low-Tc Phase Research Articles

Microscopic examination of rf-cavity-quality niobium films through local nonlinear microwave response

The performance of superconducting radio-frequency (SRF) cavities is sometimes limited by local defects. To investigate the rf properties of these local defects, especially those that nucleate rf magnetic vortices, a near-field magnetic microwave microscope is employed. Local third-harmonic response (P3f) and its temperature dependence and rf power dependence are measured for one Nb/Cu film grown by direct current magnetron sputtering (DCMS) and six Nb/Cu films grown by high-power impulse magnetron sputtering (HiPIMS) with systematic variation of deposition conditions. Five out of the six HiPIMS Nb/Cu films show a strong third-harmonic response that is likely coming from rf vortex nucleation due to a low-Tc surface defect with a transition temperature between 6.3 and 6.8 K, suggesting that this defect is a generic feature of air-exposed HiPIMS Nb/Cu films. A phenomenological model of surface-defect grain boundaries hosting a low-Tc impurity phase is introduced and studied with time-dependent Ginzburg-Landau (TDGL) simulations of probe-sample interaction to better understand the measured third-harmonic response. The simulation results show that the third-harmonic response of rf vortex nucleation caused by surface defects exhibits the same general features as the data, including peaks in third-harmonic response with temperature, and their shift and broadening with higher microwave amplitude. We find that the parameters of the phenomenological model (the density of surface defects that nucleate rf vortices and the depth an rf vortex travels through these surface defects) vary systematically with film deposition conditions. From the point of view of these two properties, the Nb/Cu film that is most effective at reducing the nucleation of rf vortices associated with surface defects can be identified. Published by the American Physical Society 2024

Microstructure and Superconducting Properties of Bi-2223 Synthesized via Co-Precipitation Method: Effects of Graphene Nanoparticle Addition.

The effects of graphene addition on the phase formation and superconducting properties of (Bi1.6Pb0.4)Sr2Ca2Cu3O10 (Bi-2223) ceramics synthesized using the co-precipitation method were systematically investigated. Series samples of Bi-2223 were added with different weight percentages (x = 0.0, 0.3, 0.5 and 1.0 wt.%) of graphene nanoparticles. The samples' phase formations and crystal structures were characterized via X-ray diffraction (XRD), while the superconducting critical temperatures, Tc, were investigated using alternating current susceptibility (ACS). The XRD showed that a high-Tc phase, Bi-2223, and a small low-Tc phase, Bi-2212, dominated the samples. The volume fraction of the Bi-2223 phase increased for the sample with x = 0.3 wt.% and 0.5 wt.% of graphene and slightly reduced at x = 1.0 wt.%. The ACS showed that the onset critical temperature, Tc-onset, phase lock-in temperature, Tcj, and coupling peak temperature, TP, decreased when graphene was added to the samples. The susceptibility-temperature (χ'-T) and (χ″-T) curves of each sample, where χ' and χ″ are the real and imaginary parts of the susceptibility, respectively, were obtained. The critical temperature of the pure sample was also measured.

Study of the Structural and Electrical Properties of Bi2-xAgxBa2-ySryCa2Cu3O10+δ System

This study included preparing samples of the compound (Bi2Ba2Ca2Cu3O10+δ) by the solid state reaction method under a hydrostatic pressure 8 ton/cm2 and annealing temperature 840oC. X-ray diffraction (XRD), scanning electron microscopy (SEM), dc electrical resistivity measurements by four point probe method were used to investigate the microstructural and superconducting properties of Bi¬2223 samples. The X-rays diffraction study for the compound (Bi2Ba2Ca2Cu3O10+δ ) showed that it has Tetragonal type of crystal structure. The partial replacement of the component Ag in Bi, and Sr component in Ba simultaneously, the compound becomes (Bi2-xAgxBa2-ySryCa2Cu3O10+δ) with (x ,y) values equal to (x= 0.2, y= 0.1, 0.2, 0.3,0.4). The study of the crystal structure test showed that the structure retains on the tetragonal type with a high Tc phases (2223), low Tc phase(2212) and impurity phases, and the critical temperature Tc steps-up from (125K) to (137K) at substitution rate (x= 0.2, y= 0.1). But at increasing the substitution rate for (y) and the stability of (x) rate more than (x= 0.2, y= 0.1), the temperature declines to (108 K). Finally, the microstructural of the samples has been studies and tested by Scanning Electron Microscope for knowing the components' rates in the compound; how the compound partial substitution affect in the components; and specifying the quantitative and qualitative rates of the components in the compound.

Layer-Number-Independent Two-Dimensional Ferromagnetism in Cr3Te4

In a conventional magnetic material, a long-range magnetic order develops in three dimensions, and reducing a layer number weakens its magnetism. Here we demonstrate anomalous layer-number-independent ferromagnetism down to the two-dimensional (2D) limit in a metastable phase of Cr3Te4. We fabricated Cr3Te4 thin films by molecular-beam epitaxy and found that Cr3Te4 could host two distinct ferromagnetic phases characterized with different Curie temperatures (TC). One is the bulk-like "high-TC phase" showing room-temperature ferromagnetism, which is consistent with previous studies. The other is the metastable "low-TC phase" with TC ≈ 160 K, which exhibits a layer-number-independent TC down to the 2D limit in marked contrast with the conventional high-TC phase, demonstrating a purely 2D nature of its ferromagnetism. Such significant differences between two distinct phases could be attributed to a small variation in the doping level, making this material attractive for future ultracompact spintronics applications with potential gate-tunable room-temperature 2D ferromagnetism.

Superconductivity of BSCCO Compound Substituted Partially by Zr Nanoparticles at Bi Site

High-temperature superconductors with a nominal composition Bi2- xZrxPb0.4Sr2Ca2Cu3Oy for (0≤x≤0.3) were prepared by solid-state reaction method. Effects of the Zr nanoparticles substitution at Bi sites have been studied to obtain the optimum concentration for the formation and stabilization of the superconducting samples. Electrical resistivity measurements of the samples showed that the higher critical temperature TC was found at 118 K, which is for the composition Bi1.95Zr0.05Pb0.4Sr2Ca2Cu3Oy. Semiconductor behavior noticed for samples with concentration higher than 0.2. The X-ray diffraction results for all superconducting samples showed an orthorhombic structure with two phases, 2223 high-TC phase and 2212 low-TC phase. The scanning electron microscope has been used to identify the morphology of the superconducting phase. The plate-like grains of the high Bi-2223 phase appeared in most samples besides changes in morphology of the samples with increasing dopant concentration

Superconductivity Measurements of (Hg,Tl)-1223 Compound Prepared in Capsule

In this paper, investigations were carried out on the effects of simultaneous partial substitution of Tl at the Hg site on the physical properties of an Hg1-xTlxBa2Ca2Cu3O8+δ cuprate superconductor with x= 0, 0.1, 0.2, 0.3 and 0.4. Two steps of the solid state reaction method were used to prepare samples in capsule. The results showed that the optimum sintering temperature was equal to 850 ᵒC and the sintering time was equal to 20 h for the prepared samples. 
 The best conditions for constitution and stabilization of the high Tc phase-1223 were obtained by investigating the effects of Tl substitution on Hg site and oxygen content (δ) on the superconducting properties.
 Structural investigation revealed that all the samples have a tetragonal structure with two phases, namely an Hg-1223 high Tc phase as a main phase and an Hg-1212 low Tc phase. Besides, some impurity phases like CuO and CaHgO2 were found. The increase of Tl content in Hg1-xTlxBa2Ca2Cu3O8+δ compound from 0 to 0.4 caused a change in the lattice parameter, density of the unit cell (ρm), and c/a values.
 HgBa2Ca2Cu3O8+δ compound exhibited a critical transition temperature that is equal to 115 K. On the other side, the results showed that the highest Tc was 119 K for Hg0.8Tl0.2 Ba2Ca2Cu3O8+δ. The oxygen content (δ= 0.46) was expected to be the optimum hole doping for Hg0.8Tl0.2 Ba2Ca2Cu3O8+δ compound, which means in our opinion that δ plays a remarkable role in the assessment of Tc.

Structure and superconducting properties of multiple phases of (NH3)yAExFeSe (AE: Ca, Sr and Ba)

We synthesized the alkaline-earth metal-doped FeSe compounds (NH3)yAExFeSe (AE: Ca, Sr and Ba), using the liquid NH3 technique, to determine their superconducting properties and crystal structures. Multiple superconducting phases were obtained in each sample of (NH3)yCaxFeSe and (NH3)yBaxFeSe, which showed two superconducting transition temperatures (Tc’s) as high as 37–39 K and 47–48 K at ambient pressure, hereinafter referred to as the ‘low-Tc phase’ and ‘high-Tc phase’, respectively. The high-Tc phases in (NH3)yCaxFeSe and (NH3)yBaxFeSe were metastable, and rapidly converted to their low-Tc phases. However, Tc values of 38.4 K and 35.6 K were recorded for (NH3)ySrxFeSe, which displayed different behavior than (NH3)yCaxFeSe and (NH3)yBaxFeSe. The Le Bail fitting of x-ray diffraction (XRD) patterns provided lattice constants of c = 16.899(1) Å and c = 16.8630(8) Å for the low-Tc phases of (NH3)yCaxFeSe and (NH3)yBaxFeSe, respectively. The lattice constants of their high-Tc phases could not be determined due to the disappearance of the high Tc phase within a few days. The XRD pattern for (NH3)ySrxFeSe indicated the coexistence of two phases with c = 16.899(3) Å and c = 15.895(4) Å. The former value of c in (NH3)ySrxFeSe is almost the same as those of the low-Tc phases in (NH3)yCaxFeSe and (NH3)yBaxFeSe. Therefore, the phase with c = 16.899(3) Å in (NH3)ySrxFeSe must correspond to the superconducting phase with the Tc of 38.4 K, while the superconducting phase with Tc = 35.6 K is assigned to the crystal phase with c = 15.895(4) Å. For (NH3)ySrxFeSe, a high-Tc phase with Tc = 47–48 K has not yet been obtained, but a new phase showing the Tc value of 35.6 K was clearly obtained. This is the first systematic study of the preparation, crystal structure, and superconductivity of alkaline-earth metal-doped FeSe, (NH3)yAExFeSe.

The Effect of Tungsten Nanoparticles on Superconducting of The Compound Bi2-xPb0.3WXSr2Ca2Cu3O10+δ

By using a conventional solid-state reaction technique, a group of the superconducting samples with nominal composition Bi2-xPb0.3WxSr2Ca2Cu3O10±δ with (0≤x≤0.5) sintered at 840ᵒC for 140h in the air have been prepared. The effect substitution of tungsten nanoparticles on the physical properties of Bi sites was studied. X-ray diffraction (XRD) studies showed that all our samples are polycrystalline with orthorhombic structures and presence two phases: high-Tc phase (2223), low-Tc phase (2212) and an impurity phase Some impurities likeSr2Ca2Cu7Oδ, CaO and WO . In the prepared samples the lattice parameter values and the volume fraction of high-Tc phase are calculated. Electrical resistivity measurements show that the values of critical temperature Tc increase with tungsten content. The highest transition temperature, Tc, obtained for Bi2-xPb0.3WXSr2Ca2Cu3O10+δ composition was 191.8K with x=0.3.

The Role of Tl Substitution on Superconducting Properties for Hg-1223 System

High temperature superconductors with a nominal composition Hg1-xTlxBa2Ca2Cu3O8+δ for (0<x<0.4) were prepared by two-step solid state reaction in air. The effect of the substitution of Tl for Hg, oxygen content (δ) and sintering time (20-200h) on the Hg-12223 superconductivity system has been investigated to obtain the optimum conditions for the formation and stabilization of the high critical temperature (Tc).The results showed that the optimum sintering temperature for the prepared samples was equal to 880 °C, whereas the sintering time is equal to 100 h.The quantity of the element content for Hg1-xTlxBa2Ca2Cu3O8+δ system were carried out using x-ray fluorescence (XRF). X-ray diffraction (XRD) analysis showed a tetragonal structure with a high Tc phases (1223) as a dominant phase and low Tc phase (1212) addition to exist of some impurity phases for all samples. It was found that the change of the Tl concentrations of prepared samples produced a change in the lattice parameters, density ρm and c/a ratio. The highest Tc for HgBa2Ca2Cu3O8+δ composition was 118 K. The results for the doped samples, represented highest Tc equal to 124 K for Hg1-xTlx Ba2Ca2Cu3O8+δ sample with x=0.4.The oxygen content was not systematic changed but it played a great role in the evaluation of Tc.

Superconducting properties of (NH3)yLixFeSe0.5Te0.5 under pressure

We prepared two superconducting phases of (NH3)yLixFeSe0.5Te0.5, which show superconducting transition temperatures (Tc’s) as high as 20.2 and 29.5 K at ambient pressure, here called the ‘low-Tc phase’ and ‘high-Tc phase’. The temperature dependence of electrical resistance (R) was measured for the low-Tc phase of (NH3)yLixFeSe0.5Te0.5 over a pressure (p) range of 0–14 GPa, and for the high-Tc phase of (NH3)yLixFeSe0.5Te0.5 over 0–19 GPa, yielding double-dome superconducting Tc–p phase diagrams, i.e. two superconducting phases (SC-I and SC-II) were found for both the low-Tc and high-Tc phases under pressure. For the low-Tc phase, the maximum Tc was 20.2 K at 0 GPa for SC-I, and 19.9 K at 8.98 GPa for SC-II. For the high-Tc phase, the maximum Tc was 33.0 K at 1.00 GPa for SC-I, and 24.0 K at 11.5–13.2 GPa for SC-II. These results imply that the maximum Tc value of the high pressure phase (SC-II) does not exceed the maximum value of the SC-I, unlike what was shown in the Tc–p phase diagrams of (NH3)yLixFeSe and (NH3)yCsxFeSe investigated previously. Nevertheless, the double-dome Tc–p phase diagram was found in metal-doped FeSe0.5Te0.5, indicating that this feature is universal in metal-doped FeSe1−zTez. Moreover, no structural phase transitions were observed for either the low-Tc or high-Tc phases of (NH3)yLixFeSe0.5Te0.5 over the wide pressure range of 0–15.3 GPa, and the Tc-lattice constant (c) plots for both phases were recorded to determine the critical point separating SC-I and SC-II.

Structural, superconducting and vortex pinning properties of Nb-substituted Bi-2212 ceramic superconductor

In this research, we have deeply focused to investigate the effects of Niobium (Nb) substitution for the Ca site in the Bi2Sr2Ca1−xNbxCu2O8+y superconductors with x = 0.00, 0.05, 0.10, 0.20, 0.30, and 0.40. The materials were synthesized via well-known solid state reaction method. We have performed X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and dc magnetization measurements in order to understand the effects of Nb-content. XRD results exhibit that the Bi-2212 phase is a major phase for pure sample. On the other hand, the volume fraction of Bi-2212 declines with increasing Nb substitution and relocates with low-Tc phase, namely Bi-2201. The maximum pinning force, FPmax, values of x = 0.05 and 0.10 Nb-substituted samples are improved in comparison to the pure sample. These values are found as 5.18 × 107 and 5.21 × 107 Oe A/cm2 at T = 10 K for x = 0.05 and 0.10 Nb-substituted sample, respectively, which are higher than the 4.92 × 107 Oe A/cm2 value of the pure sample.

Mechanism for the Structural Transformation to the Modulated Superconducting Phase of Compressed Hydrogen Sulfide

A comprehensive description of crystal and electronic structures, structural transformations, and pressure-dependent superconducting temperature (Tc) of hydrogen sulfide (H2S) compressed from low pressure is presented through the analysis of the results from metadynamics simulations. It is shown that local minimum metastable crystal structures obtained are dependent on the choice of pressure-temperature thermodynamic paths. The origin of the recently proposed ‘high-Tc’ superconducting phase with a modulated structure and a diffraction pattern reproducing two independent experiments was the low pressure Pmc21 structure. This Pmc21 structure is found to transform to a Pc structure at 80 K and 80 GPa which becomes metallic and superconductive above 100 GPa. This structure becomes dynamically unstable above 140 GPa beyond which phonon instability sets in at about a quarter in the Γ to Y segment. This explains the transformation to a 1:3 modulation structure at high pressures proposed previously. The pressure trend of the calculated Tc for the Pc structure is consistent with the experimentally measured ‘low-Tc phase’. Fermi surface analysis hints that pressurized hydrogen sulfide may be a multi-band superconductor. The theoretical results reproduced many experimental characteristics, suggesting that the dissociation of H2S is unrequired to explain the superconductivity of compressed H2S at any pressure.

Enhanced flux pinning properties in Bi1.6Pb0.4Sr2−xKxCa2Cu3O10+δ compounds

The effect of K substitutions on the structural and superconducting properties of Bi–Pb–Sr–Ca–Cu–O (BPSCCO) system has been investigated. Polycrystalline samples with stoichiometry of Bi1.6Pb0.4Sr2−xKxCa2Cu3O10+δ, where x = (0.00, 0.02, 0.04, 0.06, 0.08, and 0.1), were prepared by using the conventional solid state reaction technique. The X-ray diffraction (XRD) and scanning electron microscopy (SEM) data showed that all samples consisted of high Tc (Bi-2223) and low Tc (Bi-2212) phases, and their volume fractions were found to vary with K content (x). The zero critical temperature was found to decrease from ~ (104.5 to 94.6) K, which was attributed to the decreases in hole carrier concentration. At 65 K, the magnetization critical current density (Jc) of the K-substituted samples was enhanced in comparison with that of the pure one. The Jc enhancement might be attributed to the formation of point defects resulting from the partial substitutions of K into Sr site in the BPSCCO system. In addition, the dominant pinning mechanism was found to be point-like pinning, as described using the Dew-Hughes model.

Studying the Influence of fast neutron irradiation on properties of Bi2-xPbx Sr2Ca2Cu3-yNiy O2n+4+δ superconducting system.

The influence of a fast neutron irradiation on the structure and critical temperature of Bi2Sr2Ca2Cu3O10+δ (A), s Bi1.8Pb0.2Sr2Ca2Cu2.8Ni0.2O10+δ (B) and Bi1.6Pb0.4Sr2Ca2Cu2.6Ni0.4O10+δ (C) system were investigated utilizing X-ray diffraction analysis and four probes technique to determined lattice parameters and critical temperatures. It has been found that the critical temperature was decreased by 6.5k, 6.5k and 7k for A, B and C respectively after irradiated by 1.296 × 1011neutroncm2. associated to decrease in oxygen content values. And XRD analysis explained that the structure corresponding to orthorhombic structure with the majority high Tc (2223) phase, and the minority low-Tc (2212) phase in addition to small amount of unknown phase.

Synthesis and study the Structural and electrical and mechanical properties of High Temperature Superconductor Tl0.5Pb0.5Ba2Can-1Cun-xNixO2n+3-δ Substituted with nickel oxide for n=3

on this research is to study the effect of nickel oxide substitution on the pure phases superconductor Tl0.5Pb0.5Ba2Can-1Cun-xNixO2n+3-δ (n=3) where x=(0,0.2,0.4,0.6,0.8.and 1.0). The specimens in this work were prepared with used procedure of solid state reaction with sintering temperature 8500C for 24 h .we used technical (4-prob)to calculated and the critical temperature Tc . The results of the XRD diffraction analysis showed that the structure for pure and doped phases was tetragonal with phases high-Tc phase (1223),(1212) and low-Tc phase (1202) and add to the presence of some impure phase. It was noted the value a=b,c the parameter of the lattice increment with the increment of Ni content. The increment of (NiO) concentration effects electrical resistivity, dielectric constant and the hardness.

Pressure dependence of superconductivity in low- and high- Tc phases of (NH3)yNaxFeSe

We prepared two superconducting phases, which are called “low-Tc phase” and “high-Tc phase” of (NH3)yNaxFeSe showing Tc’s of 35 and 44 K, respectively, at ambient pressure, and studied the superconducting behavior and structure of each phase under pressure. The Tc of the 35 K at ambient pressure rapidly decreases with increasing pressure up to 10 GPa, and it remains unchanged up to 22 GPa. Finally, superconductivity was not observed down to 1.4 K at 29 GPa, i.e., Tc < 1.4K. The Tc of the 44 K phase also shows a monotonic decrease up to 15 GPa and it weakly decreases up to 25 GPa. These behaviors suggest no pressure-driven high-Tc phase (called “SC-II”) between 0 and 25 GPa for the low-Tc and high-Tc phases of (NH3)yNaxFeSe, differing from the behavior of (NH3)yCsxFeSe,which has a pressure-driven high-Tc phase (SC-II) in addition to the superconducting phase (SC-I) observed at ambient and low pressures. The Tc-c phase diagram for both low-Tc and high-Tc phases shows that the Tc can be linearly scaled with c (or FeSe plane spacing), where c is a lattice constant. The reason why a pressure-driven high-Tc phase (SC-II) was found for neither low-Tc nor high-Tc phases of (NH3)yNaxFeSe is fully discussed, suggesting a critical c value as the key to forming the pressure-driven high-Tc phase (SC-II). Finally, the precise Tc-c phase diagram is depicted using the data obtained thus far from FeSe codoped with a metal and NH3 or amine, indicating two distinct Tc-c lines below c = 17.5A° .

A comparative study of enhancements of critical temperature in Bi-Pb-Sr-Ca-Cu-O superconductors

In this work, the effects of sintering temperature and Na subtitution on zero critical temperature (Tc,0) in Bi-Pb-Sr-Ca-Cu-O superconductors were investigated. The Bi1.6Pb0.4Sr2Ca2-xNaxCu3O10+d bulk samples with x = 0.00 and 0.05 (BPSCCO) were prepared by using the solid state reaction technique at elevated sintering temperatures of 840 and 850oC. To examine the improvements of structural and superconducting properties of the BPSCCO samples, the X-ray diffraction (XRD), scanning electronic microscope (SEM) and DC resistance versus temperature (R-T) measurements were carried out. The experimental findings exhibit a co-existence of the high Tc (Bi-2223) and low Tc (Bi-2212) phases in all samples. The estimated volume fraction of the Bi-2223 phase was increased from 71.4 to 75.7%, and the average size of the Bi-2223 grains was enlarged from 4.5 to 9.8 mm as changing the sample preparation conditions. The improved connectivities between the Bi-2223 grains were also obtained by quantitively analyzing the relation between Tc,0 and residual resistance ratio (RRR). These improvements were likely to be reasons for the enhancements of Tc,0 in the BPSCCO samples.

Effect of Ce addition on the glass-forming ability and hard-magnetic properties of the Nd-Fe-Al bulk metallic glasses

The influence of Ce addition on the glass-forming ability (GFA) and hard-magnetic properties of the Nd60−xCexFe30Al10 (x=0−35) alloy prepared by suction casting have been investigated. The glass-forming ability of the as-cast rods increased with the addition of Ce content from x=0 to x=30, and then decreased for x=35. The as-cast rods with a composition of x=0 and x=30 contained two amorphous magnetic phases including Fe-rich regions and Nd-rich regions characterized by the Curie temperature Tc1 and Tc2. The Ce atoms may be unevenly distributed in the two magnetic phases, which prefer to substitute Nd in the low Tc phase. All the alloys exhibit hard magnetic behavior, while the room-temperature coercivity and remanence gradually decrease with the Ce addition. The saturation magnetization (Ms), remanence (Mr) and coercivity (iHc) of the alloy for x=30 with the best glass-forming ability are 16.30Am2/kg, 10.22Am2/kg and 162.31kA/m, respectively.

Pressure and high-Tc superconductivity in sulfur hydrides.

The paper discusses fundamentals of record-TC superconductivity discovered under high pressure in sulfur hydride. The rapid increase of TC with pressure in the vicinity of Pcr ≈ 123GPa is interpreted as the fingerprint of a first-order structural transition. Based on the cubic symmetry of the high-TC phase, it is argued that the lower-TC phase has a different periodicity, possibly related to an instability with a commensurate structural vector. In addition to the acoustic branches, the phonon spectrum of H3S contains hydrogen modes with much higher frequencies. Because of the complex spectrum, usual methods of calculating TC are here inapplicable. A modified approach is formulated and shown to provide realistic values for TC and to determine the relative contributions of optical and acoustic branches. The isotope effect (change of TC upon Deuterium for Hydrogen substitution) originates from high frequency phonons and differs in the two phases. The decrease of TC following its maximum in the high-TC phase is a sign of intermixing with pairing at hole-like pockets which arise in the energy spectrum of the cubic phase at the structural transition. On-pockets pairing leads to the appearance of a second gap and is remarkable for its non-adiabatic regime: hydrogen mode frequencies are comparable to the Fermi energy.

Effect of V substitution on vortex pinning and superconducting properties of Bi-2212 superconductor

In this work, the effect of Vanadium (V) substitution in the Bi2Sr2Ca1−xVxCu2O8+y superconductor with x = 0.0, 0.05, 0.1, 0.2, 0.3, and 0.4 has been investigated. The samples were prepared by a conventional solid state reaction technique. The effects of vanadium substitution have been investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy, and magnetic characterizations. XRD patterns indicate that the Bi-(2212) phase is the major one for pure sample, but with increasing of V content, the volume fraction of Bi-2212 is reduced and transformed to mainly low-Tc phase, namely Bi-2201. 0.05 V substitution causes a remarkable increase of superconducting critical temperature as 86.2 K, which is higher than pure sample by 2.3 K. Moreover, 0.05 V leads to improvement of intragranular JC value which is calculated as 2.53 × 104 A/cm2 at 10 K. For comparison, the enhancement in JC value is about 78 % more than those value obtained for pure sample. The whisker structure with a length of 0.25 mm in main matrix is also observed in the SEM micrographs of 0.4 V substitution.