Crystal growth and optical properties of CdS-doped lead silicate glass

The crystal growth and optical properties of CdS microcrystallite-doped lead silicate glass is investigated in this paper. The existence of CdS nanocrystals was confirmed via X-ray diffraction (XRD) and transmission electron microscopy (TEM). Results reveal that a two-stage heat-treat procedure can produce a better size distribution of CdS nanocrystals than a one-stage heat-treat procedure in glasses. The second harmonic generation (SHG) from the base glass and CdS microcrystallite doped glasses was observed, and the effects of the heat treatments and the thermal poling temperature on the crystallization of CdS and second-order harmonic (SH) intensity were discussed, respectively. It is indicated that samples doped with CdS microcrystallite showed larger SH intensity than that of the base glass. Use of a higher thermal poling temperature than the glass transformation temperature does not result in a good SH intensity in glasses.     

CuI微晶掺杂硅凝胶玻璃及其薄膜的制备与光谱性质

抄采用溶胶-凝胶工艺制成Cul微晶掺杂硅凝胶玻璃及其薄膜。通过X射线粉末衍射（XRD）和高分辨透射电镜（HRTEM）分析观察到玻璃中的晶相及其分布；由薄膜的室温透射光谱发现，随着热处理温度提高和时间延长，薄膜的特征透射谱谷向长彼方向移动（红移），并源于玻璃中的量子尺寸效应。     

Cul微晶掺杂硅凝胶玻璃及其薄膜的制备与光谱性质

采用溶胶－凝胶工艺制成ＣｕＩ微晶掺杂硅凝胶玻璃及其薄膜。通过Ｘ射线粉末衍射（ＸＲＤ）和高分辨透射电镜（ＨＲＴＥＭ）分析观察到玻璃中的晶相及其分布；由薄膜的室温透射光谱发现，随着热处理温度提高和时间延长，薄膜的特征透射谱谷向长波方向移动（红移），并源于玻璃中的量子尺寸效应。     

Preparation and optical study of CdS nanocrystals embedded phosphate glass

A new phosphate glass system with CdS nanocrystals dispersed in glass matrix was investigated. The phosphate glass composition with good stability has been used for preparation of CdS doped glasses. The CdS in the range of 0.5-7.0% has been doped into this glass composition. Effect of CdS content on the optical and other properties has been investigated. The optical characterization of the glass samples showed that with increasing concentration of CdS, there was a red shift in transmission cut-off of the glasses. From the transmission cut-off of each glass sample, the band gap of the CdS nanocrystals embedded glass was calculated. The band gap of CdS particles embedded glass was observed in the range of 3.1-4.1 eV. The present system is compared with CdS nanocrystals doped in silica based glass system. In the phosphate glass system, the UV transmission cut-off's are not sharp and the optical transmittance decreases with increasing CdS content in contrast to silica glass system. The reason for such behavior has been discussed in the present investigation. TEM of the CdS doped phosphate glasses showed CdS particle size in the range of 5-7 nm for lower concentration of CdS and 10-100 nm for higher concentration of CdS. The nanocrystals are non-uniform in size but uniformly dispersed in glass matrix.     

Nd3+/Yb3+共掺La2O3-TiO2-ZrO2微晶玻璃的制备及上转换发光研究

利用气悬浮方法制备了Nd³⁺/Yb³⁺共掺La₂O₃-TiO₂-ZrO₂前驱体玻璃, 通过热处理获得了微晶玻璃。通过DTA对前驱体玻璃的热稳定性进行了研究。利用光致发光谱, TEM和EDS对微晶玻璃进行了表征分析, 并研究了热处理对上转换发光的影响。结果表明: 玻璃转变温度和析晶起始温度分别为799℃和880℃. 在980 nm激光激发下, 样品发射出中心位于497, 523, 545, 603和657 nm处的五条发光带。热处理后样品上转换发光强度提高, 经过880℃保温50 min热处理的微晶玻璃显示了最强的上转换发光, 在545 nm处的发光强度是前驱体玻璃的11倍, 这是由于在微晶玻璃基质中存在致密柱状晶和Nd³⁺离子在晶体中富集造成的。     

LaBGeO5 single crystals in glass and second-harmonic generation

Flower-shaped crystals with diameters of 100–200 μm consisting of LaBGeO₅ (LBGO) single crystals similar to petals were observed in the interior of transparent LBGO surface-crystallized glasses. Each flower-shaped crystal was radially grown from the surface of the included bubbles. A more intense second-harmonic generation was observed from the LBGO crystallized glasses with the flower-shaped LBGO single crystals compared to the samples without such crystals based on the Maker fringe technique and second-harmonic (SH) generation microscopy. The SH intensity for the flower-shaped LBGO single crystals monotonically decreased with increasing temperature up to 350 °C, less than the Curie temperature reported so far (530 °C). It is considered that the internal compressive stress induced by the difference in the thermal expansion between the LBGO single crystal and the corresponding glass affect the ferroelectric property of the flower-shaped LBGO single crystals in glass.     

Composition dependence of thermally induced second-harmonic generation in chalcohalide glasses

By investigating the second-harmonic generation (SHG) of the series (100 − 2x)GeS₂·xGa₂S₃·xPbI₂ (x = 5, 10, 15, and 20) chalcohalide glass samples after thermal poling, it was found that there was an optimal poling temperature for each composition and there was also a relation between optimal poling temperature and glass transition temperature. With increasing x, the obtained second-order susceptibility χ⁽²⁾ shows an increase first and then decrease, and the maximum was seen at x = 15. A dipole reorientation model and structural relaxation causing by Ga₂S₃ and PbI₂ were proposed to explain the dependence of poling temperature on SH intensity for each composition and the presence of the maximum χ⁽²⁾ in this chalcohalide glass series.     

CdS/CdSSe quantum dots in glass matrix

The compositions containing 55 and 60% of silica have been formulated for preparation of glass filters having sharp cut-off at 475 and 575 nm. To achieve cut-off at these wavelengths, the glasses have been doped with CdS/CdSSe and melted at 1200–1300°C. The glass samples were transparent and pale yellow in colour due to presence of CdS/CdSSe tiny nano crystal (Q-dots). In situ growth of CdS/CdSSe nano crystals imparts the yellow/orange/red colour to these glasses. Optical study shows that as prepared glasses have optical cut-off in the range 350–370 nm. The linear crystal growth of CdS/CdSSe in glasses exhibits red shift in optical cut-off. The optical filter having cut-off at 475 nm can be prepared by doping CdS and cut-off filter of wavelength 575 nm by CdSSe. The TEM results show that the CdS/CdSSe nano crystals (Q-dots) ranging from 2–5 nm are uniformly distributed into the glass matrix.     

Second harmonic generation investigation on electric poling effects in fused silica

The influence of electric of poling conditions on the optical nonlinearity of fused silica has been investigated by the second harmonic generation (SHG) technique. The SHG intensity of the poled fused silica increased monotonically with increasing the poling voltage or poling time, and reached a maximum at a poling temperature of T = 250°C, but the SHG intensity decreased quickly as the thermal erasure time increased. The experimental results have been explained using an electric field induced dipole orientation model.     

稀土离子在硼铝玻璃结构中的作用

利用NMR、DSC及热膨胀等测试分析手段,分析了B2O3-Al2O3～BaO玻璃中不同掺量稀土氧化物对11B和27Al的配位及玻璃热学性能的影响规律.结果表明:当稀土含量逐渐增加时,硼氧三角体[BO3]逐渐向[BO4]转变;原先[AlO4]、[A1O5]、[AlO6]共存的铝氧多面体结构单元逐渐转变为以[AlO4]为主和少量[AlO5]共存的结构;玻璃的相转变温度升高,玻璃低温相转变困难.另外,随着稀土氧化物掺量不断增加,N系列玻璃网络结构的连接削弱,玻璃的析晶热稳定性和热膨胀率均有所降低.     

Rare-earth containing nanocrystal precipitation and up-conversion luminescence in oxyfluoride glasses

Rare-earth ion doped oxyfluoride glass with a composition of 25SiO2 x 5GeO2 x 15AIO1.5 x 40PbF2 x 10PbO x (4.9 - x)GdF3 x 0.1HoF3 x xYbF3 (x = 0, 0.1,0.2, 0.5,1,2, 3, and 4) in molar ratio was developed. When the oxyfluoride glasses are heat-treated at the first crystallization temperature, the glasses give transparent glass-ceramics in which rare-earth-containing fluorite-type nanocrystals of about 17.2 nm in diameter uniformly precipitated in the glass matrix. Comparing with the glasses before heat treatment, the glass ceramics exhibit very strong up-conversion luminescence under 980-nm light excitation. Rare-earth-containing nanocrystals were also space selectively precipitated upon laser irradiation in an oxyfluoride glass; the size of precipitated nanocrystals can be controlled by laser power and scan speed. The intensity of the green up-conversion luminescence is strongly dependent on the precipitation of beta-PbF2 nanocrystals and the YbF3 concentration. The reasons for the highly efficient Ho3+ up-conversion luminescence are discussed.     

碘化亚铜微晶掺杂硼硅酸盐玻璃的制备及其电致二阶非线性光学效应

采用可分相的Na2－Al2O3－B2O3－SiO2系为基础玻璃，以CuO／SnO、NaI为原料；分别引入Cu 、I－，成功地制备出CuI微晶掺杂硼硅酸盐玻璃·通过X射线粉末衍射（XRD）和高分辨透射电镜（HRTEM）分析观察到了玻璃中的晶相及其分布；由玻璃的室温透射光谱研究了玻璃的热处理条件与光吸收性的关系．首次报道了该半导体微晶掺杂玻璃中的电致二次谐波发生，并讨论了该效应的机理．     

Nonlinear optical properties and thermal stability of the poled polymer NTAB/PEK-c

Films of high glass transition temperature polymer polyetherketone doped with chromophore 2,2′-[4-[(5-nitro-2-thiazolyl)azophenyl]-amino]-bisethanol (NTAB) were prepared, poled by the corona-onset poling setup which includes a grid voltage making the surface-charge distribution uniform at elevated temperature. The thickness of the films was measured by the Model 2010 Prism Coupler system. Second harmonic generation d₃₃ was measured by the second harmonic generation method, and the d₃₃ is 38.12 pm/V at 1064 nm under the absorption correction. The nonlinear optical activity maintains 80% of its initial value.     

Formation and crystallization of chlorine- and bromine-containing hafnium fluoride-based glasses

We have studied glass-forming regions for ZBLAN-type hafnium fluoride-based glasses with the compositions (63–53)HfF₄ · 20BaF₂ · 4LaF₃ · (1–3)InF₃ · (0–20)NaF in which fluorine anions are partially replaced by chlorine and bromine anions. The crystallization mechanism of the glasses has been investigated by differential thermal analysis and X-ray diffraction. The results demonstrate that characteristic features of the glasses are a significant decrease in glass transition temperature (t _g) and the precipitation of fine-particle crystalline chloride and bromide phases at temperatures well below the crystallization temperature (t _x) of their fluoride analogs. We have studied the effect of the Cl/F and Cl/Br ratios in the glass batch and the melt cooling rate after glass preparation on the crystallization behavior of the glasses and determined the heat treatment temperature and time for the formation of transparent glass-ceramic samples upon heat treatment in the temperature range where chloride and bromide phases precipitate. Doping of the glasses with 1 at % or smaller amounts of rare-earth metals is found to have no significant effect on the phase segregation process during heat treatment.     

Photoinduced Second Harmonic Generation of Bi2S3 Microcrystallite Doped Silica Glass

Silica glasses doped with Bi2S3 microcystallite was prepared by the sol-gel process. Photoinduced second harmonic generation (SHG) was observed in the glass when it was irradiated with intense 1.06 μm and frequency doubled laser beams from a mode-locked Nd: YAG laser. It was found that the signal intensity increased with the irradiating time and approached a saturation gradually. The effect may be explained reasonably by the DC field model.     

Study of the solid-matrix phosphorescence properties of a heterocyclic aromatic amine and the heat capacities of glucose glasses as the temperature decreases

The heat capacities were obtained from 294 to 133 K for four glucose-glass systems. Two of the glasses were prepared from crystalline glucose. One of the glasses contained the heavy-atom salt NaI and the other glass did not contain NaI. The other two glasses were similar, but they were prepared from glucose melts. Correlations were developed between the solid-matrix phosphorescence (SMP) lifetimes and intensities of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) in the glucose glasses and the heat capacities of the glucose sugar glasses as the temperature was lowered. Several plots of reciprocal SMP lifetime versus reciprocal temperature and reciprocal SMP lifetime versus reciprocal heat capacity were compared. Also, the reciprocal SMP intensity versus reciprocal temperature plots were compared with the corresponding reciprocal SMP intensity versus reciprocal heat capacity plots. In addition, basic photo-physical equations were used to develop relationships among the lifetime data, the intensity data, and the heat capacity data. The heat capacity data and SMP lifetime data, obtained as the temperature was lowered, were discussed in relationship to low-frequency vibrational modes and beta-relaxation phenomena in the glucose glasses. The discussion of these phenomena offered explanations for some of the loss of the excited triplet-state energy of PhIP in the glucose sugar glasses.     

烧结温度对硼硅基质荧光玻璃发光性能影响

采用共烧结法制备了硼硅基质Ce: YAG荧光玻璃,研究了烧结温度在600℃~900℃范围内, Ce: YAG荧光玻璃的发光强度变化和色坐标漂移规律。结果表明, 随着烧结温度的升高, Ce: YAG荧光玻璃发光强度先增强后减弱, 700℃烧结时, 荧光玻璃获得最大发光强度; 超过850℃烧结时, 荧光玻璃无发光性能; 同时, 色坐标(x, y)发生漂移, 且比相同烧结温度的荧光粉漂移幅度大。通过X射线粉末衍射仪、差示扫描量热分析仪和X射线光电子能谱分析仪测试分析表明: 随着烧结温度升高, 荧光粉中的Ce³⁺被玻璃基质氧化成Ce⁴⁺, 玻璃液体腐蚀破坏了荧光粉YAG晶体结构, 降低了荧光玻璃的发光强度, 从而导致色坐标劣化漂移。     

Study of fluorine losses and spectroscopic properties of Er doped oxyfluoride silicate glasses and glass ceramics

The fluorine losses during synthesis of Er³⁺ doped transparent glasses in the SiO₂–PbO–PbF₂ system were investigated. The final fluorine contents of the glasses were detected by using a fluorine ion selective electrode. The results show that high fluorine losses are occured in the normal preparation processes. With the increase of initial PbF₂ contents or melting time resulted in the increase of the fluorine losses. The thermal and spectroscopic properties of the glasses and the corresponding glass ceramics were investigated through the analysis of the differential scanning calorimetry (DSC), absorption and upconversion luminescence spectra. The effects of fluorine contents show a decrease of the glass transition temperatures (Tg) of the glasses and an enhancement of upconversion intensity of the corresponding glass ceramics.     

Electrooptics parameters of the BiBO:Tm<Superscript>3+</Superscript> glass nanoparticles embedded in polymer matrices

We have found that BiB₃O₆:Tm³⁺ glass nanoparticles (NP) incorporated into the polymethylmethacrylate (PMMA) and polycarbonate (PC) polymer matrices additionally treated by dc-electric field (at electric strength about 8 kV/cm) at temperatures above the glassing temperature of the polymers show promising values of electrooptics coefficients (up to 10 pm/V at λ = 633 nm). It was established that only during incorporation into the highly polarized PC matrices one could observe an enhancement of the electroopitcs effect (EOE) coefficient with increasing time of the dc-electric treatment. The main increase was observed for all the samples at times higher than 80 min of dc-electric field treatment at temperature above the glassing temperatures of the corresponding polymers. The most striking feature is the achievement of effective electrooptics coefficient value below than 10 pm/V (λ = 633 nm) for the 4% content of the Tm doped BiBO glass nanoparticle (NP) embedded in the PC matrix. In the case of the bulk glasses the thermal poling unambiguously shows that the achieved maximal values of the electrooptics coefficient did not exceed 3.2 pm/V for 0.5% Tm⁺³ concentration.