25–500 ppm) at 300 °C. It was also found that the La 0.80 Ba 0.20 MnO 3+δ sensor exhibited a fast response (≈25 s) and recovery time (≈15 s) in the presence of 100 ppm acetone gas, while the response value of the La 0.80 Ba 0.20 MnO 3+δ sensor to 500 ppm acetone reached 1350%. Moreover, these sensors also had good reproducibility and sensitivity to acetone. It reveals that Ba2+ as doping agent can partially convert Mn3+ to Mn4+, introducing numerous hole carriers into the p-type LaMnO 3+δ semiconductor and increasing the amount of chemisorbed oxygen ions on the surface, which can enhance the response of the sensor toward acetone. Moreover, this doping effect may also increase the hybridization of Mn 3d - O 2p orbits and double exchange interaction existing in the hybrid Mn3+/Mn4+ system, thereby promoting the carriers' conduction rate and gas sensing speed. These results suggest that the La 1-x Ba x MnO 3+δ perovskite-type structures can have large applicability in industrial acetone sensing. [ABSTRACT FROM AUTHOR]

Titanium‐based catalysts are needed to achieve electrocatalytic N2 reduction to NH3 with a large NH3 yield and a high Faradaic efficiency (FE). One of the cheapest and most abundant metals on earth, iron, is an effective dopant for greatly improving the nitrogen reduction reaction (NRR) performance of TiO2 nanoparticles in ambient N2‐to‐NH3 conversion. In 0.5 m LiClO4, Fe‐doped TiO2 catalyst attains a high FE of 25.6 % and a large NH3 yield of 25.47 μg h−1 mgcat−1 at −0.40 V versus a reversible hydrogen electrode. This performance compares favorably to those of all previously reported titanium‐ and iron‐based NRR electrocatalysts in aqueous media. The catalytic mechanism is further probed with theoretical calculations. [ABSTRACT FROM AUTHOR]

Zn1 − xMnxO (x = 0.002–0.01) nanoparticles were synthesized by co-precipitation method. The detailed crystal structure and compositional characterizations were characterized by the XRD patterns, Raman spectra, XPS, HRTEM and SEM. the XRD and XPS results show the Mn2+ ions are substitute for Zn2+ ions in the ZnO matrix. In the Raman spectra, the E2(high) peak shifts to lower frequency and the higher intensity of A1(LO) peak appears in the sample with increasing doping concentrations of Mn, indicating a higher concentration of donor defects are introduced in ZnO nanoparticles. Then, the carrier concentration induced by oxygen vacancies are analyzed from the optical absorption spectra. By analyzing the O1s XPS spectrum by Lorentz fitting and PL spectra by Gaussian fitting, the oxygen vacancy concentration increases with Mn doping concentration. The present results suggest that the doped Mn2+ ions play a significant role on enhancing the carrier concentration of ZnO materials. [ABSTRACT FROM AUTHOR]

(Mn, Co) co-doped ZnO nanoparticles (NPs) were synthesized using the sol-gel method. Rietveld refined XRD patterns indicated that the NPs exhibited hexagonal wurtzite structures. Co and Mn ions were successfully introduced into the ZnO NPs at different concentrations. Moreover, Raman peak at 520 cm−1 was related to the defects induced by doping with Mn and Co ions. Fitting the O 1s XPS spectra of the NPs showed that more oxygen vacancies formed with increasing Co and Mn doping. Because there were more oxygen vacancies, photocatalytic dye degradation of rhodamine B enhanced at higher Co and Mn concentrations. Photoluminescence spectra showed that the NPs containing more Mn and Co had more single charged oxygen vacancies. The experimental and theoretical results showed that the exchange interactions between the Mn2+-Co2+ ions mediated by singly charged oxygen vacancies was responsible for room temperature ferromagnetism in the (Mn, Co) co-doped ZnO NPs. [Display omitted] • The magnetism of (Mn, Co) co-doped ZnO were estimated by DFT simulations. • The degradation of RhB for ZnO were enhanced by co-doping with Mn and Co. • The ferromagnetism of ZnO were improved by co-doping with Mn and Co. • Oxygen vacancies, Mn and Co ions were responsible for enhanced performance of ZnO. [ABSTRACT FROM AUTHOR]

Zn 1- x Mn x O nanoparticles with different Mn concentration (0.01–0.1) were synthesized by co-precipitation technique. The structural, optical and magnetic properties of Zn 1- x Mn x O nanoparticles were investigated. The Zn 1- x Mn x O nanoparticles keep wurtzite structure without any impurity phase until the Mn concentration reaches 0.1. The magnetic measurements show ferromagnetism of Zn 1- x Mn x O nanoparticles is improved with increase of the Mn concentration ( x = 0.01–0.08). The optimal doping concentrations for enhancement in ferromagnetism of Zn 1- x Mn x O nanoparticles is 0.08. The reduction in ferromagnetism of Zn 0.9 Mn 0.1 O is caused by coexistence of the Mn 3+ and Mn 2+ ions, which can form antiferromagnetic interaction. Results of UV-vis absorption spectra indicate that the bandgap and carrier concentration increase gradually with increasing Mn concentration, which can be explained by Burstein-Moss shift. Singly charged oxygen vacancies in the Zn 1- x Mn x O were analyzed according to the visible photoluminescence spectra results. Experiment results reveal that the singly charged oxygen vacancies and surrounding Mn 2+ ions form bound magnetic polarons model, which is responsible for the origin of ferromagnetism in Mn-doped ZnO nanoparticles. [ABSTRACT FROM AUTHOR]