Magnetic Susceptibility and High Field Magneto-transport of Silver-Added Bi-2223 Superconductor: a Revisit

The effect of Ag addition on weak link behaviour of a Bi-2223 (Bi_1.7Pb_0.3Sr₂Ca₂Cu₃O₁₀) polycrystalline sample has been investigated in terms of AC susceptibility, critical current density (J _c), electrical resistivity ρ(T)H and upper critical field (H _c2). A series of phase pure Bi-2223-Ag _x (x = 0.0–0.3) samples are prepared by the solid-state synthesis route. The phase purity, crystal structures and surface morphology are being studied using the X-ray diffraction and scanning electron microscopy (SEM) technique, respectively. The effect of Ag addition on inter- and intragranular coupling has been investigated by means of AC susceptibility and magneto-transport ρ(T)H measurements, and the results are compared with the pure Bi-2223 sample. Enhancement in granular coupling between the grains of the 20 wt% Ag-added Bi-2223 sample has been witnessed. Critical current density (J _c) has been estimated using the AC susceptibility technique, and the results are interpreted in terms of inter- and intragranular coupling of the investigated samples. The high field magneto-transport technique has been used to estimate the upper critical field (H _c2) and thermally activation flux flow (TAFF) activation energy. The ensuing results revealed that H _c2 increases for the 20 wt% Ag-added sample along with enhancement in grain alignment and intergrain connectivity.     

Synthesis of CdS Nanoparticles by Hydrothermal Method and Their Effects on the Electrical Properties of Bi-based Superconductors

Cadmium sulfide (CdS) nanoparticles were synthesized by hydrothermal process and have been characterized by x-ray diffraction (XRD), transmission electron microscopy (TEM), and energy-dispersive x-ray spectroscopy (EDXS) system. The effect of added CdS nanoparticles on the superconducting properties and flux pinning capability in (Bi,Pb)₂Sr₂Ca₂Cu₃O_y system (denoted as (Bi,Pb)-2223) has been reported. Hydrothermal method is an effective route to synthesize CdS nanoparticles with good crystallinity and having average grain size of about 12 nm. Then, small amounts (0–0.4 wt%) of nanosized CdS particles were added to Bi-2233 samples using a solid-state reaction route. The transport critical current densities and the electrical resistivity ρ(T, H) were performed using the four-probe technique. The results show that samples sintered by small amount of CdS nanoparticles (≤?0.3 wt%) exhibit the higher critical current densities and energy pinning in applied magnetic fields compared to free added sample. Consequently, the addition of CdS could introduce effective pinning centers which account for the improvement in superconducting properties in the Bi-2223 materials.     

Improvement of the Magnetization of Barium Hexaferrites Induced by Substitution of Nd<Superscript>3+</Superscript> Ions for Fe<Superscript>3+</Superscript> Ions

Barium hexagonal ferrites (BaNd _x Fe_12?x O ₁₉) have been synthesized by initial high-energy milling of the precursors and calcining subsequently. The as-prepared samples are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and vibrating sample magnetometry (VSM). XRD and SEM examinations reveal that a high-crystallized hexagonal BaNd _x Fe_12?x O ₁₉ with lamellar morphology is obtained when the precursor is calcined at 1200^°C in air for 3 h. The hexagonal crystalline structure of BaFe₁₂ O ₁₉ is not changed after doping Nd³⁺ ions in BaFe₁₂ O ₁₉. However, lattice parameters a and b values increase with an increase in Nd content at first, then decrease. Nd substitution may improve the magnetic properties of BaNd _x Fe_12?x O ₁₉. BaNd_0.1Fe_11.9 O ₁₉, obtained at 1050^°C, has the highest specific saturation magnetization value (80.81 emu/g) and magnetic moment (16.21 μ _B); BaNd_0.2Fe_11.8 O ₁₉, obtained at 950^°C, has the highest coercivity value, 4075.19 Oe.     

The Effect of Annealing on Phase Stability and Magnetic Properties of Hexaferrite BaFe<Subscript>12</Subscript><Emphasis Type="Italic">O</Emphasis><Subscript>19</Subscript>

The hexaferrite BaFe₁₂ O ₁₉ phase was synthesized through the mechanical alloying process followed by subsequent annealing. Rietveld refinements of as-milled powder annealed at 700 ^°C confirm the formation of the BaFe₁₂ O ₁₉ phase with the presence of an important amount of the α-Fe₂ O ₃ phase. Thus, prior mechanical milling shows much lower reaction temperature and less reaction time compared to conventional methods. Further annealing up to 900 and 1100 ^°C could not enable the formation of a single BaFe₁₂ O ₁₉ phase, reaching an optimum phase composition ratio close to BaFe₁₂ O ₁₉/ α-Fe₂ O ₃ 70/30. The crystallite size was found to be in the nanoscale level but increases with increasing temperature (BaFe₁₂ O ₁₉ = 20–62 nm; α-Fe₂ O ₃ = 31–74 nm). SEM micrographs show that as the annealing temperature rises, the particles become more regular with sharp edges and hexagonal-like shapes. Magnetic measurements reveal that both M _s and M _r increase with annealing temperature to reach maximum values at 900 ^°C then remain unchanged, associated with phase composition. The coercivity H _c increases upon annealing up to 700 ^°C to a much higher value, from 1.7 kOe for as-milled powder to 4.8 kOe. Its value then decreases, attributed to grain (particle) growth (formation of larger particles) due to high annealing temperatures: 900–1100 ^°C. The obtained composites show very interesting magnetic properties and can be considered for potential applications, such as hyperthermia, heavy metal and dye removal, and hard/soft magnetic composites.     

Synthesis and Magnetic Properties of Bi<Subscript>1.7</Subscript>Pb<Subscript>0.3</Subscript>Sr<Subscript>2</Subscript>Ca<Subscript>2</Subscript>Cu<Subscript>3</Subscript>O<Subscript>10+<Emphasis Type="Italic">δ</Emphasis></Subscript> Added with Nano Y

Bi₁₇Pb_0.3Sr₂Ca₂Cu₃O_10+δ superconductor samples were synthesized by the conventional solid-state reaction method. To study the effects of the addition of yttrium nanoparticles to the superconducting system, nano Y₂O₃ was introduced by small weight percentages (0.2, 0.4, 0.6, 0.8, and 1.0 wt%) in the first step of the synthesis process. Phase identification and microstructural characterization of the samples were investigated using X-ray diffraction and scanning electronic microscopy (SEM). Energydispersive X-ray spectroscopy (EDX) analysis was utilized to confirm the presence of the desired elements in the chemical composition of the samples. Moreover, DC electrical resistivity as a function of the temperature, critical current density (J _c), AC magnetic susceptibility, and DC magnetization measurements were carried to evaluate the relative performance of samples. XRD analysis showed that both (Bi,Pb)-2223 and Bi-2212 phases coexist in the samples having an orthorhombic crystal structure. Both the onset critical temperatures (T _c) (onset) and zero electrical resistivity critical temperatures (T _c) (R = 0) of the samples were determined from the DC electrical resistivity measurements. An improvement of the superconducting transition temperature of 3.0 % was obtained with increasing Y₂O₃ nanoparticles to x = 1.0 wt%, while the critical current density is improved by 200 %. AC magnetic susceptibility measurement showed that the diamagnetic fraction and intergranular coupling of the x = 1.0 wt% sample are greater than those of the others. The variation of magnetization with temperature (M–T curve) of the samples was measured by cooling the sample in zero fields (ZFC) and an applied field of 10 Oe (FC). The results of AC magnetic susceptibility and DC magnetization measurements were in good agreement with DC electrical resistivity measurement.     

Effect of refractory nitride nanoadditives on the properties of (Bi,Pb)<Subscript>2</Subscript>Sr<Subscript>2</Subscript>Ca<Subscript>2</Subscript>Cu<Subscript>3</Subscript>O<Subscript>10+δ</Subscript>

We have investigated the interaction between (Bi,Pb)₂Sr₂Ca₂Cu₃O_10+δ (Bi-2223) and small additions (0.05–0.3 wt %) of nitride powders (TaN, AlN, HfN, NbN, Si₃N₄, TiN, and ZrN) with a particle size from 0.02 to above 0.5 μm and the effect of these nitrides on the microstructure, phase composition, distribution, and morphology of the resulting second-phase inclusions. The concentration and particle size of the nitrides and sintering conditions are shown to influence the superconducting transition temperature T _c, critical current density j _c, irreversible remanent magnetization, bulk density, and mechanical properties of the Bi-2223/nitride composites.     

AC Losses in YBCO-Added Bi<Subscript>1.6</Subscript>Pb<Subscript>0.4</Subscript>Sr<Subscript>2</Subscript>Ca<Subscript>2</Subscript>Cu<Subscript>3</Subscript>O<Subscript><Emphasis Type="Italic">δ</Emphasis></Subscript> Superconductors

The effect of YBCO adding on the superconducting of BPSCCO system with nominal starting composition of (Bi_1.6Pb_0.4Sr₂Ca₂Cu₃O _δ )_1?x(YBCO) _x with x = 0.00?0.10 was studied. The preparation methods used to prepare the samples are the conventional solid-state techniques. From the XRD data, it is observed that the percentage of the Bi-2223 phase increases and Bi-2212 decreases for addition x = 0.02–0.04, respectively. The effect of YBCO addition on the BPSCCO system also has been investigated in term of AC susceptibility study. We have studied the various applied field dependence of the AC susceptibility in polycrystalline samples. The AC susceptibility measurements in the range 0.05 to 2.00 Oe show that as the applied fields increases, the intergranular AC loss peaks move to lower temperature, and also height decreases and width increases. The effect of YBCO addition for the intergranular critical current J _cm, and the presence of weak links that coupled the superconducting grains were defined.     

Vanadium Addition Effect on the Superconducting Properties of BPSCCO System

To study the vanadium addition effects on the BSCCO superconducting system, bulk samples with the general formula Bi_1.7Pb_0.3V _x Sr₂Ca₂Cu₃O_{10 + δ} (x = 0.0, 0.1, 0.2, 0.3 0.4 and 0.5) were prepared by solid-state reaction method. Energy-dispersive X-ray spectroscopy (EDX) analysis was used to test the proportions and energies of the elements of the compound. The XRD analyses showed an orthorhombic structure with two phases: a high-2223 phase and a low-2212 phase in addition to which an impure phase was found. The highest T _c at 118 K was obtained for the sample with x = 0.2. Scanning electron microscopy (SEM) was used to identify the morphology of the superconducting phase and to investigate the influence of vanadium.     

Effects of Rolling Passes on the Transport Properties of 37-Filamentary AgAu-Sheathed Bi-2223 Tapes

Thirty-seven-filamentary AgAu-sheathed Bi-2223 tapes were fabricated by a powder-in-tube (PIT) process. And, the round wires (? 1.86 mm) were rolled to 0.35-mm tapes with 12, 7, 5, and 4 rolling passes through flat rolling, respectively. The influences of different rolling passes on the core density, deformation, and transport properties of Bi-2223/AgAu tapes were systematically investigated. It was noticed that after rolling, the Vickers microhardness of the superconducting core and deform homogeneity along both the horizontal and vertical directions on the cross section of seven-pass rolled tape were better than those on the tapes with other passes, which proved the larger core density and uniform deformation with the seven-pass rolling process. Meanwhile for the wires with 12 and 7 passes, the AgAu/superconducting core interfaces were much flatter. With the rolling passes decreasing from 12 to 4, the critical current density (J_c) first increased and then decreased. Due to the better homogeneity and flatter interfaces, J_c reached the maximum value of 17.3 kA/cm² on the seven-pass sample. Meanwhile, the enhancement of current capacities in magnetic field applied parallel to the Bi-2223/AgAu tape surface could also be recognized as the evidence of improving intergrain connections due to the higher density in seven-pass rolled tapes.     

Effect of Boron Substitution for Bi on Superconductivity of the Bi-2212 Phase in the Bi-Sr-Ca-Cu-O System

Possibility of boron substitution for Bi and the substitution effect on superconductivity is investigated for the Bi-2212 phase of Bi-Sr-Ca-Cu-O. From X-ray diffraction study, it is found that samples in the (Bi_2?x B _x )Sr₂CaCu₂O _z system are mainly of the single 2212 phase in a composition range of 0.0≤x≤0.6, and both of the lattice parameters a and c change with increasing x up to 0.6. From measurements of the magnetic susceptibility and the electrical resistivity, the superconducting transition temperature is found to increase up to 0.6 with increasing x. These results are considered to show that boron is substitutable for Bi up to x=0.6 in the (Bi_2?x B _x )Sr₂CaCu₂O _z system and that the boron substitution causes the number of hole-carriers to decrease in this system.     

An Exponential Model for Critical Current Density Through a Low-Angle Grain Boundary in a High-<Emphasis Type="Italic">T</Emphasis><Subscript><Emphasis Type="Bold">c</Emphasis></Subscript> Superconductor

An analytical investigation is presented to display the distribution of critical current flow through a low-angle grain boundary in a high-T _c superconductor such as YBCO or Bi-2212 film. When a superconductor is subjected to a transport current or a magnetic field, the fluxoids are redistributed between the dislocations which comprise a low-angle grain boundary. A model considering the elastic interaction between a flux line and an edge dislocation is developed in this paper. Results of our model are consistent with those of the classic exponential model, while for high-angle grain boundaries with the misorientation angles ?? > 4^°, this model is invalid. It is helpful by using our model to understand the mechanisms of the effect of low-angle grain boundaries on critical current density.     

Effect of Annealing Temperature on the Microstructure and Magnetic Properties of MnGa Films

MnGa films are the promising magnetic recording materials and spintronic materials owing to their intrinsic properties, such as large magnetic anisotropy, high coercivity, moderate magnetization, and high spin polarization. In this paper, MnGa films with high coercivity and low surface roughness have been successfully fabricated onto MgO substrates by magnetron sputtering and post-annealing. Moreover, the effects of post-annealing temperature (T _a) on crystalline structure, surface morphology, and magnetic performances of MnGa films have also been investigated. It is found that the crystallization temperature for MnGa films is 400 ^°C. With increasing T _a, the crystallization degree enhances and an in-plane texture is formed. The grain size and surface roughness of MnGa films increase slowly when T _a is below 500 ^°C, but they exhibit a rapid rise when T _a is above 500 ^°C. As T _a increases, the coercivity (H _c) and remanence squareness ratio (S) for MnGa films improve monotonically, whereas saturation magnetization (M _s) increases firstly and then drops. The increases in H _c, S, and M _s with T _a are attributed to the grains’ growth and the improvement of crystallinity, and the decrease of M _s at higher T _a possibly is due to the partial oxidation of Mn.     

Structural,Morphological, Optical and Magnetic Properties of Al-Doped CoFe<Subscript>2</Subscript><Emphasis Type="Bold">O</Emphasis><Subscript>4</Subscript> Nanoparticles Prepared by Sol–Gel Auto-Combustion Method

CoFe_2?x Al _x O₄ (x = 0.0,0.5,1.0, and 1.5) ferrite nanoparticles have been synthesized by the sol–gel auto-combustion method. The effect of non-magnetic Al content on their structural, morphological, optical, and magnetic properties was also investigated. X-ray diffraction (XRD) diffraction analysis was applied and indicated that the synthesized nanopowders of samples with x<1.5 and calcined at 800 ^°C have single-phase spinel structure. It has shown also by increasing Al content, the particle size, lattice parameter, unit cell volume, coercivity, anisotropy constant, and magnetization decrease, while the energy band gap increases. The size of particles was measured by TEM being in the range of 65–75 nm (for x = 0.0) and 9–10 nm (for x = 1.0). For sample with x = 1.5, the minimum calcination temperature for obtaining a single-phase spinel structure was 1000 ^°C. By increasing the calcination temperature from 1000 to 1100 ^°C, the mean crystallite size and crystallinity increase, while the lattice parameter, coercivity, anisotropy constant, and magnetization decrease. The average grain size evaluated by SEM analysis was found to be \(\tilde 91\) and 166 nm for samples calcined at 1000 and 1100 ^°C, respectively.     

Cu<Superscript>2+</Superscript> and Al<Superscript>3+</Superscript> co-substituted cobalt ferrite: structural analysis,morphology and magnetic properties

Cu–Al substituted Co ferrite nanopowders, Co_1?x Cu _x Fe_2?x Al _x O₄ (0.0 ≤ x ≤ 0.8) were synthesized by the co-precipitation method. The effect of Cu–Al substitution on the structural and magnetic properties have been investigated. X-ray diffraction (XRD) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FESEM) and vibrating sample magnetometer (VSM) are used for studying the effect of variation in the Cu–Al substitution and its impact on particle size, magnetic properties such as M _s and H _c . Cu–Al substitution occurs and produce a secondary phase, α-Fe ₂ O ₃. The crystallite size of the powder calcined at 800 ^°C was in the range of 19–26 nm. The lattice parameter decreases with increasing Cu–Al content. The nanostructural features were examined by FESEM images. Infrared absorption (IR) spectra shows two vibrational bands; at around 600 (v ₁) and 400 cm ^?1 (v ₂). They are attributed to the tetrahedral and octahedral group complexes of the spinel lattice, respectively. It was found that the physical and magnetic properties have changed with Cu–Al contents. The saturation magnetization decreases with the increase in Cu–Al substitution. The reduction of coercive force, saturation magnetization and magnetic moments are may be due to dilution of the magnetic interaction.     

The Effect of Sn Substitution of Pb on Microstructure and Superconducting Properties of Bi–Pb–Sr–Ca–Cu–O Superconductor

The effect of substitution of Pb by Sn in Bi_1.6Pb_0.4?x Sn _x Sr₂Ca₂Cu₃ O _δ samples at x = 0.0, 0.1, 0.2, and 0.3 on the critical transition temperature and structural properties was investigated in this work. All the samples were prepared by the solid-state reaction method. The prepared samples were characterized by X-ray diffraction (XRD), resistance–temperature curve (R–T), scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). The Sn ⁴⁺ substitution of Pb ²⁺ caused significant changes in the properties of the samples. The formation of the (Bi, Pb)-2212 phase was stabilized and the T _c (onset) was improved at the x = 0.2 level of Sn ⁴⁺ substitution. The SEM micrographs have shown that the structure of the sample with x = 0.2 became more dense. However, samples with x = 0.1 and 0.3 have not shown zero resistance by EDS analysis because of oxygen deficiency.     

Effect of Cu-Co-Zr Doping on the Properties of Strontium Hexaferrites Synthesized by Sol-Gel Auto-combustion Method

In the present study, we have synthesized tri-substituted strontium hexaferrites SrFe _(12?2x)Cu _x/2Co _x/2Zr _x O ₁₉ (x= 0.0 ?1.0, Δx= 0.2) by sol-gel auto-combustion route. The effect of this triple doping has been studied on the structural, dielectric, and magnetic properties of M-type strontium hexaferrite nanoparticles. The characterization of these materials has been done by XRD, FT-IR, VSM, SEM, EDS, and impedance analyzer. Single-phase formation is confirmed at 800 ^°C. Real permittivity decreases while loss tangent increases with increase in substitution. The observed results propose these prepared ferrites for applications in filters, antennas, isolator, circulators, etc.     

Synthesis and luminescence properties of Tb<Superscript>3+</Superscript>-doped LiMgPO<Subscript>4</Subscript> phosphor

Polycrystalline sample LiMg_(1?x)PO₄:xTb³⁺ (x = 0.001, 0.002, 0.005, 0.01, 0.02) phosphor was synthesized via modified solid state method (MSSM). The prepared sample was characterized through XRD pattern (X-ray diffraction) and SEM (scanning electron microscope). Additionally, photoluminescence (PL), optically stimulated luminescence (OSL), thermoluminescence (TL) and other dosimetric properties including dose linearity, reusability and fading were studied. In OSL mode, sensitivity of prepared phosphor was found to be 2.7 times that of LiMgPO₄:Tb³⁺, B (BARC) phosphor and 4.3 times that of α-Al₂O₃:C (BARC) phosphor. The TL glow consists of overlapping peaks in temperature range of 50–400^°C and first peak (P₁) was observed at 150^°C, second peak (P₂) at 238^°C, third peak (P₃) at 291^°C and fourth peak (P₄) at 356^°C. The TL sensitivity of second peak (P₂) of LiMgPO₄:Tb³⁺ phosphor was compared with α-Al₂O₃:C (BARC) phosphor and found to be 100 times that of the α-Al₂O₃:C (BARC) phosphor. The minimum detectable dose (MDD) was found to be 5.6 μGy. Moreover, photoionization cross-sections, linearity, reusability, fading and kinetic parameters were calculated. Also, photoluminescence spectra of LiMgPO₄: Tb³⁺ shows characteristic green–yellow emission exciting at 224 nm UV source.     

Microstructural and Magnetic Features of SrFe<Subscript>12</Subscript><Emphasis Type="Italic">O</Emphasis><Subscript>19</Subscript> Materials Synthesized from Different Fuels by Sol-Gel Auto-Combustion Method

The nanocrystalline SrFe₁₂ O ₁₉ materials were prepared by a sol-gel auto-combustion method using different fuels such as citric acid, dextrose, aniline, and hexamine. The combustion product obtained from all the fuels except from that of aniline show a single phase of SrFe₁₂ O ₁₉ materials upon annealing at 1000 ^°C/2 h. The combustion product obtained from aniline as fuel shows SrFe₁₂ O ₁₉ as the main phase with α-Fe₂ O ₃ as impurity. No notable change in lattice parameters is observed due to variation in fuels for SrFe₁₂ O ₁₉ materials. With a little change in the NIR relative reflectance (72–85 %) on fuels, the different SrFe₁₂ O ₁₉ materials display high NIR reflectance in the wavelength range, 1500–2500 nm. The photoluminescence emission spectra of SrFe₁₂ O ₁₉ materials reveal a broad emission peak at ～350 nm which is reminiscent to the Ba-based hexaferrite, BaFe₁₂ O ₁₉. The FESEM images expose quite dissimilar morphology for the various fuels used in the synthesis of SrFe₁₂ O ₁₉ materials. Hysteresis loops for all the nanocrystalline SrFe₁₂ O ₁₉ materials observed under the applied field of ±1.5 T at room temperature exhibit hard ferromagnetic property. The SrFe₁₂ O ₁₉ materials produced from glycine and aniline as fuels exhibit highest and lowest M _s values of 61.3 and 50.5 emu/g, respectively.     

The Effect of Using Different Y<Subscript>2</Subscript>O<Subscript>3</Subscript> Layers on the Activation Energy and Irreversibility Line of MPMG YBCO Bulk at 1050 °C Growth Temperature

In this study, three kinds of YBCO samples which are named Y1, Y2 and Y3 were fabricated by a melt–powder–melt–growth (MPMG) method. The Y1 sample was placed into a platinum (Pt) crucible without Y₂O₃, the Y2 sample was located on a Al₂O₃ crucible with a freely poured Y₂O₃ powder and the Y3 sample was located on a Al₂O₃ crucible with a 1-mm-thick buffer layer of Y₂O₃. YBCO samples were investigated by magnetoresistivity (ρ–T) measurements in dc magnetic fields (parallel to the c-axis) up to 5 T. The effect of the Y₂O₃ layer on the activation energy and irreversible flux of the samples was studied. The activation energies (U) were determined using the Arrhenius activation energy law from ρ–T. The power law relationship for U with H^?α was investigated. α was calculated to find out which defects were dominant in the samples. Irreversibility fields (H_irr) and upper critical fields (H_c2) were obtained using 10 and 90% criteria of the normal-state resistivity value from ρ–T curves. Irreversibility lines (ILs) were estimated from the equation H_irr ～ (1 ? T_irr(H)/T_irr(0))ⁿ. The fitting results to giant flux creep and vortex glass models were discussed.     

Improving the Critical Temperature of MgB<Subscript>2</Subscript> Superconducting Metamaterials Induced by Electroluminescence

The MgB₂ superconductor was doped with electroluminescent Y₂O₃:Eu, to synthesise a superconducting metamaterial. The temperature dependence of the resistivity of the superconductor indicates that the critical temperature (T _C) of samples decreases when increasing the amount of doped Y ₂ O ₃ nanorods, due to impurity (Y ₂ O ₃, MgO and YB ₄). However, the T _C of the samples increase with increasing amount of doped Y ₂ O ₃:Eu ³⁺ nanorods, which are opposite to doped Y ₂ O ₃ nanorods. Moreover, the transition temperature of the sample doped with 8 wt % Y ₂ O ₃:Eu ³⁺nanorods is higher than those of doped and pure MgB ₂. The T _C of the sample doped with 8 wt % Y ₂ O ₃:Eu ³⁺ nanorods is 1.15 K higher than that of the sample doped with 8 wt % Y ₂ O ₃. The T _C of sample doped with 8 wt% Y ₂ O ₃:Eu ³⁺ is 0.4 K higher than that of pure MgB ₂. Results indicate that doping electroluminescent materials into MgB ₂ increases the transition temperature; this novel strategy may also be applicable to other superconductors.