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The interaction of 2-propanol with SrTiO3(100) surfaces is studied with a focus on the role of different surface terminations in the deprotonation upon adsorption. Preferential SrO and TiO2-termination was corroborated by AFM, ARXPS and SIMS. Surface sensitive vibrational sum frequency spectroscopy (vSFS) reveals that 2-propanol predominantly adsorbs intact on SrO-terminated SrTiO3(100), but is to a large extent deprotonated on TiO2-terminated SrTiO3(100). The latter is in contrast with the lack of deprotonation of 2-propanol when interacting with thin film TiO2as reported earlier.

LaMnO3+δnanoperovskites were prepared via the continuous and scalable spray-flame synthesis (SFS) technique from metal nitrate-based solutions by using either ethanol (EtOH) as solvent or a mixture of ethanol (50 vol %) and 2-ethylhexanoic acid (50 vol %) (EtOH/2-EHA). Solutions based on pure EtOH generated a mixture of several phases and a broad and multimodal particle size distribution, which is attributed to a combination of gas-to-particle and droplet-to particle formation of particles. The product contained a bimodal distribution of the orthorhombic (Pnma II) LaMnO3perovskite-like phase and additional, unwanted phases such as La2O3and sub-20 nm Mn-rich amorphous/poorly crystalline particles. The incorporation of 2-EHA led to high surface area (>100 m2g–1), small, and crystalline LaMnO3+δnanoparticles with sizes ranging between 4 and 15 nm in the presence of few sub-200 nm particles (<10 wt %). This sample is mainly composed of the orthorhombic Mn4+rich (Pnma I) LaMnO3+δphase, and it counts with a very high specific surface area that makes it highly promising for catalytic applications. FTIR and UV–VIS spectroscopy of the precursor solutions revealed the oxidation of the Mn2+precursor in advance of the particle formation process along with the esterification of the solvent mixture. It is assumed that the observed liquid-phase oxidation supports the formation of Mn4+-rich perovskites. According to O2-TPD and H2-TPR measurements, the EtOH/2-EHA sample presented a much higher formation of adsorbed active oxygen species and higher reducibility than the EtOH-made material, leading to a superior performance for both the catalytic oxidation of CO and the selective oxidation (SELOX) of CO.

Bismuth ferrite (BFO) is the drosophila of research in multiferroic materials due to its simultaneous magnetic and electric ordering at room temperature. The unfortunate detail is its antiferromagnetic ordering, which practically cancels magnetization and magnetoelectric coupling of the crystals. To induce finite coupling, dopants have been introduced with a certain success so far. Nanoparticles (NPs) can additionally constrain the formation of the magnetic cycloid in BFO due to size confinement. Doping nanoparticles can thus potentially provide a sizeable magnetization of BFO, making applications in computer memories and hyperthermia cancer treatment feasible. We show that the codoping of BFO NPs by Ba and Mn balances the electrochemical equilibrium, reduces the particle size, and shifts the magnetic phase transition to lower temperatures. The ferroelectric properties are retained and the remanent magnetization is increased by 1 order of magnitude: Bi0.95Ba0.05Fe0.95Mn0.05O3possesses a remanent magnetization of 0.277 Am2/kg. Our Mössbauer studies reveal that two effects drive this increase: partial destruction of the spin cycloid due to Mn and increased spin canting due to Ba doping inducing local stress fields. This dopant combination and particular concentration improve the effective magnetization value exceptionally well.

We present experimental data on the diffusivity of Pb in CaTiO3perovskite, which is commonly used for dating kimberlites and carbonatites. Experiments were performed on oriented synthetic and natural CaTiO3single crystals. The Pb-source was either a laser deposited (Ca0.83Pb0.07)Ti1.05O3thin film or a (Ca0.9Pb0.1)TiO3powder reservoir. The crystals were annealed in a high-temperature furnace between 736 and 1135 °C and for durations from 2 to 283 h. The diffusion profiles were measured with Rutherford backscattering and time-of-flight secondary ion mass spectrometry in the depth-profiling mode. The concentration profiles measured on the same samples with the two analytical methods are in agreement. The measured concentration profiles show two regions—a steep gradient at the diffusion interface that transitions sharply (at ~50 to 150 nm from the surface) to a low concentration tail that penetrates deeper into the crystal. This diffusion behavior could be modeled best using diffusion coefficients that are a function of the Pb concentration, with a different set of diffusion coefficient for the high and the low concentration region of the profile, respectively. The diffusion coefficients extracted from the thin film and powder source experiments are similar within uncertainties. Pb diffuses slower at concentrations between 8.5 and 0.6 wt% and 1.6 to 2.6 log units faster below ~0.5 wt% Pb. Temperature dependency for each region is discussed in the text, and the Arrhenius relation for the fast diffusion regime that is most relevant for natural samples is DPbfast=2.5×10−13×exp⁡(−158(24)kJ/mol/RT)m2/s.$$\begin{array}{} D_{\text{Pb}}^{\text{fast}}=2.5 \times 10^{-13}\times \exp \Big(-158\big(24\big)\text{kJ/mol}/RT\Big)m^2/s. \end{array} $$

Ultrasmall gold nanoparticles with a diameter of 1.8 nm were synthesized by reduction of tetrachloroauric acid with sodium borohydride in the presence of l-cysteine, with natural isotope abundance as well as 13C-labeled and 15N-labeled. The particle diameter was determined by high-resolution transmission electron microscopy and differential centrifugal sedimentation. X-ray photoelectron spectroscopy confirmed the presence of metallic gold with only a few percent of oxidized Au(+I) species. The surface structure and the coordination environment of the cysteine ligands on the ultrasmall gold nanoparticles were studied by a variety of homo- and heteronuclear NMR spectroscopic techniques including 1H–13C-heteronuclear single-quantum coherence and 13C–13C-INADEQUATE. Further information on the binding situation (including the absence of residual or detached l-cysteine in the solution) and on the nanoparticle diameter (indicating the well-dispersed state) was obtained by diffusion-ordered spectroscopy (1H-, 13C-, and 1H-13C-DOSY). Three coordination environments of l-cysteine on the gold surface were identified that were ascribed to different crystallographic sites, supported by geometric considerations of the nanoparticle ultrastructure. The particle size data and the NMR-spectroscopic analysis gave a particle composition of about Au174(cysteine)67.

Nearly phase-pure bismuth ferrite particles were formed by thermolysis of the single-source precursor[Cp(CO)2FeBi(OAc)2] (1) in octadecene at 245 °C, followed by subsequent calcination at 600 °C for 3 h. In contrast, the slightly modified compound [Cp(CO)2FeBi(O2CtBu)2] (2) yielded only mixtures of different bismuth oxide phases, revealing the distinctive influence of molecular design in material synthesis. The chemical composition, morphology, and crystallinity of the resulting materials were investigated by X-ray diffraction, transmission electron microscopy, and energy-dispersive X-ray spectroscopy. In addition, the optical properties were investigated by Fourier transform infrared and UV–vis spectroscopies, showing a strong band gap absorption in the visible range at 590 nm (2.2 eV). The magnetic behavior was probed by vibrating-sample and superconducting quantum interference device magnetometry, as well as 57Fe Mössbauer spectroscopy.

Like other 2D materials, the boron-based borophene exhibits interesting structural and electronic properties. While borophene is typically prepared by molecular beam epitaxy, we report here on an alternative way of synthesizing large single-phase borophene domains by segregation-enhanced epitaxy. X-ray photoelectron spectroscopy shows that borazine dosing at 1100 °C onto Ir(111) yields a boron-rich surface without traces of nitrogen. At high temperatures, the borazine thermally decomposes, nitrogen desorbs, and boron diffuses into the substrate. Using time-of-flight secondary ion mass spectrometry, we show that during cooldown the subsurface boron segregates back to the surface where it forms borophene. In this case, electron diffraction reveals a (6 × 2) reconstructed borophene χ6-polymorph, and scanning tunneling spectroscopy suggests a Dirac-like behavior. Studying the kinetics of borophene formation in low energy electron microscopy shows that surface steps are bunched during the borophene formation, resulting in elongated and extended borophene domains with exceptional structural order.