Thermal Softening Behavior and Application to Transparent Thick Films of Poly(benzylsilsesquioxane) Particles Prepared by the Sol–Gel Process

Thick films of poly(benzylsilsesquioxane) (BnSiO_3/2) particles, prepared by the sol–gel process, were deposited onto indium-tin-oxide-coated glass substrates by electrophoresis for the application to the micropatterning of the films. BnSiO_3/2 particles were thermally softened and sintered at ∼50°C, which was above the glass transition temperature of the particles. The films prepared by the electrophoretic sol–gel deposition consisted of aggregates of particles with diameters of 0.2–1 μm and were opaque. The film shrank from 2.5 μm to 1.4 μm in thickness and became transparent upon sintering of the particles during heat treatment at temperatures >100°C.     

Synthesis and Optical Properties of Rare-Earth–Aluminum Oxide Glasses

Single-phase glasses containing 37.5 mol% Y₂O₃, 7 mol% La₂O₃, and 1 mol% Pr, Ho, Nd, Er, Sm, Tm, Eu, or Yb oxide substituted for part of the Y₂O₃ were synthesized by containerless melting. The spectral transmission and absorption cross sections of the glasses were determined at wavelengths from 360 to 3300 nm. The electronic transitions were broadened compared with results obtained in a crystalline yttrium aluminum garnet (YAG) host. The infrared transmission of the host glass extended to 6000 nm. The optical and physicochemical properties of these glasses are well suited for optical device applications.     

Processing and Properties of Screen-Printed Lead Zirconate Titanate Piezoelectric Thick Films on Electroded Silicon

The printing of lead zirconate titanate (PZT, Pb(Zr,Ti)O₃) piezoelectric thick films on silicon substrates is being studied for potential use as microactuators, microsensors, and microtransducers. A fundamental challenge in the fabrication of useful PZT thick-film devices on silicon is to sinter the PZT to high density at sufficiently low temperature to avoid mechanical or chemical degradation of the silicon substrate. The goal of the present study is to develop and implement suitable electrodes and PZT sintering aids that yield attractive piezoelectric properties for devices while minimizing reactions between the silicon, the bottom electrode, and the PZT thick film. A B₂O₃-Bi₂O₃-CdO sintering aid has been found to be superior to borosilicate glass, and the use of a gold/platinum bilayer bottom electrode has resulted in better thermal stability of the electrode/film structure. Films sintered at 900°C for 1 h have relative permittivity of 970 (at 1 kHz), remnant polarization of 20 μC/cm², coercive field of 30 kV/cm, and weak-field piezoelectric coefficient d ₃₃ of 110 pm/V.     

添加剂对铅硅酸盐低熔点玻璃热性能的影响

采用常规玻璃熔融退火工艺制备了两组铅硅酸盐玻璃试样,玻璃组成为(物质的量含量,下同):(55-x)PbO-(10+x)B2O3-30SiO2-5ZnO(x=0,5,10,15)和(55-x)PbO-10B2O3-30SiO2-5ZnO-xSB2O3(x=5,10,15),以及与两组参照的传统铅硅酸盐玻璃55PbO-5Al2O3-10B2O3-30SiO2.利用热膨胀仪观察氧化物添加剂对玻璃转变温度范围△T(T1-Tg)的影响.实验结果表明,随着氧化硼加入量的不断提高,玻璃的转变温度(Tg)与软化温度(Tf)随之提高,而△T先减小后增大,即出现所谓的硼反常现象.当添加的氧化锑量在5%～10%(物质的量含量,下同)范围时,与参照样品相比,玻璃的软化温度(Tf)基本保持不变而转变温度(Tg)则提高10℃以上.当添加的氧化锑量达到15%时,玻璃的转变温度(Tg)与软化温度(Tf)均显著下降,但△T基本保持不变.     

Diffusion of Neodymium into Sputtered Films of Tantalum Pentoxide

In this communication the diffusion of neodymium into rf-sputtered films of tantalum pentoxide (Ta₂O₅) has been investigated using the SIMS technique. The diffusion characteristics were obtained for a temperature of 1100°C, and the results showed a time-dependent diffusion coefficient that reflects a transition of the sputtered films from the amorphous to the crystalline phase. The potential for doping films of Ta₂O₅ with neodymium by diffusion, for the realization of novel active optical devices, is also discussed.     

Nonradiative Energy Losses and Radiation Trapping in Neodymium-Doped Phosphate Laser Glasses

Fluorescence radiation trapping and nonradiative energy losses from the Nd³⁺⁴F_3/2 state are reported for two widely used commercial phosphate laser glasses (LHG-8 and LG-770). The effects of hydroxyl-group, transition-metal (Cu, Fe, V, Co, Ni, Cr, Mn, and Pt), and rare-earth (Dy, Pr, Sm, and Ce) impurities on the ⁴F_3/2 nonradiative decay rate in these glasses are quantified. Nd concentration quenching effects are reported for doping levels ranging from about 0.5 × 10²⁰ to 8.0 × 10²⁰ ions/cm³. The results are analyzed using the Förster–Dexter theory for dipolar energy transfer. Quenching rates for transition-metal ions correlate with the magnitude of spectral overlap for Nd emission (donor) and the metal ion absorption (acceptor). The nonradiative decay rates due to hydroxyl groups follow Förster–Dexter theory except at low Nd-doping levels (≲2 × 10²⁰ ions/cm³) where the quenching rate becomes independent of the Nd concentration. The data suggest a possible correlation of OH sites with Nd ions in this doping region. The effects of radiation trapping on the fluorescence decay are reported as a function of sample size, shape, and doping level. The results agree well with the theory except for samples with small doping-length products; in these cases, multiple internal reflections from the sample surfaces enhance the trapping effect.     

Dissolution and Separation of Ruthenium in Borosilicate Glass

The behavior of ruthenium oxide (RuO₂) in aluminoborosilicate glass used for the stabilization of nuclear waste was investigated. It was found that 0.025 mass% RuO₂ dissolved as Ru⁴⁺ in the glass at 1400°C, which caused the glass to turn yellow. When the RuO₂ amount was 0.05 mass%, needle-shaped crystals formed in the glass during slow cooling. If the added amount exceeded 0.1 mass% and the cooling rate was slow, it separated rapidly and the glass became pale after cooling. No dissolution of ruthenium was detectable after melting at 1200°C.     

Tellurite Glasses for Broadband Amplifiers and Integrated Optics

The present investigation discusses the advantage of using RE-ion-doped (Nd³⁺, Tm³⁺, and Er³⁺) TeO₂ glasses for developing fiber and planar broadband amplifiers and lasers. The spectroscopy of RE-ion-doped fibers and glasses is discussed along with the thermal properties of glass hosts. The results of emission from the ³H₄ level in single-mode Tm³⁺-doped tellurite fiber show that the emission band overlaps with Er³⁺ emission from the ⁴I_13/2 level and Nd³⁺ emission from the ⁴F_3/2 level in silicate and tellurite glasses, thereby enabling the development of amplifiers and lasers between 1350 and 1650 nm. Recent results using Z-scan measurements of nonlinear refractive index and absorption demonstrate that the third-order nonlinearity in undoped TeO₂ glasses is of the order of 2 × 10⁻¹⁵ to 3 × 10⁻¹⁵ cm²·W⁻¹ between 1300 and 1550 nm. These results are briefly discussed in view of an amplifier operation combined with ultrafast all-optical switching.     

Ultrafast Optical Switches and Wavelength Division Multiplexing (WDM) Amplifiers Based on Bismuth Oxide Glasses

Glasses with a high refractive index exhibit interesting properties. All optical switching and broadband amplification performances have been demonstrated using glasses based on bismuth oxide (Bi₂O₃). Optical Kerr shutter (OKS) switching and degenerated four-wave mixing experiments for nonresonant-type Bi₂O₃–B₂O₃–SiO₂ glasses have been performed using femtosecond lasers. This glass exhibits an ultrafast response (<150 fs) in OKS operation. Moreover, terahertz-range (THz-range) optical switching has been successfully performed with this glass, using a 1.5-THz pulse train. Erbium-doped bismuth-based oxide glasses also have been prepared for wavelength division multiplexing (WDM) amplifiers. These glasses exhibit broadband emission and negligible concentration quenching, which indicates that the bismuth-based glass is suitable for broadband amplifiers and highly doped short-length fiber applications for metro use.     

硼硅酸锌玻璃的制备及其发光特性

由于发光玻璃独特的透明性,在激光、光学放大器、光通讯、储能和显示等光电子领域有着广泛的应用.本文利用高温固相法制备出了新型硼硅酸锌:铕掺杂的硼硅酸锌玻璃,讨论了掺杂离子浓度对玻璃发光特性的影响.结果表明Eu2+掺杂的硼硅酸锌玻璃在250～400 nm波长范围可以被很好地激发,有很宽的激发波长范围,发射谱为一个宽带峰,位于450 nm.掺杂不同浓度的Eu2+的硼硅酸锌发光玻璃的激发光谱有所不同,随着掺杂Eu2+浓度的增加,荧光强度增强,但发射光谱峰位置基本没有变化.另外,Eu2+掺杂硼硅酸锌玻璃较易合成,是一种很好的蓝色发光材料,具有较大的应用价值.     

The Red-Shift of Ultraviolet Spectra and the Relation to Optical Basicity of Ce-Doped Alkali Rare-Earth Phosphate Glasses

The ultraviolet absorption and emission spectra of Ce³⁺ doped phosphate glasses based on gadolinium and sodium phosphates are studied in the present work. Compared with the cerium-free phosphate glass matrixes, CePO₄ doping shifts the ultraviolet absorption edge of glasses into the longer wavelength because of the 4f–5d absorption transition of Ce³⁺. The emission spectra correlate such red-shift with glass compositions. Explanations are based on variation in the optical basicity of glasses, which corresponds not only to the alkali content but also to the O/P ratio. The latter is proportional to the number of nonbridging oxygen in the oxyanion unit (PO₄), and most likely plays an overwhelming role in the overall optical basicity of glasses.     

硅硼比对镁铝硼硅酸盐玻璃结构、化学稳定性和介电性能的影响

采用熔融冷却的方法制备了镁铝硼硅玻璃。研究了SiO_2取代B_2O_3对玻璃结构、化学稳定性和介电性能的影响。傅里叶变换红外光谱(FTIR)结果表明,随着SiO_2/B_2O_3比的增大,玻璃网络结构中桥氧增多,非桥氧减少。镁铝硼硅酸盐玻璃的耐酸侵蚀能力随SiO_2/B_2O_3比的增大而增强,而耐碱侵蚀的能力则变差。随SiO_2/B_2O_3比的增大介电常数逐渐增大。当SiO_2/B_2O_3摩尔比为2.08时,玻璃具有最小的介电常数值4.9。SiO_2/B_2O_3比为3.11时,玻璃的介电损耗出现最小值。     

Dispersion and Upconversion Fluorescence of Nd3+ Ions in Zinc Chloride-Based Glasses

Nd³⁺-ion-doped ZnCl₂-based glasses were prepared via the melt-quenching method. The Nd³⁺-ion upconversion excitation mechanism and the ability to disperse Nd³⁺ ions into ZnCl₂-based glasses were investigated using absorption and upconversion fluorescence spectra of Nd³⁺ ions. The ZnCl₂-based glass that had an average cationic radius equal to the ionic radius of Nd³⁺ (98 pm) had the greatest ability to disperse Nd³⁺ ions. The 20KCl·25BaCl₂·55ZnCl₂glass, which had the average cationic radius nearest to 98 pm, dispersed Nd³⁺ ions the most, and it had the strongest upconversion fluorescence.     

(Na2O-Al2O3)/B2O3对高硼硅酸盐玻璃粘度和热学性能的影响

采用熔融冷却法制备了不同R’系数的高硼硅酸盐玻璃,其中R’=(Na2O-Al2O3)/B2O3.利用红外光谱、高温旋转粘度计和热膨胀仪等对玻璃的结构和性能进行表征.结果表明:高温段粘度-温度关系符合阿伦尼乌斯定律;R’值的增大导致非桥氧的增加,高温粘度和熔制温度呈显著降低.当R’＞0.5时,热膨胀系数近似线性增大,玻璃化转变温度增大至590℃基本维持不变.R’值影响结构中的[BO3]与[BO4]的比例及硅氧网络的完整程度,从而决定高硼硅酸盐玻璃的性能.     

Spectroscopic Study of Neodymium(III) in Sodium Tellurite Glass

The local environment of Nd-O in a sodium tellurite glass was elucidated as a function of Nd₂O₃ concentration, from 0.1 to 2.5 mol%, using optical spectroscopy. The Judd-Ofelt (J-O) theory was used to determine the oscillator strength parameters (J-O parameters) of the glasses. According to the J-O parameters, a significant change in the local environment of Nd-O was suggested for the glass containing 1 mol% Nd₂O₃; the asymmetry of the Nd-O crystal field was shown to be at a maximum and the bond covalency at a minimum. The results were further supported by a significant shift of the structural hypersensitive band of the glass with 1 mol% Nd₂O₃, as compared with those of the other glasses.     

Physical Properties of Barrier Ribs of Plasma Display Panels: I, Formation of Pores during Sintering of Lead Borosilicate Glass Frits

The effects of chemical compositions on the sintering behavior and physical properties of lead borosilicate glass developed for barrier ribs of plasma display panels (PDP) were investigated. The formation of pores during sintering of the glass was noted, and their formation mechanism was investigated using XPS, TG/DTA, and XRD. A change in the oxidation state of the lead was discussed as a possible cause for the formation of pores in the sintered samples.     

Compositional Dependence of Microwave Dielectric Properties in (1 −x)(Na1/2Nd1/2)TiO3−xNd(Mg1/2Ti1/2)O3 Ceramics

The compositional dependence of microwave dielectric properties has been investigated in the (1 − x )(Na_1/2Nd_1/2)TiO₃− x Nd(Mg_1/2Ti_1/2)O₃ (NNT-NMT) system. The addition of NMT results in significant improvement in the quality factor and the temperature coefficient of frequency, but gradually decreases the dielectric constant from ∼100 for pure NNT to ∼25 for pure NMT. The single perovskite phase is observed with various { hkl } superlattice reflections over the entire compositional range. The increasing tendency of peak splitting with increasing x at some perovskite reflections strongly suggests that the crystal structure of the system changes to lower symmetry structures. This is confirmed using infrared reflectivity spectra. The superlattice reflections related to structural deviation become more predominant as the composition reaches pure NMT. Particularly, {111} superlattice reflections are believed to be associated with the 1:1 cation ordering and responsible for the observed abrupt increase in quality factor at x > 0.7.     

Nanostructured Silicon Oxide–Nickel Oxide Sol–Gel Films with Enhanced Optical Carbon Monoxide Gas Sensitivity

Sol–gel derived silica (SiO₂) films doped with nickel oxide (NiO) nanocrystals were fabricated. A bifunctional ligand was used, bearing amine groups capable of coordinating the nickel ions and hydrolysable siloxane groups for anchoring the metal complex moiety to the silicate matrix. Nickel oxide nanocrystals precipitated at 500°C while the film was still porous. The nanocomposite films showed a reversible change in the optical transmittance in the VIS-NIR range when exposed to carbon monoxide gas. The effects of residual porosity, testing temperature, and carbon monoxide gas concentration on optical transmittance were studied.     

Microstructure and Dielectric Properties of Barium Strontium Magnesium Niobate

Dielectric properties and their related microstructural characteristics in solid solutions of (1 – x )Ba(Mg_1/3Nb_2/3)O₃– x Sr(Mg_1/3Nb_2/3)O₃ (BMN–SMN, or BSMN) were investigated by measuring the relative permittivity (ɛ_r), Q values, and temperature coefficient of resonator frequency (τ_f), and by observing microstructure using transmission electron microscopy. When the tolerance factor ( t ) was >0.99 in BSMN with composition 0 < x < 0.5, where the tilting of oxygen octahedra was not involved, the microstructure included only 1:2 ordered phase. In the region where 0.99 > t > 0.97 with 0.7 < x < 1.0, the phase due to the antiphase tilting of oxygen octahedral, the disordered phase, and the 1:2 ordered phase were also present. In a few of the grains, core–shell-type structures, whose main components were dislocations and stacking faults, were found in the solid solution of BSMN.