Increase Of Y3 Research Articles

Improved microwave dielectric properties of LaZn1/2Ti1/2O3 through Y3+ substitution

LaZn1/2Ti1/2O3 is a double perovskite with promising microwave dielectric properties for applications towards dielectric resonators and antennas. Its dielectric properties can be enhanced through the substitution of suitable ions in either A- or B-sites. In this paper, we report a significant improvement in the quality factor (Q) by substituting Y3+ in the La site with a marginal reduction in dielectric constant (εr). A single phase is confirmed in XRD indicating the formation of La1-xYxZn1/2Ti1/2O3 (0 ≤ x ≤ 0.25) solid solutions. The substitution results in an expansion of lattice along the b direction while there is a contraction in both a and c directions, leading to a reduction in unit cell volume. The dielectric constant, εr, is observed to reduce from 33.4 to 29.6 due to the polarizability of A-site atoms. The temperature coefficient of resonant frequency (τf) increases with an increase in x which does not appear to correlate with reducing tolerance factor (t). This non-conventional behaviour of τf in this perovskite based solid solutions brings bond valence of O site (VO) into picture. VO appears to show competing effect on τf. The non-monotonic behaviour is observed in Q×f with a maximum value of 41,400 GHz at x = 0.15 and a sharp decline for x > 0.15. This observation is correlated with variations in the A-site bond valence (VA) and a long-range ordering (LRO) of B-site ions. LRO is associated with Ag mode at 710 cm−1 in the Raman spectra. The low frequency (< 250 cm−1) Raman modes shift to a higher frequency with the increase in Y3+. Y3+ substitution also induces lattice distortion which is discussed in terms of variations in FWHM and relative intensity of the Raman modes.

Effects of Y3+ doping on the microstructure evolution, optical, dielectric, and non-Ohmic properties of Na1/3Cd1/3Bi1/3Cu3Ti4O12 ceramics

In this study, Na1/3Cd1/3(Bi1-xYx)1/3Cu3Ti4O12 (NCBYCTO, x = 0−0.20) ceramics were successfully prepared via solid state method. Their microstructure along with the optical, dielectric, and non-Ohmic properties were investigated systemically. It was shown that Y3+ doping caused the decrease in cation vacancy concentration and the increase in optical energy band. With the increase of Y3+ content, ceramics exhibited a more stable structure, while their average grain size increased from 6.80 μm to 9.12 μm and then decreased to 2.17 μm with the dopant amount. The relative density increased from 94.7 % for the undoped specimen to 95.6 % for the specimen with x = 0.20. The giant dielectric constant (ɛ′ = 44200) at a relatively low dielectric loss (tanδ = 0.048) at 10 kHz was obtained in the specimen with x = 0.08, being more than three times that of undoped sample and demonstrating the outstanding frequency stability in the range of 40−106 Hz. The giant dielectric constant below 106 Hz originated from Maxwell–Wagner relaxation related to the insulating grain boundaries (GBs) and followed the internal barrier layer capacitor model. Besides that, Y3+ doping improved the nonlinearity properties of NCBYCTO ceramics. The specimen with x = 0.20 had the largest nonlinearity coefficient α (∼9.60) and breakdown field strength Eb (∼7.15 kV/cm). At last, the nonlinear J-E characteristics were closely related to the GB conductivity activation energy.

Effect of Y2O3 doping content on phase composition, mechanical properties and cavitation erosion performance of ZrO2 ceramics

Y2O3 stabilized ZrO2 (YSZ) is considered to be promising in resisting force-heat coupling damage caused by cavitation erosion (CE). However, the impact of doping Y2O3 on the microstructure and properties of ZrO2 is extremely complex, and there is still a lack of understanding about it, let alone the mechanism of these factors on the CE performance. In light of this, the present study investigated the effects of Y2O3 doping content (3 mol%, 7 mol% and 17 mol%) on the phase composition, grain size, microstructure, density, mechanical properties and CE performance of YSZ, and deeply analyzed the CE mechanism. The results indicated that the Y3+ entering the zirconia lattice effectively stabilized the high-temperature phases (t, t′ and c) and suppressed the formation of m-phase. With the increase of Y3+ concentration, the content of t continuously decreased while that of c continuously increased, so that only t + t′ phases were contained in the 3YSZ and only t′+c phases were contained in the 17YSZ. Meanwhile, the grain sizes and pores were constantly increasing, which obviously deteriorated the hardness, toughness and CE resistance. The t→m transformation under the action of cavitation load effectively absorbed impact energy and suppressed the propagation of fatigue cracks, thereby significantly delaying the fatigue spallation of materials. The 3YSZ with the densest microstructure, the best mechanical properties, the smallest grain size and the highest content of t-phase exhibited the best CE resistance. However, the continuous accumulation of m-phase at the grain edge, especially the amorphous structure formed by hydrolysis promoted by cavitation heat, provided a preferential channel for the propagation of fatigue cracks, and thus ultimately led to the exfoliation of the grains.

Corrosion behavior of YxYb(2−x)Si2O7 environmental barrier coating materials against molten calcium-magnesium-aluminosilicate (CMAS) at 1475 °C

The molten calcium-magnesium-aluminosilicate (CMAS) corrosion resistance of a series of YxYb(2−x)Si2O7 (x = 0.3, 0.5, 0.8, 1.0) environmental barrier coating (EBC) materials were systematically investigated at 1475 °C. The results have shown that the precipitate apatite Ca2(Y/Yb)8(SiO4)6O2 formed after CMAS corrosion of YxYb(2−x)Si2O7 pellets. The reactivity of YxYb(2−x)Si2O7 pellets and CMAS increased with the increase of Y3+/Yb3+ ratio, leading to the thickest reaction layer formed in Y1.0Yb1.0Si2O7. Furthermore, “blister” cracks were not found at the zone of uncorroded YxYb(2−x)Si2O7 pellets. It demonstrated that the YxYb(2−x)Si2O7 materials have excellent CMAS corrosion resistance, which can serve as promising candidates for EBC against CMAS corrosion.

Tunable emission color and anti-thermal-quenching behaviors in niobates for high-sensitive optical thermometry

Non-contact remote optical thermometers as a significant technique have been extensively developed. However, it is still a challenge to design new Bismuth-doped phosphor materials with tunable spectra for high-sensitive optical temperature sensors. Herein, a novel YxLu1-xNbO4:Bi3+ (0 ≤ x ≤ 1.0) phosphor is constructed by the isomorphic end components LuNbO4 and YNbO4. Owing to the modification of crystal field strength around Bi3+ ions, the emission positions controllably shifted from 475 to 462 nm with the increase of Y3+ ions concentrations. Besides, systematic luminescence modifying from blue to red across the white light region could be achieved via the design of Bi3+→Eu3+ energy transfer (ET). Intriguingly, an anti-thermal-quenching behavior of Eu3+ ion originating from the ET is found in Y0.8Lu0.2NbO4:Bi3+, Eu3+ (YLNO:Bi3+, Eu3+) phosphors, while Bi3+ ion presents a great emission intensity loss with only retaining 46.8% at 383 K. Based on the disparate thermal responses, the fluorescence intensity ratio (FIR) of Eu3+ to Bi3+ demonstrates excellent thermometry properties from 303 to 503 K. The maximum absolute sensitivity (Sa) and relative sensitivity (Sr) reach 0.318 K−1 (@328 K) and 1.62%K−1 (@393 K). In addition, the thermochromic performance of the resultant phosphors could be applied to qualitatively estimate the surrounding temperature. The spectral adjustability and high-sensitive of the developed phosphors highlight their multiplicity of applications in non-contact temperature measurement and white LED.

Preparation and Electrochemical Properties of Cathode Materials Ln2-x Y x CuO4+δ for Solid Oxide Fuel Cell.

Ln2-x Y x CuO4+δ (Ln = Pr, Nd, Sm; x = 0, 0.025, 0.05, 0.1) cathode materials were synthesized using a sol-gel method and calcination at 1000 °C for 24 h. The phase structure, coefficient of thermal expansion (CTE), electrical conductivity, and electrochemical impedance of cathode materials were characterized. X-ray diffraction (XRD) patterns show that the cell volume of each cathode material decreases with the increase in the Y3+ doping amount and has good chemical compatibility with the Sm0.2Ce0.8O1.9 electrolyte. The thermal expansion test shows that the increase in Y3+ doping reduces the average CTE of Ln2CuO4+δ. The conductivity test shows that Y3+ doping increases the conductivity of Ln2CuO4+δ, and Pr1.975Y0.025CuO4+δ has the highest conductivity of 256 S·cm-1 at 800 °C. The AC impedance test shows that Y3+ doping reduces the polarization impedance of Ln2CuO4+δ, and Pr1.9Y0.1CuO4+δ has a minimum area-specific resistance (ASR) of 0.204 Ω·cm2 at 800 °C. In conclusion, Pr1.975Y0.025CuO4+δ has the best performance and is more suitable as a cathode material for a solid oxide fuel cell (SOFC).

Effects of yttrium doping on structural, electrical and optical properties of barium titanate ceramics

In this report, we study the Yttrium-doped Barium Titanate (Y-BT) Ba1 − xYxTiO3 (with x = 0.00, 0.01, 0.03, 0.05, 0.07 mmol) perovskite ceramics synthesized by sol-gel method. The as-made powder samples were pressed into a pellet shape and subsequently sintered at 1300 °C for 5 h in air. The structural, morphological, electrical, and optical properties of the synthesized samples were investigated by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), impedance analyzer, and UV-Vis-NIR Spectroscopy respectively. The XRD study revealed the formations of single phase tetragonal structure of Barium Titanate (BT) with ∼23–33 nm mean crystallite size. The crystallite size increases initially with Y-doping, found at about 33 nm for x = 0.01, and reduces for increase in Y3+ concentration further. The microstructural study from FESEM depicts the uniform distribution of compact and well-faceted grain growth for Y-BT in contrast with undoped barium titanate. The average grain size (∼0.29–0.78 μm) of the Y-BT decreases with increasing doping concentration. Frequency-dependent impedance analyses show enhanced dielectric properties like dielectric constant, quality factor, and conductivity with low dielectric loss in the presence of Yttrium. The optical bandgap energy (∼2.63–3.72 eV) estimated from UV-Vis-NIR diffuse reflection data shows an increasing trend with a higher concentration of yttrium doping.

Enhancement of magnetic properties of Ni–Mg–Co ferrites by Y3+ ions doping

In this study, yttrium ion-doped nickel–magnesium–cobalt ferrite powder was prepared by the sol–gel auto combustions method. The chemical formula is Ni0.2Mg0.1Co0.7Fe2–xYxO4 (where x = 0.00, 0.02, 0.04, 0.06, and 0.08). The structure and magnetic properties were studied by X-ray diffractometer (XRD), Fourier infrared spectroscopy (FTIR), ultraviolet–visible (UV–Vis), scanning electron microscope (SEM), and vibrating sample magnetometer (VSM). XRD measurements show that Ni–Mg–Co ferrite has a good phase formations, and all samples have single-phase cubic spinel structure. As the doping amount of yttrium ions increases, the lattice constant of the samples increases first and then decreases. FTIR measurements also confirm the formations of the cubic spinel structure of ferrite. The UV–Vis optical analysis shows that the bandgap value of optical energy decreases after doping Y3+ ions. SEM confirmed that the sample was spherical spinel with a particle size of 54–60 nm. The saturation magnetizations (Ms) and remanent magnetizations (Mr) increase first and then decrease with the increase of Y3+ ions content at room temperature. This shows that the small amount of Y3+ ions-doped nickel–magnesium–cobalt nanoferrite can optimize the magnetic properties of the ferrite. The coercivity of the samples also showed a downward trend. The comprehensive measurement data show that the sample has the best magnetic properties when x = 0.02. This is also confirmed that the ferrite can be used as magnetic storage material.

Discussions on the film design and mechanical properties of Y3+/PVA polymeric composite films: enhancement of the electrical conductivity and dielectric properties

This paper focuses on the impact of yttrium nitrate salt (Y3+ ions) on the microstructural, mechanical, optical, and dielectric characteristics of poly(vinyl alcohol) (PVA) films. Simple solution casting technique was used to synthesize yttrium nitrate salt-doped PVA of different weight percent. These films are characterized using various methods such as differential scanning calorimetry, X-ray diffraction, stress–strain, UV–visible spectroscopy, and dielectric measurements. The thermal study reveals the reduction in the glass transition temperature Tg by a rise of Y3+ ions in the PVA matrix. The degree of crystallinity $${X}_{c}$$ and X-ray diffraction results support the increase of the crystallinity of PVA due to the doping effect. The mechanical characteristics of PVA: Y3+ ions’ films like Young's modulus are reduced, but the percentage elongation at break is raised, by the increase of Y3+ ions content. UV–Vis spectroscopy has been used for the optical characteristics of the studied films, demonstrating the transmittance of UV–Vis films is decreasing with the rise of Y3 + ions content in the composites. The bandgap Eg of Y3+/PVA films is significantly reduced with the addition of Y3 + ions. The changes in optical characteristics of PVA are ascribed to the interaction of Y3+ ions with the PVA matrix. Also, the dielectric constant measurement of the studied polymeric composites examined and revealed a highly attractive dielectric constant for the dielectric media. With the increase in the incident frequency, both the dielectric constant and dielectric loss of the studied films is decreased exponentially. At the same time, the AC electrical conductivity is improved with increasing the Y3+ ions content. Y3+/PVA films have unique properties to be used in a different field such as electronic, optoelectronic, and device fabrication.

Site engineering of Ce3+-doped calcium scandate phosphors and understanding of relevant red-shifted emitting from green to yellow

CaSc2O4:Ce3+ is a well-known green emitting phosphor, but needs to match with suitable red emitting phosphors in practical white lighting. Herein, a site engineering strategy is proposed to modify the local coordination environment of Ce3+ by introducing Y3+ and Mg2+ ions into the CaSc2O4 crystal lattice. The obtained results indicate in the modified Ce3+-doped samples (CSO-YMg), Y3+ ions can occupy both Sc3+ and Ca2+ sites simultaneously, and the Y3+ ions tend to occupy Ca2+ sites in low-doped stage and enter into the Sc3+ sites in the high-doped stage. The introduction of Y3+ ions gives rise to the existence of MgO in as-prepared CSO-YMg samples, and it can be effectively washed through pickling. In the spectral aspect, with the increase of Y3+ and Mg2+ ions, the main emission peak is red-shifted from 512 nm to 530 nm upon excitation at 450 nm. However, the high-doped sample presents much stronger thermally induced fluorescence quenching than CaSc2O4:Ce3+. The lattice defects caused by doped ions (Y3+ and Mg2+) and the non-radiative energy transfer process between the Ca2+ (Ce3+) and Sc3+ (Ce3+ or Ce4+) sites should be responsible for such evident quenching phenomenon in CSO-YMg, which is obviously different from the emitting feature of CaSc2O4:Ce3+ (only at Ca2+ sites). Besides, utilizing the as-prepared CSO-5 phosphors and a blue LED (~450 nm), a WLED was successfully fabricated, yielding a comparable performance to those with commercial Y3Al5O12:Ce3+ phosphors. What discussed in this study would bring some inspirations in the exploration and understanding of Ce3+-based phosphors according to local structural modification.

Substitution effect of Y3+ ions on the structural, magnetic and electrical properties of cobalt ferrite nanoparticles

Abstract Y3+-doped cobalt ferrite nanoparticles, CoYxFe2-xO4 (x=0.00, 0.05, 0.10, 0.15), were synthesized using the sol-gel auto-combustion technique. Single-phase cubic spinel structure was confirmed by the X-ray diffraction technique. The lattice parameter increased with the increase of Y3+ content in the cobalt ferrite and varied from 8.3876 to 8.4271 Å. FE-SEM images showed that the samples had distinct crystalline nanoparticles of spherical shape with small agglomeration. EDAX results showed good agreement with the particularized composition. Magnetic measurement using a vibrating sample magnetometer (VSM) recorded a reduction in saturation magnetization (Ms) and coercivity (Hc) by Y3+ substitution. The values of Ms and Hc ranged from 66.61 to 17.52 emu/g and 1168.9 to 801.9 Oe, respectively. The electrical properties of Y3+-substituted cobalt ferrite were studied by measuring the dielectric constant and loss. With increasing frequency, the value of the dielectric constant decreased, as a natural behavior of the ferrite material.

Structural, Optical, and Multiferroic Properties of Yttrium (Y3+)-Substituted BiFeO3 Nanostructures

Nanoparticles of Bi1-xYxFeO3 (x = 0.0, 0.1, 0.15, 0.2) were synthesized by sol-gel pursued auto-combustion route. X-ray diffraction (XRD) pattern was recorded for analysis of the phase formation of pristine BiFeO3 (BFO) and Y3+-substituted samples. A systematic decrease in crystallite size with increasing concentration of Y3+ was observed by XRD and W-H plot. FESEM micrograph demonstrated clearly that the average grain size is decreased with increasing Y3+ ion concentration. Compositional analysis was carried out by EDS. Optical properties of the developed nanoparticles were examined by diffuse reflectance spectroscopy; it is observed that optical band gap decreases with increase in Y3+ ion concentration. Vibrating sample magnetometer (VSM) analysis revealed weak ferromagnetic behavior for pristine BFO. The ferromagnetic behavior has been enhanced with increasing concentration of Y3+ ions in BFO. Temperature dependence of dielectric constant shows an anomaly near the antiferromagnetic transition temperature in the developed materials that revealed the existence of magnetoelectric coupling in all the samples. Improved ferroelectric property has been observed by virtue of enhancement in the polarization of all substituted samples. Variation of electric field–guided strain with applied electric field has shown asymmetric behavior for samples x ≤ 0.15 and symmetric loop has been observed for x = 0.2 with the highest peak to peak strain value which makes it active material for electronic and magnetic devices.

New negative temperature coefficient ceramics in Ca1−xYxCu3Ti3.9Zr0.1O12 system

The new negative temperature coefficient (NTC) ceramics based on Ca1−xYxCu3Ti3.9Zr0.1O12 (x = 0, 0.01, 0.03, 0.05) compositions have been successfully synthesized by traditional solid-state method. The results of X-ray diffraction show that the major phase of all samples is CaCu3Ti4O12 (CCTO) with body-centered cubic structure. Scanning electron microscope images confirm that Y3+ doping can inhibit the growth of grains. X-ray photoelectron spectroscopy analysis fully demonstrates the coexistence of Cu+/Cu2+ and Ti3+/Ti4+ ions in ceramic samples, and also proves that with the increase of Y3+ content, the concentration of Cu+ and Ti3+ ions increases, which is the main reason for the decrease of resistivity. The resistivity of all ceramic specimens decreases with the increase of temperature, which is consistent with NTC behavior. The obtained values of ρ25, B200/500, and Ea of the sintered samples are in the range of 2.76 × 107–1.10 × 108 Ω cm, 6633–6755 K, and 0.572–0.582 eV, respectively.

Emission enhancement of bifunctional La2MoO6:Sm3+ nanoparticles by doping Y3+ ions for flexible display and high CRI WLEDs

Red-emitting La2MoO6:xSm3+ and La2MoO6:xSm3+/yY3+ nanoparticles-based phosphors were prepared via a traditional sol-gel reaction technique. The crystal structure, elemental composition, morphology, luminescent properties and thermal stability of the obtained samples were analyzed in detail. Under 406 nm light excitation, all the obtained samples showed the characteristic emission of Sm3+ ions while the optimum concentration was 2 mol% in which chromatic coordinate was measured to be (0.593, 0.406). Meanwhile, a series of Y3+ ion concentrations were used to activate La2MoO6:0.02Sm3+ nanoparticles and the photoluminescence emission intensity of La2MoO6:0.02Sm3+/yY3+ nanoparticles gradually increased with the increase of Y3+ ion concentration. Moreover, the La2MoO6:0.02Sm3+/0.05Y3+-polydimethylsiloxane film was prepared and exhibited pure red light under near-ultraviolet light irradiation. Finally, the packaged white light-emitting diode (WLED) device was fabricated and exhibited a bright white-emitting glow with high color rendering index (CRI) value of 84.45 under a forward bias current of 150 mA, further suggesting that the Y3+-activated La2MoO6:Sm3+ nanoparticles could enhance the emission intensity and are a potential candidate for flexible display and high CRI WLEDs.

Differently shaped nanocrystalline (Fe, Y)3O4 and its adsorption efficiency toward inorganic arsenic species

Herein we report effects of partial substitution of Fe3+ by Y3+ in magnetite (Fe3O4) on morphology and inorganic arsenic species adsorption efficiency of the Fe3−xYxO4 nanoparticles formed. The series of Fe3−xYxO4 (x = 0.00, 0.042 and 0.084, labeled as Y00, Y05 and Y10, respectively) was synthesized using co-precipitation followed by microwave-hydrothermal treatment (MW) at 200 °C. With increase of yttrium content (x value), both the morphological inhomogeneity of the samples and the fraction of spinel nanorods as compared to spinel pseudospherical particles increased. By both transmission electron microscopy and x-ray powder diffraction analyses, it was determined that the direction of growth of the spinel nanorods is along the [110] crystallographic direction. The Fe3−xYxO4 affinities of adsorption toward the inorganic arsenic species, As(III) (arsenite, AsO33−) and As(V) (arsenate, AsO43−), were investigated. Increased Y3+ content related to changes in sample morphology was followed by a decrease of As(III) removal efficiency and vice versa for As(V). The increase in Y3+ content, in addition to increasing the adsorption capacity for As(V), significantly expanded the optimum pH range for the maximum removal and decreased the contact time for necessary 50% removal (t1/2) of As(V) (Y00: pH 2–3, t1/2 = 3.12 min; Y05: pH 2–6, t1/2 = 2.12 min and Y10: pH 2–10, t1/2 = 1.12 min). The results point to incorporation of Y3+ in the crystal lattice of magnetite, inducing nanorod spinel structure formation with significant changes in sorption properties important for the removal of inorganic arsenic from waters.

Microstructure and magnetic properties of Y substituted M-type hexaferrite BaYxFe12−xO19

Y (yttrium)-substituted M-type hexaferrite of composition BaYxFe12−xO19 (x ranges from 0.1 to 0.8 with step of 0.1) was synthesized through ceramic process. Pure phase formation of M-type hexaferrite was confirmed by XRD patterns for prepared sample when x < 0.4. The second phase (Y3Fe5O12) was detected when the substitution content exceeded 0.4. As the substitution dosage of yttrium increased, unconspicuous transform were observed in the microstructure of all samples BaFe12−xYxO19, such as compactness, size of grain. The bulk densities (ρ) of the samples decreased first and then increased with the increase of X. It means that the compactness of the sample receded first and then enhanced with rise of Y3+ substitution contents. Moreover, with increase of Y3+ amount, Y3+ substituted the Fe3+ in the octahedral position of m-type barium ferrite, the saturation magnetization (Ms) of the sample decreases rapidly and obtained a minimum of 55.63 emu/g, and then increased gradually attributed to the appearance of the second phase (Y3Fe5O12). Appropriate values of Ms (56.57 emu/g) and Hc (1794.17 Oe) were obtained simultaneously when x = 0.6. These two characters made the material suitable for the applications infield of magnetic recording.

Structural and Magnetic Properties of Y3+ Doped Ni–Cu–Co Ferrites Prepared by Sol–Gel Auto‐Combustion Method

In this work, rare earth Y3+ ion doped Ni0.2Cu0.2Co0.6Fe2−xYxO4 (x = 0.0, 0.025, 0.05, 0.075, 0.1) ferrite nanoparticles are synthesized by sol–gel auto‐combustion technology. High purity metal nitrates and citric acid are used as precursor solutions, and citric acid is used as a complexing agent. The X‐ray diffraction (XRD) analysis, Fourier transform infrared (FT‐IR) spectroscopy, energy dispersive X‐ray (EDX) spectroscopy, and vibrating sample magnetometer (VSM) measurements are used to investigate the effect of Y3+ doping on the structure and magnetic properties of the samples. The analysis of the XRD patterns confirms that all the samples showed cubic spinel structure. The FT‐IR also confirms the spinel structure of ferrite, and with the increase of Y3+ ion content, the peak of the Fe–O bond moved to high frequency. It has been proved that the synthesized ferrite has pure phase and structure by EDX, and Y3+‐doping is successfully achieved. The magnetic parameters of the samples are measured by VSM at room temperature with a maximum magnetic field of 1 T. By characterization with VSM it can be found that saturation magnetization and remanent magnetization increase first and then decrease with increasing doping amount of Y3+ ions. Compared with pure sample and other doped samples, the best magnetic properties are obtained when the doping amount of Y3+ ions is x = 0.025.

Electrical and Dielectric Properties of Y3+-Substituted Barium Hexaferrites

In this study, Y3+ ion-substituted M-type barium hexaferrites (BaM; BaFe12O19) were fabricated via facile ceramic route. As-prepared powders were characterized by X-ray powder diffractometry (XRD), Fourier transform infrared (FT-IR) spectroscopy, and impedance spectroscopy. XRD (Rietveld) analyses confirmed the presence of a single characterization of all samples (except x = 0.0 and 0.1 samples). The crystallite sizes of products are found in the range of 47.2–63.2 nm. Spectral analysis (FT-IR) also presented the formation of spinel structure for all products. The ac conductivity of the substituted samples was found to initially decrease slightly with increase in Y3+ compared with unsubstituted, and then variation tendency changes at the medium substitution ranges are observed with a different attitude against temperature. In the end, the lower conductivity for high substitutions is recorded and increases as functions of frequency while it also increases with the elevation of temperature. It was observed that ac conductivities of products increased by increasing frequency which indicate that observed ac conductivity is due to both electronic and polaron hopping mechanism.

Synthesis and optical characterizations of Nd, Y: CaF2 transparent ceramics

Highly transparent Nd, Y co-doped calcium fluoride (Nd, Y: CaF2) ceramics with different Y3+ ions doped concentrations were fabricated by hot-pressed method using Nd, Y: CaF2 nanopowders synthesized by co-precipitation method. According to the XRD calculations and SEM observations, the average grain size of nanopowders was about 22 nm. From the SEM micrograph of the nanopowders, it clearly shows that the nanoparticles exhibit nearly spherical morphology and agglomerated slightly. For 2 mm thickness sample, the transmittance of the as-fabricated Nd, Y: CaF2 (1 at.% Nd and 2 at.% Y) ceramic at 1400 nm reached up to 87%. The microstructure, absorption spectra and emission spectra of the Nd, Y: CaF2 ceramics were measured and discussed. Compared with the Nd: CaF2 ceramic, the Nd, Y: CaF2 ceramics fluorescent intensity increased drastically with the increase of Y3+ ions doped concentration.

Microstructure and Dielectric Properties of Yttrium-Doped BaSn0.05Ti0.95O3 Ceramics

The microstructure and dielectric properties of Y3+-doped BaSn0.05Ti0.95O3 (BTS5) ceramics were investigated. All BTS5 ceramics possess a single phase with a perovskite structure, and the Rietveld analysis further shows that the material exhibits tetragonal structure with space group P4mm. The amount of Y2O3 can greatly affect the dielectric properties of BTS5. The Curie peak of the blank sample is the highest, and the Curie peak of the samples is obviously suppressed after the doping of Y3+, and the dielectric maximum decreased up to 0.05 mol.% of Y3+ doping and then increased beyond 0.05 mol.% of Y2O3. Due to the amount of doping of Y3+ ions, the lattice distortion is decreased with the increase of Y3+ concentration, which decreases the short-range harmonic restoring force, so Tc shifts to a higher temperature in Y3+ doped BTS ceramics. In addition, the dielectric losses of 0.05–0.6 mol.% Y3+-doped BTS5 ceramics are very stable with the increasing environmental temperature, making them superior candidates for applications.