共查询到18条相似文献,搜索用时 156 毫秒
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掺钕磷酸盐激光玻璃的光谱特性 总被引:3,自引:1,他引:2
掺钕激光玻璃广泛应用于核聚变、高功率激光放大器和光纤激光器等领域。磷酸盐玻璃热膨胀系数高、热稳定性和化学稳定性差、热机械强度低。通过改变玻璃组分,即添加Al2O3和F2,并改进制备工艺来降低热膨胀系数,除去铂和分子水。测量了磷酸盐玻璃中Nd3+离子的荧光光谱、吸收光谱及玻璃的热膨胀系数。根据吸收光谱计算掺钕磷酸盐激光玻璃的光谱参数。通过对掺钕磷酸盐玻璃的热膨胀系数的实际测量和计算,分析了玻璃的热稳定性。结果表明,在基质玻璃中引入Al2O3使激光玻璃的热膨胀系数可降低到α=38.75×10-7/℃,引入F2既达到了除水的目的又降低了玻璃的声子能量,提高了荧光发射的量子效率,并优化了光谱性能,拓展了掺钕磷酸盐激光玻璃的应用范围。 相似文献
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以测量玻璃热膨胀系数和折射率温度系数实验、太阳能电池基本特性测量实验为基础,介绍了用MatLab曲线拟合工具箱处理物理实验数据、拟合实验曲线的基本方法,展示了其简单、快捷、高效的特点。 相似文献
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苑晓丽 《原子与分子物理学报》2013,30(6)
本文主要通过平面波赝势密度泛函理论的第一性原理计算方法,采用了广义梯度近似(GGA)交换相关函数,研究了六角结构的Zr4Al2的EOS态方程和热动力学性质。通过采用了声子效应的准谐近似德拜模型,我们成功得到了晶胞体积V随温度以及V/V0、德拜温度Θ、热熔CV 随压强P的变化关系。另外,我们还研究了热膨胀系数α及格林参数γ随温度和压强的变化关系,计算结果表明格林参数和热膨胀系数随温度的升高而增加,但是在较高的温度下,热膨胀系数几乎不受温度的影响。 相似文献
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根据溴化锂水溶液的相关物性计算模型,提出了当已知溴化锂溶液比焓和浓度时求其温度的计算机解法,并针对烟气型双效并联溴化锂吸收式制冷机组,利用Visual Basic面向对象的编程技术编制了其可视化设计程序,为工程上设计计算提供了一种高效、快捷的解决方法. 相似文献
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在303~383 K和NPT系综和COMPASS力场下对β-1,3,5,7-四硝基-1,3,5,7-四氮杂环辛烷(HMX)超晶胞初始结构的分子动力学模拟,得到常压下各温度的晶体平衡构型并发现分子的堆积方式不变;通过线性拟合求算出线膨胀系数与实验值相近,体现出明显的各向异性. 采用密度泛函理论方法对沿各晶轴方向膨胀率变化(100%~105%)的HMX单胞模型进行了总能计算,得到的能量变化率体现各向异性并与热膨胀系数值关联,建立了关联方程. 由此阐
释了HMX晶体热膨胀各向异性的本质即特定的分子堆积模式. 相似文献
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为实现对干凝胶法空心玻璃微球(HGM)渗透性能的有效调控,研究了初始玻璃配方、载气成分、精炼温度、精炼区长度、HGM壁厚对HGM渗透性能的影响。结果表明:当精炼温度低于1400 ℃时,初始玻璃配方对HGM渗透性能有显著影响。但是,随着精炼温度的升高和精炼区长度的延长,液态玻璃中碱金属氧化物的挥发比例逐渐增大,由不同初始玻璃配方制备的HGM对氘气的渗透性能逐渐趋近于相同。随着载气中氦气体积分数的降低或HGM壁厚的增大,室温下HGM对氘气的渗透系数逐渐减小。 相似文献
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本文主要通过平面波赝势密度泛函理论的第一性原理计算方法,采用广义梯度近似(GGA)交换相关函数,研究了六角结构的Zr4Al2的EOS态方程和热动力学性质.通过采用了声子效应的准谐近似德拜模型,我们成功得到了晶胞体积V随温度以及V/V0、德拜温度(?)、热熔CV随压强P的变化关系.另外,我们还研究了热膨胀系数α及格林参数γ随温度和压强的变化关系,计算结果表明格林参数和热膨胀系数随温度的升高而增加,但是在较高的温度下,热膨胀系数几乎不受温度的影响. 相似文献
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介绍了第八届亚洲物理奥林匹克竞赛中实验考题——"干涉法测量玻璃热膨胀系数和折射率温度系数"的内容、实验原理,并对实验的考试结果进行了分析. 相似文献
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Thermodynamic and structural properties of polystyrene/C_(60) composites: A molecular dynamics study 下载免费PDF全文
《中国物理 B》2020,(2)
To tailor properties of polymer composites are very important for their applications.Very small concentrations of nanoparticles can significantly alter their physical characteristics.In this work,molecular dynamics simulations are performed to study the thermodynamic and structural properties of polystyrene/C_(60)(PS/C_(60)) composites.The calculated densities,glass transition temperatures,and coefficient of thermal expansion of the bulk PS are in agreement with the experimental data available,implying that our calculations are reasonable.We find that the glass transition temperature Tg increases accordingly with an added concentration of C_(60) for PS/C_(60) composites.However,the self-diffusion coefficient D decreases with increase of addition of C_(60.)For the volumetric coefficients of thermal expansion(CTE) of bulk PS and ps/C_(60) composites,it can be seen that the CTE increases with increasing content of C_(60) above Tg(rubbery region).However,the CTE decreases with increasing content of C_(60) below Tg(glassy region). 相似文献
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Samir Y. Marzouk 《哲学杂志》2013,93(33):4393-4407
The longitudinal and shear ultrasonic wave velocities for different compositions of SiO2–Na2O–CaO–P2O5 glasses were measured at room temperature (305 K) using a pulse-echo method at a frequency of 4 MHz. The elastic moduli, Poisson's ratio, microhardness, Debye temperature and other ultrasonic parameters were obtained from experimental data and analyzed using bond compression theory. By calculating the number of network bonds per unit volume, the average stretching constant, and the average ring size, information about the structure of the glass can be deduced. Structural changes after doping with CeO2 were investigated by FTIR spectroscopy, and by measurements of the thermal expansion coefficient, glass transition and softening temperature to throw more light on the characterization of these glasses. 相似文献
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Edge-cladding is a key factor in improving saturated small signal gain coefficient βs of large laser disc glass. In this paper, the glasses were melted with traditional method. The influences of mixed alkali effect (MAE) on refractive index, thermal expansion coefficient α, glass transition temperature Tg, dilatometer softening temperature Td, and relative chemical durability of phosphate edge-cladding glasses were studied.The results reveal that when Li/(Na + Li) = 0.5, Tg, Td, and dissolution rate (DR) reach a minimal value.These results are preferred in phosphate edge-cladding glasses. 相似文献
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折射率与电声子相互作用的关系 总被引:1,自引:1,他引:0
从微观出发研究电声子相互作用对折射率的影响。用半经典方法导出一个适用于晶态和无序度小的介质折射率公式和折射率温度系数公式。首次指出电声子相互作用引起的折射率温度系数,高温时为一常数,低温时与T~3成正比。并与实验作了对比,理论曲线与实验符合得很好。用得到的公式计算了好几种材料的温度系数。计算值与实验值相符合。 相似文献
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J. Uchil K. P. Mohanchandra K. Ganesh Kumara K. K. Mahesh T. P. Murali 《Physica B: Condensed Matter》1999,270(3-4)
Phase transformation in the near-equiatomic, cold-worked Nitinol, exhibiting shape memory effect, has been investigated through the study of thermal expansion by employing thermomechanical analyser (TMA). The characteristic transformation temperatures determined by this method are compared with those obtained through DSC thermograms. The reliability and sensitivity of the thermal expansion probe have been discussed. The variation of thermal expansion coefficient with temperature in different heat treated samples has been studied in the range 30–120°C. Thermal expansion coefficient is found to be −ve during M↔A transformation and +ve in R↔A transformations. Thermal expansion coefficient in martensitic region in the presence and absence of R-phase has been determined. 相似文献