Effects of rare-earth elements on the glass-forming ability and mechanical properties of Cu_(46)Zr_(47-x)Al_7M_x(M = Ce,Pr,Tb,and Gd) bulk metallic glasses

Cu46Zr47-xA17Mx （M = Ce, Pr, Tb, and Gd） bulk metallic glassy （BMG） alloys were prepared by copper-mold vacuum suction casting. The effects of rare-earth elements on the glass-forming ability （GFA）, thermal stability, and mechanical properties of Cu46Zr47-xA17Mx were investigated. The GFA of Cu46Zr47-xA17Mx （M = Ce, Pr） alloys is dependent on the content of Ce and Pr, and the optimal content is 4 at.%. Cu46Zr47-xA17Thx（X = 2, 4, and 5） amorphous alloys with a diameter of 5 mm can be prepared. The GFA of Cu46Zr47-xA17Gdx（x = 2, 4, and 5） increases with increasing Gd. Tx and Tp of all decrease. Tg is dependent on the rare-earth element and its content. ATx for most of these alloys decreases except the Cu46Zra2Al7Gd5 alloy. The activation energies △Eg, △Ex, and △Ep for the Cu46Zr42A17Gd5 BMG alloy with Kissinger equations are 340.7, 211.3, and 211.3 kJ/mol, respectively. These values with Ozawa equations are 334.8, 210.3, and 210.3 kJ/mol, respec- tively. The Cu46Zr45Al7Tb2 alloy presents the highest microhardness, Hv 590, while the Cu46Zr43A17Pr4 alloy presents the least, Hv 479. The compressive strength （at.f.） of the Cu46Zra3A17Gd4 BMG alloy is higher than that of the Cu46Zr43Al7Tb4 BMG alloy.

Tm^(3+)-doped tellurite glass with Yb^(3+) energy sensitized for broadband amplifier at 1400–1700 nm bands

A kind of novel experiment was disclosed as it possessed two bands of fluorescence emission at 1.4 and 1.6 μm, which were perfectly complimentary to the current C band of optic communication. The fluorescence was based on energy transfer and up-conversion processes between Tm^3＋ and Yb^3＋ under direct pumping of 975 nm LD. The spectra and lifetimes of Tm^3＋ fluorescence in the tellurite glass were described. The corresponding fluorescence characteristics and energy migration process were analyzed by the method of lifetime and intensity comparison. The mechanism of the up-conversion based IR fluorescence was presented upon analyzing the multi-photon pumping process. The potential advantages of Tm^3＋/Yb^3＋ co-doped tellurite glass as amplifier material were concluded.

Gain properties of germanate glasses singly doped with Tm^(3+) and Ho^(3+) ions

Two kinds of germanate glasses singly doped with the ion concentration of 2.0mol.%Tm3＋ and 2.0mol.%Ho3＋, respectively, were prepared.According to McCumber theory, the absorption and stimulated emission cross-sections corresponding to the 3H6←→3F4 transitions of Tm3＋（at 1.8 μm） and the 5I8←→5I7 transitions of Ho3＋（at 2.0 μm） were obtained, and respective gain cross-section spectra were also computed as a function of population inversion according to absorption and emission cross-sections and the ion concentrations.For Tm3＋-doped germanate glasses, the maximum of the absorption, emission, and gain cross-sections reached a value higher than those reported for fluorozirconate, fluoride, and oxyfluoride glasses.For Ho3＋-doped germanate glasses, the maximum of absorption, emission, and gain cross-sections reached a value higher than that reported for fluorozircoaluminate glasses.Hence, these Tm3＋-doped and Ho3＋-doped germanate glasses exhibited an advantage for application in mid-infrared lasers at about 1.8 and 2.0 μm wavelength.

High Quantum Efficiency and High Concentration Erbium-Doped Silica Glasses Fabricated by Sintering Nanoporous Glasses

A new method was used to prepare erbium-doped high silica （SiO2 % 〉 96 % ） glasses by sintering nanoporous glasses. The concentration of erbium ions in high silica glasses can be considerably more than that in silica glasses prepared by using conventional methods. The fluorescence of 1532 nm has an FWHM （Full Wave at Half Maximum） of 50 nm, wider than 35 nm of EDSFA （erbium-doped silica fiber amplifer）, and hence the glass possesses potential application in broadband fiber amplifiers. The Judd-Ofelt theoretical analysis reflects that the quantum efficiency of this erbium-doped glass is about 0.78, although the erbium concentration in this glass （6 × 10^3） is about twenty times higher than that in silica glass. These excellent characteristics of Er-doped high silica glass will be conducive to its usage in optical amplifiers and microchip lasers.

Structure and Luminescence Properties of Eu^(3+) Doped SiO_2 Glass Synthesized by Sol-Gel Process

Under different annealing temperatures, Eu 3+ doped SiO 2 gel and glass were prepared by sol gel method, and the structure and luminescent properties were studied with excitation spectra, emission spectra, IR and DTA TG. The results show that the fluorescent intensity tends to get stable when concentration of Eu 3+ doped is above 1 86 % (mass fraction) most water absorbed by the gel was removed at 300 ℃, and that the emission spectrum of Eu 3+ , with peaks at 614, 588, 577 nm, is due to 5D 0→ 7F 2, 5D 0→ 7F 1, 5D 0→ 7F 0 transitions, and the excitation peaks at 318, 362, 380, 393, 412 and 462 nm were observed. These results illustrate that the temperature range of 300～500 ℃ is critical for the structure conversion from gel to glass, and the fluorescence is strongly quenched by water.

Experimental and numerical investigation of mid-infrared laser in Pr^(3+)-doped chalcogenide fiber

We report on a chalcogenide glass fiber doped with Pr^(3+) that can be used for commercialized 1.5-μm and 2-μm laser excitations by emitting broadband 3 μm–5.5 μm fluorescence, which is extruded into a preform and then drawn into a step-index fiber. The spectroscopic properties of the fiber and glass are reported, and the mid-infrared fiber lasers are also numerically investigated. Cascade lasing is employed to increase the inversion population of the upper laser level. The particle swarm approach is applied to optimize the fiber laser parameters. The output power can reach 1.28 W at 4.89-μm wavelength, with a pump power of 5 W, excitation wavelength at 2.04 μm, Pr^(3+) ion concentration at 4.22 × 10^(25) ions/m^3,fiber length at 0.94 m, and fiber background loss at 3 dB/m.

Upconversion luminescence properties of Er^(3+) doped GeS_2-Ga_2S_3-KCl chalcohalide glasses

Er^3＋ ions doped chalcohalide glasses with the composition of 56GeS2-24Ga2S3-20KCl were fabricated by a melt-quenching method.Under 800 nm laser excitation,strong green emissions centered at 525 nm and 550 nm and weak red emission centered at 660 nm were observed,which were assigned to ^2H11/2→^4I15/2,^4S3/2→^4I15/2,and ^4F9/2→^4I15/2 transitions,respectively.The intensity reached maximum when the Er^3＋ ions concentration was 0.1 mol%.The possible upconversion luminescence mechanism was proposed from the discussion on the above results as well as the results of lifetimes of the metastable ^4I13/2 level and local environment of Er^3＋ ions.It is found that chalcohalide glass can be good host materials for upconversion luminescence.

Three-photon-excited fluorescence of Tb^(3+)-doped CaO-Al_2O_3-SiO_2 glass by femtosecond laser irradiation

A near infrared to visible blue, green, and red upconversion luminescence in a Tb^3＋-doped CaO-Al2O3-SiO2 glass was studied, which was excited using 800 nm femtosecond laser irradiation. The upconversion luminescence was attributed to ^5D3→^7F5, ^5D3→^7F4, ^5D3→^7F3, ^5D4→^7F6, ^5D4→^7F5, ^5D4→^7F4, and ^5D4→^7F3 transitions of Tb^3＋. The relationship between upconversion luminescence intensity and the pump power indicated that a three-photon simultaneous absorption process was dominant in this upconversion luminescence. The intense red, green, and blue upconversion luminescence of Tb^3＋-doped CaO-Al2O3-SiO2 glass may be potentially useful in developing three-dimensional display applications.

Spectral and Lasing Properties of Er^(3+0/Yb^(3+) Co-Doped Phosphate Glasses Pumped by LD

Er^3 ＋/Yb^3 ＋ phosphate glasses were fabricated. According to McCumber theory, the stimulated emission cross-section of Er^3＋ ions at 1533 nm was calculated on the basis of absorption spectrum, and 0.84 × 10^-20 cm^2 is derived, the fluorescence lifetime of ^4I13/2 level is 8.5 ms. An Er^3＋/Yb^3＋ co-doped phosphate glass CW laser pumped by LD was demonstrated at room temperature. The maximum output power is 80 mW and slope efficiency is 16.5%.

Spectroscopic Properties of Nd^(3+)-Doped Tellurite Glasses

The Nd^3＋-doped pared. The absorption and tellurite glasses were preemission spectra of Nd^3 ＋- doped tellurite glasses at room temperature were measured. The Judd-Ofelt parameters （Ω2, Ω4, Ω6） of the glasses were calculated from measured absorption spectra. The calculation results of luminescence properties （A, β, τrad, σ） of Nd^3＋ ions in the tellurite were glasses were given. Spectroscopic properties, concentration quenching in these kinds of the glasses were investigated. The results indicate that the tellurite glasses with composition of 70% TeO2, 20% ZnO, （ 10 - x ） % La2O3, x % Nd2O3 （ mol% ） show high emission cross section and low phonon energy. The fluorescent intensity and the emission cross section have a maxi- mum value at x = 0.5, namely, the optimum Nd^3 ＋ ion concentration in the tellurite glass is 0.5% （1.93 × 10^20 ions·cm^-3）. The fluorescence properties of Nd^3＋ measured are basically in accord with the calculated results.

Optical Properties of a Novel Trivalent Erbium Ions Doped into Phosphate Glass

A novel Er (3+)-doped (ZnO)(P_2O_5)(B_2O_3) glass with excellent optical properties was prepared. The glasses were proved to have high stability by the investigation of the durability in boiling water. The properties of their spectra at about 1.5 μm change a lot with the concentrations of both Er (3+) and B_2O_3. Compared with Er (3+)-doped into the borate glass and the zinc phosphate glass,the glass prepared in our laboratory shows a larger quenching concentration and a much broader emission band at 1.54 μm.

Spectroscopic Properties of Er^(3+)-Doped TeO_2-WO_3-ZnO-ZnF_2 Glasses

The Er^(3+)-doped TeO_2-WO_3-ZnO-ZnF_2(TWZOF) glasses were prepared. The absorption spectra, 1.5 μm emission spectra and fluorescence lifetimes of Er^(3+), excited at 970 nm, were measured. The J-O parameters Ω_ t (t =2, 4, 6), absorption and emission cross-sections were calculated. The dependence of the 1.5 μm emission intensity, fluorescence lifetime and bandwidth of the Er^(3+) emission upon the contents of ZnF_2 in glass were investigated. In TWZOF glass, Er^(3+) ions had a broad emission profile around 1.5 μm with the maximum FWHM of 83 nm. With the increasing of the content of ZnF_2, the emission intensity at peak wavelength and the fluorescence lifetime of Er^(3+) at 1.5 μm increase.

Pr^(3+)掺杂Ge-As-Ga-Se硫系玻璃和光纤的制备及性能

面向4μm波段光纤激光器用增益光纤,制备出0.2%(质量分数)高浓度Pr^(3+)离子掺杂的Ge_(12)As_(20.8)Ga_(4)Se_(63.2)玻璃,通过棒管法拉制了单模双包层增益光纤。采用X射线衍射、差示扫描量热、电子探针元素分析、椭偏仪、红外热像仪、红外显微测试、红外傅里叶变换光谱仪、荧光光谱仪等分析了不同工艺下制备的玻璃和光纤的光学特性,最终所制备光纤的基底损耗约为2.65 dB/m,并成功获得光纤在3.8~4.8μm处的强荧光发射。该硫系玻璃光纤具有较高的Pr^(3+)溶解度、良好的热稳定性与发光性能,具有作为4μm波段光纤激光器增益介质的潜力。

Rare Earth Doped Glass Waveguide Amplifiers

Progress in rare earth doped planar glass waveguide devices has been significant over the past few years. The history and applications of these devices are reviewed.

Rare earth element-doped porous In_(2)O_(3) nanosheets for enhanced gas-sensing performance

Rare earth(La,Pr,Sm,Ce and Yb)-doped porous In_(2)O_(3) nanosheets are prepared by a solvothermal method.The effect of rare earth elements on the structure,morphologies and gas-sensing performance of In_(2)O_(3) nanosheets is systematically investigated.The mixed phase composed of c-In_(2)O_(3) and rh-In_(2)O_(3) can be transformed into rh-In_(2)O_(3) by doping with rare earth elements.After doping with rare earth elements,the morphology can be changed from compact nanosheets to porous sheets.Compared with pure In_(2)O_(3) and La,Pr,Sm,Ce-doped porous In_(2)O_(3) nanosheets,Yb-doped In_(2)O_(3) nanosheets present the best gas-sensing performance.Among 3%-10%Yb-doped samples,6%Yb-doped In_(2)O_(3) porous nanosheets exhibit the optimal gas-sensing performance to 5×10^(-6)-750×10^(-6) acetone,giving a high response of 15.3 toward 50×10^(-6) acetone and fast response/recovery time at the operating temperature of 220℃.Moreover,6% Yb-doped porous In_(2)O_(3) nanosheet sensor also exhibits excellent selectivity and stability,indicating its potential in the nextgeneration gas sensor.

Properties of Local Structure Surrounding Eu^(3+)Ion in Various Niobate-Silicate Glasses

A Series of niobate silicate glasses doped with Eu 3+ ions were prepared. The emission, phonon side band spectra, fluorescence line narrowing spectroscopy and fluorescence lifetimes in these glasses were studied. The intensity parameters and crystal field parameter of Eu 3+ were obtained. The results indicate that the intensity ratio of the electric dipole to magnetic dipole transition and the intensity parameter Ω 2 increase with the increasing concentration of Nb 2O 5, indicating that the symmetry becomes lower, the Eu O bonds become stronger and the covalency of Eu O bond increases. The value of B 20 decreases with the increasing concentration of Nb 2O 5, indicating that the distance between the Eu 3+ ion and oxygen decreases and the Eu O bond becomes strong, corresponding to the results of the former. As the concentration of Nb 2O 5 increases, the electron phonon coupling becomes stronger, thus the nonradiative transition rate of 5D 0 becomes larger and the lifetime of 5D 0 becomes shorter.

钆含量对Fe-B-Nb-Gd非晶合金磁学性能和氧化机制的影响规律

研究了Gd含量对(Fe_(73)B_(22)Nb_(5))_(100–x)Gd_(x)(x=0,0.5,1.0,1.5,2.0)合金非晶形成能力、热稳定性和磁学性能的影响规律,并对比分析了非晶氧化机制.通过添加Gd元素,合金的原子尺寸差超过13%,构型熵增大了30%,提升了合金的非晶形成能力.随着Gd含量的增大,过冷液相区范围达到73 K,热稳定性得到明显增强.Gd元素导致合金局部各向异性受到限制,准位错偶极子型缺陷密度降低.这有效减少了阻碍磁畴壁旋转的钉扎位点,提高合金软磁性能.此外,Gd元素使得非晶在氧化过程中对温度的变化更为敏感,达到最大氧化速率的温度降低了15 K,但是并未恶化其抗氧化性能.Gd原子受结合能影响向表层迁移,形成的富Gd氧化物填充了表层缺陷,占据了大量顶部空间,合金表面附近的结构更加致密.这种结构减少了氧原子通过微观组织界面进行扩散的通道,有助于增强抗氧化性能.

Sm^(3+)掺杂LaOF荧光粉的制备及光学性能

以LaOF晶体为基质,利用水热辅助固相法制备出一系列Sm^(3+)掺杂LaOF荧光粉。采用XRD、TEM、荧光光谱仪等测试手段对所制得的样品的相结构、微观形貌及光学性能进行表征。结果表明,LaOF在不同煅烧温度下会产生四方相和斜方六面体两种不同晶相。此外,由于受跃迁概率和局域对称性的影响,Sm^(3+)掺杂四方相LaOF发光强度更大,其各浓度样品在405 nm光激发下,于567 nm、605 nm、651 nm和710 nm等处均出现了Sm^(3+)的特征发射峰,并且随着Sm^(3+)掺杂量的增加,其发光强度呈现先增大后减小的趋势,且当Sm^(3+)掺杂量为3.0%(摩尔分数,下同)时,La_(1-x)Sm_(x)OF样品发光强度达最大值。此外,所得样品的色纯度极高,其多个激发峰均位于商用近紫外和蓝光LED芯片的发射波长附近,可实现多种波长激发下的可见橙光发射。

稀土掺杂CeO_(2)的合成及其CMP性能研究

CeO_(2)作为一种常用的稀土抛光粉,其抛光性能十分优异,但在现有的抛光研究中,平衡材料去除速率(MRR)和表面粗糙度(Ra)两者的关系一直是重点与难点。为探究这一问题,采用溶剂热法合成形貌规整、粒径较为均一、分散性良好的球形CeO_(2),并对其进行Pr、Y等稀土元素的掺杂,研究稀土元素掺杂对氧空位形成的改变,以及引起的Ce^(3+)比例的变化对抛光性能的影响。根据材料表面Ce^(3+)的含量,与CMP抛光实验结合,结果显示Ce^(3+)含量较高的抛光磨料对硅片的抛光效果更好,其中Pr掺杂的CeO_(2)磨料,MRR高达445.71 nm/min,抛光后硅片的平均粗糙度(Ra)为1.23 nm,Pr元素的掺杂能够改变Ce基抛光粉表面的化学状态,进而影响抛光过程。通过对氧化铈形貌、粒径及表面Ce的化学状态的调控,稀土元素掺杂后的CeO_(2)抛光粉具有较快的材料去除速率和较好的表面粗糙度,该研究可为开发高性能氧化铈基抛光粉提供一定的理论及技术指导。

玻璃基中子及γ射线屏蔽材料研究进展

玻璃材料具备高化学稳定性和高辐照稳定性,同时还具备高折射率以及高透光性的光学特性,这使玻璃基中子及γ射线屏蔽材料有望成为同时实现辐射屏蔽以及视觉监控的独特材料。本文从中子辐射及γ射线辐射屏蔽机理入手,结合蒙特卡罗法介绍了屏蔽材料设计思路及手段,以及多种玻璃基屏蔽材料研究现状。铅玻璃由于高毒性正逐步被淘汰,而硅酸盐、硼酸盐、硼硅酸盐等无铅玻璃已成为工业市场的主流。通过向玻璃中掺入重金属化合物(如Bi_(2)O_(3)、BaO)和稀土元素(如La、Gd),可以有效增加质量衰减系数并降低半值层,从而显著提升其屏蔽效果,但是这种掺杂方式可能会对材料的机械性能产生不利影响。此外,本文还比较了玻璃基屏蔽材料与其他类型屏蔽材料的优劣。进一步提升玻璃基屏蔽材料的综合性能,以及开发既环保又智能的新型屏蔽材料,对于推动屏蔽技术的进步与应用具有重大意义。