Nickel Acetate Solution Research Articles

Electron field emission property of NiO-decorated ZnO nanorods grown on diamond films

ZnO/micron diamond (MCD) composite structure combines two wide-band gap semiconductor materials, providing stable performance suitable for high-performance electron field emission (EFE) devices operating in various complex environments. Nonetheless, the optical and electrochemical limitations of ZnO constrain its effectiveness. Typically, NiO can compensate these inherent defects in ZnO, thereby enhancing the performance of field-emitting devices. In this research, NiO-decorated ZnO thin films were fabricated on diamond surfaces using hydrothermal/sol-gel two-step method. The impact of varying Ni doping concentrations caused by nickel acetate solutions on the field emission properties was thoroughly investigated. Furthermore, this study involved the fabrication of NiO-decorated ZnO/micron diamond heterojunction composite structures, exploring the impact of the structure on the optoelectronic performance of the devices. The Ni doping concentration increases in the NiO films formed between the ZnO nanorods, the doped Ni exists in the ZnO/MCD composite structure as both Ni2+ and Ni3+, which are important materials for semiconductor electronic devices. The NiO decoration process induced the creation of defect levels within the bandgap of the nanorod array structure, consequently enhancing the photoluminescence performance of ZnO. Furthermore, the interaction between NiO and ZnO facilitated the formation of a p-n junction at the interface, generating an internal electric field. This electric field significantly improved the current conduction field and maximum current density of ZnO, thereby enhancing its electric field emission performance. The optical and electrical properties of ZnO nanorods doped at 0.1M exhibited the most favorable characteristics among all tested samples. At a doping concentration of 0.1 M, the turn-on electric field reaches a minimum value of 0.96 V/μm and the maximum current density J reaches a maximum value of 2.54 mA/cm2. These results offer novel insights for advancing the development of integrated broadband optical devices.

Electrodeposition of nickel nanoparticles on graphene/iron (III) phthalocyanine-4,4’,4,”,4’”-tetrasulfonic acid coated electrode for glucose sensing

Glucose is vital to the body and a significant source of energy for both human activity and all bodily cells. In order to diagnose, monitor, and treat diabetes, we make use of the blood glucose index to measure the blood glucose concentration. Herein, we present the development of an electrochemical sensor for the detection of glucose levels utilizing graphene incorporated with an iron (III) phthalocyanine-4,4’,4,”,4”’-tetrasulfonic acid and nickel nanoparticles (Gr/FePc/Ni) nanocomposite material. For this purpose, the screen-printed carbon electrode (SPE) was coated with graphene/FePc film, which was later dipped into 10 mM nickel acetate solution. In this step, nickel ions were adsorbed on to graphene/FePc film modified SPE which was later reduced to Ni nanoparticles by electrochemical reduction process. Next, as-prepared Gr/FePc/Ni film was characterized by FE-SEM, FT-IR, EDS and cyclic voltammetry (CV). Gr/FePc/Ni composite-modified screen-printed electrode (Gr/FePc/Ni/SPE) had demonstrated remarkable electrocatalytic activity and sensitivity towards glucose in 0.1 M KOH by CV and amperometry methods. The observed high electrocatalytic activity of Gr/FePc/Ni/SPE was credited to the synergistic effect between the anchored nickel nanoparticles (NPs) and the Gr/FePc film. Moreover, Gr/FePc/Ni/SPE was used to detect glucose from 5 µM to 930 µM by amperometry (i-t) and the lowest limit of detection (LOD) was 0.227 μM. Finally, Gr/FePc/Ni modified sensor was applied to detect glucose in the human blood samples with the acceptable the recovery rate from ∼ 99.48 to 99.94 %.

Functional Surfaces via Laser Processing in Nickel Acetate Solution.

This study presents a novel laser processing technique in a liquid media to enhance the surface mechanical properties of a material, by thermal impact and micro-alloying at the subsurface level. An aqueous solution of nickel acetate (15% wt.) was used as liquid media for laser processing of C45E steel. A pulsed laser TRUMPH Truepulse 556 coupled to a PRECITEC 200 mm focal length optical system, manipulated by a robotic arm, was employed for the under-liquid micro-processing. The study's novelty lies in the diffusion of nickel in the C45E steel samples, resulting from the addition of nickel acetate to the liquid media. Micro-alloying and phase transformation were achieved up to a 30 µm depth from the surface. The laser micro-processed surface morphology was analysed using optical and scanning electron microscopy. Energy dispersive spectroscopy and X-ray diffraction were used to determine the chemical composition and structural development, respectively. The microstructure refinement was observed, along with the development of nickel-rich compounds at the subsurface level, contributing to an improvement of the micro and nanoscale hardness and elastic modulus (230 GPa). The laser-treated surface exhibited an enhancement of microhardness from 250 to 660 HV0.03 and an improvement of more than 50% in corrosion rate.

Converting Fabric to Textile Nickel Current Collector with Ag2s Decoration for Producing Dendrite-Free Lithium Metal Anode

1. Introduction Lithium (Li) metal is regarded as the ideal anode for lithium batteries due to its ultra-high theoretical specific capacity (3860 mAh g-1), low density (0.59 g cm-3) and lowest negative electrochemical potential (-3.04 V vs. Standard Hydrogen Electrode).(1) However, caused by several remaining hurdles, including i) the thermodynamic instability of Li metal and ii) the growth of Li dendrites, the practical application of Li metal anode is still facing challenges from low Coulombic efficiency (CE), insufficient safety performance and poor cyclic stability. To overcome these problems, several strategies have been employed, including the optimization of electrolyte, utilization of solid-state electrolyte and the anode host structure design.(2) The use of hierarchically porous 3D current collector as Li metal host is an effective way to enhance the performance of Li metal anode. In this study, through a simple bio-template method, a textile-structured nickel (Ni) framework is fabricated as current collector for Li metal anode, whose unique micro-nano hierarchical structure is adequate for accommodating Li. With further decoration of uniform silver sulfide nanoparticles (Ag2S NPs), which endows lithiophilicity to the textile-structured Ni framework, a dendrite-free and highly reversible Li metal anode can be achieved after plating Li metal onto the obtained Ni current collector. 2 Experimental Textile-structured Ni current collectors were prepared as follows. Cotton fabric was firstly soaked in aqueous ammonia solution of nickel acetate ((CH3COO)2Ni in NH3·H2O) to form the Ni source coated textile precursor. The precursor was then calcined in air to remove the cotton template and obtain the textile-structured nickel oxide (NiO). Finally, the oxide textile was reduced under hydrogen flow at elevated temperatures to prepare the textile-structured Ni current collector (Textile-Ni). Then, the Textile-Ni was soaked into a prepared silver ammonia solution to form uniformly distributed silver nanoparticles (Ag NPs). After performing a mild sulfidation reaction in a sulfur-dimethyl sulfoxide (S in DMSO) solution, the Ag NPs can be converted to Ag2S NPs without any damage of the Textile-Ni framework.The Li plating/stripping behavior on different current collectors (including planar Cu foil, Textile-Ni, Ag2S decorated Textile-Ni) was firstly examined in a half cell configuration, in which a Li foil was used as the reference and counter electrode and a current collector was used as the working electrode. Li was repeatedly plated/striped to/from the current collectors with controlled capacity and current density. The plating/stripping voltage was monitored and the Coulombic Efficiency (CE) was calculated. Symmetric cells with two identical pre-plated Li@current collector electrodes were also assembled to observe the cycling stability. Finally, full cells consisting of Li@current collector anode and LiCoO2 cathode was also assembled and cycled at specific current densities.The structure and morphology of the current collectors were observed by XRD, SEM and EDS.The morphology and composition of Li plated/stripped current collectors were observed by SEM and XPS. 3. Results and discussion As shown in Fig. 1a, the Textile-Ni was successfully prepared, with the textile structure being similar to the cotton template. Moreover, after the decoration of uniformly distributed Ag2S NPs, the Ag2S decorated Textile-Ni can still maintain the textile structure (Fig. 1b).Fig. 2 shows the dendrites-free morphology of Ag2S decorated Textile-Ni after Li plating. Benefiting from the dendrites-free nature, the Li@Textile-Ni (with Ag2S) supported a Li | LiCoO2 battery to stably cycle for 300 cycles with a high CE (>99%) and a high capacity retention (>140 mAh g-1 for the 1st cycle and maintained 90% capacity after 300 cycles, Fig. 3). As a comparison, the cell using Li foil only maintained a capacity retention of ~30% due to the severe formation of Li dendrites. The electrochemical measurements in symmetric cell and full cell also show that Textile-Ni (with Ag2S) presents superior performance of higher stability and rate capability. The large surface area of Textile-Ni network decreases the local current density and the presence of Ag2S enhance the lithophilicity of the scaffold, which results in uniform deposition of Li.(1) W. Xu, J. Wang, F. Ding, X. Chen, E. Nasybulin, Y. Zhang, J-G. Zhang, Energy Environ. Sci. 2014, 7, 513–537.(2) X. Cheng, R. Zhang, C. Zhao, F. Wei, J. Zhang, Q. Zhang, Adv. Sci. 2016, 3, 1500213. Figure 1

Many Faces of Ni3Bi2S2: Tunable Nanoparticle Morphology via Microwave-Assisted Nanocrystal Conversion

Several combinations of the microwave-assisted polyol route and conversion chemistry techniques were exploited to access the bimetallic sulfide Ni3Bi2S2 with a variety of morphological features. First, Bi2S3 microstructures can be converted into Ni3Bi2S2 at 240 °C; the precursor’s rod-like shape and size pertain to the final product. Second, round Ni3Bi2S2 particles can be obtained directly from a presynthesized NiBi intermetallic precursor; the resultant submicron size particles agglomerate and thus differ from the starting alloy’s shape. Third, microwave reflux of bismuth nitrate and nickel acetate solution in ethylene glycol in the presence of thiosemicarbazide can be employed to produce Ni3Bi2S2 with a peculiar flower-like morphology. The presence and the decisive role of the in situ generated NiBi intermediate are unraveled, confirming that the reaction proceeds via transformation of solid rather than via a solution–dissolution process. NiBi nanoparticles preconfigure the Ni3Bi2S2 product morphology ...

General Strategy for Controlled Synthesis of NixPy/Carbon and Its Evaluation as a Counter Electrode Material in Dye-Sensitized Solar Cells.

Hydrothermal treatment of nickel acetate and phosphoric acid aqueous solution followed with a carbothermal reduction assisted phosphorization process using sucrose as the carbon source for the controlled synthesis of NixPy/C was successfully realized for the first time. The critical synthesis factors, including reduction temperature, phosphorus/nickel ratio, pH, and sucrose amount were systematically investigated. Remarkably, the carbon serves as a reducer and plays a determinative role in the transformation of Ni2P2O7 into Ni2P/C. The synthesis strategy is divided into four distinguishable stages: (1) hydrothermal preparation of Ni3(PO4)2·8H2O precursor for stabilizing P sources; (2) dimerization of Ni3(PO4)2·8H2O into more thermal stable Ni2P2O7 amorphous phase along with the generation of NiO; (3) carbothermal reduction and phosphidation of NiO into NixPy (0 ≤ y/x ≤ 0.5); and (4) further phosphidation of mixed-phase NixPy and carbothermal reduction of Ni2P2O7 into single-phase Ni2P. The resultant Ni2P, the highly active phase in electrocatalysis, was applied as counter electrode in a dye-sensitized solar cell (DSSC). The DSSC based on Ni2P with 10.4 wt.% carbon delivers a power conversion efficiency of 9.57%, superior to that of state-of-the-art Pt-based cell (8.12%). The abundant Niδ+ and Pδ- active sites and the metal-like conductivity account for its outstanding catalytic performance.

A study on characterization of nano-porous NiO thin film to improve electrical and optical properties for application to automotive glass

Nano-porous nickel oxide (NiO) film is coated on the indium tin oxide glass using nickel acetate solution containing block copolymer as the surfactant by the sol-gel method with a spin coating technique. The block copolymer assists the porosity of NiO thin film, which improves the ion intercalation and deintercalation. The electrochromic properties of NiO thin films with different thickness are investigated in an aqueous alkaline electrolyte (0.1M KOH) by means of cyclic voltammetry, chronoamperometry and transmittance measurements. The nano-porous structure of NiO thin film gives good reaction kinetics with high diffusion coefficient of 1.79×10−9cm2s−1. In the case of NiO thin film with thickness of 170nm, the electrochromic properties are observed with the coloration efficiency of 129.73cm2C−1, coloration/bleaching time of 7.95/3.33s and transmittance modulation of 28% at a wavelength of 550nm. The thinner NiO film is, the better diffusion coefficient and coloring change time are. However, the transmittance modulation and coloration efficiency of the device are better as NiO film is thicker. Therefore, it is important to optimize the electrochromic device parameters depending on application area because they are trade-off relation.

Deposition of Nickel on Electrodeposited Cu2O Films at Potentials More Positive than the Nernst Potential of Ni2+/Ni0

Deposition of nickel on electrodeposited Cu2O films was investigated at potentials more positive than the estimated Nernst equilibrium potential of Ni2+/Ni0 for the purpose of developing a monolayer deposition method that will act as a protective and catalytic overlayer on the oxide films. Cu2O films were subjected to 0.08 mM nickel acetate solutions for 60 s at potentials more positive than the estimated Nernst equilibrium potential of Ni2+/Ni0. The quantities of Ni recovered from the Cu2O films were determined by atomic absorption spectrometry. The oxidation state of Ni deposited on the Cu2O was determined to be +3 via X-ray photoelectron spectroscopy. The absence of evidence of reduction of Ni2+ to Ni0 suggests that the nature of the nickel deposition is adsorption, and it is not characterized as underpotential deposition. Photoelectrochemical measurements showed that deposited Ni protected Cu2O films from the photodecomposition to Cu0 by interfering with H+ binding to the O2− surface sites, and indicated the possibility of catalytic activity of deposited nickel for H+ reduction. The catalytic activity of deposited nickel was explained by the shift of the Cu2O Fermi level by 50 mV in negative direction upon nickel deposition.

Characteristics of Zinc Phosphate Coating Activated by Different Concentrations of Nickel Acetate Solution

Activation pretreatment with nickel acetate solution at various concentrations was performed prior to the phosphating step to enhance the corrosion resistance of carbon steel substrates. The activation solution was studied over various concentrations: 10, 50, and 100 g/L. The effects of these concentrations on surface characteristics and microstructural evolution of the coated samples were characterized by scanning electron microscopy and energy-dispersive spectroscopy. The electrochemical behavior was evaluated using potentiodynamic polarization curves, electrochemical impedance spectroscopy, and immersion test in a 3.5 pct NaCl solution. Significant increases in the nucleation sites and surface coverage of zinc phosphate coating were observed as the concentration of activation solution reached 50 g/L. The electrochemical analysis revealed that the activation treatment with 50 g/L nickel acetate solution significantly improved the protection ability of the zinc phosphate coating. The corrosion current density of activated phosphate coating with 50 g/L was reduced by 64.64 and 13.22 pct, compared to the coatings obtained with activation solutions of 10 and 100 g/L, respectively.

The role of nanosized nickel particles in microwave-assisted dry reforming of lignin

Dry reforming (DR) of lignin with supported Ni nanoparticles under microwave irradiation (MWI) with plasma generation has been studied. Nickel depositing on the lignin surface was carried out by two different procedures. According to the first procedure, Ni was deposited from an aqueous solution of nickel acetate by impregnation. The second procedure included depositing a colloid solution of nickel particles in toluene preliminary obtained by metal vapor synthesis (MVS). As a result in both cases Ni particles of 6nm size were formed on the lignin surface. Both types of nanocatalysts govern the microwave (MW)-assisted DR of lignin. MW treatment of the mechanical mixture of a carbon sorbent with a high dielectric loss factor, and a Ni-containing lignin sample obtained by the first method resulted in the 65wt.% lignin conversion to synthesis gas with the H2/CO ratio of ∼1/1. The content of syngas in the products was 8090wt.%. It was found that MW treatment sharply increases the yield of syngas in the reforming as compared with the convective heating. The Ni-containing lignin samples before and after reforming were investigated by XRD, TEM, EDA, and magnetic measurements. It was established that different depositing procedures lead to the formation of X-ray amorphous Ni particles with markedly different magnetic properties. In contrast to entirely paramagnetic sample obtained from nickel acetate solution, superparamagnetic Ni0 particles formed by MVS exhibited a high capacity for absorption of MWI, sufficient for plasma to be generated and the reforming temperature to be reached without an additional sorbent.

Preparation and properties of nickel–zirconia nanocomposite coatings

The possibility of preparing and properties (surface morphology, microhardness, corrosion resistance) of nickel–zirconia composite coatings electrodeposited from nickel acetate solutions containing a dispersed phase in the form of a conventional polydisperse crystalline micropowder and a sol with nanoscale particles have been discussed. The effect of the particle size and concentration and the electrolysis conditions on the properties of the coatings has been determined.

Underpotential Deposition of Nickel on Cu2o Films and Its Effects on Reactivity and Stability of Cu2o Films

Our studies on crystal facet and reactivity relationship suggest that the (111) face of Cu2O films electrodeposited from pH 12 cupric lactate solution is a preferred surface for photogeneration of H2 from water, owing to its polar O2--termination. In order to prevent photodecomposition of this Cu2O surface, which is initiated by interaction of the terminal O2- and H+ (Cu2O + 2H+ + 2e- --> 2Cu0 + H2O), while maintaining the attraction of H+ to the surface and potentially catalyzing H2 generation, we have attempted to deposit a monolayer of nickel via underpotential deposition (UPD). Underpotential deposition on oxides has not been explored much unlike the underpotential deposition on metals as a monolayer deposition method. Nickel was deposited on Cu2O films from a 0.08 M nickel acetate solution by applying various potentials for 1 min at room temperature. The Cu2O films with nickel deposited were dissolved in HNO3, and then the quantities of the deposited nickel at the various potentials were determined with atomic absorption spectrometry (AAS). The AAS results indicate that the underpotential deposition at -0.2 V vs. SCE (the calculated Nernst potential of the nickel solution is -0.49 V vs. SCE) deposited nickel that is equivalent to a 23 % monolayer coverage, corresponding to 60 kJ stronger interaction of Ni2+(aq) with O2- at Cu2O surface than with bulk Ni surface, as predicted for the polar Cu2O (111) face. For the estimate of the 100 % coverage of Cu2O surface, the atomic radius of Ni (124 pm) was used as well as the surface roughness of 1.09 obtained by atomic force microscopy measurements. At -0.3 V vs. SCE, more than a monolayer of nickel (205 %) was deposited. According to the x-ray photoelectron spectroscopy (XPS), the binding energy (BE) of Ni 2p3/2 electron changed from 855 eV for -0.2 V vs. SCE UPD sample to 851 eV for -0.3 V vs. SCE UPD sample. Since the BEs of 854.6 eV and 852.6 eV have been assigned for Ni2+ and Ni0, respectively, the XPS data indicate that the full reduction of nickel at the Cu2O surface occurs at potentials more negative than -0.2 V vs. SCE. The effects of underpotentially deposited nickel on the activity and stability of Cu2O films will be compared with respect to the deposition potential.

Preparation and Performance of Electroless Nickel on AZ91D Magnesium Alloy

The corrosion of magnesium alloy in different plating solutions was researched. The results demonstrated that corrosive condition of the alloy immersed in nickel chloride solution and nickel sulfate solution is serious and in nickel acetate solution and nickel nitrate solution is less. Magnesium alloy was handled with four acid pickling formulas and two activation formulas and the effects of different pickling formulas and activation formulas were researched through comparative experiment. The experimental results indicated that after handed with pickling formula about 500 mL L−1 H3PO4 (85%), 110 mL L−1 HNO3 (68%), room temperature for 30 s and activation formula about 375 mL L−1 HF (40%), room temperature for 10 min, magnesium alloy could realize electroless nickel plating directly and the performance of the prepared plating was much better. The properties of the nickel-plating coating were researched by electrochemical workstation, scanning electron microscope, and X-ray diffraction. The results demonstrated that this Ni–P coating was very uniform and meticulous; the structure of Ni–P coating was amorphous; and comparing with magnesium alloy, the corrosion potential of this plating increased about 799 V and the corrosion current density declined obviously. The nickel-plating coating effectively improved the anticorrosion performance of magnesium alloy.

Effect of the preparation conditions on the physicochemical and catalytic properties of Ni2P/SiO2 catalysts

The effect of the reduction conditions on the physicochemical and catalytic properties of Ni2P/SiO2 catalysts was studied. The catalysts were prepared by impregnating silica with a solution of nickel acetate and diammonium hydrogen phosphate followed by drying, calcination, and temperature-programmed reduction. The Ni2P/SiO2 catalysts were reduced prior to hydrodeoxygenation (HDO) of methyl palmitate in the catalytic reactor (in situ) at temperatures of 550, 600, and 650 °С for 3 h and at 600 °С for 1 and 6 h. The reduction temperature and reduction time were shown to affect the conversion of methyl palmitate, and the optimal reduction conditions of the Ni2P/SiO2 catalysts were found. The Ni2P/SiO2 catalyst synthesized according to a widely used preparation method, including steps of passivation and rereduction at 450 °С in addition to the reduction step, is inferior in activity to the samples prepared in situ.

NiO films grown epitaxially on MgO substrates by sol–gel method

NiO films were grown epitaxially on MgO (100) substrates by a sol–gel spin-coating technique using a solution of nickel acetate tetrahydrate in 2-methoxyethanol stabilized by monoethanolamine. X-ray diffraction, high-resolution transmission electron microscopy, and selected-area electron diffraction analyses indicated that the NiO films grew epitaxially on the MgO substrates. X-ray reciprocal space maps around the asymmetric 311 diffraction point revealed that the NiO films were in a partially strained state, with the lattice parameter contracted along the direction normal to the surface and expanded along the direction parallel to the surface in each film, caused by a lattice mismatch between NiO and MgO. Strain relaxation was gradually enhanced as the film thickness increased. In addition, the Poisson's ratio of NiO was estimated to be about 0.22 from the lattice parameter changes, which is somewhat lower than the value predicted from the elastic constants of NiO.

Recyclable Non-Enzymatic Glucose Sensor Based on Ni/NiTiO3 /TiO2 Nanotube Arrays.

A non-enzymatic amperometric glucose sensor that can be renewed by light irradiation is described. It is composed of Ni/NiTiO3 /TiO2 nanotube arrays (NTAs) prepared by a simple hydrothermal treatment of as-anodized TiO2 NTAs in a nickel acetate solution followed by annealing under H2 /Ar. The Ni/NiTiO3 /TiO2 NTAs exhibit excellent electrocatalytic activity towards glucose oxidation in a 1.0 M NaOH supporting solution at a low applied potential of 0.4 V (vs. Ag/AgCl) with a high sensitivity of 456.4 μA cm-2 mM-1 and a low detection limit of 0.7 μM (S/N=3). The excellent electrochemical biosensing properties for glucose detection can be attributed to the orderly vertical alignment, large accessible surface, high conductivity, and electroactive NiII /NiIII redox couple. Meanwhile, owing to their high photocatalytic activity, Ni/NiTiO3 /TiO2 NTAs can readily decompose the organic fouling species generated on the electrode surface during glucose detection under light irradiation so that the original sensitivity and selectivity can be restored. The Ni/NiTiO3 /TiO2 NTAs electrode provides a promising renewable platform enabling long-term glucose monitoring with high sensitivity and selectivity.

Preparation of a reduced graphene oxide hydrogel by Ni ions and its use in a supercapacitor electrode

A three-dimensional (3D) reduced graphene oxide hydrogel (rGOH) was prepared by hydrothermal synthesis based on the electrostatic force and chemical reaction between graphene oxide (GO) and Ni ions in a nickel acetate solution.

Formation of T4(1) water tapes interconnected via centrosymmetric nickel(II) Schiff base complex to produce a 3D architecture

Addition of an aqueous methanol solution of nickel(II) acetate tetrahydrate into a methanol solution of the tridentate Schiff base, 3-(methylamino)propyliminomethylphenol (HL), resulted in the solid-state isolation of an octahedral nickel(II) complex [Ni(L)2]·3H2O, where lattice water molecules formed hydrogen-bonded water tetramers, which were connected among themselves to form a T4(1) tape. The tape, stabilized by hydrogen bonding interactions with the nickel(II) complex, was characterized by X-ray diffraction studies, FTIR, and thermo-gravimetric (TG) analyses. When thermally decomposed, the water loss was irreversible.

Synthesis and crystal structure of nickel(II) complex based on 2-trifluoroacetylcycloalkanone benzoylhydrazones

The reaction of ethanol solutions of benzoylhydrazones of 2-trifluoroacetylcycloalkanones (H2L) with a solution of nickel(II) acetate in aqueous ammonia in 1 : 1 ratio gave complexes NiL · NH3 with square structure. The composition and structure of the complexes were determined by elemental analysis, IR and 1H NMR spectroscopy, and X-ray diffraction analysis.

Deposition of p-type NiO films by chemical spray pyrolysis

NiO films were fabricated by spray pyrolysis method using aqueous and alcohol based solutions of Ni chloride and acetate, and growth temperatures in the range of 350–500 °C. Films are of cubic NiO phase, the crystallite size increases and film thickness decreases with the film growth temperature. When NiO films are prepared from chloride solutions the crystallites grow along the (111) plane parallel to the substrate while, by contrast, they grow with no preferred orientation when grown from nickel acetate solutions. Spray of NiCl2 results in films with uneven thickness, rough surface and porous microstructure while smooth films with uniform thickness can be obtained spraying Ni acetate solutions. Effect of Li-doping has been studied with NiO films from acetate solutions, LiCl and LiNO3 were used as dopant sources. According to XRD, sprayed NiO:Li films are of NiO phase where the lattice parameter decreases with increasing Li concentration in solution indicating the incorporation of Li atoms into NiO lattice. NiO and NiO:Li films show p-type conductivity, Li-doping decreases resistivity by two orders of magnitude, from ca. 300 to some Ω cm, as the carrier concentration increases from 1016 to 1018 cm−3 ([Li+] = 25 at.%, LiNO3). At similar doping rates LiNO3 is more efficient dopant source compared to LiCl.