Rietveld Refinement Procedure Research Articles

Effects of Mg Substitution on the Structural with Rietveld Analysis, Magnetic and Magnetocaloric Properties of Ni-Cu-Cd Bulk Ceramics

Bulk ceramics with optimized density are highly prioritized over ferrite nanoparticles to fabricate devices for their optimal magnetic saturation, lower coercivity, and anisotropy, enhanced resistance, etc. To achieve such bulk specimen using Ni0.5-yMgyCu0.2Cd0.3Fe2O4 disc samples are sintered at 1423 K keeping the heating and cooling rate at 10 K and 5 K respectively. In due course, structural as well as theoretical Rietveld analysis, optical, and magnetic properties have been analyzed using these bulk samples. XRD has explored structural properties and after that these values have analyzed with the Rietveld refinement procedure and obtained goodness of χ2 (1–2) value and other parameters such as lattice parameters, crystal structures, cation distribution, and maximum entropy mapping. Surface morphology and grain size have examined from the as-grown surface without further polishing and annealing by electron microscopy and revealed a decreasing trend of grain size 6.1 µm to 4.2 µm. UV–Vis spectroscopy characterization ensured optical properties for bulk as well as nanopowders and the band gap has been found in the range of 1.4 to 1.6 eV and is increasing with Mg content. Magnetic hysteresis loop exhibits a less decreasing nature up to y = 0.3 of magnetic saturation along with the Law of Approach to saturation which compiles magnetic anisotropy. The temperature-dependent magnetization curves exhibit a sharp decreasing value (i.e. dM/dT maximum) at Curie point, decreasing from 630 K to 505 K with increasing Mg content. At.3 T magnetic field the changes in relative cooling power value have been found in the range 53.82Jkg-1 to 37.79Jkg-1 which could be considered as potential for magnetocaloric refrigeration.

Correlating pH-controlled green synthesis of NiO nanoparticles with their magnetic properties and catalytic performance

Nickel oxide nanoparticles (NiO) were prepared through environmentally friendly methods, using Nigella sativa seed extract as a stabilizing agent and different pH for the working solutions (pH=7, 9 and 11, respectively). In a second step, these NiO NPs were characterized with various and complementary techniques, as X-ray diffraction (XRD), Fourier transfer infrared spectroscopy (FTIR), Brunauer–Emmett–Teller method (BET), scanning electron microscopy (SEM) with EDS profiles, and a vibrating sample magnetometer (VSM). XRD patterns confirmed the one and only formation of NiO, as revealed by the Rietveld refinement procedure. The use of Williamson equation showed a significant variation in structural and microstructural parameters. Fourier transfer infrared spectroscopy (FTIR) analysis revealed vibration modes specific to Ni-O nanomaterials at 470 cm−1. On the other hand, magnetic investigations highlighted the fact that NiO, obtained in a solution with a pH equal to 9,called NiO-9, has the highest Ms and Mr values, of the order of 1.524 and 0.084 emu/g respectively, thus improving its ferromagnetic performance. Moreover, in the presence of NaBH4 and with the aim to reduce 4-nitrophenol to 4-aminophenol, in the case of water treatment, it appeared that the total time for the catalytic activity of NiO-9 was the lowest, i.e., 30 min. Moreover, NiO-9 was characterized by the faster rate constant, namely 0.29 min−1, which could be linked to intrinsic properties of this material (microstrain, electroactive sites and generated carrier charges).

Investigations of Structural, Magnetic, and Electrochemical Properties of NiFe2O4 Nanoparticles as Electrode Materials for Supercapacitor Applications.

Magnetic nanoparticles of NiFe2O4 were successfully prepared by utilizing the sol-gel techniques. The prepared samples were investigated through various techniques such as X-ray diffraction (XRD), transmission electron microscopy (TEM), dielectric spectroscopy, DC magnetization and electrochemical measurements. XRD data analysed using Rietveld refinement procedure inferred that NiFe2O4 nanoparticles displayed a single-phase nature with face-centred cubic crystallinity with space group Fd-3m. Average crystallite size estimated using the XRD patterns was observed to be ~10 nm. The ring pattern observed in the selected area electron diffraction pattern (SAED) also confirmed the single-phase formation in NiFe2O4 nanoparticles. TEM micrographs confirmed the uniformly distributed nanoparticles with spherical shape and an average particle size of 9.7 nm. Raman spectroscopy showed characteristic bands corresponding to NiFe2O4 with a shift of the A1g mode, which may be due to possible development of oxygen vacancies. Dielectric constant, measured at different temperatures, increased with temperature and decreased with increase in frequency at all temperatures. The Havrilliak-Negami model used to study the dielectric spectroscopy indicated that a NiFe2O4 nanoparticles display non-Debye type relaxation. Jonscher's power law was utilized for the calculation of the exponent and DC conductivity. The exponent values clearly demonstrated the non-ohmic behaviour of NiFe2O4 nanoparticles. The dielectric constant of the nanoparticles was found to be >300, showing a normal dispersive behaviour. AC conductivity showed an increase with the rise in temperature with the highest value of 3.4 × 10-9 S/cm at 323 K. The M-H curves revealed the ferromagnetic behaviour of a NiFe2O4 nanoparticle. The ZFC and FC studies suggested a blocking temperature of ~64 K. The saturation of magnetization determined using the law of approach to saturation was ~61.4 emu/g at 10 K, corresponding to the magnetic anisotropy ~2.9 × 104 erg/cm3. Electrochemical studies showed that a specific capacitance of ~600 F g-1 was observed from the cyclic voltammetry and galvanostatic charge-discharge, which suggested its utilization as a potential electrode for supercapacitor applications.

Phase evolution, microstructure and electrical response of KNNT ceramics with Li+ substitution and doping

Lead-free (K0.5Na0.5)(Nb0.7Ta0.3)O3 (KNNT) ceramics with Li+ substitution (KN0.5-xLixNT) and direct (KNNT-xLi) doping at x = 0, 0.01, 0.02, 0.03 and 0.04 mol% were synthesized by the solid-state combustion route. The phase, microstructure, dielectric and ferroelectric properties of the ceramics were examined. The XRD pattern of the ceramics revealed orthorhombic and tetragonal phases in all specimens. The Rietveld refinement procedure showed that increasing either the Li+ substitution or doping levels enhanced the amount of the tetragonal phase. It was found that Li+ doping, either substitutional or additional, enhanced the Curie temperature (T C) by increasing the tetragonal distortion, while the dielectric constant (ε C) decreased. The good remanent P-E loops of the KN0.5-xLixNT ceramics were found with x = 0.01 (P r∼10.89 µC/cm2 and E C∼13.09 kV/cm), while for KNNT-xLi ceramics, it was obtained with x = 0.02 (P r∼15.65 µC/cm2 and E C∼11.46 kV/cm), which were confirmed by remanent P-E hysteresis measurements.

In-depth investigations of size and occupancies in cobalt ferrite nanoparticles by joint Rietveld refinements of X-ray and neutron powder diffraction data.

Powder X-ray diffraction (PXRD) and neutron powder diffraction (NPD) have been used to investigate the crystal structure of CoFe2O4 nanoparticles prepared via different hydro-thermal synthesis routes, with particular attention given to accurately determining the spinel inversion degrees. The study is divided into four parts. In the first part, the investigations focus on the influence of using different diffraction pattern combinations (NPD, Cu-source PXRD and Co-source PXRD) for the structural modelling. It is found that combining PXRD data from a Co source with NPD data offers a robust structural model. The second part of the study evaluates the reproducibility of the employed multipattern Rietveld refinement procedure using different data sets collected on the same sample, as well as on equivalently prepared samples. The refinement procedure gives reproducible results and reveals that the synthesis method is likewise reproducible since only minor differences are noted between the samples. The third part focuses on the structural consequences of (i) the employed heating rate (achieved using three different hydro-thermal reactor types) and (ii) changing the cobalt salt in the precursors [aqueous salt solutions of Co(CH3COOH)2, Co(NO3)2 and CoCl2] in the synthesis. It is found that increasing the heating rate causes a change in the crystal structure (unit cell and crystallite sizes) while the Co/Fe occupancy and magnetic parameters remain similar in all cases. Also, changing the type of cobalt salt does not alter the final crystal/magnetic structure of the CoFe2O4 nanoparticles. The last part of this study is a consideration of the chemicals and parameters used in the synthesis of the different samples. All the presented samples exhibit a similar crystal and magnetic structure, with only minor deviations. It is also evident that the refinement method used played a key role in the description of the sample.

Phase Evolution, Microstructure and Electrical Behavior of (Ba0.97Ca0.03)(Ti0.94-x/2Sn0.06-x/2Wx)O3 Ceramics Synthesized via the Solid-State Combustion Technique

This research studied the effect of W4+ substitution on the phase formation, microstructure and electrical properties of (Ba0.97Ca0.03)(Ti0.94-x/2Sn0.06-x/2Wx)O3 (BCTSW) ceramics with x = 0, 0.005, 0.010, 0.015 and 0.020 mol%. The BCTSW ceramics were synthesized by the solid-state combustion technique, using glycine as fuel. The powders and green pellets of BCTWS were calcined and sintered at 1100 °C for 4 h and 1400 °C for 2 h, respectively. A pure perovskite phase with coexisting orthorhombic and tetragonal phases were observed for all samples. The content of the tetragonal phase increased when x rose, as verified by the Rietveld refinement procedure. The average grain size and the measured density of the samples tended to decrease from 35 ± 0.56 to 1.9 ± 0.12 µm and 5.59 to 4.88 g/cm3, respectively, when x increased. The dielectric behavior of the ceramics strongly degenerated upon W4+ substitution. The undoped BCTS ceramic showed a well-saturated P-E hysteresis loop. With W4+ substitution, the samples’ P-E loops became unsaturated and a leakage current was created.

Impact of composition ratio on the structure and optical properties of (1 – x)MnFe2O4/(x)ZnMn2O4 nanocomposite

(1 – x)MnFe2O4 (MFO)/xZnMn2O4 (ZMO) (x = 0, 0.2, 0.5, 0.8, and 1.0) nanocomposite samples were prepared using co-precipitation procedure. The phase percentage, cell parameters, and crystallite size of MFO and ZMO phases in each nanocomposite sample were calculated using Rietveld refinement procedure. The x-ray diffraction (XRD) analysis and Fourier-transform infrared spectroscopy techniques established the variation in the lattice parameters of each phase are due to permutation of all cations among the octahedral and tetrahedral sites of MFO and ZMO. The different oxidation states of different ions in all samples were determined using x-ray photoelectron spectroscopy (XPS) technique. The variation in absorbance of the nanocomposite samples with composition parameter (x) is dependent on the wavelength region. The optical bandgap of the nanocomposite samples is decreased as the content of ZMO phase increased. The effect of alloying on the refractive index, extinction coefficient, dielectric constant, optical conductivity, and the nonlinear optical behaviors of all samples were studied in detail. The nanocomposite sample x = 0.5 disclosed upgraded optical parameters with the highest refractive index, optical conductivity, and PL intensity, which nominate it to be functional in various application fields.

Structural changes and band gap tailoring on α-MoO3 by exfoliation techniques

Layered α-MoO3 is prepared via the hydrothermal procedure and a facile exfoliation technique is followed to cut down the number of layers. The polyhedral structure is obtained from Rietveld refinement procedure and the importance of van der Waals interaction in formation of layered nature is identified. The absence of (0 10 0) peak in the exfoliated x-ray diffraction profiles, and diminishing of the characteristic peak of lamellar α-MoO3 (at 486.4 cm−1) in exfoliated Raman spectra indicates the suppression of layered nature along the b axis. The bandgap widening (3.6–4.1 eV) obtained from tauc plots also confirms the effect of exfoliation in the material.

Effect of sulfur deficiency on the structural, optical and electronic properties of MnS nanostructures

In the current work, the effect of sulfur deficiency on the structural, optical and electronic properties of MnS nanostructures has been investigated. Non-stoichiometric MnS nanostructures (MnS1−x, x = 0, 0.03 and 0.05) samples were synthesized via thermolysis procedure. X-ray diffraction technique using Rietveld refinement procedure was used to identify the different phases percentages, average crystallite size and lattice parameters in different samples. The effect of sulfur deficiency on the different vibrational bands of MnS1−x was explored using Fourier transform infrared (FTIR) technique. UV–visible diffused absorption technique was applied to investigate the absorption, refractive index and optical conductivity of the samples. The energy gap of the system reveals a nonlinear optical bowing effect. Nano MnS1−x semiconductor shows a UV–visible spectra emission depending on Mn to S ratio in the prepared sample. Different electronic parameters (extinction coefficient, dielectric constants, absorption coefficient, refractive index and energy loss function) for (α, β and γ) stoichiometric and non-stoichiometric MnS phases are also explored using the density functional calculation (DFT) and correlated with the obtained experimental results.

Structural and spectroscopic analysis of green glowing down-converted BYO:Er3+ nanophosphors for pc-WLEDs

An energy efficient solution combustion technique was selected for fabricating a series of energy-efficient novel down-converted Ba3Y4O9:Er3+ nanoparticles with green emission. Crystal structure engineering along with the morphological aspects was investigated via certain advanced characterizations such as Rietveld refinement and powder X-ray diffractometry (PXRD) procedure, microscopic practices like scanning and transmission electron microscope techniques, photoluminescence and diffuse reflectance spectroscopic analysis. Average crystallite size (65.71 nm–74.15 nm) and micro strain (0.0012) of the optimum powder nanomaterial were analyzed from high quality XRD data using Williamson-Hall (W–H) plot method. Alluring spectroscopic features were realized by photoluminescent (PL) spectra recorded upon excitation via near ultraviolet (NUV) source of 381 nm; displaying an intense emission peak (562 nm) situated in the visible region that is solely responsible for the green glow of the prepared phosphor. PL analysis witnessed a bright green emission via a reliable emanation transition (4S3/2 → 4I15/2) of Er3+ ions. Excellent colorimetric parameters of optimized nanophosphor like CIE coordinates (0.3420, 0.6064), 5356K CCT and 79.02% color purity validated its advanced photonic and optoelectronic applications for cool light emitting WLEDs, lasers, optical sensors, solar and photovoltaic cells.

Structural and dielectric properties of cobalt ferrite based nanocomposites

Nanocomposites of cobalt ferrite (CoFe2O4) were synthesized using chemical co-precipitation route. For preparing the nanocomposites, cobalt ferrite was combined with strontium ferrite (C/S-1/1) and with barium ferrite (C/B-1/1) in equal weight ratio of 1:1. Dual phase Rietveld refinement procedure was employed for phase analysis of the specimens. Electrical transport properties were investigated within frequency scale 20 Hz–106 Hz at different temperatures ranging from 100 °C to 400 °C. Dielectric permittivity of the composites was found to increase with temperature. Polarization mechanism was attributed to Koop's theory due to the presence of conductive and non-conductive part in ferrite composites. The ac conductivity mechanism in the composites was ascribed to Maxwell-Wagner model. With increase in temperature, C/S-1/1 depicts greater conductivity compared to C/B-1/1.

Ultrafast synthesis of the nanostructured Al59Cu25.5Fe12.5B3 quasicrystalline and crystalline phases by high-energy ball milling: Microhardness, electrical resistivity, and solar cell absorptance studies

In this study, the Al59Cu25.5Fe12.5B3 nanoquasicrystalline alloy and related crystalline phases were synthesized through mechanical alloying using a high-energy ball milling and consolidated by a cold isostatic pressing apparatus. This paper focuses on the synthesis, structural and microstructural evolutions, thermal stability, microhardness, and electrical and optical properties of the Al59Cu25.5Fe12.5B3 nanoquasicrystalline alloy for solar selective absorber usages. The structural evolutions of the mechanically alloyed and heat-treated AlCuFeB powders were investigated by X-ray diffractometry. Accordingly, the effect of milling time and heat treatment on the formation of quasicrystalline and related crystalline phases were studied in the AlCuFeB alloy system. The microstructure, morphology, and chemical microanalysis of the un-milled and as-milled powders were examined by field-emission scanning electron microscopy and energy-dispersive X-ray spectroscopy. The composition of the as-milled AlCuFeB powders was estimated employing inductively coupled plasma-atomic emission spectroscopy. The thermal stability of the AlCuFeB powders was recorded by differential thermal analysis, and the weight gain of the particles during annealing was investigated through thermogravimetric analysis. The nanostructured Al59Cu25.5Fe12.5B3 stable quasicrystalline phase and crystalline Al(Cu,Fe) solid-solution were synthesized by the ultrafast milling procedure in 1 h. The rationale behind using the term ultrafast synthesis is to synthesize the QC i-phase only by the high-energy ball milling procedure in short-term ball milling without subsequent annealing treatment. However, the single quasicrystalline phase could not be obtained even after the annealing treatment. The quasicrystalline size was calculated by the Williamson–Hall method and optimized by the Rietveld refinement procedure, and it was found that the size is varied between 53 and 61 nm. Furthermore, the particle size distribution of the as-milled AlCuFeB powders was measured using laser static light scattering, which ranges from 0.1 to 50 μm. The microhardness of the consolidated as-milled and heat-treated samples was estimated utilizing the Vickers microhardness indenter. At the same time, their electrical resistivity was assessed by the four-point probe method at room temperature. The spectral analyses of absorption on the consolidated as-milled samples were carried out in the ultraviolet, visible, and near-infrared regions. It was found that the presence of the quasicrystalline phase in the AlCuFeB alloy prominently improves the microhardness, electrical resistivity, and particularly sunlight absorptance.

Distinguishing space groups by electron channelling: centrosymmetric full-Heusler or non-centrosymmetric half-Heusler?

X-ray emission under electron-channelling conditions is used to distinguish between a non-centrosymmetric half-Heusler and a centrosymmetric full-Heusler crystal. For TiCo1.5+xSn the space-group determination based on a Rietveld refinement procedure became challenging for increasing Co content (x > 0.2), while electron channelling proved successful for higher Co content (x = 0.35). This technique can be used on crystals as small as (10 nm)3.

Redox-Active 1D Coordination Polymers of Iron-Sulfur Clusters.

Here we describe the combination of an archetypal redox-active metal sulfide cluster, Fe4S4, with an organic linker, 1,4-benzenedithiolate, to prepare coordination polymers containing infinite chains of Fe4S4 clusters. The crystal structures of two solid materials have been solved from synchrotron X-ray powder diffraction data using simulated annealing and refined by a least-squares Rietveld refinement procedure. The electronic properties of these chains have also been characterized by UV-visible and Mössbauer spectroscopies. Additional experiments demonstrated that these chains can be solubilized by variation of the countercation and that the chain structure is maintained in solution. The redox-activity of the Fe4S4 clusters can be accessed with chemical reagents. Introduction of charge carriers by reduction of the Fe4S4 clusters is found to increase the electrical conductivity of the materials by up to 4 orders of magnitude. These results highlight the utility of Fe4S4 clusters as redox-active building blocks in preparing new classes of coordination polymers.

Real-Time Investigation of Recovery, Recrystallization and Austenite Transformation during Annealing of a Cold-Rolled Steel Using High Energy X-ray Diffraction (HEXRD)

The annealing process of cold-rolled ferrite/pearlite steel involves numerous metallurgical mechanisms as recovery/recrystallization of deformed phases, ripening of carbide microstructure, and austenite transformation in the intercritical domain. The interactions between these mechanisms govern the morphogenesis of the transformed austenite microstructure and, thus, the final properties of the steel. This paper demonstrates that high energy X-ray diffraction (HEXRD) on synchrotron beamline offers the unique possibility to follow concomitantly these mechanisms in situ during a single experiment. A cold-rolled ferrite-pearlite steel dedicated to the industrial production of Dual-Phase steel serves as case-study. Synchrotron experiments have been conducted in transmission at 100 keV with a 2D detector. Diffraction patterns acquired all along an annealing treatment are first analyzed after circular integration. A Rietveld refinement procedure coupled with a Williamson-Hall approach is used to determine phase transformation and recovery kinetics. In this paper, a new method inspired by the 3D X-ray diffraction tomography is proposed to follow recrystallization kinetics at the same time. It is based on a systematic detection of individual diffraction spots related to newly recrystallized grains appearing on Debye-Scherrer rings. The deduced recrystallization kinetics is compared and validated by more conventional ex situ methods.

The Crystal Structure of the Ba-Hexacelsian Phases Doped with Ca2+ and Pb2+

The ion-exchange procedure is used for doping the Ba-hexacelsian structure with Ca2+ and Pb2+ cations. The hexacelsian doped with Ca2+ has a composition of Ba0.64Ca0.36Al2Si2O8, and hexacelsian doped with Pb2+ has a composition Ba0.9Pb0.1Al2Si2O8. The crystal structure of both doped hexacelsians was refined by Rietveld refinement procedure. The crystal structure of Ca-hexacelsian is refined in the space group $$P\bar{3}c1$$ , and results indicate ordering distribution of Si and Al (unit cell parameters is a = 5.2995, c = 15.594 A and agreement factors: R exp = 15.3 R p = 19.9, R wp = 19.0, R B = 15.0 R F = 4.08). Structural model for Pb-hexacelsian samples is described in the space group P63 /mcm with disorder distribution Si/Al (unit cell parameter is a = 5.2973, c = 15.591 A and agreement factors R exp = 21.5 R p = 21.5, R wp = 19.0, R B = 5.74 R F = 4.08). The results of Rietveld refinements indicate that Ca2+ and Pb2+ cations are incorporated into hexacelsian structure in different position.

Applying the X-ray diffraction analysis for estimating the height and width of nanorods in low symmetry crystal multiphase materials

In this work the potential of Rietveld refinement procedure is used to study the shape and size of non-spherical nanocrystallites. The main advantages of this approach are that not only it can successfully extend to all nanomaterials with different crystal symmetries but also it can evaluate the various phases of multiple materials comparing to electron microscopy methods. Therefore, between seven crystal systems, the formulation of monoclinic and hexagonal crystals is developed. This procedure is applied for the mixture of sodium carbonate and zinc oxide nanocrystallites at different fractions of doped gadolinium oxide. It is found that the crystallites of sodium carbonate and zinc oxide have the rod and ellipsoidal shapes, respectively. The microstructure results are compared with the results of scanning electron microscopy imaging. Good agreement is achieved between the results of scanning electron microscopy and Rietveld methods.

Structural analysis of the foldecture derived from racemic peptide foldamers

The molecular packing structure of an elongated parallelogram plate shaped foldecture composed of a 1:1 racemic mixture of 11-helical peptide foldamers was resolved by powder X-ray diffraction (PXRD) analysis. A comprehensive Rietveld refinement procedure compensated for powder texture and identified the principal face of the foldecture. Each foldamer makes head-to-tail intermolecular hydrogen bonds, creating extended chains of single enantiomers that form a network of hydrophobic close contacts with foldamers of both the opposite and the same chiralities. An isosurface for anisotropic microstrain was calculated and found to be smallest along the x-axis, which is parallel to the network of intermolecular hydrogen bonds. Comparison with the single crystal structure found molecular packing motifs to be almost identical—a result infrequently observed in enantiopure foldectures. This is the first powder X-ray diffraction structural analysis of a foldecture composed of multiple components.

Synchrotron-based crystal structure, associated morphology of snail and bivalve shells by X-ray diffraction

Synchrotron-based high-resolution X-ray powder diffraction spectra from the body parts of a snail and bivalve (CaCO3), have been recorded with Pilatus area detector. Experiments were performed at Desy, Hamburg, Germany, utilizing the Resonant and Diffraction beamline (P9), with 15keV X-rays (λ=0.82666Å). The external shell of these living organisms, is composed of calcium carbonate, which carries strong biological signal. It consists of some light elements, such as, Ca, C and O, which constitute part of the soft tissue and other trace elements. The knowledge of these diffraction patterns and hence the understanding of structures at molecular level are enormous. The application of synchrotron radiation to powder diffraction is well suited for samples of biological nature via changes in their patterns and also to investigate crystallographic phase composition. With the use of Rietveld refinement procedure, to the high-resolution diffraction spectra, we were able to extract the lattice parameters of orthorhombic polymorph of CaCO3, the most abundant mineral produced by these living organisms. The small size of the crystallite is a very important factor related to the biological structure. The natural model presents a combination of organic and inorganic phases with nanometer size. For the present study, we also used the scanning electron microscopy (SEM) to explore the associated morphology of the snail and bivalve.

Influence of magnetic fields on the critical temperature of bulk YBCO superconductor with nanometer-sized Al<sub>2</sub>O<sub>3</sub> inclusions

YBCO specimens along with different amounts of nano-sized Al 2 O 3 were prepared using solid state reaction method. The structural characterization of all samples has been carried out by X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. The XRD patterns with Rietveld refinement procedure was used to characterize the samples crystal microstructure. SEM analysis revels the phases with distribution of Al 2 O 3 nanoparticles along the YBCO grain boundaries systematically. Superconducting parameters are affected by the nanoparticle addition, and results are discussed in bearing to the structural and microstructure differences between pure Y-123 and doped Y-123. The temperature dependence of electrical resistivity ρ (T) has been measured and the effect of addition of Al 2 O 3 nanoparticles with and without magnetic fields in the superconductivity and normal region has been reported. Keywords : YBa 2 Cu 3 O 7-δ ; Al 2 O 3 nanoparticles; critical temperature; magnetic fields.