FTIR structural investigation of gamma irradiated BaO–Na2O–B2O3–SiO2 glasses

Fourier transform infrared (FT-IR) spectra of xBaO–15Na₂O–(70−x)B₂O₃–15SiO₂ glass system with x=0, 5, 10, 15 and 20 (mol%) has been measured in the spectral range 400–4000 cm⁻¹ at room temperature in order to understand the characteristic frequencies of the chemical bonds and bonding mechanisms, which are susceptible to the structural and spectral changes. The effect of gamma irradiation in the dose range 0.1 kGy–60 kGy on the infrared absorption spectra of these glasses is also reported. The change in the glass structure due to the effect of composition is also discussed. It has been observed that irradiation of the glasses with the gamma rays increases the BO₃ groups and the non bridging oxygens which make the network loose.     

Investigation of structural,physical and optical properties of CeO2–Bi2O3–B2O3 glasses

xCeO₂–30Bi₂O₃–(70−x) B₂O₃ glasses are synthesized by using the melt quench technique. A number of studies such as XRD, density, molar volume, optical band gap, refractive index and FTIR spectroscopy are employed to characterize the glasses. The band gap decreases from 2.15 to 1.61 eV, refractive index increases from 2.67 to 2.93 and density increases from 4.151 to 4.633 g/cm³. The decrease in band gap with CeO₂ doping approaches the semiconductor behavior. FTIR spectroscopy reveals that incorporation of CeO₂ into glass network helps to convert the structural units of [BO₃] into [BO₄] and results in Bi–O bond vibration of [BiO₆].     

Magnetic and structural properties of CaO–SiO2–P2O5–Na2O–Fe2O3 glass ceramics

Magnetic properties of glass ceramics derived from glasses with composition 41CaO·(52−x)SiO₂·4P₂O₅·xFe₂O₃·3Na₂O (2?x?10 mol% iron oxide (Fe₂O₃)) are reported. Structural investigation revealed the presence of nanocrystalline magnetite phase in the heat-treated samples containing x?2 mol% Fe₂O₃. Magnetic hysteresis cycles of the glass-ceramic samples were obtained with a maximum applied field of ±20 kOe as well as a low field of ±500 Oe, in order to evaluate the potential of these glass ceramics for hyperthermia treatment of cancer. Samples with x>2 mol% of iron oxide exhibited magnetic behavior similar to soft magnetic materials with low coercivity. The evolution of magnetic properties in these samples as a function of iron oxide molar concentration is correlated with the amount and crystallite size of magnetite phase present in them.     

Physical,optical and radiative properties of CaSO4–B2O3–P2O5 glasses doped with Sm3+ ions

Trivalent rare earth ions doped borosulfophosphate glasses are in high demand owing to their several unique attributes that are advantageous for applications in diverse photonic devices. Thus, Sm³⁺ ion doped calcium sulfoborophosphate glasses with composition of 25CaSO₄–30B₂O₃–(45?x)P₂O₅–xSm₂O₃ (where x?=?0.1, 0.3, 0.5, 0.7 and 1.0 mol%) were synthesized using melt-quenching technique. X-ray diffraction confirmed the amorphous nature of the prepared glass samples. Differential thermal analyses show transition peaks for melting temperature, glass transition and crystallization temperature. The glass stability is found in the range 91?°C to 116?°C which shows increased stability with addition of Sm₂O₃ concentration. The Fourier transform infrared spectral measurements carried out showed the presence of vibration bands due to PO linkage, BO_3, BO₄, PO₄, POP, OPO, SOB, and BOB unit. Glass density showed increase in value from 2.179 to 2.251?g cm^?3 with increase in Sm₂O₃ concentration. The direct, indirect band gap and Urbach energy calculated were found to be within 4.368–4.184?eV, 3.641–3.488?eV and 0.323–0.282?eV energy ranges, respectively. The absorption spectra revealed ten prominent peaks centered at 365, 400, 471, 941, 1075, 1228, 1375, 1477, 1528 and 1597?nm corresponding to ⁴D_3/2,⁶H_5/2→⁴I_11/2,⁶P_3/2, ⁶F_11/2, ⁶F_9/2, ⁶F_7/2, ⁶F_5/2, ⁶F_3/2, ⁶H_15/2 and ⁶F_1/2 transitions respectively. Photoluminescence spectra monitored at the excitation of 398?nm exhibits four emission bands positioned at 559, 596,643 and 709?nm corresponding to ⁴G_5/2→⁶H_5/2, ⁶H_7/2, ⁶H_9/2 and ⁶H_11/2 transitions respectively. The nephelauxetic parameters calculated showed good influence on the local environment within the samarium ions site and the state of the SmO bond. The Judd–Ofelt intensity parameters calculated for all glass samples revealed that Ω_6?>?Ω_4?>?Ω₂. The emission cross-section and the branching ratios values obtained for ⁴G_5/2→⁶H_7/2 transition indicate its suitability for LEDs and solid-state laser application.     

关于Li2O·P2O5·CdO玻璃的核磁共振研究

以³¹P核为探针对具有不同摩尔比(x,y)的xLi₂O·P₂O₅·yCdO玻璃样品进行了核磁共振研究。通过Bruker MSL-300谱仪得到了静态核磁共振谱,工作频率为121.487MHz。在玻璃中,三种基本类型的磷结构组元随机地连在一起形成网络,每种组无有自己的核磁共振特征,基本结构组元的相对含量依赖于Li₂O和CdO的摩尔比,即依赖于x和y。为了描述组元的含量,我们提出了一个简洁的模型,它的合理性已被其预言结果与对实验观测核磁共振粉末谱的拟谱结论的一致性所证实。 关键词：     

Optical,thermal, and structural properties of Nb2O5–TeO2 and WO3–TeO2 glasses

Glass samples from two systems, Nb₂O₅–TeO₂ and WO₃–TeO₂, were prepared at two melt quenching rates and characterized by density, DSC, UV-visible, and Raman spectroscopy. Addition of Nb₂O₅ decreased the density while increase in the WO₃ concentration increased the density. Glasses prepared at higher quenching rates had smaller densities than glasses of the same composition prepared at lower quenching rate although the short-range structure of both glasses were identical, as revealed by Raman spectroscopy. Optical studies found an intense absorption band just below the absorption edge in both the glass series. This band was attributed to electronic transitions of Nb⁵⁺ and W⁶⁺ ions and a lone pair of electrons on Te atoms. Glass transition temperature increased with increase in Nb₂O₅ and WO₃ mol% due to the increase in average bond strength in the glass network. Raman spectroscopy showed that the concentration of TeO₄ units decreased with the increase in Nb₂O₅ and WO₃ concentrations.     

P2O5—Li2O—LiCl-Al2O3系统非晶态离子导体与金属电极间界面阻抗的色散关系

本文研究了非晶态锂离子导体29.6P₂O₅-44.4Li₂O-26.0LiCl和36.3P₂O₅-44.4Li₂O-15.1LiCl-4.2Al₂O₃的阻抗谱,给出了测量盒系统的等效电路,得出了界面阻抗的色散关系。在一定条件下,此界面阻抗过渡到恒相角阻抗。 关键词：     

Nonlinear optical properties of 75TeO2－20Nb2O5－5ZnO glasses doped with CeO2

Nonlinear optical properties of 75TeO_2－20Nb_2O_5－5ZnO glasses doped with CeO_2 have been investigated with a self-diffracted time-resolved degenerate four-wave mixing (DFWM) technique at different excitation intensities and lattice temperatures. The DFWM signal exhibits three peaks at higher excitation intensities, where a main peak appears at zero delay time and two rather weak side peaks are located symmetrically at the negative and positive time delay. Due to destructive interferences between the fifth- and third-order polarizations, the line-shape of the main peak around the zero time delay evolves from single peak into a double-peak structure with increasing excitation intensity. Two side peaks emerge at the positive and negative time delay and gradually intensify with increasing excitation intensity or lattice temperature, and their positions are independent of the pulse duration, temperature and excitation intensity, which are attributed to the many-body Coulomb interaction.     

Preparation and characteristics of?a?BaO–Al2O3–B2O3–SiO2–La2O3 glass ceramic via spray pyrolysis

The characteristics of a BaO–Al₂O₃–B₂O₃–SiO₂–La₂O₃ glass ceramic prepared by spray pyrolysis were studied. Glass powders with spherical shape and amorphous phase were prepared by complete melting at a preparation temperature of 1 500°C. The mean size and geometric standard deviation of the powders prepared at the temperature of 1 500°C were 0.6 μm and 1.3. The glass powders had similar composition to that of the spray solution. The glass transition temperature (T _g) of the glass powders was 600.3°C. Two crystallization exothermic peaks were observed at 769.3 and 837.8°C. Densification of the specimen started at a sintering temperature of 600°C, in which Ba₄La₆O(SiO₄)₆ as main crystal structure was observed. Complete densification of the specimen occurred at a sintering temperature of 800°C. The specimens sintered at temperatures above 800°C had main crystal structure of BaAl₂Si₂O₈.     

Varistor and dielectric properties of Cr2O3 doped SnO2–Zn2SnO4 composite ceramics

Cr₂O₃ doped SnO₂–Zn₂SnO₄ composite ceramics were prepared by traditional ceramic processing and the varistor, dielectric properties were investigated. With increasing Cr₂O₃ content, the breakdown electrical field E_B increases from 11 to 92 V/mm and the relative dielectric constant ε_r measured at 1 kHz, 50 °C decreases from 11,028 to 3412, respectively. The barrier height ?_B about 0.8–0.84 eV and the decreasing of SnO₂ grain size suggest that the varistor behavior with high ε_r is originated from SnO₂–SnO₂ or SnO₂–Zn₂SnO₄ grain boundary. In the dielectric spectra lower than 1 kHz, a dielectric peak is presented and depressed with increasing bias voltage. Similarly, at high temperature, the dielectric constant also presents a dielectric peak in the temperature spectra and the peak becomes faint with increasing frequency. The exhibition of the dielectric peak is thought to be attributed to the conduction of grain boundary since it is accompanied by the sharp increase of dielectric loss. In addition, a dielectric relaxation with the activation energy about 0.4–0.5 eV was observed in the temperature range of 20–100 °C. Based on the results, the formation mechanism of Schottky barriers at grain boundaries and the varistor behavior with high dielectric constant are well understood.     

Broadband near-IR emission and temperature dependence in Er/Tm co-doped Bi2O3–SiO2–Ga2O3 glasses

The broadband near-IR emission has been investigated in a series of Er/Tm co-doped Bi₂O₃–SiO₂–Ga₂O₃ (BSG) glasses with 800 nm laser diode as an excitation source. A broadband emission extending from 1350 to 1650 nm with a full width at half maximum (FWHM) around 165 nm is obtained in 0.2 wt% Er₂O₃ and 1.0 wt% Tm₂O₃ co-doped BSG glass. The fluorescence decay curves of glasses are measured and maximum energy transfer efficiency from Er³⁺ to Tm³⁺ reaches 71% when Tm³⁺ concentration is 1.0 wt%. The temperature dependence of the broadband emission spectra in Er³⁺–Tm³⁺ co-doped BSG glass is also recorded to further understand the energy-transfer processes between Er³⁺ and Tm³⁺. The present work suggests that Er/Tm co-doped BSG glasses can be a potential candidate for broadband integrated amplifier.     

Sol–gel synthesis,structural and ion transport studies of lithium borosilicate glasses

Lithium borosilicate (LBS) glasses of different modifier to formers (m/f) ratios were synthesized through sol–gel process. Structural characterisation of LBS glasses were made using XRD, FTIR and DSC techniques. XRD pattern of LBS samples showed amorphous phase for gels heat treated between 573 and 698 K and further heat treatment above 698 K showed the formation of crystalline multiphases. FTIR spectra for dried LBS gels between 338 and 443 K showed the presence of hydroxyl group on the surface of silicate and borates matrix and on heat treatment, the FTIR spectra revealed the formation of silicate and borate linkages in LBS glassy matrix. DSC curve confirmed the presence of adsorbed water molecules in LBS glassy matrix. Impedance measurements were carried out on LBS samples of different m/f ratios as a function of temperature and data were analyzed using Boukamp equivalent circuit software. The conductivity of LBS glasses at different temperatures was calculated from analyzed impedance data. Activation energy (E_a) is obtained from Arrhenius plots of the dc conductivity and it is found to be 0.64 (±0.02) eV for high conducting sample. ac conductivity is calculated from impedance data and analyzed using Jonscher's power law (JPL) exponent (s) for m/f ratios of LBS samples at different temperatures. The power law exponent s of LBS glasses exhibited a non-linear behavior with temperature. The electric modulus data were fitted with Kohlraush–William–Watts (KWW) stretched exponential function and the modulus formalism is used to study the ionic relaxation behavior in LBS samples.     

Optical and IR study of Li2O–CuO–P2O5 glasses

Infrared (IR) and UV spectra of ternary Li₂O–CuO–P₂O₅ glasses in two series Li₂O(65−X)%–CuO(X%)–P₂O₅(35%), X = 20, 30, 40 and Li₂O(55−X)%–CuO(X%)–P₂O₅(45%), X = (10, 20, 30) were studied. Infrared (IR) investigations showed the metaphosphate and pyrophosphate structures and with increase of CuO content in metaphosphate glass, the skeleton of metaphosphate chains is gradually broken into short phosphate groups such as pyrophosphate. IR spectra showed one band at about 1,220 and 1,260 cm⁻¹ for P₂O₅(35%) and P₂O₅(45%) series, respectively, assigned to P=O bonds. For CuO additions ≤20 mol%, the glasses exhibit two bands in the frequency range 780–720 cm⁻¹ which are attributed to the presence of two P–O–P bridges in metaphosphate chain. But for CuO addition ≥30 mol%, the glasses exhibit only a single band at 760 cm⁻¹ which is assigned to the P–O–P linkage in pyrophosphate group. In optical investigations, absorption coefficient versus photon energy showed three regions: low energy side, Urbach absorption, and high energy side. In Urbach’s region, absorption coefficient depends exponentially on the photon energy. At high energy region, optical gap was calculated and investigations showed indirect transition in compounds and decreases in optical gap with increases of copper oxides contents that is because of electronic transitions and increasing of nonbridging oxygen content.     

非晶锂离子导体P2O5-0.7Li2O-0.4LiCl-0.1Al2O3的离子导电性与结构研究

本文研究了非晶锂离子导体P₂O₅-0.7Li₂O-0.4LiCl-0.1Al₂O₃的60目、120目、200目粉末、粉末压片和整片非晶在60至380℃的离子电导率和激活能。发现颗粒度减小能使离子电导率提高四倍以上,但不影响激活能,它归因于同一非晶相的界面效应。各样品在380℃等温热处理76h内的离子电导率和X射线衍射研究表明:颗粒度越小,晶化就越容易。整片非晶比粉末压片不仅电导率提高两个数量级,激 关键词：     

Li2SO4—Li2B2O4,Li2SO4—(NH4)2SO4赝二元系相图及离子导电性研究

本文用差热分析和X射线衍射方法对Li₂SO₄-Li₂B₂O₄和Li₂SO₄-[NH₄]₂SO₄两个赝二元系相图进行了研究。Li₂SO₄-Li₂B₂O₄是共晶体系,共晶温度为720℃ 关键词：     

Li2O-P205O-V2O5系统非晶材料电学性质与磁共振研究

本文对Li₂O-P₂O₅-V₂O₅系统非晶态中的几组试样进行了电导率、核磁共振及顺磁共振测试。实验分析表明非晶态的log(σΤ)-1/Τ曲线都是由两个直线段构成。电导率在转变温度以后的“晶化前期”异常增大,这归因于该阶段非晶态结构有序化程度增加所致,利用ESR实验结果对非晶态进行钒离子价态分析表明,该系统非晶态中钒离子仅以V⁴⁺和V⁵⁺状态存在。固定P< 关键词：     

Effects of BaCu（B2O5 ） addition on sintering temperature and microwave dielectric properties of Ba5Nb4O15–BaWO4 ceramics

The effects of BaCu(B2O5)(BCB) addition on the microstructure, phase formation, and microwave dielectric properties of Ba5Nb4O15–BaWO4ceramic are investigated. As a sintering aid, BaCu(B2O5) ceramic could effectively lower the sintering temperature of Ba5Nb4O15–BaWO4ceramic from 1100?C to 950?C due to the liquid-phase effect. Meanwhile,BaCu(B2O5) addition effectively improves the densification of Ba5Nb4O15–BaWO4ceramic and significantly influences the microwave dielectric properties. X-ray diffraction analysis reveals that Ba5Nb4O15and BaWO4coexist with no crystal phase of BaCu(B2O5) in the sintered ceramics. The Ba5Nb4O15–BaWO4ceramics with 1.0 wt% BaCu(B2O5) sintered at 950?C for 2 h presents good microwave dielectric properties of εr = 19.0, high Q × f of 33802 GHz and low τfof2.5 ppm/?C.     

Li2O-2B2O3熔体的物性研究

系统测量了四硼酸锂(Li₂Ｏ-２Ｂ_２Ｏ_３)熔体的密度ρ、表面张力γ随着温度的变化规律，实验结果表明在1100K到1500K范围内Li₂Ｏ-２Ｂ_２Ｏ_３高温熔体的密度和表面张力随着温度的升高均线性减小.通过实验数据拟合得出熔体密度与温度关系为ρ(T)=2.574—4.89×１０^－４T，熔点处Li₂Ｏ-２Ｂ_２Ｏ关键词： 功能晶体 四硼酸锂 密度 表面张力