Effect Of Li Content Research Articles

Structure and electrical properties of [(K0.49Na0.51)1−xLix](Nb0.90Ta0.04Sb0.06)O3 lead-free piezoceramics

Lead-free [(K0.49Na0.51)1−xLix](Nb0.90Ta0.04Sb0.06)O3 (KNLNTS) ceramics were prepared by a conventional ceramic processing method, and the effects of Li content on the crystal phases and electrical properties of the ceramics were investigated. A secondary phase was identified by XRD analysis when x=0.08, indicating that the maximum solid solubility of lithium in KNLNTS solid solutions is lower than 8 mol%. The Curie temperature TC increased while the polymorphic phase transition (PPT) temperature TO–T decreased with the increasing Li content. The coexistence of orthorhombic and tetragonal phases was observed near room temperature when x=0.04. The optimum electrical performance, i.e. piezoelectric coefficient d33=215 pC/N, electromechanical coupling coefficient kp=0.313, kt=0.306, relative permittivity ε33T/ε0=805 and loss tangent tan δ=0.045, was obtained for x=0.04.

Effects of Li content on the phase structure and electrical properties of lead-free (Ag0.85−xLixNa0.1K0.05)NbO3 piezoelectric ceramics

Lead-free ceramics (Ag0.85−xLixNa0.1K0.05)NbO3 (ALNKN−x, x = 0−0.16) doped with 0.5 mol. % CuO were prepared by solid state reaction method under air atmosphere. The effects of Li content on the phase structure and electrical properties of the ALNKN−x ceramics were investigated. A morphotropic phase boundary (MPB) between orthorhombic and rhombohedral phases is found at x ≈ 0.08−0.14. Both the ferroelectric–ferroelectric phase transition temperature (TFE) and Curie temperature (TC) shift toward higher temperatures with increasing x. Only the phase transition peak near the TC is observed when x ≥ 0.12. The ferroelectric phase of the ALNKN−x ceramics becomes more stable with increasing x. Furthermore, the ceramics with x = 0.12 exhibit relatively good electrical properties along with a high Curie temperature (d33 = 44 pC/N, kp = 17.7%, Pr = 14.5 µC/cm2, Ec = 37.2 kV/cm, and Tc = 335 °C). The results provide helpful guidance to develop new lead-free piezoelectric materials with good temperature stability.

Local Electronic Structure of Lithium-Doped ZnO Films Investigated by X-ray Absorption Near-Edge Spectroscopy

Lithium-doped ZnO films were deposited by radio frequency magnetron sputtering on Corning 1737 glass substrates. The Li content in the films varied from 0 to 10 at. %, as determined by wavelength-dispersive X-ray analysis and inductively coupled plasma mass spectrometry. The effect of Li content on the microstructure and electrical properties was studied. The XRD results indicated that all the samples have a ZnO wurtzite structure, and no secondary phase formed as the Li atoms were incorporated into ZnO thin films. The Hall and electrical resistance measurements revealed that the resistivity is decreased by Li doping. The EXAFS measurement showed that the bonding length of both Zn–O and Zn–Zn was decreased after converting to p-type conduction due to incorporation of lithium atoms. All the results confirmed that the Li ions were well incorporated into the ZnO lattices as a result of substituting Zn sites without changing the wurtzite structure, and no secondary phase appeared in the Li-doped ZnO thin film.

Strain-Hardening Behavior of Mg-Li-Zn Alloy Thin Sheets under Tension

This work examined the effects of Li content on the strain-hardening behaviors of three varieties of Mg−Li−Zn alloys containing approximately 6 wt%, 9 wt%, and 10 wt% of Li. Tensile tests were carried out on specimens in the directions of 0, 45 and 90° to the rolling direction. Kocks–Mecking type plots were constructed to illustrate different stages of strain-hardening. The cold-rolled Mg−6Li−1Zn (designated as LZ61) alloy sheet showed stage II and stage III strain-hardening behaviors at room temperature. The specimens of Mg−9Li−1Zn (designated as LZ91) and Mg−10Li−1Zn (designated as LZ101) alloy sheets did not show stage II strain-hardening. Higher initial strain-hardening rates were observed in the 90° direction for these alloys as a result of the cold-rolled fibrous structure affording stronger barriers to dislocation movements in this direction.

Temperature dependence of the optical band gap and electrical conductivity of sol–gel derived undoped and Li-doped ZnO films

Undoped and lithium (Li)-doped ZnO films were prepared by sol–gel method using spin coating technique. The effects of Li content on the crystallinity and morphological properties of ZnO films were assessed by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM). XRD patterns of the films showed the hexagonal wurtzite type polycrystalline structure and that the incorporation of lithium leads to substantial changes in the structural characteristics of ZnO films. The SEM and AFM measurements showed that the surface morphology of the films was affected from the lithium incorporation. The wrinkle network was observed on the surface from both SEM and AFM results for undoped ZnO. The wrinkle structure disappeared with increasing Li content. The absorption spectra of the ZnO and 5% Li-doped ZnO (LZO5) films were carried out between 140 and 400 K temperatures. The optical band gap of ZnO and LZO5 films (calculated at various temperatures) showed a linear dependence on the temperature. The absolute zero value optical band gap and the rate of change of the band gap with temperature of the ZnO and LZO5 films were found to be 3.339 and 3.322 eV, and 2.95 × 10 −4 and 1.60 × 10 −4 eV/K, respectively. The transport mechanisms in the ZnO and LZO5 films have been investigated by analyzing of the temperature (80–300 K) dependence of the conductivity. The activation energies of the ZnO film increased with Li content.

Effect of Li Content on Electronic Structure by First-Principle Calculation for Li1+xNi0.5Mn0.5O2 Cathode Active Material of Lithium-Ion Battery

We investigated the crystal and electronic structures of Li1+xNi0.5Mn0.5O2 by Rietveld analysis and first-principle calculations. The crystal structure was well refined by Rietveld analysis using R-3m as the space group, and it was found with MEM using synchrotron X-ray diffraction that the sample showing better cycle performance had higher electron density at a saddle point of 3b–6c. The first-principle calculation clarified that the covalent bond of Ni–O and Mn–O in near a cation mixing position was stronger than that of normal position.

Electrical properties of Li-doped NiO films

Lithium-doped NiO films were deposited by radio frequency magnetron sputtering on Corning 1737 glass substrates. The Li concentrations in the films varied from 0 to 16.29 at.%, as determined by wavelength-dispersive X-ray analysis and inductively coupled plasma mass spectrometry. The effects of Li content on properties such as microstructure, resistivity, and electrical stability were studied. The results show that the doped Li ions tend to occupy crystal defect sites such as vacancies or segregate on the film surface. Initially, doped Li occupied the nickel vacancies in the film, decreasing the electrical conductivity. When the Li concentration was further increased, some Li segregated on the film surface and formed bulges at high Li concentrations. These Li-rich oxides covering the film surface served as partitions between the film and moisture from the atmosphere. As a result, the Li-doped NiO films show a relatively high arrestment to electrical resistance aging.

Effect of Li content on the microstructure and properties of lead-free piezoelectric (K 0.5Na 0.5) 1– xLi xNbO 3 ceramics prepared by SPS

Lead-free piezoelectric (K 0.5Na 0.5) 1– x Li x NbO 3 ( x = 0at%-20at%) ceramics were synthesized by spark plasma sintering (SPS) at low temperature and the effects of LiNbO 3 addition on its crystal structure and properties were also studied. When the Li content was less than 6at%, a single proveskite phase with the similar structure of (K 0.5Na 0.5)NbO 3 was formed; and a secondary phase with K 3Li 2Nb 5O 15 structure was observed in the 6at% ≤ x ≤ 20at% compositional range. Furthermore, LiNbO 3 existed as the third phase when the Li content was higher than 8at%. The grain sizes increased from 200-500 nm to 5-8 μm when the K 3Li 2Nb 5O 15 and LiNbO 3 like phases were formed. With increasing Li content, the relative density of the ceramics first decreased from 97% to 93% and then kept constant. The piezoelectric coefficient d 33, dielectric constant, and planner electromechanical coupling factor exhibited a decreasing tendency with increasing Li content because of the decrease in density and the formation of the secondary phase such as K 3Li 2Nb 5O 15 and LiNbO 3. The formation of dense microstructure with a single phase is necessary in improving the properties of the (K 0.5Na 0.5) 1– x Li x NbO 3 ceramics.

Effects of Li content on the phase structure and electrical properties of lead-free (K0.46−x∕2Na0.54−x∕2Lix)(Nb0.76Ta0.20Sb0.04)O3 ceramics

Lead-free (K0.46−x∕2Na0.54−x∕2Lix)(Nb0.76Ta0.20Sb0.04)O3 piezoelectric ceramics were prepared by the conventional solid state sintering method without cold-isostatic pressing process. The x-ray diffraction and Raman scattering results show that the phase structure of the ceramics undergoes a transition from pseudocubic to tetragonal phase with increasing x from 0 to 0.10. Significantly enhanced electrical properties (d33=259pC∕N, kp=0.42, εr=1653, and tan δ=0.027) were obtained in the ceramics with x=0.04 near the morphotropic phase boundary, and only the tetragonal-cubic phase transition was observed above the room temperature in the εr-T curve. The temperature stability of the ceramics with x=0.04 was also investigated.

Influence of Microstructural Change on Damping Capacity of Mg-X%Li Alloys

The Effects of Li content and annealing treatment on microstructure and damping capacity for Mg-X%Li alloys have been investigated, based on experimental results from X-ray diffractometry (XRD), optical microscopy (OM), hardness tests and vibration damping tests in a flexural mode. The Mg-X%Li alloys containing Li of 3%, 8% and 13% consist of α (HCP) single phase, (α + β (BCC)) dual phases and β single phase, respectively. In as-rolled state, the damping capacity for Mg-Li alloys shows a similar level regardless of Li content. The annealing treatments at 200oC and 400οC give rise to an enhancement of damping capacity only for the Mg-3%Li and Mg-8%Li alloys containing α phase, and at the same annealing temperature, the Mg-3%Li alloy with fully α structure exhibits higher damping capacity. This result indicates that the damping capacity of Mg-Li alloys depends principally on α phase, and that the annealing treatment is necessary to improve its damping capacity.

Realization of p-type ZnO films via monodoping of Li acceptor

p-Type ZnO thin films have been realized via monodoping of Li acceptor by adopting DC reactive magnetron sputtering. The lowest room-temperature resistivity was found to be 17.6Ωcm with a Hall mobility of 3.47cm2V–1s–1 and carrier concentration of 1.01×1017cm−3 for Li-doped p-type ZnO film deposited on glass substrate. The Li-doped ZnO film possessed a good crystallinity with c-axis orientation and a high transmittance (90%) in the visible region. Moreover, the effects of Li content on the crystallinity, electrical and optical properties of p-type ZnO films were discussed.

LixNi1‐xO (0 < x ≤ 0.3) Solid Solutions: Formation, Structure and Transport Properties

AbstractFor Abstract see ChemInform Abstract in Full Text.

LixNi1−xO (0<x≤0.3) solid solutions: formation, structure and transport properties

The formation, structure and transport properties of Li x Ni 1− x O solid solutions with x ≤0.3 are described. Pure stoichiometric nickel oxide is a green insulator compound with rocksalt structure. When Li + partially substitute the normal sites of Ni 2+ , a hole is introduced in the form of Ni 3+ or O − to keep charge neutrality conditions, and the oxide becomes a black semiconductor. For Li atomic fraction x >0.3 a rhombohedral distortion of the cubic structure by partial lithium and nickel ions ordering on alternate 〈1 1 1〉 planes takes place, giving rise to a hexagonal structure. Some questions, regarding the hole state, the ordering and vacancy presence in the solid solutions, are discussed. The effect of Li content in the solid solutions on the most typical charge-and-mass transport properties, as electrical conductivity, thermoelectric power and chemical diffusivity, is reviewed.

Li xNi 1− xO (0< x≤0.3) solid solutions: formation, structure and transport properties

The formation, structure and transport properties of Li x Ni 1− x O solid solutions with x≤0.3 are described. Pure stoichiometric nickel oxide is a green insulator compound with rocksalt structure. When Li + partially substitute the normal sites of Ni 2+, a hole is introduced in the form of Ni 3+ or O − to keep charge neutrality conditions, and the oxide becomes a black semiconductor. For Li atomic fraction x>0.3 a rhombohedral distortion of the cubic structure by partial lithium and nickel ions ordering on alternate 〈1 1 1〉 planes takes place, giving rise to a hexagonal structure. Some questions, regarding the hole state, the ordering and vacancy presence in the solid solutions, are discussed. The effect of Li content in the solid solutions on the most typical charge-and-mass transport properties, as electrical conductivity, thermoelectric power and chemical diffusivity, is reviewed.

The effect of Li content on the natural aging response of AlCuLiMgAgZr alloys

The natural aging response of AlCuLi alloys containing trace additions of Mg and Ag was examined as a function of the Li level while the copper level was maintained between 5.0 and 6.5 wt%. A peak in strength was observed at a Li level of ∼ 1.3 wt% with the naturally aged strengths (yield strength = 435 MPa; ultimate tensile strength = 580 MPa) being competitive with those of several high-strength aluminum alloys in the artificially peak-aged condition. The microstructure in the naturally aged condition was characterized using transmission electron microscopy techniques; phases present were identified by selected area diffraction, and dislocation morphology (helices vs loops) was examined by two-beam bright field imaging. Observations were correlated with the measured properties and the peak in strength at ∼ 1.3 wt% Li is explained on the basis of these microstructural observations.

Hot cracking susceptibility of Al–Cu–Li and Al–Cu–Li–Mn alloys

The effect of Li content (up to 4%), Cu content (up to 5%), and Mn content (up to 1·4%) on the hot cracking susceptibility of Al alloys containing Li was investigated. The usual tests, principally the measurement of crack length in ring castings, were used to evaluate the hot cracking susceptibility of the alloys. The values of linear shrinkage and elongation to failure in the bnttle temperature range in the solid–liquid condition were compared. An increase in Li and Cu content in the Al–Cu–Ll system results in a decrease in the hot cracking susceptibility corresponding to a rise in the elongation to failure in the brittle range in the solid–liquid condition. The addition of Mn increases the hot cracking susceptibility associated with a decrease in elongation to failure in this temperature range.MST/2009

Role of Lithium in Multicomponent Oxide Catalysts for Oxidative Coupling of Methane

The effect of Li content in a series of multicomponent oxides LixLa0.5Ti0.5 For methane oxidative coupling has been studied. The catalytic activities of LiLa0.5Ti0.5 catalyst before and after washing with boiling water have been compared. The surface and

Ａｌ‐Ｌｉ合金の鋳造割れ性

Effects of Li content and grain-refiner addition on the hot-tearing characteristics of Al-Li binary word alloys (0-3mass%) and the commercial Al-Li alloys (2090, 2091, 8090 and 2219+1.5mass%Li) were investigated by using hindered type hot-tearing test (I-beam test). High strength alloys, 2024 and 7075 were also investigated to compare with the commercial Al-Li alloys. In Al-Li binary alloys, the tearing tendency was decreased with increasing Li content, but was not improved by the grain-refiner addition, and the efficiency of grain refinement was less than in the pure aluminum. In the commercial Al-Li alloys, the tearing tendency was same as 2024 and 7075 alloys in the case of no additioning grain-refiner, but was not so improved by the grain-refiner addition, while in 2024 and 7075 alloys remarkably improved, and the efficiency of grain refinement was less than in 2024 and 7075 alloys.