Infrared-to-visible upconversion emission of Er3+/Yb3+-codoped SrMoO4 phosphors as wide-range temperature sensor

Er³⁺/Yb³⁺-codoped SrMoO₄ phosphors were prepared by a high-temperature solid-state reaction method. At room temperature, all the as-prepared samples exhibited strong upconversion properties and the emission intensity increased dramatically with the increase of Yb³⁺ ion concentration, reaching its maximum value when the concentration was 5 mol%. The dependence of emission intensity on the pump power suggested that the upconversion emission was a two-photon process. Furthermore, the optical temperature sensing properties based on green upconversion emissions of the SrMoO₄:0.01Er³⁺/0.05Yb³⁺ phosphor were studied. It is found that the SrMoO₄:0.01Er³⁺/0.05Yb³⁺ phosphor can be operated over a very wide temperature range of 93–773 K with a maximum sensitivity of ∼0.0128 K⁻¹, indicating that low- and high-temperature thermometry can be simultaneously realized in this phosphor.     

Thermal decomposition behavior of the rare-earth ammonium sulfate R2(SO4)3·(NH4)2SO4

Rare-earth ammonium sulfate octahydrates of R₂(SO₄)₃·(NH₄)₂SO₄·8H₂O (R=Pr, Nd, Sm, and Eu) were synthesized by a wet process, and the stable temperature region for the anhydrous R₂(SO₄)₃·(NH₄)₂SO₄ form was clarified by thermogravimetry/differential thermal analysis, infrared, Raman, and electrical conductivity measurements. Detailed characterization of these double salts demonstrated that the thermal stability of anhydrous R₂(SO₄)₃·(NH₄)₂SO₄ is different between the Pr, Nd salts and the Sm, Eu salts, and the thermal decomposition behavior of these salts was quite different from the previous reports.     

Effect of Ti and C additions on structural and magnetic properties of (Pr,Nd)–Fe–B nanocrystalline magnetic materials

Effects of titanium carbide (TiC) addition on structural and magnetic properties of isotropic (Pr,Nd)–Fe-B nanocrystalline magnetic materials have been investigated. In this work, we investigate the effect of TiC addition on a (Pr,Nd)-poor and B-rich composition, as well as on a B-poor and (Nd,Pr)-rich composition. Rapidly solidified (Pr,Nd)–Fe–B alloys were prepared by melt-spinning. The compositions studied were (Pr_1−xNd_x)₄Fe₇₈B₁₈ (x=0, 0.5, and 1) with addition of 3 at% TiC. Unlike the (Pr_xNd_1−x)_9.5Fe_84.5B₆ materials that present excellent values for coercive field and energy product, the (Pr,Nd)-poor and B-rich composition alloys with TiC addition present lower values. Rietveld analysis of X-ray data and Mössbauer spectroscopy revealed that samples are predominantly composed of Fe₃B and -Fe. For the RE-rich compositions (Pr_xNd_1−x)_9.5Fe_84.5B₆ (x=0.1, 0.25, 0.5, 0.75, and 1) with the addition of 3 at% TiC, the highest coercive field and energy product (8.4 kOe and 14.4 MGOe, respectively) were obtained for the composition Pr_9.5Fe_84.5B₆.     

Luminescence properties of efficient X-ray phosphors of YBa3B9O18, LuBa3(BO3)3, α-YBa3(BO3)3 and LuBO3

The samples of YBa₃B₉O₁₈, LuBa₃(BO₃)₃, α-YBa₃(BO₃)₃ and LuBO₃ powders have been synthesized by the solid-state reaction methods at high temperature and their X-ray excited luminescent properties were investigated. All the studied materials show a broad emission band in the wavelength range of 300-550 nm with the peak centers at about 385 nm for YBa₃B₉O₁₈ and LuBa₃(BO₃)₃, 415 nm for α-YBa₃(BO₃)₃ and 360 nm for LuBO₃ powders, respectively. Even though those compounds have the different atomic structures, they have the common structural feature of each yttrium or lutetium ion bonded to six separate BO₃ groups, i.e., octahedral RE(BO₃)₆ (RE=Lu or Y) moiety. This octahedral RE(BO₃)₆(RE=Lu or Y) moiety seems to be an important structural element for efficient X-ray excited luminescence of those compounds, as are the edge-sharing octahedral TaO₆ chains for tantalate emission.     

稀土（Nd,Pr）（Ⅲ）双酞菁衍生物的合成,表征和气敏特性

合成了八－４－（四氢糖氧基）酞菁钕（Ⅲ）（Ａ）、八－４－（β－萘氧基）酞菁钕（Ⅲ）（Ｂ）、八－４－（２，４－二叔戊基苯氧基）酞菁钕（Ⅲ）（Ｃ）和八－４－（２，４－二叔戊基苯氧基）酞菁镨（Ⅲ）（Ｄ）４种新的稀土（Ｎｄ、Ｐｒ）（Ⅲ）双酞菁衍生物，经元素分析、红外光谱、核磁共振谱表征。紫外可见光谱表明，它们在氯仿（１０＾－６ｍｏｌ／Ｌ）溶液中以单分子形式存在。热重分析证明配合物的热稳定性：Ｂ＞Ｃ￣Ｄ＞Ａ     

“Constrained geometry” catalysts of the rare-earth metals for the hydrosilylation of olefins

A series of yttrium and lutetium alkyl complexes [Ln(η⁵-C₅Me₄ZNR′-κN)(CH₂SiMe₃)(THF)_n] (Ln = Y, Lu) was prepared by reacting the tris(trimethylsilylmethyl) precursor [Ln(CH₂SiMe₃)₃(THF)₂] with different linked amino-cyclopentadienes of the type (C₅Me₄H)ZNHR′ (Z = SiMe₂, CH₂SiMe₂; R′ = tBu, Ph, C₆H₄-tBu-4, C₆H₄-nBu-4). The catalytic activity of these alkyl complexes in the hydrosilylation of 1-decene and styrene using PhSiH₃ as reagent was examined under standard conditions. A significant influence of the ligand structure on the catalytic property (turnover frequency, regioselectivity) was observed with the yttrium complex [Y(η⁵-C₅Me₄CH₂SiMe₂NtBu-κN)(CH₂SiMe₃)(THF)] being the most active for 1-decene hydrosilylation.     

Preparation and crystal structure of ternary rare-earth platinum metal aluminides R2T3Al9 (T=Rh, Ir, Pd) with Y2Co3Ga9-type structure and magnetic properties of the iridium compounds

The ternary aluminides R₂Rh₃Al₉ (R=Y, La-Nd, Sm, Gd-Tm, Lu), R₂Ir₃Al₉ (R=Y, La-Nd, Sm, Gd-Lu), and R₂Pd₃Al₉ (R=Y, Gd-Tm) have been prepared by arc melting of the elemental components with an excess of aluminum and dissolving the aluminum-rich matrix in hydrochloric acid. They crystallize with Y₂Co₃Ga₉-type structure: Cmcm, Z=4. The crystal structures of Ho₂Rh₃Al₉ and Er₂Ir₃Al₉ have been refined from single-crystal X-ray data; Ho₂Rh₃Al₉: a=1316.8(3) pm, b=760.2(2) pm, c=933.7(2) pm, R=0.044 for 255 structure factors and 27 variables; Er₂Ir₃Al₉: a=1313.8(2) pm, b=758.5(1) pm, c=933.8(2) pm, R=0.057 (392 F values, 27 variables). The structure may be viewed as consisting of atomic layers of the compositions A=R₂Al₃ and B=T₃Al₆ which alternate in the sequence ABAB along the z direction. Approximately 33% and 27% of the A layers were found to be misplaced in the crystals investigated for Ho₂Rh₃Al₉ and Er₂Ir₃Al₉, respectively. The magnetic properties of most iridium-containing compounds have been determined with a superconducting quantum interference device magnetometer. The yttrium and the lanthanum compounds show Pauli paramagnetism, others reflect the magnetic behavior of the rare-earth components. The magnetic ordering temperatures are all lower than 20 K.     

Magnetic and calorimetric studies on rare-earth iron borates LnFe3(BO3)4 (Ln=Y, La-Nd, Sm-Ho)

A series of rare-earth iron borates having general formula LnFe₃(BO₃)₄ (Ln=Y, La-Nd, Sm-Ho) were prepared and their magnetic properties have been investigated by the magnetic susceptibility, specific heat, and ⁵⁷Fe Mössbauer spectrum measurements. These borates show antiferromagnetic transitions at low temperatures and their magnetic transition temperatures increase with decreasing Ln³⁺ ionic radius from 22 K for LaFe₃(BO₃)₄ to 40 K for TbFe₃(BO₃)₄. In addition, X-ray diffraction, specific heat, and differential thermal analysis (DTA) measurements indicate that the phase transition occurs for the LnFe₃(BO₃)₄ compounds with Ln=Eu-Ho, Y, and its transition temperature increases remarkably with decreasing Ln³⁺ ionic radius from 88 K for Ln=Eu to 445 K for Ln=Y.     

Synthesis, structure, and physical properties of Ce2PdGa10

A new ternary compound, Ce₂PdGa₁₀, has been synthesized using Ga flux and characterized by single-crystal X-ray diffraction. Ce₂PdGa₁₀ adopts a tetragonal structure in the I₄/mmm space group and is isostructural to Ce₂NiGa₁₀. Lattice parameters are , , , and Z=2. The compound is metallic (dρ/dT>0), with the resistance decreasing roughly linearly with temperature from 300 to 175 K. The magnetic susceptibility of Ce₂PdGa₁₀ is consistent with local-moment paramagnetism and no long-range magnetic ordering occurs down to 2 K. A large positive magnetoresistance over 200% is observed at 2 K for fields of 9 T. In this paper, we present the structure and physical properties of Ce₂PdGa₁₀ and compared them to CePdGa₆.     

RING-OPENING POLYMERIZATION OF ε-CAPROLACTONE BY LANTHANOCENE CATALYSIS*

Ring-opening polymerization of ε-caprolactone (CL) catalyzed bylanthanocenes, O(C_2H_4C_5H_3CH_3)_2YCl (Cat-YCl) and Me_2Si[(CH_3)_3SiC_5H_3]_2NdCl(Cat-NdCl) has been carried out for the first time. It has been found that both yttroceneand neodymocene are very efficient to catalyze the polymerization of CL, giving high molec-ular weight poly (ε-caprolactone) (PCL ). The effects of [cat] / [ε- CL] molar ratio, polymeriza-tion temperature and time, as well as solvents were investigated and polymerization tem-perature is found to be the most important factor affecting the polymerization. The bulkpolymerization gives higher molecular weight PCL and higher conversion than that in solu-tion polymerization. NaBPh_4 was found to promote the polymerization of ε-caprolactone,and thus to increase both the polymerization conversion and MW of poly (ε- caprolactone ).