Composition Y1 Research Articles

X-Ray fluorescence analysis of paraniobate based ceramics of composition Y<sub>3–x</sub>Yb<sub>x</sub>NbO<sub>7</sub>

A two-stage technique for X-ray fluorescence analysis of ceramic samples of composition Y3–xYbxNbO7 (where x = 0 – 3) has been developed. At the first stage, using the method of fundamental parameters (FPM), a rapid semi-quantitative analysis of ceramic samples and products of intermediate synthesis was carried out to determine their preliminary composition. At the second stage, the quantitative composition of the samples was determined using the constructed calibration dependencies. To construct calibration dependencies a series of reference samples containing 3.16 – 56.55% Y, 8.78 – 71.0% Yb, and 12.83 – 19.70% Nb was synthesized using a method similar to that used for preparation of the ceramic samples under study. Analytical lines of elements free from spectral overlaps and XRF conditions (current and voltage of an X-ray tube, exposure time, method of taking into account the background near the analytical line) were selected. The relative standard deviation of the results of Y, Yb, and Nb determination in ceramic samples did not exceed 0.66%, the relative error was no more than 1.63%. The results obtained were compared with the calculated content of analytes in the samples of stoichiometric composition and with the results of ICP-AES analysis of real ceramic samples. The developed technique provides determination of the main components of ceramic samples and can be used for analytical control of synthesis of rare earth paraniobates.

Analysis of cerium-substituted yttrium iron garnets by inductively coupled plasma atomic emission spectrometry with preliminary microwave decomposition

An analytical procedure for inductively coupled plasma atomic emission (ICP-AES) analysis of iron garnets of the composition Y3 – xCexFe5 – yGayO12, where x = 0.4 – 0.5 and y = 2.4 – 2.6 with preliminary microwave decomposition of the sample is described. The compositions of acid mixtures (HCl/HNO3), as well as modes of microwave heating (holding time and temperature), providing complete dissolution of the samples are proposed. In addition to optimized sample preparation, conditions for ICP-AES analysis of cerium-doped yttrium iron garnets were studied. The effect of matrix components (Y, Ce, Fe, Ga) on the determination of doping elements was revealed and studied. The operating parameters of the spectrometer (ICP power and nebulizer flow rate) have been substantiated, which make it possible to reduce the matrix effect of Fe, Ga, Y, Ce on the elements Na, Mg, Al, Si, P, K, Ca, Sc, Cr, Mn, Co, Ni, Cu, Zn, Se, Cd, Sn, Te, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Pb in iron yttrium garnets by the ICP-AES. ICP-AES measurements were performed in the axial and radial mode for trace elements and in the radial mode for matrix elements. The limits of quantification (LOQs) of most elements ranged within n × 10–5 – n × 10–4 wt.%. The accuracy is confirmed by the spike recovery test. The relative standard deviation is in the range of 1 – 5% depending on the selected plasma view mode and the analyzed analytes. The developed method makes it possible to determine macro- and microcomponents in yttrium iron garnets in a wide range of concentrations with a high accuracy.

THE COMBINED EFFECT OF SINTERING ADDITIVES MgO AND TEOS ON THE STRUCTURE AND OPTICAL PROPERTIES OF CERAMICS YAG:Yb, Er

In this work, the effect of sintering additives based on magnesium oxide (MgO) and silicon oxide (TEOS) in concentrations from 0.02 to 0.10 wt. % and 0.2 to 0.5 wt. %, respectively, was investigated on the microstructure and optical properties of ceramics of the composition Y2,82Yb0,15Er0,03Al5O12, made from powders synthesized by chemical co-deposition. The results presented in the paper showed that the introduction of a sintering additive based on MgO into a ceramic powder does not affect its phase composition, structural and morphological characteristics. It is shown that for ceramics of the composition Y2,82Yb0,15Er0,03Al5O12, the best value of the optical transmission coefficient was achieved at a vacuum sintering temperature of 1800 °C and a concentration of sintering additives of 0.06 wt. % MgO and 0.3 wt. % TEOS. It is shown that the sintering mechanism of ceramics Y2,82Yb0,15Er0,03Al5O12 depends on the ratio of sintering additives MgO and TEOS.

Highly Efficient Orange-Red Emission in Sm3+-Doped Yttrium Gallium Garnet Single Crystal

High-quality single crystals with empirical composition Y2.96Sm0.04Ga5O12 (YGG: Sm3+) were successfully prepared by the optical floating zone method for the first time and compared with related single crystals of Y2.96Sm0.04Al5O12 (YAG: Sm3+). With both crystals, XRD showed that Sm3+ entered the cubic-phase structure. Optical absorption spectra produced a series of peaks from Sm3+ in the 250 nm to 550 nm range, and photoluminescence excitation (PLE) spectra detected at 613 nm showed strong excitation peaks at 407 nm and 468 nm. A strong emission peak at 611 nm (orange-red light) was observed in the photoluminescence (PL) spectra under excitations at both 407 and 468 nm, respectively, but it was much brighter under excitation at 407 nm. Furthermore, with both emission spectra, the peaks from the YGG: Sm3+ crystal were significantly more intense than those from the YAG: Sm3+ crystal, and both experienced a blue shift. In addition, under excitation at 407 nm, the color purity of the emitted orange-red light of YGG: Sm3+ was higher than that of the YAG: Sm3+ crystal, and the fluorescence lifetime for the 4G5/2 → 6H7/2 transition of YGG: Sm3+ was longer than that of the YAG: Sm3+ crystal. The optical properties of the YGG: Sm3+ crystal are better than those of the YAG: Sm3+ crystal.

Comparative Study of the Synthesis of a Red Ceramic Pigment Using Microwave Heat Treatment

In this study, a new red ceramic pigment has been developed within a perovskite structure, and microwave heat treatments have been applied. Those red ceramic pigments within the YAlO3 system doped with chromium with the nominal composition Y0.98Al0.98Cr0.04O3 were synthesized by traditional routes and alternative methods like coprecipitation. Also, heat treatment has been studied comparing a traditional electric and microwave kiln. Different flux agents have been incorporated to improve the synthesis reaction. Prepared pigments have been characterized by X-ray diffraction (XRD) as having a predominant phase of perovskite structure, which is responsible for the red shade, and a minority garnet phase that causes more brown colorations. Studies by Ultraviolet-Visible spectroscopy gave rise to a series of absorption bands that indicate the presence of Cr(III) in the octahedral position corresponding to perovskite and Cr(IV) corresponding to garnet in both the octahedral and tetrahedral positions. The perovskite phase is favored with the use of flux mix, corroborating the UV-visible results and being more pronounced in traditional high temperature thermal treatments. The coprecipitation route has been studied to increase the reactivity of the particles given their nanometric size; however, this reactivity favors a greater appearance of undesirable garnet phases with both types of flux. Scanning Electron Microscopy (SEM) micrographs offer information obtained from the secondary electrons of predominantly cubic crystalline phases with sizes between 1 µm and 2 µm in pigments synthesized via the traditional method and sizes less than 1µm together with the glassy phase in pigments synthesized via coprecipitation. Microwave thermal treatments have been studied, obtaining pigments with a majority structure of perovskite and garnet at lower temperatures and relatively short synthesis times. The feasibility of use in porous single-fired ceramic glazes has been studied, whose chromatic coordinates have been collected using an Ultraviolet-Visible Spectrophotometer based on the CIEL*a*b* system.

Fabrication and optical properties of YSAG:Cr optical ceramics

YSAG:Cr3+ optical ceramics with compositions Y2.8Sc1.2Cr0.005Al3.995O12, and Y2,88Сr0,005Sc0.2Al4,915O12 were fabricated for the first time. The linear transmittances of the ceramic samples exceeded 80% in the visible and IR regions. It was observed that as the concentration of scandium in YSAG:Cr3+ solid solutions increased, the refractive index of ceramics at a wavelength of 632.8 nm increased from 1.828 ± 0.005 to 1.857 ± 0.005. The effect of scandium cations on the spectral-luminescent properties of Cr3+ cations in the crystal lattice of yttrium-scandium-aluminum garnet was also investigated. It was demonstrated that as the scandium content in dodecahedral site increased from 4 to 50 at%, the effective lifetime of excited states of Cr3+ cations increased from 1.71 ms to 2.72 ms. On the contrary, as scandium content in octahedral site increased, the effective lifetime of excited states of Cr3+ cations decreased from 1.71 ms to 0.71 ms.

Structure of Y0.75La0.25PO4·0.67H2O rhabdophane nanoparticles synthesized by the hydrothermal microwave method

Nanopowders with a rhabdophane structure of nominal composition Y0.75La0.25PO4·0.67H2O were obtained by hydrothermal-microwave synthesis. The monoclinic structure of rhabdophane was refined by the Rietveld method within the C2 (5) space group. The nanopowders were studied by X-ray diffraction (XRD), transmission electron microscopy (TEM) and electron microdiffraction (selected area electron diffraction, SAED), small angle X-ray scattering (SAXS), thermal analysis, low-temperature nitrogen adsorption-desorption measurements for analysis of surface area and porosity (ASAP) and pycnometric density measurements. These methods showed the formation of rod-like single-crystal rhabdophane nanoparticles with isolated pores inside the nanoparticles. To describe the formation of such nanoparticles, a mechanism of coherent-accommodative intergrowth of nanoscale clusters with rhabdophane structure is proposed.

Fabrication and optical properties of garnet ceramics based on Y3-xScxAl5O12 doped with ytterbium and erbium.

Optical ceramics YSAG:Yb,Er with an average grain size of 6 ± 1 microns were fabricated by vacuum sintering of nanocrystalline powders of the compositions Y2.34Yb0.45Er0.09Sc0.20Al4.92O12, Y1.66Yb0.45Er0.09Sc1.00Al4.80O12 and Y0.96Yb0.45Er0.09Sc1.70Al4.80O12. The linear transmittance coefficients of the YSAG:Yb,Er ceramic samples exceed 80% in the visible and infrared regions. The refractive index of ceramics increased from 1.827 to 1.859 with an increase in scandium content. The effect of scandium cations at the dodecahedral site of the YSAG crystal lattice on the optical and luminescence characteristics of Yb3+ (2F7/2 and 2F5/2) and Er3+ (4I15/2, 4I13/2, 4F9/2 and 4S13/2) in wavelength ranges of 530-690 nm, 890-1080 nm, and 1430-1680 nm was revealed.

Structural, microstructural and magnetic properties of Melt-Spun Y1-xTbxFe2 alloys

This letter reports the structural, microstructural and magnetic properties of bulk and melt-spun Y1-xTbxFe2 (x = 0, 0.25, 0.5, 0.75&1) alloys. Based on the Y/Tb ratio, minor (Y,Tb)Fe3 phase was found to co-exist with the major (Y,Tb)Fe2 phase. Mossbauer studies indicated enhancement in Fe moments with the substitution of Tb for Y. Curie temperature was found to increase with increase in Tb addition. Owing to grain refinement, a considerable improvement in coercivity has been achieved in Tb containing alloys. Magnetization studies indicated compensation of sub-lattice moments around the composition Y0.5Tb0.5Fe2. Consequently, a large coercivity of about 5.7 kOe has been realized for this composition.

Effect of Aliovalent Substitution in Y2.9Bi0.1Fe₅O₁₂: Magnetization Dynamic Study

Multifunctional multiferroic materials, such as rare-earth-doped yttrium iron garnet (YIG), are advantageous for low-energyconsumption devices. In this work, we investigated aliovalent (Ce <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4+</sup> ) substitution in Y <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2.9</sub> Bi <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.1</sub> Fe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12</sub> ferrite with different compositions Y <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2.9-x</sub> Ce <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> Bi <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.1</sub> Fe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12</sub> (x = 0.0, 0.2, 0.4), respectively. The ferrites were fabricated by a conventional solid-state reaction method, and their structural, static, and dynamic magnetic properties were studied at room temperature. The X-ray diffraction (XRD) pattern confirmed the Ia3̅d cubic phase of all the ferrite compositions together with ceric oxide (CeO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ) as a residual phase containing aliovalent ions. The lattice parameter “a” of synthetic garnets decreases linearly with Ce concentration. From the static magnetic measurements, we observed that the saturation magnetization (4πMS) decreases due to combined effect of Ce <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> paramagnetic ions and Ce <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4+</sup> diamagnetic aliovalent ions. Magnetization dynamics have been studied by ferromagnetic resonance (FMR) technique in flip-chip geometry on the coplanar waveguide. Field sweep FMR spectra revealed that the microwave absorption in the X-band and the Ku-band decreases with Ce concentration due to a decrease in the super-exchange interaction between Fe ions at [a] and (d) sites due to electronic transition of Ce <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> ion. A major investigation of this study shows a decrease in the Gilbert damping constant (α) from 1.6 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> to 1.52 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> and increase in extrinsic contribution Δ(H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">o</sub> ) to the FMR linewidth A(H) from 0.38 to 0.54 kOe with Ce concentration. Therefore, this investigation opens a door for the next generation magneto-electric, magneto-optic, and magneto-dielectric effect-based spintronics/magnonics devices in the microwave regime.

Синтез и магнитные свойства соединений Y0,5Ca0,5Cr0,5Mn0,5O3

In this work,a solid solution of chromite-manganite of the composition Y0,5Ca0,5Cr0,5Mn0,5O3 was synthesized using the sol-gel method. Based on the results of experimental studies of the magnetostatic properties of the polycrystalline system Y0,5Ca0,5Cr0,5Mn0,5O3. It is found that the predominant is the intracrystalline ferromagnetic interaction, while the intercrystalline interaction is antiferromagnetic in nature.In the field of 2000 Oe and 5000 Oe at a temperature of 5 K, the magnetic moment is not even positive. These dependencies were obtained after the sample was in a large negative field. This initial moment is approximately equal to the residual moment on the hysteresis loop for a temperature of 5 K. When the external field is increased gradually, for example, in increments of 250 Oe, this moment increases to 1.2 emu/g at 2000 Oe. Based on the results of magnetostatic measurements, it was found that hysteresis loops of magnetization are observed at low temperatures.

Molecular-field Molecular-field Study on Sn Substituted Yttrium Iron Garnet

Samples with the compositions Y2.9Ca0.1Fe4.9Sn0.1O12 and Y3Fe4.9Sn0.1O12 were prepared by using a sol-gel technique. The influence of the substituted non-magnetic cations with different valences in the structural and magnetic properties was studied. X-ray diffraction and field-emission electron scanning microscope techniques were used to study the crystal structure and morphology. Magnetization curves in fields up to 10 kOe and in temperature range from 80 K to 570 K were measured by means of a vibrating sample magnetometer. Saturation magnetization as a function of temperature of the two samples was analyzed based on the molecular-field theory from that models for site occupancy and valence states of cations in the crystal structures were derived.

Garnet Solid Solution (Y1 – xBi x )3Fe2.5Ga2.5O12

Samples of composition (Y1–xBi x )3Fe2.5Ga2.5O12 (0 ≤ х ≤1), synthesized by the polyvinyl alcohol gel combustion method, have been studied by X-ray diffraction. It has been shown that the homogeneity range of the solid solution persists up to the composition Y1.5Bi1.5Fe2.5Ga2.5O12. This allows to consider gallium- substituted bismuth yttrium ferrites with an equimolar Fe: Ga ratio as stable materials for possible use in magnetooptics.

Synthesis and sintering of submicron Nd:YAG particles prepared from carbonate precursors

Using high-temperature X-ray diffraction, differential scanning calorimetry, and electron microscopy, we have studied the formation of yttrium aluminates and Nd:YAG (YAG) activated garnet nanoparticles during the thermal decomposition of a poorly crystallized carbonate precursor prepared in the NH4Al(OH)2CO3–(Y,Nd)(ОН)CO3 nanosystem and the development of the morphological structure of powders during heating to a temperature of 1350°C. The results demonstrate that heat treatment in the temperature range 850–950°C leads to the formation of metastable nonstoichiometric YAlO3 with a garnet-like structure, which reacts with Al2O3 at a temperature of 1000°C to form YAG. The cubic cell parameter a and X-ray density of YAG crystals with the composition Y2.97Nd0.03Al5O12 synthesized at 1200°C are 1.2009 nm and 4.565 g/cm3, respectively, and the average particle size is 108 nm. Using carbonate route, we prepared transparent Nd:YAG ceramics with a relative density of 99.7%, X-ray density of 4.562 g/cm3, and crystallite size in the range 1–7 μm.

Closo-Dodecaborate Intercalated Yttrium Hydroxide as a First Example of Boron Cluster Anion-Containing Layered Inorganic Substances

The first member, Y2(OH)5.46(B12H12)0.23Cl0.08·4.98H2O, of a new family of boron-containing substances, closo-dodecaborate intercalated layered rare-earth hydroxides, was synthesized using a microwave-assisted hydrothermal method. The structure and composition of this compound were studied by X-ray diffraction, transmission and scanning electron microscopy, thermal analysis, inductively coupled plasma mass spectrometry, IR spectroscopy, and X-ray photoelectron spectroscopy. The title compound had the composition Y2(OH)5.46(B12H12)0.23Cl0.08·4.98H2O and crystallized in a form of plate-like, aggregated particles less than 10 nm thick. The coordination of closo-dodecaborate anions with yttrium hydroxide host layers was demonstrated.

Phase diagrams of stratified bismuth–praseodymium-containing iron garnet films in an external magnetic field

The form of phase diagrams has been determined for epitaxial magnetic films of the composition Y3–x–yBixPryFe5O12 on the plane (H‖H⊥), where H‖ and H⊥ are the external magnetic field components parallel and orthogonal, respectively, to the direction of the normal n to the surface of the film. The specific features have been revealed in the magnetization reversal of the objects under investigation, which are associated with their structural stratification.

The Influence of Ca Content on the Current Density of the Superconducting Y1−xCa x Ba2Cu3O7−δ Compound

In this research, we study the effect of Ca content on charge transfer mechanism of YBa2CU3O7−δ compound, for composition Y1−xCaxBa2Cu3O7−δ (x=0, 0.05, 0.1, 0.2). Substitution of Ca changes the charge content, and as a result, potential energy changes; this will lead to structural changes (positions of ions and distances between them); this also leads to variations in Cu 2–O 3 and Cu 2–O 2 bond lengths and the effective coordination of Cu 2 with respect to oxygen ions. Starting from zero Ca content, the positions and distances for all ions in the crystal were calculated for all Ca concentrations. Moreover, the charge transfer mechanism from CuO chains to CuO 2 planes was studied and also the effective hole-doping dependences P(x) on bond valence sum. The hole concentration, energy gap, and current density, in Y1−xCaxBa2Cu3O7−δ (where x=0.1 to x=0.2) have been calculated, assuming that the net doping of CuO 2 layers is the sum of contributions from CuO chains and from substitution of Y 3+ by Ca 2+. Applying the concept of bond valence sum model for the calculation of the hole concentration in the CuO 2 plane. The model proposed assumes that the oxygen valence sum and Cu(2) valence sum influence the hole concentration in the CuO 2 plane and as a result on the hole conduction in the crystal. These p(x) dependences are combined with universal (parabolic) phase relation Tc(p). Thus, current density may be calculated considering the Ca concentration effect according to one of the following equations: $$\begin{array}{@{}rcl@{}} J=2.22e~\ast~\sqrt{\frac{E_{\mathrm{g}}}{m}}\langle 0.16 + 0.11 \sqrt{1-\frac{T_{c}}{T_{c \max}}\rangle},\\ J=2.22\ast\,e\, \sqrt{\frac{E_{g}}{m}}\langle 0.16 + \frac{n_{\text{Ca}}}{\mathrm{2}}-(7-\delta)\rangle \end{array} $$ Here, Tc and Eg were calculated as a function of Ca content.

Control of Co content and SOFC cathode performance in Y1−ySr2+yCu3−xCoxO7+δ

The electrochemical performance of the layered perovskite YSr2Cu3−xCoxO7+δ, a potential solid oxide fuel cell (SOFC) cathode, is improved by increasing the Co content from x = 1.00 to a maximum of x = 1.30. Single phase samples with x > 1.00 are obtained by tuning the Y/Sr ratio, yielding the composition Y1−ySr2+yCu3−xCoxO7+δ (where y ≤ 0.05). The high temperature structure of Y0.95Sr2.05Cu1.7Co1.3O7+δ at 740 °C is characterised by powder neutron diffraction and the potential of this Co-enriched material as a SOFC cathode is investigated by combining AC impedance spectroscopy, four-probe DC conductivity and powder XRD measurements to determine its electrochemical properties along with its thermal stability and compatibility with a range of commercially available electrolytes. The material is shown to be compatible with doped ceria electrolytes at 900 °C.

Two-photon excitation of anti-stokes photoluminescence in Y1.80Er0.10Yb0.10O2S

Phosphors with the composition Y1.80Er0.10Yb0.10O2S have been prepared by solid-state reaction. We have analyzed the diffuse reflectance, luminescence excitation, and photoluminescence spectra of this material under Stokes and anti-Stokes optical excitation by two light sources. Visible luminescence was observed when two resonance infrared photons of different energies were absorbed successively. This effect can be understood in terms of the metastable states of the 4 I 11/2 excited-state level of the erbium ion, from which transitions to higher energy levels occur when infrared photons are absorbed.

Influence of Sm and Yb Pollution on Superconducting Properties of YBCO Bulk Superconductors

YBa2Cu3O7−δ (YBCO, Y-123) bulk superconductors with a nominal composition Y1.5Ba2Cu3Ox and 1 wt% CeO2 addition were prepared by the Top Seeded Melt Growth (TSMG) process. Small single-crystalline pieces, cut from the SmBa2Cu3Oy (Sm-123) bulk, were used for seeding of epitaxial growth. Wavelength-dispersive spectrometry (WDS) con rmed the presence of 0.1 wt% Sm from the seed and 0.25 wt% Yb from the substrate, practically in the whole sample volume. The in uence of this Sm and Yb contamination on superconducting properties of grown bulk materials is reported. DOI: 10.12693/APhysPolA.126.358 PACS: 74.60.Bf, 74.72. h, 81.40.Rs, 74.25.Ha, 74.81.Bd, 74.25.Op