Synthesis of infinite-layer LaNiO2 films by metal-organic deposition

We report the synthesis of infinite-layer LaNiO2 thin films by metal organic decomposition. Our work is aimed to synthesize perovskite-like oxides with 3d9 electronic configuration, which is common to high-Tc copper oxides. The 3d9 configuration is very rare in oxides other than cuprates. Ni1+ oxides, even though Ni1+ is an unusual oxidation state, may be one of very few candidates. One example of the Ni1+ phases is infinite-layer LaNiO2. The bulk synthesis of LaNiO2 is difficult, but we demonstrate in this article that the thin-film synthesis of LaNiO2 by metal organic decomposition is rather easy. This is due to the advantage of thin films with a large-surface-to-volume ratio, which makes oxygen diffusion prompt. Resistivity measurements indicate that LaNiO2 is essentially a metal but unfortunately with no trace of superconductivity yet.Comment: 13 pages, 4 figure

Tuning the properties of complex transparent conducting oxides: role of crystal symmetry, chemical composition and carrier generation

The electronic properties of single- and multi-cation transparent conducting oxides (TCOs) are investigated using first-principles density functional approach. A detailed comparison of the electronic band structure of stoichiometric and oxygen deficient In$_2$O$_3$, $\alpha$- and $\beta$-Ga$_2$O$_3$, rock salt and wurtzite ZnO, and layered InGaZnO$_4$ reveals the role of the following factors which govern the transport and optical properties of these TCO materials: (i) the crystal symmetry of the oxides, including both the oxygen coordination and the long-range structural anisotropy; (ii) the electronic configuration of the cation(s), specifically, the type of orbital(s) -- $s$, $p$ or $d$ -- which form the conduction band; and (iii) the strength of the hybridization between the cation's states and the p-states of the neighboring oxygen atoms. The results not only explain the experimentally observed trends in the electrical conductivity in the single-cation TCO, but also demonstrate that multicomponent oxides may offer a way to overcome the electron localization bottleneck which limits the charge transport in wide-bandgap main-group metal oxides. Further, the advantages of aliovalent substitutional doping -- an alternative route to generate carriers in a TCO host -- are outlined based on the electronic band structure calculations of Sn, Ga, Ti and Zr-doped InGaZnO$_4$. We show that the transition metal dopants offer a possibility to improve conductivity without compromising the optical transmittance

Structural evolution and dopant occupancy preference of yttrium-doped potassium sodium niobate thin films

Sodium potassium niobate (KNN) is the most promising candidate for lead-free piezoelectric material, owing to its high Curie temperature and piezoelectric coefficients among the non-lead piezoelectric. Numerous studies have been carried out to enhance piezoelectric properties of KNN through composition design. This research studied the effects of yttrium concentrations and lattice site occupancy preference in KNN films. For this research, the yttrium-doped KNN thin films (mol% = 0, 0.1, 0.3, 0.5, 0.7 and 0.9) were fabricated using the sol-gel spin coating technique and had revealed the orthorhombic perovskite structures. Based on the replacement of Y3+ ions for K+/ Na+ ions, it was found that the films doped with 0.1 to 0.5 mol% of yttrium had less lattice strain, while films with more than 0.5 mol% of Y3+ ions had increased strain due to the tendency of Y3+ to occupy the B-site in the perovskite lattice. Furthermore, by analysing the vibrational attributes of octahedron bonding, the dopant occupancy at A-site and B-site lattices could be identified. O-Nb-O bonding was asymmetric and became distorted due to the B-site occupancy of yttrium dopants at high dopant concentrations of >0.5 mol%. Extra conduction electrons had resulted in better resistivity of 2.153× 106 Ω at 0.5 mol%, while higher resistivity was recorded for films prepared with higher concentration of more than 0.5 mol%. The introduction of Y3+ improved the grain distribution of KNN structure. Further investigations indicated that yttrium enhances the surface smoothness of the films. However, at high concentrations (0.9 mol%), the yttrium increases the roughness of the surface. Within the studied range of Y3+ , the film with 0.5 mol% Y3+ represented a relatively desirable improvement in dielectric loss, tan δ and quality factor, Qm

Transparent Coating Oxide - Indium Zinc Oxide As Conductive Coating : A Review

: This paper reviews the transparent conductive oxide with emphasis on indium doped zinc oxide (TCO-IZO). TCO has been growing faster year by year, especially in semiconductor,solar devices and electronic field. There are many methods that can be used to produce IZO coating such as dip coating, sol-gel, magnetron sputtering, thermal evaporation and atomic layer deposition. IZO has gained significant attention for transparent electrodes due to its good electrical conductivity, high visible transmittance in the range from 400 to 900 nm, large work function, excellent surface smoothness, and low deposition temperature. Many studies have been done on the IZO coating onto glass substrate, but there is still less study on the low processing temperature substrates such as polymers and natural fibres. Parameters such as coating thickness, annealing temperature and number of cycles have to be considered in order to achieve the desired electrical conductivity and optical properties of IZO

INFLUENCE OF WATER AND PRECURSOR MOLARITY ON THE TiO2 THIN FILMS DEPOSITED FROM SOLVENTLESS SOL-GEL

Titania (TiO2) of anatase, anatase-rutile and anatase-brookite-rutile thin films were successfully established from sol-gel dip coating technique using titanium tetraisopropoxide (TTIP) as precursors without the presence of solvent. The thin films were deposited on glass substrate and the type of TiO2 crystalline structure produced was depending upon the molar ratio of the TTIP and water. Results shown that the TTIP molarity is more substantial in determining the TiO2 thin films crystallinity and crystallite size as compared to the water molarity. Meanwhile, the desired phases and crystallite size can be controlled by manipulating the molar ratio of water and TTIP. Thus, the establishment of the desired phases (anatase mixed rutile), crystallinity and crystallite size (anatase: 15 nm, rutile: 30 nm) of TiO2 thin films from solvent less sol-gel can be controlled and encouraging to explore as an effort toward producing a sustainable green photocatalytic material

X-ray Absorption Studies of Ceria with Trivalent Dopants

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65899/1/j.1151-2916.1991.tb04328.x.pd

EFFECT OF DEGUSSA P25 CONTENT ON THE DEPOSITION OF TiO2 COATING ON CERAMIC SUBSTRATE

TiO2 coatings were deposited on unglazed ceramic tiles to study the property of its antimicrobial activity. Here, the effect of TiO2 nanoparticles content (Degussa P25) on the TiO2 coatings’ characteristics was investigated. TiO2 sol containing 25, 50, and 100 g/L Degussa P25 were deposited few times on ceramic tiles via sol-gel dip coating method and heat treated at 500°C. The coatings were analyzed using SEM and the phases were characterized using GAXRD. The results show that Degussa P25 content significantly influences the TiO2 coatings morphology and thickness. Increasing the Degussa P25 content led to a thicker and denser coating with different Degussa P25 content yielded different thickness at specific dipping time. 50 g/L of Degussa P25 was discovered as the maximum amount to be used for achieving good adherence coating on the ceramic tiles. Five dipping of TiO2 sol containing 50 g/L Degussa P25 was found appropriate to generate coating of continuous layer with average thickness of ~29 µm. The Degussa P25 content, however, shows insignificant effect on coating crystallinity

Effect of Annealing Time on Resistivity of Kenaf Fiber Modified Indium Zinc Oxide Prepared Via Dip Coating Process

This paper reviewed the annealing time effect on resistivity of kenaf fiber modified indium zinc oxide (KF-IZO) as a functional material. Firstly, kenaf fiber (KF) had undergone alkaline surface treatment using Sodium Hydroxide (NaOH) solution with 5 % concentration. Dip coating process was applied in order to deposit amorphous IZO (In/Zn : 6.0 %) solution at room temperatures, 27ᵒC at 5 mm/s dipping rate. The thin film built up was annealed at 150ᵒC for 2, 4, 8 and 16 hours. Electrical resistivity was tested by Four Probe Method with copper attachment to determine the resistance of KF-IZO. As a result, KF-IZO with 4 hours annealing time showed the lowest resistivity with 0.12 Ω.mm while the highest resistivity 12.62 Ω.mm was shown by 16 hours annealing time. Surface morphology was observed under optical microscope, Scanning Electron Microscope (SEM) and SEMEDX to reveal coating distribution, elemental analysis and imperfection of KF-IZO. Moreover, the entire KF-IZO samples image illustrated revealed no significant fiber damages