UV-visible and infrared absorption spectroscopic studies of gamma irradiated tungsten-doped lithium phosphate glasses

Ultraviolet-visible and infrared spectroscopic techniques were employed to investigate the undoped lithium phosphate glass and other samples of the same composition doped with varying WO₃ contents. The same spectroscopic properties were remeasured after subjecting the samples to 3 and 6 Mrad doses of gamma irradiation on the measured properties. Such combined analytical techniques are expected to give information about the state of tungsten ions in such lithium phosphate glass and justify the effect of gamma irradiation. The work aims to deduce the radiation-induced defects generated through successive gamma irradiation by optical measurements. Also, the study is expected to realize through IR spectroscopy, the main structural building groups and the influence of tungsten ions within the structural vibrational groups of the studied glasses.     

UV-visible and infrared absorption spectra of gamma irradiated CuO-doped lithium phosphate, lead phosphate and zinc phosphate glasses: A comparative study

Undoped and CuO-doped lithium phosphate, lead phosphate and zinc phosphate glasses were prepared. UV-visible and infrared absorption spectra of the prepared samples were measured before and after successive gamma irradiation. Experimental optical spectra of the undoped samples reveal strong UV absorption bands, which are attributed to the presence of trace iron impurities in both the lithium and zinc phosphate glasses while the lead phosphate glass exhibits broad UV bands due to combined absorption of trace iron impurities and divalent lead ions. The CuO-doped glasses reveal an extra broad visible band due to Cu²⁺ ions in octahedral coordination. The effects of gamma irradiation have been analyzed for both the sharing of all constituent components including trace iron impurities. Infrared absorption spectra of the prepared samples were investigated by the KBr disk technique. The FTIR spectra reveal main characteristic absorption bands due to different phosphate groups. The IR spectra are observed to be slightly affected by the increase of CuO in the doping level (0.2-3%) indicating the stability of the main network units.     

γ射线辐照与O2退火对Bi∶CdWO4单晶体光谱性能的影响

用500和800℃,在氧气下,对掺Bi钨酸镉晶体进行热退火处理,测定了处理后晶体的吸收光谱与发射光谱。随退火处理温度的升高晶体的吸收强度降低,吸收边带发生蓝移。在373与980nm的光激发下,分别观察到发光中心为528nm的CdWO4晶体本征发光与发光中心为1 078nm的Bi 5+发光。晶体样品通过高温氧气处理,发光中心为528nm的荧光带强度增强,但发光中心为1 078nm的荧光带强度变弱。这可能是由于氧退火使Bi 5+转化成Bi 3+所致。经退火处理后,晶体的颜色逐渐变浅,透光率明显提高,这是由于晶体中氧空位减少所致。经γ射线辐照处理后,528nm处的发光增强,而1 078nm处的发光减弱,这可能是由于γ射线辐照后导致Bi 5+变成Bi 3+。     

Study of glasses and glass ceramics in Bi2O3-GeO2-Fe2O3 and Bi2O3-GeO2-Cr2O3 systems by optical spectroscopy

The ferroelectric Bi₂GeO₅ crystalline phase is synthesized by heat treatment of 1Bi₂O₃-1GeO₂-xFe₂O₃ and 1Bi₂O₃-1GeO₂-yCr₂O₃ glasses. The obtained glass ceramics and initial glasses are studied using X-ray diffraction analysis and optical spectroscopy. The dielectric characteristics are measured, and the Curie temperature is determined. The effect of chromium and iron ions on the absorption spectra and dielectric properties of glasses and glass ceramics is determined.     

掺Bi的GeO2-Al2O3-Na2O玻璃的热学和光学性质

用高温熔融法制备了96GeO-(3-χ)Al2O3-χNa2O-1NaBiO3 （将χ分别为0,0.5,1.5的玻璃命名为A1,A2,A3）和 96GeO-(3.5-ψ)Al2O3-ψχNa2O-0.5Bi2O3（将ψ分别为0,0.5,2的玻璃命名为B1,B2,B3）玻璃。观察到样品在1 220 nm处（800 nm 激光二极管激发）的超宽带发光特性（半高宽约250 nm）。结果表明,以NaBiO3形式引入Bi5+到玻璃原料中比以Bi2O3形式引入Bi3+到原料中得到的玻璃在1 220 nm处的发光强度大4.6倍,且荧光寿命和荧光半高宽也分别从280 μs和195 nm增加到了434 μs和275 nm。从A3,A2和A1的吸收边带的红移可初步推断出A3,A2及A1玻璃中Bi5+的含量逐步增加。总结吸收光谱与发射光谱的变化规律,认为Bi离子近红外高发射强度和宽荧光半高宽是由Bi5+的发光引起的。在两组玻璃中,热稳定性以及荧光发射截面积与荧光寿命的乘积值和荧光发射截面积与荧光半高宽的乘积值随着Na2O含量的增加而增加。     

以间质隔离法研究CH3O分子在p-H2间质中的红外吸收光谱

本研究利用低温间质隔离技术搭配红外光谱仪研究CH3ONO在p-H2间质中的光解产生CH3O。实验观察到位于689.3/694.6cm-1、945.9/951.7cm-1、1041.8cm-1、1224.7cm-1、1235.5cm-1、1347.7cm-1、1365.4cm-1、1427.5cm-1、1519.5cm-1、1522.3cm-1等处的CH3O红外吸收谱线,并分析得出各振动模式分别为电子态E1/2a1对称性的ν6、电子态E1/2a2对称性的ν6、电子态E3/2对称性的ν2、电子态E3/2e对称性的ν6、电子态E1/2e对称性的ν6、电子态E1/2a1对称性的ν5、电子态E3/2对称性的ν2、电子态E1/2对称性的ν2、电子态E3/2e对称性的ν5及电子态E1/2e对称性的ν5。     

以间质隔离法研究CH3O分子在p-H2间质中的红外吸收光谱

本研究利用低温间质隔离技术搭配红外光谱仪研究CH3ONO在p-H2间质中的光解产生CH3O。实验观察到位于689.3/694.6cm-1、945.9/951.7cm-1、1041.8cm-1、1224.7cm-1、1235.5cm-1、1347.7cm-1、1365.4cm-1、1427.5cm-1、1519.5cm-1、1522.3cm-1等处的CH3O红外吸收谱线,并分析得出各振动模式分别为电子态E1/2a1对称性的ν6、电子态E1/2a2对称性的ν6、电子态E3/2对称性的ν2、电子态E3/2e对称性的ν6、电子态E1/2e对称性的ν6、电子态E1/2a1对称性的ν5、电子态E3/2对称性的ν2、电子态E1/2对称性的ν2、电子态E3/2e对称性的ν5及电子态E1/2e对称性的ν5。     

Optical spectra and local structure of Eu3+ ions doped in Nb2O5-La2O3-B2O3-BaO glasses

The xNb2O5-(15-x)La2O3-40B2O3-45BaO (x = 5, 7.5, 12.5 mol%) glasses doped with Eu3+ ions in 1mol% are fabricated by the melting method. The Fourier transform infrared (FTIR) spectra, phonon sideband spectra, emission and excitation spectra of the glasses are measured. The crystal field parameter and coordination number of Eu3+ ions in the glasses are obtained according to the splitting of their 5D0 - 7F1levels. The intensity parameters Ω2 and Ω4 of Eu3+ ions for optical transition are calculated from their emission spectra in terms of reduced matrix U(t) (λ= 2,4,6) character for optical transitions. The results indicate that the intensity parameters Ω2 and Ω4 increase with the increase of Nb2O5 content, suggesting that the symmetry becomes lower, the band of Eu and O atoms becomes stronger and the covalence increases with the increase of Nb2O5 content.     

纯铌酸锂晶体红外光谱的低温研究

测量了同成分纯铌酸锂的低温红外光谱,发现低温下铌酸锂晶体将会出现位于3200 cm^-1左右的新红外吸收峰.研究发现该峰与晶体中的氢离子无关,并且其峰强和峰形都随温度的升高发生复杂的变化.基于上述实验结果,认为该峰应该起源于电子在相邻的小极化子（Nb⁴⁺_Li）和自由极化子（Nb⁴⁺_Nb）之间的跃迁.另外,通过拟合发现新红外吸收峰可分解成三个高斯峰,这三峰应归因于能量有细微差别的三种跃迁. 关键词： 铌酸锂 红外吸收光谱 杂质缺陷