Spectral analysis of Cu<Superscript>2+</Superscript> and Mn<Superscript>2+</Superscript> ions doped borofluorophosphate glasses

We report here on the development and spectral analysis of Cu²⁺ (0.5 mol%) and Mn²⁺ (0.5 mol%) ions doped in two new series of glasses. The visible absorption spectra of Cu²⁺ and Mn²⁺ glasses have shown broad absorption bands at 820 nm and 495 nm, respectively. For Cu²⁺ BFP glasses, excitation at 380 nm, a blue emission at 441 nm and also a weak emission at 418 nm ions have been observed. For Mn²⁺ ions doped BFP glasses, excitation at 410 nm and a red shift at 605 nm emission have been observed.     

Spectral parameters of Er<Superscript>3+</Superscript> ion in Yb<Superscript>3+</Superscript>/Er<Superscript>3+</Superscript>:KY(WO<Subscript>4</Subscript>)<Subscript>2</Subscript> crystal

The spectral parameters of Er³⁺ in Yb³⁺/Er³⁺:KY(WO₄)₂ crystal with space group C2/c have been investigated based on Judd-Ofelt theory. The spectral parameters were obtained: the intensity parameters are: ₂ = 6.33 × 10^–20 cm², ₄ = 1.35 × 10^–20 cm², ₆ = 1.90 × 10^–20 cm². The radiative lifetime and the fluorescence branch ratios were calculated. The emission cross section _e (at 1536 nm) is 2.0 × 10^–21 cm².     

Adsorption study of Pb<Superscript>2+</Superscript> ions on nanosized SnO<Subscript>2</Subscript>, synthesized by self-propagating combustion reaction

Novel combustion synthetic route for the synthesis of nanosized SnO₂ is reported. X-ray, tap and powder densities of SnO₂ are calculated. Adsorption of Pb²⁺ ions on combustion derived nanosized SnO₂ is studied. The as synthesized SnO₂ and lead ions adsorbed SnO₂ are characterized by X-ray diffraction (XRD), scanning electron micrograph (SEM), and infrared spectroscopic (IR) techniques. The eluent is characterized by atomic absorption spectroscopy (AAS) and solution conductivity (SC) to know the reduction in the concentration and increase in conductance of lead solution after adsorption on the SnO₂ surface. The potential use of solid adsorbents for the adsorption of heavy metal pollutants is envisaged in the present work.     

Synthesis,characterization and application of semiconducting oxide (Cu<Subscript>2</Subscript>O and ZnO) nanostructures

In the present study, we report the synthesis, characterization and application of nanostructured oxide materials. The oxide materials (Cu₂O and ZnO) have been synthesized by electrolysis based oxidation and thermal oxidation methods. Cuprous oxide (Cu₂O) nanostructures have been synthesized by anodic oxidation of copper through a simple electrolysis process employing plain water (with ionic conductivity, ～6 μS/m) as electrolyte. In this method no special electrolytes, chemicals and surfactants are needed. The method is based on anodization pursuant to the simple electrolysis of water at different voltages. Two different types of Cu₂O nanostructures have been found. One type got delaminated from copper anode and was collected from the bottom of the electrochemical cell and the other was located on the copper anode itself. The nanostructures collected from the bottom of the cell are either nanothreads embodying beads of different diameters, ～ 10–40 nm or nanowires (length, ～ 600–1000 nm and diameter, ～ 10–25 nm). Those present on the copper anode were nanoblocks with preponderance of nanocubes (nanocube edge, ～ 400 nm). The copper electrode served as a sacrificial anode for the synthesis of different nanostructures. Aligned ZnO nanorod array has been successfully synthesized by simple thermal evaporation catalyst free method. Detailed structural characterizations revealed that the as synthesized aligned ZnO nanorods are single crystalline, with a hexagonal phase, and with growth along the [0001] direction. The room-temperature photoluminescence spectra showed a weak ultraviolet emission at 380 nm, a broad blue band at 435 nm and a strong orange-red emission at 630 nm. Structural/microstructural characterization of these nanomaterials have been carried out employing scanning (XL-20) and transmission electron microscopic (Philips EM, CM-12 and Technai 20G²) techniques and X-ray diffraction techniques having graphite monochromater with CuKα radiation (λ =1.54439 Å) (X’Pert PRO PAN analytical). The UV-visible absorption spectra were recorded on Model-VARIAN, Cary 100, and Bio UV-visible spectrophotometer. The photoluminescence (PL) measurement was carried out at room temperature with a He-Cd, a laser excited at 325 nm.     

Superconducting Properties of Iodine-Intercalated Bi<Subscript>2</Subscript>Sr<Subscript>2</Subscript>Ca<Subscript>2</Subscript>Cu<Subscript>3</Subscript>O<Subscript>10+<Emphasis Type="Italic">x</Emphasis></Subscript>

The superconducting properties of iodine-intercalated high-temperature superconducting Bi₂Sr₂Ca₂Cu₃O_10+x phase (Bi-2223) were systematically studied. It was found that for samples containing a significant amount of Bi₂Sr₂CaCu₂O_8+x , iodine intercalation results in the dramatic decrease of the inter-granular critical current density, as well as a significant decrease of the critical temperature (T _c), the critical current density in the grains (J _cg), and of the amount of Bi-2223. For samples with a large amount of Bi-2223, T _c changes insignificantly, whereas J _cg can even increase. We argue that the different behavior of the superconducting parameters is the result of various oxygen concentrations, and we explain the effect of iodine intercalation based on the parabolic dependence between T _c and the number of holes per CuO₂ layer. The H(T) curves (determined from the peak position in the loss signal of ac susceptibility) for intercalated samples deviate significantly from the quasi 2D-like behavior, pointing toward an enhancement of the 3D fluctuations of vortices. For the change in the values and dimensionality of the flux pinning in the process of the intercalation, we attempted a qualitative explanation based on the models proposed in literature.     

Bridgman growth and defects of Nd<Superscript>3+</Superscript> : Sr<Subscript>3</Subscript>Ga<Subscript>2</Subscript>Ge<Subscript>4</Subscript>O<Subscript>14</Subscript> laser crystals

Nd³⁺ : Sr₃Ga₂Ge₄O₁₄ crystals have been grown by the modified Bridgman method. The growth defects, such as striations, scattering particles and dislocations were investigated. Some featherlike striations were observed in as-grown crystals. EPMA analysis suggested that these inclusions were caused by the segregation of Nd₂O₃ from the melt. Chemical etching results showed that the dislocation density was in the range of 10³ ∼ 10⁵/cm².     

Growth of Nd<Superscript>3+</Superscript> doped LiNbO<Subscript>3</Subscript> crystals using Bridgman method and its spectral properties

The growth of Nd³⁺ doped lithium niobate crystals using Bridgman method has been reported in this paper. By means of the optimum conditions such as proper feed materials, sealed platinum crucibles, growth rate of 1–1·5 mm/h and temperature gradient of 30–35°C/cm across the solid-liquid interface under the furnace temperature of 1300°C, single crystals containing Nd³⁺ ion with 0·54 mol% concentration were obtained. X-ray diffraction and ICP-AES were used to characterize the crystals and its composition. The absorption, emission and fluorescence lifetime are also measured. Based on the Judd-Ofelt theory, we obtained the optical parameters of the crystal such as the luminescent quantum efficiency, the radioactive lifetimes, the branching ratios and the emission cross-section.     

One-pot simple synthesis and characterisation of Mn2+-doped GaN nanorods by RAPET method

In this work, we display one-step reactions under autogenic pressure at elevated temperature (RAPET) method-based synthesis of Mn-doped GaN nanorods by varying the atomic ratio of Mn:Ga as 0, 0.02, 0.04, 0.06 and 0.08, respectively. The synthesised nanorods are characterised by X-ray diffraction, high-resolution transmission electron microscopy (HRTEM) and Raman spectral methods. It is observed that there is a decrease in the lattice constant with an increase in the concentration of Mn (from 0.02 to 0.08 wt%). Moreover, the smaller covalent radius of Mn is the key for the doping process. The Mn-doped GaN nanocrystals show rod-like morphology with a length of 40–50 nm and width of 8–12 nm. This size factor mainly depends on the doping of Mn [from transmission electron microscopy (TEM) analysis] into GaN components. Well-defined lattice fringes are elucidated for the growth of crystalline hexagonal GaN (wurtzite type) nanocrystals.     

Density Equation for Saturated <Superscript>3</Superscript>He

A density equation for saturated vapor and liquid ³He is presented based on 205 experimental measurements for temperatures greater than 0.2 K collected after a careful survey of the literature. The average deviation of the densities predicted by the equation against the experimental values is 0.39%. There are only 16 points with deviations larger than 1%. This equation is valid for both liquid and vapor densities of ³He up to the critical temperature of 3.3157 K. The form of the equation satisfies known scaling laws approaching the critical point, with β=0.3653. In the low-density limit, the vapor curve of our equation matches smoothly to the published virial equation density at a temperature of 1.62 K and at the saturation pressure. The rectilinear density deviates from the critical density by less than 0.28% down to 0.48 K.     

Li<Superscript>+</Superscript> ion conductivities in boro-tellurite glasses

Lithium ion conductivity has been investigated in a boro-tellurite glass system, LiCl.LiBO₂.TeO₂. In the absence of LiCl, the conductivity increases with increasing non-bridging oxygen (NBO) concentration. LiCl addition has little influence on total conductivity although the observed barriers are low. Formation of LiCl clusters appears evident. In the a.c. conductivity and dielectric studies, it is observed that the conductivity mechanism remains the same in all compositions and at all temperatures. A suggestion is made that Li⁺ ion transport may be driven by bridging oxygen ↔r non-bridging oxygen (BO ↔r NBO) switching, which is why the two different types of Li⁺ ions in the clusters and in the neighbourhood of NBOs, do not manifest in the conductivity studies.     

Dependence of kinetic variables in the short-term release of Hg<Superscript>2+</Superscript>, Cu<Superscript>2+</Superscript> and Zn<Superscript>2+ </Superscript>ions into synthetic saliva from an high-copper dental amalgam

The short term (up to 14 days after restoration) release of selected ions (i.e., Hg(2+), Cu(2+) and Zn(2+)) from Dispersalloy into artificial saliva has been evaluated in regards to the nature of the saliva (Fusayama and McCarty and Shklar's solutions), the amount of amalgam, the time of contact and the periodical renewal (every 48 h interval) of artificial saliva. The evaluation of the ionic fraction of such metals has been accomplished by using anodic stripping methods (i.e., Differential Pulse Anodic Stripping Voltammetry, DPASV) with a 7 microm graphite disk microelectrode as a working electrode. Data obtained in this work are almost unprecedented in the literature due the fact that such analytical method exclude metals in non-ionic forms (e.g., metals or organometallic compounds). The high concentrations measured in every experimental condition confirm the concern for the short-term release of metals from amalgam into saliva.     

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.     

Spectroscopic studies of Cu<Superscript>2+</Superscript> ions in sol-gel derived silica matrix

The Cu²⁺ ion doped silica gel matrices in monolithic shape were prepared by hydrolysis and condensation of tetraethyl orthosilicate (TEOS). The absorption, transmittance and fluorescence spectra of the gel matrices heat treated at different temperatures were monitored. The loss of water and hydroxyl group from silica network changes the optical properties of the Cu²⁺ ions in the host, noted by the change in colour of monolith and spectral characteristics. The pronounced blue shift observed (700–900 nm to 600–850 nm) for the broad band of the absorption spectra of the samples heated up to 700°C is attributed to the ligand field splitting and partial removal of hydroxyl group from the silica matrices. The results indicate broadband filtering effects of the samples in the wavelength region 400–600 nm. Absorption and fluorescence spectra of the glass matrices heated to 1000°C confirms the conversion of Cu²⁺ ion to Cu⁺ ion.     

Recombination luminescence of CaI<Subscript>2</Subscript> crystals activated with Eu<Superscript>2+</Superscript>, Gd<Superscript>2+</Superscript>, Tl<Superscript>+</Superscript>, Pb<Superscript>2+</Superscript>, and Mn<Superscript>2+</Superscript>

The spectral characteristics of thermostimulated luminescence, steady-state roentgenoluminescence and photostimulated luminescence (PSL) buildup and decay kinetics, and the effect of IR irradiation on the roentgenoluminescence yield and glow curves of CaI₂:Eu²⁺, CaI₂:Gd²⁺, CaI₂:Tl⁺, CaI₂:Pb²⁺, CaI₂:Mn²⁺, and CaI₂: Pb²⁺, Mn²⁺ crystals grown by the Bridgman-Stockbarger method have been studied in the temperature range 90–295 K. Coupled with earlier data, the present results on the influence of oxygen and hydrogen impurities on the spectral characteristics of CaI₂ indicate that the activation of calcium iodide with Eu²⁺, Gd²⁺, Tl⁺, Pb²⁺, and Mn²⁺ leads to the formation of cation impurity-native defect complexes, which act as carrier traps and are responsible for the thermostimulated luminescence in the range 150–295 K. IR exposure after 90-K x-ray excitation gives rise to flash PSL and influences the thermostimulated luminescence light sum. The nature of the emission and trapping centers involved and the mechanisms of recombination luminescence excitation in the crystals are discussed.     

Electrical Conductivity of Bi<Subscript>2</Subscript>WO<Subscript>6</Subscript> Crystals Doped with Ca<Superscript>2+</Superscript>, Pb<Superscript>2+</Superscript>, Sr<Superscript>2+</Superscript>, and Ba<Superscript>2+</Superscript>

Single crystals of Bi₂WO₆ (a layered perovskite-like compound) doped with Ca²⁺, Pb²⁺, Sr²⁺, and Ba²⁺ on the Bi³⁺ site are grown, and their oxygen ionic conductivity is measured along the polar axis. The intrinsic conductivity of the doped crystals differs insignificantly from the conductivity of undoped Bi₂WO₆, indicating that the oxygen ions in the Bi₂O₂ layers contribute little to the oxygen ionic conductivity of the crystals. The sharp change in the activation energy for conduction at 600°C attests to a transition from one conduction mechanism to another in going from low to high temperatures.__________Translated from Neorganicheskie Materialy, Vol. 41, No. 7, 2005, pp. 863–865.Original Russian Text Copyright © 2005 by Kharitonova, Voronkova, Yanovskii.     

Enhanced Superconducting Properties of Air-Processed GdBa<Subscript>2</Subscript>Cu<Subscript>3</Subscript>O<Subscript>7-δ</Subscript> Single Domains with BaCO<Subscript>3</Subscript>/BaCuO<Subscript>2−<Emphasis Type="Italic">x</Emphasis></Subscript> Addition

Single domain GdBa₂Cu_7-δ (Gd123) bulk superconductors were fabricated in air by top-seeding melt-texture growth. Performance of the air-processed Gd123 was successfully enhanced by addition of both BaCO₃ and BaCuO_2−x , which suppress the formation of Gd_1+x Ba_2−x Cu₃O_7-δ solid solutions. The optimum doping amount ranges from 0.05 to 0.15, M BaCO₃ and 0.05 to 0.1, M BaCuO_2−x per molar Gd123. The distribution of the second phase particles was observed by scanning electron microscopy. A narrow band formed by Gd₂BaCuO₅ particle concentration appeared around the seeding zone in both a–b plane and c-growth sector in Gd123 single grain. Trapped magnetic field density reached 0.67, T for sample with 24 mm in diameter and 8, mm in thickness and a high critical current density J _c up to 91,200, A/cm² was achieved at 77, K under self-field.     

Influence of Cu<Superscript>2+</Superscript> ions on structural and magnetic properties of NiZn ferrites

The paper is devoted to the preparation of NiZn ferrite with small substitutions of copper by means of ceramic technology. The influence of small Cu substitution on the microstructural and magnetic properties of NiZn ferrites have been analysed by means of various experimental methods and interpreted from the point of view of preparation technology optimisation and possible applications of such materials. A strong correlation between the substituent content and resulting properties has been observed, thus allowing preparation of material with the properties tailored for any particular application.     

Luminescence of Cu<Superscript>+ </Superscript>in halosulphate phosphor

Ultraviolet photo-excited luminescence from Cu-doped halosulphate phosphors has been investigated. The intense emission of the spectrum is assigned to electronic transitions 3d⁹4s¹ → 3d¹⁰ in Cu⁺ ions. Increase in photoluminescence (PL) peak intensity suggesting that Cu plays an important role in PL emission in the present matrix. However, limited hosts with Cu⁺ as luminescence center were studied due to difficulties in incorporating it in a luminescence form. Cu-doped halosulphate phosphors were synthesized by wet chemical method. X-ray diffraction and PL characterization of phosphors has been reported in this article. The article discusses the luminescence of Cu⁺ and the simple method of incorporation in various new hosts.     

Comparative investigation on the effect of alkaline earth oxides on the intensity of absorption bands due to Cu<Superscript>2+</Superscript>, Mn<Superscript>3+</Superscript> and Cr<Superscript>3+</Superscript> ions in ternary silicate glasses

Absorption characteristics of Cu²⁺, Mn³⁺ and Cr³⁺ ions in ternary silicate (20Na₂O·10RO·70SiO₂, where R=Ca, Sr, Ba) glasses were investigated. The intensities of absorption bands due to Cu²⁺ ion was found to increase with increasing ionic radii of the alkaline earth ions whereas it was found to decrease in case of Mn³⁺ and Cr³⁺ ions with increasing ionic radii of the alkaline earth ions. The results were discussed in the light of relation between linear extinction coefficients of these ions and coulombic force of alkaline earth ions. The change in intensities of Cu²⁺, Mn³⁺ and Cr³⁺ ion is attributed due to change in silicate glass compositions.     

CdTe纳米棒的水相合成与铜离子识别研究

水相以巯基乙酸和半胱氨酸为混合稳定剂合成了光谱可调的CdTe纳米棒, 具有双波长发射纳米棒被用作铜离子荧光探针.铜离子加入后, 纳米棒645nm处的缺陷发射显著减弱,535nm处的激子发射未见变化.在弱碱性条件下,纳米棒缺陷发射强度与铜离子的浓度成良好线性相关,响应区间为 0～2.8×10-6 mol/L,检测下限为4.0×10-9mol/L.本文初步探讨了铜离子与CdTe纳米棒之间的作用机理.