Increasing Ni Doping Research Articles

Effect of Ni doping on martensitic transformation and magnetic properties for Co50V25Ga25∼26 Heusler alloy

ABSTRACTIn this work, we have investigated the crystalline structure, martensitic transformation (MT) and magnetic properties of Co50V25-xNixGa25 (x = 5, 6, 7, 8, 9, 12.5) together with Co50V17Ni7Ga26 Heusler alloys. It was found that the MT behavior can occur in the Ni-doped Co50V25Ga25 Heusler alloys, and the MT temperature increases with the increase of Ni doping, which can reach about room temperature as the Ni doping increases up to x = 12.5. In the temperature interval of MT, with the decrease of temperature, the metamagnetic behavior appears from the ferromagnetic austenitic phase to the paramagnetic martensitic phase in the Co50V17Ni7Ga26 Heusler alloy. As a result, the magnetocaloric effect was observed, and the calculated magnetic entropy change can achieve about 11.5 J/kg K around 94 K for the magnetic field changes of 7 T.

Study of structural, optical and enhanced multiferroic properties of Ni doped BFO thin films synthesized by sol-gel method

Abstract Pure and nickel (Ni) doped bismuth ferrite (BiFeO3, BFO) thin films were successfully deposited on the SnO2:F (FTO)/glass substrate by a sol-gel method. The structure, phase evolution, chemical composition, surface element chemical states, surface morphology, multiferroic and optical properties were systematically investigated. The structural analyses using XRD and Raman techniques revealed that Ni doping induced a structure transition from rhombohedral toward orthorhombic or tetragonal structure. The surface element chemical states examined by XPS demostrated that Ni doping resulted in the increase of oxygen vacancies while decrease of Fe2+ concentration. SEM images demonstrated that Ni doping impacted the grain growth mechanism and the average grain size increased with increase of Ni doping. EDS analysis further confirmed the element composition with presence of Ni element in the Ni doped BFO thin films. The leakage current density of Ni doped BFO thin films was observed to increase with increase of Ni doping due to the higher oxygen vacancies. An enhanced ferroelectric and piezoelectric properties were obtained in the BFO thin film with Ni doping x = 0.10, giving a high remnant polarization (2Pr) of 22.95 μc/cm2 with a coercive field (2Ec) of 728.24 kV/cm and high piezoelectric coefficient (d33,eff) of 37.76 p.m./V. Meanwhile, the magnetization measurement revealed that Ni doped BFO thin films showed an enhanced magnetization, compared to pure BFO thin film. The highest saturation of 2.85 emu/cm3 under a magnetic field of 10 k Oe is also observed in BFO thin film with Ni doping x = 0.10. The transmittance and optical band gap decreased with increase of Ni doping and when Ni doping is x = 0.10, the lowest band gap of 2.46 eV was observed.

Magnetic and superconducting anisotropy in Ni-doped RbEuFe4As4 single crystals

We investigate the effect of Ni doping on the Fe-site in single crystals of the magnetic superconductor RbEuFe$_4$As$_4$ for doping concentrations of up to 4%. A clear suppression in the superconducting transition temperature is observed in specific heat, resistivity and magnetization measurements. Upon Ni-doping, the resistivity curves shift up in a parallel fashion indicating a strong increase of the residual resistivity due to scattering by charged dopand atoms while the shape of the curve and thus the electronic structure appears largely unchanged. The observed step $\Delta C/T_c$ at the superconducting transition decreases strongly for increasing Ni doping in agreement with expectations based on a model of multi-band superconductivity and strong inter-band pairing. The upper critical field slopes are reduced upon Ni doping for in- as well as out-of-plane fields leading to a small reduction in the superconducting anisotropy. The specific heat measurements of the magnetic transition reveal the same BKT behavior close to the transition temperature $T_m$ for all doping levels. The transition temperature is essentially unchanged upon doping. The in to out-of-plane anisotropy of Eu-magnetism observed at small magnetic fields is unaltered as compared to the undoped compound. All of these observations indicate a decoupling of the Eu magnetism from superconductivity and essentially no influence of Ni doping on the Eu magnetism in this compound.

Cycle of Ni(II)-Ni(III)-Ni(II) in Ni-doped layered double hydroxides for activation of intercalated peroxydisulfate

Peroxydisulfate (PDS) activation has attracted much attention for the treatment of drinking water systems. In this work, Ni-doped MgAl layered double hydroxides (Ni-LDHs, Ni:Mg = 1:100 to 1:1, molar ratio) were prepared for the activation of PDS via intercalation. Compared with the case without Ni, doping with Ni resulted in much higher phenol degradation at the same PDS dosage. This was attributed to the activation of PDS, as the PDS consumption increased with increasing Ni doping amount. Moreover, radicals corresponding to organic decomposition were detected in the presence of Ni. Physical characterization results reveal that Ni(II) was converted to Ni(III) with PDS and then reduced back to Ni(II) during organic decomposition. To our best knowledge, this is the first study to report a cycle of Ni(II)-Ni(III)-Ni(II) in LDHs for the efficient activation of PDS. This effect was also observed in cases of odorous substances such as 4-bromophenol, 2-methylisoborneol, and geosmin. Our work provides a promising approach for the activation of PDS by Ni-LDHs.

Facile precipitation synthesis, structural, morphological, photoluminescence and photocatalytic properties of Ni doped ZrO2 nanoparticles

In this study, Pure ZrO2 (600 °C) and Ni (0.02, 0.04, 0.06, 0.8 M) doped ZrO2 (600 °C) nanoparticles were obtained by facile precipitation method. The obtained products have been characterized by XRD, FTIR, UV-DRS, PL, FESEM-EDX, TEM-SAED pattern and XPS. The tetragonal structure of ZrO2 (600 °C) gradually increases with the increasing Ni doping concentration and then a small NiO diffraction peak was detected at increasing Ni content. The Ni (0.08 M) doped ZrO2 (600 °C) nanoparticles were approximately in spherical morphology was confirmed by FESEM and TEM results. The energy gap value of the pure ZrO2 (600 °C) and Ni doped ZrO2 (600 °C) nanoparticles decreased from 5.12 to 3.2 eV with enhancing nickel concentration. The surface defects and oxygen vacancies were analyzed by PL spectroscopy. This peak intensity gradually decreased with increase in nickel concentration. The photocatalytic activities of the Ni (0.08 M) doped ZrO2 (600 °C) catalysts were studied by the photodegradation of MV and MB aqueous solution under sunlight irradiation. The Ni (0.08 M) doped ZrO2 (600 °C) catalyst exhibited good photocatalytic efficiency and the enhanced photocatalytic mechanism was discussed.

Influence of Ni Doping in SnO2 Nanoparticles with Enhanced Visible Light Photocatalytic Activity for Degradation of Methylene Blue Dye

In this article, Nickel doped rutile structure tin oxide (SnO₂) nanoparticles have been prepared by simple chemical co-precipitation method and prepared samples were characterized by Powder X-ray Diffraction, Fourier transform infrared Spectroscopy, Microraman analysis, Photoluminescene Spectroscopy, UV-Visible Spectroscopy, Energy dispersive analysis and Field emission scanning electron microscope. XRD studies revealed the single phase tetragonal rutile structure with space group of P42/mnm. The average crystallite size of the particles was decreased from 27 to 22 nm with increasing Ni doping concentration. FTIR spectra confirmed the presence of various bands such as O-H, C-H, Sn-O-Sn. Raman modes Eg, A1g and B2g were assigned at 478, 630 and 740 cm-1 which confirmed the single phase of pure and Ni doped SnO₂ nanoparticles. The photoluminescence spectra confirmed that the defect related emissions increased with increasing of Ni concentration. The UV absorption spectra showed that the absorption of the particles decreased with increasing Ni concentration and the band gap values decreased from 3.7 to 3.4 eV. EDX spectra confirmed the presence of Sn, Ni, O in pure and doped samples. The photocatalytic activity of the pure and Ni doped SnO₂ nanoparticles were analyzed by using methylene blue dye under visible light irradiation. It is concluded Ni (7%) doped SnO₂ nanoparticles have higher degradation efficiency compared to pure SnO₂ nanoparticles.

Magnetocaloric effect and electron paramagnetic resonance studies of the transition from ferromagnetic to paramagnetic in La0.8Na0.2Mn1-xNixO3 (0≤x≤0.06)

In this paper, we showed the effect of Ni doping on the physical properties of La0.8Na0.2Mn1-xNixO3 perovskite manganites. All the compounds crystallized in a rhombohedral structure with R3¯cspace group. Magnetic studies showed a ferromagnetic (FM)–paramagnetic (PM) phase transition around the Curie temperature (TC); values for x = 0, 0.03 and 0.06 were 297, 275 and 257 K, respectively. A monotonous decrease in TC was achieved with the increase of Ni content. This decrease can be related to the weakness of the Mn3+–O–Mn4+ double exchange mechanism. Interestingly, the electron PM resonance technique confirmed the decrement of the FM ordering following the increase of Ni doping. The magnetocaloric effect was estimated by calculation of the magnetic entropy change (−ΔSMmax) as a function of temperature at different applied magnetic fields. The highest values of −ΔSMmaxat 5T applied magnetic field decreased from4.5±0.1to3.7±0.1J.kg−1.K−1for x = 0 and 0.06, respectively, with Ni doping.

Studying the structural, morphological, and optical properties of CuS:Ni nanostructure prepared by a hydrothermal method for biological activity

In recent years, copper sulfide has attracted great interest in biological application, due to its biocompatibility and low toxicity. Undoped and nickel (Ni)-doped copper sulfide nanostructures were synthesized using a hydrothermal method at 150 °C for 15 h. XRD patterns show that all samples have confirmed the formation of a hexagonal phase. Absorbance spectra were measured by using a UV–vis spectrophotometer. The optical bandgap energy of CuS nanostructure decreased with increasing Ni doping concentration. Their optical bandgap energies were 3.2, 3.21, 2.9, and 2.9 eV for undoped and Ni-doped copper sulfide nanostructures with concentrations of 1, 3, and 5%, respectively. The antibacterial activity of CuS nanostructure against E. coli, P. aeruginosa, and S. aureus was evaluated by zone of inhibition. The test revealed that the minimum concentration of CuS nanostructure has a strong antibacterial activity against Gram-positive bacteria than for Gram-negative bacteria. Antitumor treatment was applied based on employing CuS nanostructures by exploiting their unique optical and morphological properties as therapeutic agents against rhabdomyosarcoma (RD) and murine fibroblast (L20B) cancer cell lines without using laser. The cytotoxicity effect was evaluated by MTT assay; the results demonstrated that CuS nanostructure with 1% Ni doping exhibits more toxicity effect than undoped and doped nanostructures, with 3 and 5% for all particle concentrations, where cytotoxicity reaches 34.3% at 0.125 mg/ml, being the most influential concentration, which could be a promising agent for cancer treatment.

Enhanced gas-sensitivity and ferromagnetism performances by the Ni-doping induced oxygen vacancies in (Mn, Ni) codoped ZnO nanorods

Doping with transition metal ion is an effective way to modulate the physical properties of ZnO. Here, structural, optical, gas-sensing and magnetic properties of (Mn, Ni) codoped ZnO nanorods prepared by hydrothermal method are investigated systematically. Reitveld refinement of X-ray diffraction patterns reveal (Mn, Ni) codoped ZnO nanorods with hexagonal crystal structure and a contraction in lattice parameters Mn and Ni-doping. Since transition metal ions doping could influence the microstructure and defect state, the (Mn, Ni) codoped ZnO nanorods show the higher sensitivity to ethanol gas and stronger room temperature saturation magnetization of nanorods. X-ray photoelectron spectra and UV–vis absorption spectra analysis reveal that oxygen vacancies related to defects in the nanorods increase with increasing Ni doping concentration, resulting in the increased carrier concentration. And the singly charged oxygen vacancies increase with Ni doping concentration derived from Gaussian fitting PL spectra result. This work demonstrates that the singly charged oxygen vacancies and surrounding transition metal ions forming bound magnetic polarons are accountable for the origin of ferromagnetism in (Mn, Ni) codoped ZnO nanorods. • Improved gas sensing and ferromagnetism properties are related to the concentration of oxygen vacancy. • The bandgap and carrier concentration increase with Ni concentration of (Mn, Ni) codoped ZnO nanorods. • Singly charged oxygen vacancies in the nanorods were analyzed by the PL spectra results. • V O + and surrounding Ni 2+ and Mn 2+ ions are responsible for ferromagnetism in (Mn, Ni) codoped ZnO nanorods.

Structural, optical and thermal properties of nickel doped bismuth borate glasses

Nickel doped Bismuth Borate glasses with composition (70B2O3-(30-x)Bi2O3-xNiO) where x = 0,0.5,1.0,1.5,2.0 (wt%) have been synthesized by conventional melt quenching technique. X-Ray Diffractograms have confirmed the amorphous nature of the prepared glasses. The calculated physical parameters such as density, molar volume, average boron‑boron separation, ion concentration and inter ionic distance provided the information about the structural stability of glass samples. DTA and OPD confirmed the decrease in glass transition temperature (Tg) with increase in Ni content. The FTIR and Raman studies clearly revealed that the glass network mainly comprises of [BiO3], [BiO6], [BO3] and [BO4] units. It is also observed that the introduction of dopant (Ni) and modifier (Bi) leads to the conversion of [BO3] trigonal units into the [BO4] tetragonal units due to the increase in non-bridging oxygen atoms which results in the increase of degree of disorder in the glass network. The optical absorption measurements (UV) carried out for well polished glass samples show a decrease in optical band gap with the increase in Ni doping. This observation was further supported by the urbach energy calculations and metallization criterion of the prepared glass samples. The electronegativity and electronic polarizability values revealed the ionic character of glass samples.

Investigation of structural, morphological and optical properties of Nickel-doped Zinc oxide thin films fabricated by co-sputtering

In this study, it was aimed to grow Nickel doped (0.0 at.%, 0.16 at.%, 0.20 at. % and 0.24 at. %) Zinc Oxide (NZO) thin films on quartz substrates using Magnetron Sputtering technique. NZO thin films were obtained at a temperature of 450 °C, a pressure of 480 m Torr and a deposition time of 30 min. Co-sputtering process for both Ni and ZnO target was performed using two separate power sources. The DC power of the Ni target material was 20, 30 and 40 W, respectively while the radio frequency (RF) power of the Zinc oxide (ZnO) target material was set to 150 W. Using XRD analysis, thin films were found to have polycrystalline morphology, and the average crystallite size changed significantly depending on the increased Ni doping level. The optical Transmittance of the thin films was greater than 90% in the visible region (550 nm), and this value tends to decrease slightly by Ni doping. The optical band gap (Eg) firstly decreased and then slightly increased with the Nickel doping ratio and these values were found to be 3.23 eV, 3.11 eV and 3.15 eV, respectively, with increase of Ni doping.

Investigation on the structural, multiferroic and magnetoelectric properties of BaTi1-xNixO3 ceramics

In this paper, we report the influence of Ni doping on the structural, electrical, magnetic and magnetoelectric properties of BaTiO3 (BTO) ceramics. X-ray diffraction (XRD) analysis indicates a phase transition from tetragonal to hexagonal at x = 2.5 mol%. Further, XRD data has been refined using Rietveld method to extract the phase formation, lattice parameters, and the phase fraction of BaTi1-xNixO3(BTNO)(0≤x≤10mol%) ceramics. The ferroelectric polarization decreases with Ni doping concentration. The relative permittivity of BTNO compositions decreases while the corresponding dielectric loss increases with Ni doping concentration. Room temperature magnetic hysteresis (M-H) loop of all BTNO samples exhibit ferromagnetic nature with a saturated loop except for x = 2.5 mol% Ni doping concentration. At x = 2.5 mol% Ni doping concentration, a small amount of diamagnetism is observed at higher fields along with ferromagnetism. The origin of ferromagnetism is due to the F- center exchange interaction via oxygen vacancies. The highest remnant magnetization (Mr) is 11.76 memu/g for x = 10 mol%. The Magnetodielectric coefficient (MD) and magnetoelectric coefficient (ME) gradually increases with increasing Ni doping concentration, and are 1.72% and 4.51 mVcm−1Oe−1 respectively for x = 10 mol%.

Structural, electric transport response and electro -strain - Polarization effect in La and Ni modified bismuth ferrite nanostructures

In this work, we reported the structural properties, electrical transport response and electro-strain polarization effect of La-Ni bismuth ferrite nanostructures, Bi1-XLaXFe1-YNiYO3 (x = 0.0, 0.1; y = 0.0, 0.03, 0.05, 0.07) prepared via sol gel technique. X-ray diffraction (XRD) analysis confirmed the rhombohedral crystal structure with space group R3c of BiFeO3. The Ni ion doping at a Fe - site in BiFeO3 escorts to some structural changes and the average crystallite size was found to be in range ∼13–20 nm. The higher tensile strain was observed in W-H Plot for the prepared samples. The morphological and chemical composition studies of as prepared samples were carried out via using SEM and EDS. Dielectric constant (έ) and AC conductivity (σAC) were deliberated as a function of frequency in the range 10 Hz to 5 MHz. A significant reduction in the dielectric constant has been observed with increasing Ni doping. An enhancement in the remanent polarization (2Pr) value (up to 1.04 μC/cm2 with applied field 8 kV/cm) and AC conductivity has been observed with La/Ni co-doping. The high Curie temperature (Tc) of BFO makes it a suitable candidate for high temperature electromechanical applications. Moreover, an enhanced value of the electric field driven strain as a function of frequency and the applied field is observed which exhibits highly asymmetric S-E hysteresis loops. The peak to peak strain value of Sp and SN is achieved up to 1.019% and 1.582%, respectively, which is the largest value of strain ever obtained in BiFeO3 based nano ferrites. The highest value of peak to peak strains (SP & SN) and strain memory (Sme) has been observed for Bi0.9La0.1Fe0.93Ni.07O3 sample at 8 kV/cm which makes it a suitable candidate for high temperature electromechanical applications (like sensors and actuators etc) in addition to electronic and magnetic applications.

Characteristics of the Li-Ni Doped Cobalt Oxide Thin Films Prepared by Pulsed Laser Deposition.

Cobalt oxide spinel thin films doped with Ni and Li were deposited on c-sapphire single crystal substrates at various substrate temperatures and oxygen partial pressures by pulsed laser deposition. The effects of the doping and processing parameters on the crystal structure, electrical and optical properties of cobalt oxide base spinel thin films were analyzed by XRD, four point probe and UV spectrometry. The electrical conductivity increased with increasing Ni doping concentration, x, up to x = 0.7. The thin films grew on the sapphire substrates with a strong (111) preferred orientation. Li0.1Ni0.6Co2.3O4 spinel phase decomposed to a rock salt phase when the oxygen partial pressure was lower than 5 mtorr. The electrical conductivity decreased rapidly with the formation of a rock salt phase due to the limited charge transfer between the divalent and trivalent cations.

Visible light photocatalytic activity of sol–gel Ni-doped TiO2 on p-arsanilic acid degradation

Nickel-doped TiO2 (0.1, 0.5, 1.0, 2.5, 5.0, and 10.0 wt%) photocatalysts were prepared by the sol–gel method. Physicochemical properties were determined by the characterization using X-ray diffraction, Raman and UV–vis diffuse reflectance spectroscopies, N2 physisorption, and zeta potential determination (PZC). The synthesized materials exhibited the photocatalytically active anatase crystalline phase and the catalysts exhibited stronger absorption in the visible light region with a red shift in the adsorption edge with the increase of Ni doping. The photocatalytic evaluation of TiO2−Ni materials was carried out on p-arsanilic acid (p-ASA, 10 mg L−1) degradation in aqueous suspension under visible radiation. Compared with bare TiO2, the TiO2–Ni 1.0 material (1 wt% Ni-doped TiO2) exhibited higher photocatalytic activity on p-ASA degradation under visible light irradiation allowing a 76% degradation percentage in 180 min reaction time while 60% degradation percentage was achieved with undoped TiO2. The TiO2–Ni 1.0 material showed the highest surface area in comparison with the other prepared materials. Meanwhile, the photocatalytic activity of TiO2–Ni 1.0 can keep even after three cycles with not loss of activity since nickel was not leached from the TiO2-based catalyst into the solution during photocatalytic reaction. Therefore, the doping of the nickel into the TiO2 lattice by the sol–gel method allowed its activation under visible radiation and an efficient photoexcited charge separation to prevent electron-hole recombination showing high chemical stability.

H2S sensing characteristics of Ni-doped CaCu3Ti4O12 films synthesized by a sol-gel method

The problem of detecting the toxic hydrogen sulfide (H2S) gas at part per million levels in air by means of simple solid state gas sensors is relevant to environmental and gas processing industries. In this work, high-performance H2S gas sensors are developed based on nickel-doped calcium copper titanate (Ni-doped CCTO) thin films synthesized by a sol-gel method. From gas-sensing measurements, the response of Ni-doped CCTO sensing films increased substantially with increasing Ni doping level from 1.5 to 7.3 wt%, revealing a catalytic effect of Ni on the surface reactions with adsorbed H2S molecules. In particular, 7.3 wt% Ni-doped CCTO sensors offered a high response of 120 for 10 ppm of H2S at the optimal operating temperature of 250 °C, an order of magnitude higher than that of undoped one. In addition, the response time dropped significantly from ∼80 s to ∼4 s while the recovery time slightly improved as the Ni doping content increased from 0 to 7.3 wt%. Moreover, the Ni-doped CCTO sensors exhibited good reproducibility and high H2S selectivity against ethanol, H2, NO2 and NH3. Therefore, the Ni-doped CCTO sensors are highly promising for sensitive and selective detections of H2S.

A Comparative Study on Impact of Nickel Nitrates and Nickel Chloride on the Structural Properties of ZnFe2O4 Nanostructures

Ni-Zn ferrite (NixZn1-xFe2O4, for x=0, 0.1, 0.3, 0.5, 0.7) nanoparticles have been successfully synthesized using chemical coprecipitation method for two different compositions of nickel nitrides (Ni(NO3)2.6H2O) and nickel chlorides (NiCl2.6H2O) respectively. X-ray analysis explored that nanoparticles for each value of x have cubic spinal structure. No extra peaks were observed in XRD spectra indicating the absence of any un-reacted component in the samples for both the series. The d-spacing and lattice parameter were found to lay in the range of 2.54 Ao to 2.51 Ao and 8.42 Ao to 8.33 Ao for nickel chloride series and 2.56 Ao to 2.54 Ao and 8.49 Ao to 8.42 Ao for nickel nitride series respectively. Both of these decreased by increasing Ni doping due to the less ionic radius of Ni2+ ions then Zn2+ and for strong preference of Ni2+ ions for octahedral sites. The crystallite size was observed to vary between 10-13 nm and its value is maximum for x=0.3 for nickel chloride series, whereas it vary between 18-36 nm and its value is maximum for x=0.5 and x=0.7 which shows that by adding nickel chloride a better result of 10 nm is achieved at x=0.7 whereas, 18 nm is achieved at x=0.1 and it increases by increasing nickel nitride.

Structural and electron transport properties of single-crystalline In2O3 films compensated by Ni acceptors

For device applications, the ability to grow semi-insulating or p-type indium oxide (In2O3) is highly desirable. With this in focus, high quality single-crystalline Ni-doped In2O3 films have been grown by plasma-assisted molecular beam epitaxy and structurally and electrically characterized. Within a concentration range of approximately 1017–1019 cm−3, Ni is fully incorporated in the In2O3 lattice without the formation of secondary phases. At doping higher than roughly 1020 cm−3, secondary phases seem to start forming. No film exhibits p-type conductivity at room temperature. Instead, Ni is shown to be a deep compensating acceptor—confirming theoretical calculations, the effect of which only becomes apparent after annealing in oxygen. Combined Hall and Seebeck measurements reveal the compensation of bulk donors already at low Ni concentrations (∼1018 cm−3) and a residual film conductance due to mainly the interface region to the substrate. This residual conductance is gradually pinched off with increasing Ni doping, eventually resulting in semi-insulating films at excessive Ni concentrations (∼1021 cm−3).

Correlation between magnetic properties and cationic distribution of Zn0.85−x Ni x Mg0.05Cu0.1Fe2O4 nano spinel ferrite: effect of Ni doping

The correlation among magnetic properties and cationic distribution of Ni-doped Zn0.85−xNixMg0.05Cu0.1Fe2O4 (x = 0.00, 0.17, 0.34, 0.51, 0.85) ferrite, synthesized using sol–gel auto-combustion process is studied by X-ray diffraction (XRD), scanning electron microscope (SEM), energy-dispersive X-ray analysis (EDAX), and magnetic measurements. XRD patterns revealed a pure phase spinel ferrite structure for all samples with Scherrer’s grain diameter (D) ranging from 33.55 to 42.07 nm. Experimental, theoretical lattice constant (aexp., ath.), specific surface area (S), and the distances between cations (Me–Me) (b, c, d, e, f) of the annealed Zn–Ni–Mg–Cu ferrite decrease with the increase in Ni doping. Elemental analysis, particle diameter, and surface morphology were examined by EDAX and SEM. Coercivity (Hc) and saturation magnetization (Ms) of Zn–Ni–Mg–Cu ferrite ranges between 0.97–167.5 Oe and 47.63–136.93 Am2 kg−1, respectively, signifying the soft character of annealed samples. Magnetic parameters such as Hc, magnetocrystalline anisotropy (K1), remanence (Mr), and reduced remanent magnetization (Mr/Ms) increase up to x = 0.51 and then reduce thereafter with Ni doping. Particle size dependence of Hc reveals superparamagnetic, single domain, and multi-domain nature of the studied ferrite. Observed similar trend of Ms, Neel/experimental magnetic moment (nBN, nBe) with Ni content (x) follows the Neel’s two-sublattice model of ferrimagnetism and is accredited to the cationic distribution and B–B exchange interaction. All these results establish a strong connection between magnetic properties and cationic distribution of Zn0.85−xNixMg0.05Cu0.1Fe2O4 ferrite.

Studies on structure and spectra characterization of Ni-doped PTCDA films

3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) films without and with light Ni-doping were prepared in high vacuum chamber and studied by a combination of atomic force microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, ultraviolet–visible (UV–Vis) spectrophotometry and Raman spectroscopy. The results indicated that the undoped PTCDA film and the PTCDA film doped in the (PTCDA:Ni) molar ratio of 1:0.73 were β-phase crystallites with the crystallinity of 13.80 and 3.22 %, respectively. The crystallite morphologies were changed gradually and appeared in amorphous states with the increase of Ni-doping, and Ni in its amorphous state was dispersed in Ni-doped PTCDA films; also the UV–Vis absorption were reduced gradually with the increase of Ni-doping. Nevertheless, the fluorescence background of Raman spectra of PTCDA film was effectively restrained by the low concentration of Ni-doping, which was advantageous to the Raman spectra detection.