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Nanocrystalline and thermally stable hydroxyapatite (HA) powder with nominal composition of Ca10(PO4)6(OH)2 was prepared by wet chemical route from calcium hydroxide Ca(OH)6 and mono ammonium phosphate NH4H2PO4 as calcium and phosphate sources, respectively. The effect of calcination temperature on the structure, microstructure, molecular bonding, thermal behavior and morphology was investigated by X-ray diffraction patterns (XRD), Fourier Transform Infra-Red (FT-IR), Raman spectroscopy, thermogravimetry (TGA), differential thermal analysis (DTA) and scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDS) analysis. The XRD patterns of the as-prepared and calcined powders exhibit a single phase of hydroxyapatite. The crystallite size of as-prepared and calcined HA is in the range of 44-182 nm. FT-IR and Raman spectroscopy results are in good agreement with XRD ones. The EDS analysis reveals the presence of all elements. The thermal stability of the synthesized powders is evidenced by TGA/DTA scans which show a weight loss smaller than 2%.

The effect of the B content on the microstructural, structural, and magnetic properties of partially amorphous Fe92−xNb8Bx (x = 5, 10, 15, and 20) alloys has been investigated by means of scanning electron microscopy, X-ray diffraction, high and low-temperature extraction-type magnetometers. The XRD results reveal the formation of a nanocomposite structure where nanocrystalline bcc α-Fe and Fe2B phases are embedded into an amorphous matrix. The FeB boride is observed for higher boron contents (x = 15 and 20), and the crystallite sizes are in the range of 7–24 nm. As the B content increases, the amorphous phase-relative proportion and coercivity increase, whereas the saturation magnetization decreases. An important magnetic hardening occurs by lowering the temperature from 400 to 5 K for x = 20% B. The variation of the Curie temperature can be attributed to the heterogeneity of the amorphous matrix This work has been supported by the Algerian Ministère de l’Enseignement Supérieur et de la Recherche Scientifique, the PHC-Maghreb 15 MAG07 program and the Spanish MINECO projects MAT2013-47231-C2-2-P and MAT2016-75967-P

(Fe1−xMnx)2P phosphide powders in the composition range 0.15 ≤ x ≤ 0.75 have been mechanically alloyed and their structural, magnetic and thermal changes with composition have been investigated by means of X-ray diffraction, 57Fe Mossbauer spectrometry, magnetization measurements and differential scanning calorimetry. The milling process induces changes in the crystal phase diagram of the (Fe1−xMnx)2P system. The XRD results reveal the coexistence of a bcc Fe(Mn)-type, hexagonal (Fe2P and Mn2P-type), orthorhombic (MnP-type) and tetragonal Fe3P-type structures for all compositions. The room temperature Mossbauer spectra confirm the formation of the Fe(Mn)-type, non-stoichiometric Fe2P-type, FeP-type and Fe3P-type structures. Saturation magnetization exhibits a comparable behavior to that of the average hyperfine magnetic field. The DSC scans show the existence of several endothermic and exothermic peaks in the temperature range (100–700) °C related to different phase transitions. The endothermic peak at about 582–589 °C can be related to the ferromagnetic/paramagnetic transition temperature (Curie temperature, TC) of the Fe(Mn)-type structure.

Molybdenum-doped In2O3 thin films with different atomic ratios of $$ y = \frac{{[{\text{Mo}}^{6 + } ]}}{{[{\hbox{In}}^{3 + } ]}} $$ = 0 at.%, 1 at.%, 3 at.%, 5 at.%, and 7 at.% have been prepared by spray pyrolysis. X-ray diffraction (XRD) analysis showed that the Mo-doped In2O3 thin films crystallized in cubic structure with (222) preferred orientation. The best crystallinity was obtained for molybdenum concentration of 3 at.%, with an increase in grain size up to 155 nm. MAUD software was applied to the x-ray diffraction patterns to determine the phases, average grain size (d), microstrain ( $$ \left\langle {\sigma^{2} } \right\rangle^{1/2} $$ ) and lattice parameters. The optical transmission was close to 75%. Doped films displayed large bandgap energy on the order of 3.52 eV to 3.56 eV. Optical parameters such as refractive index (n), packing density (p), porosity, oscillator energy (E 0), and dispersive energy (E d) were studied using the envelope method. The electrical resistivity (ρ) decreased from 650.20 × 10−3 Ω cm to 2.03 × 10−3 Ω cm for undoped and In2O3:Mo(3 at.%) thin film, respectively. Heat treatment of In2O3:Mo(3 at.%) thin film under nitrogen atmosphere at 250°C for 2 h led to further decrease in the electrical resistivity to about 5.55 × 10−4 Ω cm. These results prove that annealed In2O3:Mo(3 at.%) thin film can be considered a key material for use in optoelectronic devices as a transparent electrode or an optical window for solar cells.

The structural, optical and electrical properties of un-doped and (Al,Er) co-doped zinc oxide (ZnO) powders synthesized by hydrothermal method were investigated. The obtained samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), energy-dispersive spectroscopy and magnetic measurements. XRD results reveal that the incorporation of Al and Er in ZnO matrix leads to the formation of a nanostructured hexagonal (wurtzite) ZnO structure and α-Al2O3 secondary phase. High-resolution transmission electron microscopy image also shows the hexagonal shape of the ZnO nanoparticles. The magnetic behavior of the nanoparticles changes with concentration of dopant elements due to the competition between oxygen vacancies, secondary phase effect and exchange interaction between dopant elements.

Structural, morphological, optical and electrical properties of europium doped In2O3 thin films grown by spray pyrolysis technique are studied in this work. The atomic percentages of europium dopant in In2O3-based solution were y = ( [ Eu 3 + ] [ In 3 + ] ) sol =0; 0.1; 0.3 and 0.5 at%. All films crystallize into the body centered cubic structure. The preferred orientation peak along the (222) plane was changed to (400) after doping. It is further revealed a best crystallinity for y =0.3 at% followed by a noticeable increase of the grain size. Some structural and microstructural parameters are determined using Rietveld refinement of XRD patterns. The optical transmission of doped films was above 68% in the visible range. The optical band gap (Eg) is in the range of [3.43–3.51] eV. Optical constant such as refractive index (n), packing density (p), porosity, oscillator energy (E0) and dispersive energy (Ed) were also studied in this report using envelope method based on transmission-reflection spectra. Electrical properties show a lowest resistivity (ρ) for a doping concentration equals to 0.3 at% reaching 0.031 Ω cm. At this doping ratio, an enhancement of free carrier concentration is also remarked. A heat treatment under nitrogen atmosphere is then applied on optimized In2O3:Eu (0.3 at%). A significant decrease of the resistivity is noted at 250 °C during 2 h reaching 0.004 Ω cm. These results lead to conclude that annealed In2O3:Eu(0.3 at%) can be a good candidate to be used in many optoelectronic devices and especially as optical window or transparent electrode in solar cells.

Using low cost spray pyrolysis technique, polycrystalline CaSO4 thin films were successfully grown on a glass substrate with a thickness of about 1 μm. Samarium doping has been performed on CaSO4 thin films to explore luminescence properties. The characterizations of these films were carried out using X-ray diffraction, Scanning Electron Microscopy and optical measurements. The structural analyses reveal the existence of hexagonal CaSO4 phase with a (200) preferred orientation belonging to CaS compound for substrate temperatures below 350 °C. It is shown that the crystallinity of the sprayed thin films can be improved by increasing substrate temperature up to 250 °C. Warren-Averbach analysis has been applied on X-ray diffractogram to determine structural parameters involving the phase with its amount, the grain size and the lattice parameters using Maud software. The surface topography shows a rough surface covered by densely packed agglomerated clusters having faceted and hexagonal shapes. Energy dispersive microscopy measurements confirm the presence of calcium and sulfur in equal proportions as well as high percentage of oxygen. Photoluminescence at room temperature revealed that luminescence peaks are attributed to the intrinsic emission of pure CaSO4 phase.

Nanostructured Fe1−x Ni x and Fe1−x−y Ni x Cr y (x = 30, 40; y = 10) powders were obtained by mechanical alloying technique (MA) from elemental powders using a planetary ball mill. The evolution of structure, microstructure and magnetic properties of mechanically alloyed powders were studied by X-ray diffraction, scanning electron microscopy and a vibrating sample magnetometer. The MA powders for 7 h consist of two solid solutions bcc and fcc. The saturation magnetization was found to decrease with increasing Ni content and so with increasing fcc solid solution amount. Oxidation of MA powders results in the formation of tree phases: antiferromagnetic NiO, hematite α-Fe2O3, and ferrimagnetic spinel structure NiFe2O4. According to the magnetic measurements, the oxidation leads to the deterioration of magnetic behavior due to the exchange bias anisotropy.

Zinc doped indium oxide thin films (In2O3:Zn) have been successfully prepared on glass substrates using spray pyrolysis technique for different zinc concentrations y $$\big( {{\text{y}} = \frac{{[{\text{Zn}}^{2 + } ]}}{{[{\text{In}}^{3 + } ]}} = \, 0,1, \, 2, \, 3, \, 4, \, 5\;{\text{and}}\,6\,{\text{at}}.\% } \big)$$ . The structure, surface morphology, optical and electrical properties of In2O3:Zn thin films were investigated by X-ray diffraction, atomic force microscopy, spectrophotometer, fluorescence spectrometer and Hall Effect. It is found that physical properties of In2O3 material are affected by doping with zinc element. Structural analysis shows that In2O3 thin layers are polycrystalline with cubic structure. After doping, a double transition of preferential orientation was observed from (222) to (400) for y = 1 at.% and from (400) to (440) for y = 3 at.%. The best crystallinity is obtained for y = 1 at.% with (400) as a preferred orientation. The maximum grain size is obtained for y equals to 1 at.%. Optical transmission shows an average value after doping of about 80 % with interference fringes revealing the good uniformity and homogeneity of deposited layers. After doping, the direct band gap Eg is equals to 3.51 eV for In2O3:Zn (1 at.%). The single oscillator energy E0 and dispersion energy Ed were determined by Wemple model using the envelope method. We obtained E0 = 2 × Eg for doped films. Electrical resistivity (ρ) decreases from 650.20 × 10−3 to 198.50 × 10−3 Ω cm for respectively undoped and In2O3:Zn (1 at.%). A heat treatment under nitrogen atmosphere of In2O3:Zn (1 at.%) thin films leads to enhanced optical transmission especially for 250 (2 h) and 450 °C (2 h). A significant decrease of the resistivity to about 2.82 × 10−3 Ω cm is obtained for annealing temperature equals to 250 °C (2 h). All these experimental results lead to consider that annealed zinc doped indium oxide thin films can be used as transparent conductive oxide material in optoelectronic applications.

Nanostructured Fe65Si20Cr15 powders were prepared by mechanical alloying in a planetary ball mill. Morphological, microstructural, structural, and magnetic characterizations of the milled powders were investigated by scanning electron microscopy, X-ray diffraction, Mossbauer spectroscopy and vibrating sample magnetometer. A mixture of substitutional bcc Fe(Si) (˜29 nm) and bcc Cr(Si) (˜45 nm) is obtained after 3 h of milling. Upon prolonged milling, all the as-milled powders exhibit non-equilibrium α-Fe(Si,Cr) solid solution with an average crystallite size of 19–23 nm. The lattice parameter decreases initially up to 3 h and then increases with further increase in milling time due to dissolution of Cr and Si into Fe host lattice. The variation of microstructural parameters such as average crystallite size, r.m.s. microstrain, static Debye–Waller parameter, and dislocation density as a function of milling time show good correlations. Mossbauer spectra of the milled powders, recorded at room temperature, reveal the decrease of the average hyperfine field suggesting a random distribution of atoms during milling and point out the formation of the disordered bcc Fe(Si,Cr) solid solution. After 15 h of milling, the coercivity and magnetization values are 81.7 Oe and 120.3 emu/g, respectively.

Iron doped indium oxide thin films were grown by chemical spray pyrolysis technique at different concentrations y = [Fe 2+ ]/[In 3+ ] ( y = 0, 2, 4 and 6 at.%). Structural, morphological, optical and electrical properties were studied by X-ray diffraction, Raman spectroscopy, atomic force microscopy, spectrophotometer, fluorescence spectrometer and Hall Effect. The XRD analyses show that indium oxide crystallizes into cubic structure with (2 2 2) as a preferred orientation. An enhancement of the crystallinity followed by a change in plan orientation from (2 2 2) to (4 0 0) was observed when iron doping concentrations is increasing. The optimum of In 2 O 3 crystal structure is obtained for iron concentration equals to 6 at.%. Transmission and reflection spectra reveal the presence of interference fringes with oscillatory character indicating the good uniformity and optical homogeneity of deposited films. The obtained band gap energy E g is in the range of [3.29–3.45] eV. The single oscillator energy E 0 and dispersion energy E d were determined by Wemple model using the envelope method applied for all obtained XRD spectra. We found that E 0 = 2 × E g for iron doped films and E 0 = 1.5 × E g for undoped ones. Measured electrical resistivity decreases from ρ = 6502 × 10 −4 to 197.9 × 10 −4 Ω cm for respectively undoped and In 2 O 3 :Fe(6 at.%) thin films. A heat treatment was carried out at different temperatures (200 °C, 300 °C and 400 °C) under nitrogen atmosphere to try to reduce more electrical resistivity. We found that it decreases to about 26.94 × 10 −4 Ω cm for 300 °C annealing temperature.

Nanostructured Fe–20Al–2Cr (wt.%) powders have been prepared using high energy planetary ball-mill. Changes in structural, morphological and magnetic properties of the powders during mechanical alloying (MA) and during subsequent annealing have been examined by X-ray diffraction, scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM). The observed structural and microstructural changes have been related to several processes occurring during MA. After MA, the material becomes significantly disordered and refines to nanoscale grain sizes (~ 14 nm). The obtained bcc α-Fe(Al,Cr) solid solution shows a ferromagnetic behavior. Upon subsequent annealing at 400 °C, α-Fe2O3 and spinel oxides are formed at the surface of particles, while structural defects disappeared as Fe(Al,Cr) solid solution becomes more ordered and grain growth occurs. The saturation magnetization (Ms) shows lower values after annealing, attributed to the formation of metal oxides with low magnetic moment.

X-ray diffraction and thermal measurements were used to investigate the microstructural, structural, and thermal properties of nanocrystalline Fe prepared by ball milling process. The crystallite size refinement down to the nanometer scale is accompanied by the increase of the internal level strains and the dislocations density. The lattice distortion is evidenced by the increase of both the lattice parameter and the static Debye–Waller parameter. The grain boundary enthalpy decreases above 12 h of milling. The nanostructured paramagnetic bcc α-Fe domain is extended by about 75 K at the expense of both the magnetic bcc α-Fe and nonmagnetic fcc γ-Fe domains as compared to coarse-grained pure α-Fe.

Structural, optical and room temperature magnetic properties of Mn-doped MgO nanoparticles with Mn fractions (5–50 at.%), were investigated. The as-prepared pure MgO, with grain size of about 15 nm, exhibits two magnetization components, one is diamagnetic and another is superparamagnetic. After removing the diamagnetic contribution, the magnetization curve exhibits superparamagnetic behavior which may be attributed to vacancy defects. As the Mn content increases, the lattice parameter decreases, the ferromagnetism appears and the emission bands were considerably blue shifted. First principle electronic structure calculations reveal the decrease of both the gap and the Curie temperature with increasing Mn concentration. The obtained results suggest that both Mn doping and oxygen vacancies play an important role in the development of room temperature ferromagnetism.

The mechanical alloying process has been used to prepare nanocrystalline Fe 73.5 Si 13.5 B 9 Nb 3 Cu 1 powders in a high energy planetary ball-mill Retsch PM400/2. Morphological, microstructural, structural, thermal and magnetic characterizations of the powders milled several times were investigated by scanning electron microscopy, X-ray diffraction, differential scanning calorimetry and hysteresis meter. A mixture of Fe(Si)-type nanograins (14 nm), Fe 2 B boride phase (∼12 nm), and bcc substitutional Fe(B)-type solid solution is obtained after 150 h of milling. The coercivity and saturation magnetization values are about 62 Oe and 14 emu/g, respectively. Several magnetic transition temperatures are revealed in the DSC scans of the ball-milled powders in the temperature ranges 500–560 °C and 599–606 °C, related to the Fe(B) and Fe(Si)-type phases, respectively.

The mechanical alloying process has been used to prepare nanostructured Fe31Co31Nb8B30 (wt%) alloy from pure elemental powders in a high energy planetary ball-mill Retsch PM400. Microstructural changes, phase transformation and kinetics were studied by X-ray diffraction, differential scanning calorimetry and M?ssbauer spectrometry. The crystallite size reduction down the nanometer scale (~8 nm) is accompanied by the introduction of internal strains up to 1.8% (root-mean square strain, rms). Further milling time leads to the formation of partially paramagnetic amorphous structure in which bcc FeCo nanograins are embedded. The kinetics of amorphization during the milling process can be described by two regimes characterized by different values of the Avrami parameter n1 = 1.41 and n2 = 0.34. The excess enthalpy due to the high density of defects is released at temperatures below 300°C. The glass transition temperature increases with increasing milling time.

Wastewater containing heavy metal ions is considered as a serious environmental problem for human society. Advances in nanoscale science and engineering provide new opportunities to develop more cost-effective and environmentally acceptable water treatment technologies. Nanomaterials have a number of physicochemical properties that make them particularly attractive as nanoadsorbents for decontamination of wastewaters from heavy metals. These materials are capable of removing heavy metal ions at low concentrations with high selectivity and adsorption capacity. The use of various nanoadsorbents in treating contaminated water, mainly including carbon-based nanomaterials, iron-based nanomaterials and photocatalytic nanomaterials, was overviewed; their advantages and drawbacks in such applications were evaluated.

Dilute magnetic semiconductors (DMS) have attracted a great deal of interest in recent years due to the possibility of inducing room-temperature ferromagnetism. These materials are of particular interest for spintronic devices. This review chapter describes the experimental and theoretical status of the DMS including the recent results on oxide-based systems.

Nanostructured Co 50 Ni 50 powders were mechanically alloyed from elemental Co and Ni powders using a planetary ball mill type Fritsch P7 under argon atmosphere. The milled powders were characterized by scanning electron microscopy, X-ray powder diffractometry (XRD) and differential scanning calorimetry (DSC). The SEM micrographs show a progressive refinement of the particles size with milling time. For longer milling time, the particles morphology is homogenous indicating the formation of the alloy. The XRD reveals the interdiffusion of the Ni and Co elements as milling proceeds and the formation of an heterogeneous solid solutions with two structures: fcc-Ni(Co) and fcc-Co(Ni), having different structural and microstructural parameters. The XRD patterns refinement reveals also the Co allotropic transformation from the hcp to fcc structure form at the early stage of milling. DSC results show a broad exothermic reaction indicating a strain relaxation and a recovery process.

Mossbauer spectrometry and Rietveld analysis of X-ray diffraction patterns were used to follow the solid state amorphization transformation during the milling process of the Fe 27.9 Nb 2.2 B 69.9 powders. The reaction between elemental Fe, Nb and B powders leads to the formation of the Nb(B) and Fe(B) solid solutions after 1 and 10 h of milling, respectively. A mixture of α-Fe, Nb(B) and highly disordered Fe(Nb, B) solid solution is found after 25 h of milling. An amorphous structure is obtained on further milling time (100 h). From the Mossbauer spectrometry results, it is observed that the total mixing of the elemental powders, at the atomic level, is achieved after 50 h of milling and a stationary state corresponding to a full paramagnetic amorphous phase is reached after 100 h of milling. The amorphization process can be described by an Avrami parameter close to n = 1.

L'alliage Fe 61 Co 21 Nb 3 B 15 a ete prepare a partir d'un melange de poudres par broyage mecanique haute energie. Les changements structuraux et microstructuraux ont ete suivis par diffraction des rayons X (DRX), spectrometrie Mossbauer, et calorimetrie differentielle programmee (DSC). Une structure amorphe, hautement desordonnee dans laquelle sont loges des grains de taille nanometrique de borure de fer, a ete decelee, apres un broyage de 48 h, par DRX et par spectrometrie Mossbauer. Un processus de recristallisation mecanique mene a la formation de nano-grains de α-Fe et α-FeCo, apres un temps de broyage prolonge. Le desordre dans les poudres broyees a ete confirme par DSC ou plusieurs courbes exothermiques se chevauchent sur un large domaine de temperature. Ce comportement provient de la relaxation des contraintes et du grossissement des grains.

Nanocrystalline Fe 75 Si 15 B 10 powders were obtained by mechanical alloying in a high energy planetary ball mill. Morphological, microstructural, structural and magnetic property changes during the milling process were followed by scanning electron microscopy, X-ray diffraction and magnetic measurements. The crystallite size reduction to the nanometer scale (6–13 nm) is accompanied by an increase in atomic level strain. The Fe 2 B boride phase is formed after 5 h of milling. The dissolution of B and Si into the Fe lattice leads to the formation of bcc α-Fe(Si,B) solid solution. On prolonged milling time, a mixture of highly disordered α-Fe(Si,B) solid solution and Fe 2 B boride is obtained. The coercivity and magnetization values are 55 Oe and 6.7 emu/g, respectively, after 150 h of milling.

Amorphous (Fe 50 Co 50 ) 62 Nb 8 B 30 powder mixture was prepared by mechanical alloying from elemental Fe, Co, B and Nb powders in a planetary ball mill under argon atmosphere. Structural, thermal and magnetic properties were performed on the milled powders by means of X-ray diffraction, differential scanning calorimetry and magnetic measurements. The amorphous state is reached after 125 h of milling. The excess enthalpy due to the high density of defects is released at temperature below 300 °C. Crystallisation and growth of crystal domains are the dominating processes at high temperatures. The saturation magnetisation decreases rapidly during the first 25 h of milling to about 15.24 A m 2 /kg and remains nearly constant on further milling. Coercivity, H c , value of about 160 Oe is obtained after 125 h of milling.

Nanostructured Fe and Fe50Co50 powders were prepared by high-energy ball milling. Microstructural and magnetic properties changes with milling time were followed by x-ray diffraction, differential scanning calorimetry and vibrating sample magnetometry. The nonequilibrium microstructure originates from a grain size reduction to about 12 nm and the introduction of internal strain up to 1.5% (root-mean-square strain). The occurrence of disorder in the ball-milled powders is evidenced by the broad exothermic reaction during the heating of ball-milled samples, the variation of lattice parameters and the increase of the saturation magnetization during the first 3 h of milling for Fe and continuously for the Fe50Co50 powder mixture. According to both the reduction of Fe Curie temperature, Tc, and the increase of the phase transformation , the paramagnetic temperature domain of nanostructured bcc α-Fe is extended by about 50 °C. The Fe50Co50 nanostructured powder behaves as a soft ferromagnet with low values of both the coercive field and the squareness ratio Mr/Ms.

Fe 61 Co 21 Nb 3 B 15 powder mixture was prepared by mechanical alloying process in a high energy planetary ball mill. Structural and thermal changes of the milled powders were followed by X-ray diffraction (XRD), Mossbauer spectrometry and differential scanning calorimetry (DSC). Both XRD and Mossbauer spectrometry results reveal the formation, after 48 h of milling, of a highly disordered amorphous-like structure where nanometer-sized iron borides were embedded. A mechanical recrystallisation process gives rise to the formation of α-Fe and α-FeCo nanograins on further milling. The occurrence of structural disorder in the milled powders might be confirmed by broad exothermic reaction in the DSC scans which consists of several overlapping exothermic peaks. Such behaviour originates from recovery, strain relaxation, grain growth and crystallisation.