Lanio leucothorax
Ontology highlight
ABSTRACT:
PROVIDER: PRJNA960062 | ENA |
REPOSITORIES: ENA
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Project description:Over the last few decades, manipulating the metal-insulator (MI) transition in perovskite oxides (ABO3) via an external control parameter has been attempted for practical purposes, but with limited success. The substitution of A-site cations is the most widely used technique to tune the MI transition. However, this method introduces unintended disorder, blurring the intrinsic properties. The present study reports the modulation of MI transitions in [10 nm-NdNiO3/t-LaNiO3/10 nm-NdNiO3/SrTiO3 (100)] trilayers (t = 5, 7, 10, and 20 nm) via the control of the LaNiO3 thickness. Upon an increase in the thickness of the LaNiO3 layer, the MI transition temperature undergoes a systematic decrease, demonstrating that bond disproportionation, the MI, and antiferromagnetic transitions are modulated by the LaNiO3 thickness. Because the bandwidth and the MI transition are determined by the Ni-O-Ni bond angle, this unexpected behavior suggests the transfer of the bond angle from the lower layer into the upper. The bond-angle transfer eventually induces a structural change of the orthorhombic structure of the middle LaNiO3 layer to match the structure of the bottom and the top NdNiO3, as evidenced by transmission electron microscopy. This engineering layer sequence opens a novel pathway to the manipulation of the key properties of oxide nickelates, such as the bond disproportionation, the MI transition, and unconventional antiferromagnetism with no impact of disorder.
| S-EPMC6934756 | biostudies-literature
Project description:Conductive LaNiO3 (LNO) films with an ABO3 perovskite structure deposited on silicon wafers are a promising material for various electronics applications. The creation of a well-defined columnar grain structure in CSD (Chemical Solution Deposition) LNO films is challenging to achieve on an amorphous substrate. Here, we report the formation of columnar grain structure in LNO films deposited on the Si-SiO2 substrate via layer-by-layer deposition with the control of soft-baking temperature and high temperature annealing time of each deposited layer. The columnar structure is controlled not by typical heterogeneous nucleation on the film/substrate interface, but by the crystallites' coalescence during the successive layers' deposition and annealing. The columnar structure of LNO film provides the low resistivity value ρ~700 µOhm·cm and is well suited to lead zirconate-titanate (PZT) film growth with perfect crystalline structure and ferroelectric performance. These results extend the understanding of columnar grain growth via CSD techniques and may enable the development of new materials and devices for distinct applications.
| S-EPMC9959992 | biostudies-literature
Project description:The adsorption of H₂ on LaNiO₃ was investigated using density functional theory (DFT) calculations. The adsorption sites, adsorption energy, and electronic structure of LaNiO₃(001)/H₂ systems were calculated and indicated through the calculated surface energy that the (001) surface was the most stable surface. By looking at optimized structure, adsorption energy and dissociation energy, we found that there were three types of adsorption on the surface. First, H₂ molecules completely dissociate and then tend to bind with the O atoms, forming two -OH bonds. Second, H₂ molecules partially dissociate with the H atoms bonding to the same O atom to form one H₂O molecule. These two types are chemical adsorption modes; however, the physical adsorption of H₂ molecules can also occur. When analyzing the electron structure of the H₂O molecule formed by the partial dissociation of the H₂ molecule and the surface O atom, we found that the interaction between H₂O and the (001) surface was weaker, thus, H₂O was easier to separate from the surface to create an O vacancy. On the (001) surface, a supercell was constructed to accurately study the most stable adsorption site. The results from analyses of the charge population; electron localization function; and density of the states indicated that the dissociated H and O atoms form a typical covalent bond and that the interaction between the H₂ molecule and surface is mainly due to the overlap-hybridization among the H 1s, O 2s, and O 2p states. Therefore, the conductivity of LaNiO₃(001)/H₂ is stronger after adsorption and furthermore, the conductivity of the LaNiO₃ surface is better than that of the LaFeO₃ surface.
| S-EPMC5344605 | biostudies-other
Project description:Amongst the rare-earth perovskite nickelates, LaNiO3 (LNO) is an exception. While the former have insulating and antiferromagnetic ground states, LNO remains metallic and non-magnetic down to the lowest temperatures. It is believed that LNO is a strange metal, on the verge of an antiferromagnetic instability. Our work suggests that LNO is a quantum critical metal, close to an antiferromagnetic quantum critical point (QCP). The QCP behavior in LNO is manifested in epitaxial thin films with unprecedented high purities. We find that the temperature and magnetic field dependences of the resistivity of LNO at low temperatures are consistent with scatterings of charge carriers from weak disorder and quantum fluctuations of an antiferromagnetic nature. Furthermore, we find that the introduction of a small concentration of magnetic impurities qualitatively changes the magnetotransport properties of LNO, resembling that found in some heavy-fermion Kondo lattice systems in the vicinity of an antiferromagnetic QCP.
| S-EPMC7075863 | biostudies-literature
Project description:In the present study, an enzyme-less amperometric sensor based on Nafion (NF) and a LaNiO3 (LNO) nanocomposite was constructed for H2O2 detection. LNO from the perovskite group was mixed with NF as an effective solubilizing and stabilizing agent that was used as a novel modifier for modification of the glassy carbon electrode (GCE). The designed sensor showed a desirable electrocatalytic response toward H2O2 reduction. The calibration curve revealed two linear portions in the concentration ranges of 0.2-50 μM and 50-3240 μM, and the detection limit was 0.035 μM. The accuracy of the interference-free sensor was checked by recovery analysis in serum samples.
| S-EPMC9054932 | biostudies-literature
Project description:The nature of the metal-insulator transition in thin films and superlattices of LaNiO3 only a few unit cells in thickness remains elusive despite tremendous effort. Quantum confinement and epitaxial strain have been evoked as the mechanisms, although other factors such as growth-induced disorder, cation non-stoichiometry, oxygen vacancies, and substrate-film interface quality may also affect the observable properties of ultrathin films. Here we report results obtained for near-ideal LaNiO3 films with different thicknesses and terminations grown by atomic layer-by-layer laser molecular beam epitaxy on LaAlO3 substrates. We find that the room-temperature metallic behavior persists until the film thickness is reduced to an unprecedentedly small 1.5 unit cells (NiO2 termination). Electronic structure measurements using X-ray absorption spectroscopy and first-principles calculation suggest that oxygen vacancies existing in the films also contribute to the metal-insulator transition.
| S-EPMC5992201 | biostudies-literature