Y-doped Sample Research Articles

Dinuclear Dysprosium Compounds: The Importance of Rigid Bridges.

We report the synthesis, structures and magnetic behaviour of two isostructural dinuclear Dy3+ complexes where the metal ions of a previously reported monomeric building block are connected by a peroxide (O22-) or a pair of fluoride (2 x F-) bridges. The nature of the bridge determines the distance between the metal ion dipoles leading to a dipolar coupling in the peroxido bridged compound of only ca. 70% of that in the bis-fluorido bridged dimer. The sign of the overall coupling between the metals is antiferromagnetic for the peroxido bridged compound and ferromagnetic for the bis-fluorido bridged complex. This in turn influences the magnetisation dynamics. We compare the relaxation characteristics of the dimers with those of the previously reported monomeric building block. The relaxation dynamics for the bis-fluorido system are very fast. On the other hand, comparing the properties of the monomer, the peroxido bridged sample and the corresponding Y-doped sample show that the relaxation properties via a Raman process have very similar parameters. We show that a second dysprosium is important for either tuning or detuning the Single Molecule Magnet (SMM) properties of a system.

Reveal of relationship between microscopy architecture and mechanical performance of Y/Bi substituted Bi-2212 engineering ceramics.

This study aims to find out how the crystallinity quality, surface morphology, and mechanical performances change with the substitution of yttrium (Y) for bismuth (Bi) impurity within molar ratios of 0.00 ≤ x ≤ 0.12 in the Bi2.0-xYxSr2.0Ca1.1Cu2.0Oy (Bi-2212) cuprates to reveal the dependence of micro surface topology on the substitution mechanism and achieve a strong relation between the impurity ions and crystallization mechanism. The materials are prepared by ceramic method. It is found that all the experimental findings improve remarkably with increasing yttrium impurity molar ratio of x = 0.01. Scanning electron microscopy (SEM) images indicate that the optimum Y ions strengthen the formation of flaky adjacent stacked layers due to the changes of thermal expansion, vibration amplitude of atoms, heat capacitance, reaction kinetics, activation energy, nucleation temperature, thermodynamic stability, and intermolecular forces. Besides, new engineering novel compound produced by optimum Y ions presents the best crystallinity quality, uniform surface view, greatest coupling interaction between grains, largest particle size distributions/orientations, and densest/smoothest surface morphology. Hardness measurement results totally support the surface morphology view. Moreover, mechanical design properties and durability of the tetragonal phase improve significantly with increasing replacement level of x = 0.01 due to the induction of new surface residual compressive stress areas, slip systems, and chemical bonding between the foreign and host atoms. Besides, the same sample exhibits the maximum strength and minimum sensitivity to loads depending on reduction of stored internal strain energy and degree of granularity. Consequently, cracks tend to propagate predominantly within the transcrystalline regions. Furthermore, each material investigated exhibits the characteristic behavior of the indentation size effect. In summary, the optimum Y-doped Bi-2212 sample paves the way for the expanded use of engineering ceramics across various applications based on the enhanced service life. RESEARCH HIGHLIGHTS: The presence of the optimum yttrium impurity significantly decreases the Ea value. As the Y/Bi replacement increases up to the molar substitution level of x = 0.01, the mechanical design properties and durability of the tetragonal phase enhance significantly.

Enhanced magnon thermal transport in yttrium-doped spin ladder compounds Sr14−xYxCu24O41

Magnons are quasiparticles of spin waves, carrying both thermal energy and spin information. Controlling magnon transport processes is critical for developing innovative magnonic devices used in data processing and thermal management applications in microelectronics. The spin ladder compound Sr14Cu24O41 with large magnon thermal conductivity offers a valuable platform for investigating magnon transport. However, there are limited studies on enhancing its magnon thermal conductivity. Herein, we report the modification of magnon thermal transport through partial substitution of strontium with yttrium (Y) in both polycrystalline and single crystalline Sr14−xYxCu24O41. At room temperature, the lightly Y-doped polycrystalline sample exhibits 430% enhancement in thermal conductivity compared to the undoped sample. This large enhancement can be attributed to reduced magnon-hole scattering, as confirmed by the Seebeck coefficient measurement. Further increasing the doping level results in negligible change and eventually suppression of magnon thermal transport due to increased magnon-defect and magnon-hole scattering. By minimizing defect and boundary scattering, the single crystal sample with x = 2 demonstrates a further enhanced room-temperature magnon thermal conductivity of 19Wm−1K−1, which is more than ten times larger than that of the undoped polycrystalline material. This study reveals the interplay between magnon-hole scattering and magnon-defect scattering in modifying magnon thermal transport, providing valuable insights into the control of magnon transport properties in magnetic materials.

Structural and dielectric properties of Y3+ doped SrTiO3: a novel anode materials for solid oxide fuel cell

An ongoing and elusive task is to create single phase anode materials for solid oxide fuel cells (SOFC). Compared to the typical Ni-YSZ cermet anode, perovskite oxide based anode material has a number of benefits. Here, we present the structural and electrical characteristics of Y3+ doped SrTiO3 ceramics that are used as the anode in solid oxide fuel cells. The samples with nominal composition x = 0 and 0.05 were synthesized by high energy ball milling. The powder X-ray diffraction pattern reveals that the synthesized samples crystallize into cubic crystal structure with space group Pm3m for both the compositions. The samples were sintered at a temperature of 1300 °C for 6h. The sintered density of the samples was found to be greater than 97%. The temperature dependent dielectric measurement studies reveal that dielectric constant increases with yttrium doping and shows relaxer behavior. A higher dielectric constant and electrical conductivity was observed for the Y-doped sample which fulfill the basic requirement for anode materials of solid oxide fuel cells.

Enhanced magnetic and ferroelectric properties of La[formula omitted]M[formula omitted]FeO[formula omitted] (M = Dy and Y) nanoparticles: A comparison of A-site doping

The room temperature magnetic hysteresis (M-H) loops reveal ferromagnetic-like behavior in an antiferromagnetically ordered LaFeO3 (LFO) material system synthesized by the sol–gel method. The maximum magnetization (Mmax) for the undoped sample annealed at 800 °C is 1.08 emu/g, whereas, with the same annealing, materials that are Dy and Y doped (25%) exhibit four times higher magnetization. It is interesting to note that non-magnetic ion Y3+ doped LFO has the same magnetization as magnetic ion Dy3+ doped nanomaterials. Reduction of particle and crystallite size plays a significant role in enhancing the net magnetization of doped materials. While the magnetization in Y-doped materials is attributed to the anti-symmetric exchange interaction (AEI) through spin canting, the greater magnetization for Dy doped samples is related to the AEI as well as inherent magnetic moment of the Dy3+ ion. The quantified tilting angle (Fe–O–Fe) is higher and the bond length (Fe–O) is smaller for Y-doped compounds compared to Dy-doped samples. X-ray photoelectron spectroscopy for oxygen 1s spectra shows that the relative area of O1− is higher in Dy-doped LFO than Y-doped sample. Ferroelectric hysteresis loops exhibit spontaneous electric polarization with reduced leakage current for Y-doped LFO, while other compounds show leaky behavior.

Electrochemical performance and stability improvement of triclinic LiVOPO4 cathode material via simultaneous Y doping and YPO4 surface modification

Here, we report the development of a facile approach in co-modification of triclinic lithium vanadyl phosphate [ε-LiVOPO4] with simultaneous yttrium (Y) doping and yttrium phosphate (YPO4) surface modification. Due to synergistic effects of YPO4 surface modification and Y doping, the resultant ε-LiVOPO4 (LVOP) exhibited significantly enhanced stability and electrochemical performance cycled in wide voltage 1.5–4.5 V. Among different proportions of Y (0, 3.5, 5, and 7 %), 5 % Y-doped sample (5 %Y-LVOP) exhibited the best electrochemical performance with a discharge capacity of 268 mAh g−1 at 0.1C and retained best cycling stability with capacity retention of 91 % after 40 cycles, showing stable high-voltage (4 V) performance with no capacity fade. The sample also showed best high-rate and long-term cycling stabilities with capacity retentions of 87 % after 40 cycles and 67 % after 200 cycles at relatively high current rates of 2C and 1C, respectively. Some of Y doped into LVOP expanded channels for Li-ion diffusion and resulted in improved ionic and electronic conductivity of 5 %Y-LVOP compared to pristine sample. In addition, YPO4 surface modification also improved cycling and thermal stability.

A comparative study of the magnetic and magnetocaloric effect of polycrystalline Gd0.9Y0.1MnO[formula omitted] and Gd0.7Y0.3MnO[formula omitted] compounds: Influence of Y-ions on the magnetic state of GdMnO[formula omitted

The modification of the magnetic ground state of the GdMnO3 compound has been explored with Y-doping on the Gd-site. The study on the magnetic properties indicates the existence of a weak ferromagnetic phase upon a 10% Y-doped sample. However, the strength of the ferromagnetic interaction becomes feeble in the 30% Y-doped sample. Such modifications of the magnetic ground states are analyzed considering the breaking of correlated weak ferromagnetic chains due to doping of non-magnetic Y-ions. In addition to that, the magnetocaloric effect has also been affected by the doping concentrations of Y-ions. The significant value of magnetic entropy change and relative cooling power of both the studied systems indicate the possible utilization of the materials as efficient magnetic refrigerants at the cryogenic temperature.

Defect manipulation of WO3 nanostructures by yttrium for ultra-sensitive and highly selective NO2 detection

Nanostructured transition metal oxides have gained much attention in gas sensing applications due to their superior size-dependent adsorption and catalytic properties. Among them, WO3 based nanostructured thin films exhibit relatively high sensitivity towards toxic gases such as CO, NO2, NH3, and H2S, which makes them promising materials for gas sensing applications. Herein, we have attempted to prepare pure and yttrium-doped WO3 nanoplates by one-step hydrothermal method and their gas sensing performance was studied. The selectivity of the fabricated device was studied against NH3, NO2, and H2S gases. Pure and Y-doped samples exhibited an excellent selectivity towards NO2. The gas sensitivity, response time, and recovery time have been significantly enhanced for the Y-doped samples compared to the pure sample. Interestingly, the Y-doped sample (3 mM) exhibits an excellent response towards 20 ppm of NO2, which is comparatively 94- fold higher than pure WO3. The sample exhibited a short response T90 ~ 7 s and recovery time T10 ~ 38 s. The Y-2 sensor showed excellent repeatability and long-term stability. This is due to oxygen vacancy defects and the high surface area of the material. The enhancement in gas sensing performance has been explained by the gas sensing mechanism and work function measurement. The Y-doped WO3 nanostructures provide a new pathway for improving the performance of transition metal oxide-based gas sensors.

Effect of calcium or yttrium doping on cation ordering and electrochemical performance of Li(Ni0.80−xCo0.15Al0.05Mx)O2 (M = Ca, Y) as a Li-ion battery cathode

The electrochemical performance of Li(Ni0.80Co0.15Al0.05)O2 (NCA) cathode was demonstrated to be improved by calcium and yttrium doping. Samples were synthesized by ultrasonic sound-assisted co-precipitation method which satisfied precipitation of nano-sized particles around 20 nm. Doping elements were introduced to the structure by solid-state reaction route and single phase, layered Li0.993(Ni0.804Co0.154Al0.035Y0.014)O2±σ and Li0.991(Ni0.801Co0.152Al0.037Ca0.019)O2±σ samples were successfully synthesized. Lattice parameters and site occupancy of the atoms were calculated by Rietveld refinement. Occupancy refinement of the atomic sites confirmed that doping elements occupied the transition metal layer as it was aimed. The presence of doping elements in the transition metal layer stabilized nickel and decreased the amount of cation mixing. Y-doped NCA sample exhibited the highest initial specific discharge capacity (157 mAh g−1) and Ca-doped sample showed the highest rate capability. Pristine NCA showed the lowest capacity, in any case, indicating the necessity of further treatment to achieve improvement in NCA cathode.

Abnormal dependence of microstructures and electrical properties of Y-doped VO2 thin films on deposition temperature

Doping is considered the most effective way to modify semiconductor-to-metal transition (SMT) characteristics of VO2. Recent investigations have focused on the relationship between SMT characteristics and doping concentration, but effects on crystallinity are less understood. In this paper, such effects have been studied by fixing yttrium doping concentrations and varying deposition temperature. The Y-doped sample deposited at higher temperature was found to exhibit nanocrystal-in-amorphous structure, while the sample with same yttrium doping concentrations at lower temperature has polycrystalline structure. Higher deposition temperature can promote more Y–O bonds and deferring the formation of crystallized VO2. The resistivity of Y-doped polycrystalline VO2 gives changes by two orders of magnitude during SMT. The unique nanocrystal-in-amorphous structure exhibits suppressed SMT response, similar to that of the amorphous VO2. Compared with pristine amorphous VO2, Y doping could further reduce the resistivity and enhance the thermostability. Such doped nanocrystal-in-amorphous samples exhibit ultralow resistivity of 0.01 Ωcm, temperature coefficient of resistivity (TCR) of −1.5%/°C and thermostability. This thermal-sensitive material is promising candidate for use in microbolometer arrays.

Y Katkılı Piramit ZnO Tozlarının Sentez ve Karakterizasyonu

The present study focuses on the structural changes in ZnO powder induced by doping of a rare earth metal of Y. For this aim, we synthesized four ZnO samples with different Y-content using the combustion reaction method. X-ray powder diffraction (XRPD) technique and scanning electron microscopy (SEM) results confirm that the as-investigated structural parameters and morphology of the ZnO structure were affected directly by the concentration of Y dopant. For each Y-doped sample, randomly-oriented pyramidal morphology and the formation of a minority phase of Y2O3 were observed. A gradual increase in both lattice parameters and unit cell volume was detected with increasing Y content. All samples were found to be thermally stable in the temperature interval of 25-950 °C.

Dosimetric properties of Y-doped MgO transparent ceramics

We have prepared Y-doped (0.001, 0.01 and 0.1%) MgO samples by using a Spark Plasma Sintering (SPS) method. Subsequently, photoluminescence (PL), scintillation and thermally-stimulated luminescence (TSL) dosimetric properties were investigated. The PL emission peak appeared around 410 nm in all the samples. The PL decay time constants at 410 nm were ∼10 and ∼100 ns which were on the typical order of the emission from F+ centers in the undoped MgO. Scintillation emission peaks were detected at 330, 400 and 760 nm under X-rays irradiations. Compared with TSL glow curve of undoped MgO, a glow peak around 140 °C shifted to high temperature in proportion to dopant concentration, and it was shown at 152 °C in 0.1% Y-doped sample. The TSL response was confirmed to be linear to the irradiation dose over the dose range from 0.1 to 1000 mGy.

Disorder effects in the S=1 antiferromagnetic spin ladder CaV2O4

We study the physical properties of the antiferromagnetic spin ladder CaV2O4 (CVO) and the Y-doped related compound Ca0.9Y0.1V2O4. In the latter, X-ray diffraction demonstrates the segregation of a small amount of a vanadium–perovskite impurity phase, leading to the formation of V vacancies within the main CVO-type structure. The 1D character of this calcium–vanadite enhances the influence of the vacancies on the electric and magnetic properties of Ca0.9Y0.1V2O4. Electrical transport is characterized by a variable-range hopping mechanism determined by the charging energy of nm-sized segments of V chains delimited by V vacancies, i.e. a Coulomb gap is formed at the Fermi level. These vacancies also locally affect the magnetic correlations, breaking the long-range AFM order observed in CaV2O4 and producing exchange bias when the Y-doped sample is cooled with an applied magnetic field.

Effects of yttrium doping on the thermoelectric properties of Hf0.6Zr0.4NiSn0.98Sb0.02 half-Heusler alloys

The (Y,Sb) codoped (Hf0.6Zr0.4)1−xYxNiSn0.98Sb0.02 (x=0, 0.01, 0.015, 0.02, and 0.025) half-Heusler alloys were prepared by levitation melting and spark plasma sintering. The effects of Y doping on the electrical conductivity, the Seebeck coefficient, and the thermal conductivity have been investigated in the temperature range of 300–900 K. It was found that the Y doping decreased the carrier concentration and electrical conductivity due to the introduction of hole carriers. The thermal conductivity was also reduced upon Y doping, mainly due to the reduced carrier thermal conductivity. The Y-doping substantially increased the Seebeck coefficient because of the decrease in carrier concentration. Pisarenko plot showed that the measured room temperature Seebeck coefficients agrees well with the predicted single parabolic band behavior as a function of the carrier concentration, suggesting that no additional mechanisms cause the extra enhancement of Seebeck coefficient in the Y–Sb codoped half-Heusler alloys. The figure of merit ZT of 1% Y-doped sample was increased by a factor of about 25% than that of the undoped sample.

Thermoelectric Properties of Rare Earth-doped SrTiO3 Using Combination of Combustion Synthesis (CS) and Spark Plasma Sintering (SPS)

Thermoelectric properties of combustion synthesized and spark plasma sintered rare-earth-doped (La, Sm, Gd, Dy and Y) SrTiO3 was investigated from room temperature to 870 K from viewpoint of energy and time saving without deterioration in thermoelectric properties. All single phases of rare-earth-doped SrTiO3 were successfully synthesized and sintered with high densities. With temperature increasing, the absolute value of Seebeck coefficient of all the samples increased and the electric conductivity decreased; the power factor of all the samples decreased except Y-doped sample in the considering temperature range. In all the samples, the La-doped sample and the Y-doped sample had the highest and lowest power factor, respectively. The figure of merit of La-doped samples with different doping amounts was evaluated and the maximum figure of merit 0.22 was obtained at 800 K from Sr0.92La0.08TiO3 sample. Comparing Y and La-doped samples prepared by our synthesis method with that of conventional solid-state reaction method, the thermoelectric properties of our samples were relatively higher. Thus the combination of combustion synthesis and spark plasma sintering has a potential to prepare perovskite-oxide materials with relatively higher thermoelectric properties for high-temperature application.

Thermoelectric Properties of Combustion Synthesized and Spark Plasma Sintered Sr<SUB>1−<I>x</I></SUB>R<I><SUB>x</SUB></I>TiO<SUB>3</SUB> (R = Y, La, Sm, Gd, Dy, 0<<I>x</I>≤0.1)

Thermoelectric properties of combustion synthesized and spark plasma sintered rare-earth-doped (Y, La, Sm, Gd and Dy) SrTiO3 was investigated from room temperature to 870 K toward the viewpoint of energy and time saving without deterioration in thermoelectric properties. All the rare-earth-doped SrTiO3 were successfully synthesized and sintered with high purities and high densities. With temperature increasing, the absolute value of Seebeck coefficient increased and the electric conductivity decreased; the power factor of all the samples decreased except Y-doped sample in the experimental temperature range. In all the samples, the La-doped SrTiO3 and the Y-doped SrTiO3 had the highest and the lowest power factor, respectively. The dimensionless figure of merit ZT of La-doped samples with different doping amount was evaluated and the maximum ZT was 0.22, which was obtained at 800 K from Sr0.92La0.08TiO3 sample. Comparing Y and La-doped samples prepared by our method with that of conventional solid-state reaction method, the thermoelectric properties of our samples were relatively higher. Thus the combination of combustion synthesis and spark plasma sintering has a potential to prepare perovskite-oxide materials with relatively higher thermoelectric properties for high-temperature application.

Structure and magnetic properties on [formula omitted][formula omitted

We have studied the structure and magnetic properties of the A 0.33 Sr 0.67 CoO 3 - δ ( A = Y , Gd ) . X-ray diffraction and Rietveld refinement show that the structure is the perovskite-type structure with layered alternate ion of CoO 6 octahedron and CoO 4 tetrahedral polyhedron. In the Y-doped sample, a magnetization jump was observed around 180 K below the Curie temperature T C = 304 K during the magnetic field cooling. The magnetization jump may be associated with the onset of antiferromagnetism appeared as the Co 3 + ion orbital ordering state in the intermediate spin state. The Gd-doped sample exhibits higher magnetization and lower Curie temperature than Y-doped sample. The field magnetization vs temperature curve reveals a paramagnetic behavior below 100 K, which suggests there is a possible spin state transition of Co 3 + ions from the intermediate to low spin state at 100 K in addition to the Gd 3 + ion paramagnetic contribution.

Thermoelectric performance of SPS sintered [(Ca0.95M0.05)2CoO3][CoO2]1.61

The doped [(Ca0.95M0.05)2CoO3][CoO2]1.61 ceramics were sintered by the spark plasma sintering (SPS). The electrical conductivity, Seebeck coefficient and thermal conductivity of all samples were measured from 373 K to 973 K. The doped ions improve thermoelectric performance due to increase of Seebeck coefficient and decrease of thermal conductivity. Since the electrical resistivity of the Y-doped sample has no enhancement, the thermoelectric performance of the Y-doped sample is superior to that of the Gd-doped sample. The reason of the different effects on the thermoelectric performance comes from magnetic action.

The Applicability of Sr-deficient n-type SrTiO3 for SOFC Anodes

Here we discuss the effect of preparation conditions on structural stability and electrical properties of Sr-deficient n-type SrTiO3. In particular, an explanation of a wide scatter of conductivity values in Y- and Nb-doped SrTiO3. reported in the literature is proposed, based on the existing defect chemistry model of n-doped SrTiO3. It was confirmed that when sintered in air, Sr-deficient SrTiO3 doped with Nb and/or Y, remains single phase until the solubility limit (e.g., 30% for Nb or 4% for Y). However, when sintered at low po2, the material transforms from a vacancy compensated to an electronically compensated compound with a strontium deficient second phase. Measured at 800°C in low po2, the maximum conductivity of these multi-phase compounds was 340 S/cm and 100 S/cm for the Nb-doped and Y-doped sample, respectively. However, the conductivity dropped dramatically to less than 10 S/cm when samples of the same compositions were sintered in air, again measured in reducing atmosphere.

Preparation and characterization of cerium oxide doped TiO2 nanoparticles

A mixed oxide consisting of TiO2 as the major phase and CeO2−y (0<y<0.5) as the dopant phase was prepared via the sol-gel reaction of Ti(i-OC3H7)3 in an aqueous solution of Ce(NO3)3. The resulting oxide powders with different CeO2−y contents were all composed of nano-sized spheres. The CeO2−y phase was identified to have retarding effect on the phase transition from anatase TiO2 to rutile TiO2 at calcinations temperature as high as 800°C, which would otherwise be a thorough conversion. The CeO2−y–TiO2 powders could apparently shift the UV-absorption band of TiO2 toward visible range, and there was an optimal CeO2−y content in association with the maximum absorbance. This effect is interpreted as the existence of an n-type impurity band, due to the substitution of Ti4+ for Ce3+/4+ at the interface between the two oxides, in the gap of TiO2. According to X-ray photoelectron spectroscopy (XPS) investigation, the Ti element mainly existed as the chemical state of Ti4+ and the Ce oxide doping did not affect the peak position of Ti 2p. The Ce 3d spectrum of CeO2−y-doped TiO2 sample basically denotes a mixture of Ce3+/4+ oxidation states giving rise to a myriad of peaks.