Bi2O3-B2O3-Ga2O3玻璃的光学折射率和带隙研究

采用传统熔融淬冷法制备了5组高Bi2O3含量的Bi2O3-B2O3-Ga2O3系统玻璃样品.测试了玻璃样品的密度,折射率和吸收光谱.利用经典的Tauc方程计算了样品的间接允许光学带隙Eopgi,直接允许光学带隙Eopgd和Urbach能量ΔE.根据Duffy等人提出的经验推导公式计算了样品的能量带隙Eg.研究了Ga2O3含量对玻璃样品的密度、折射率、摩尔折射度Rm、金属标准值Mm、光学带隙、能量带隙和Urbach能量的影响,并分析了它们之间的关系.结果表明:随着Ga2O3含量的增加,玻璃样品的密度和折射率逐渐增大,但Ga3+对玻璃折射率的影响要小于B3+;玻璃样品的紫外吸收增强,光学带隙和能量带隙逐渐减小,光学带隙和能量带隙的比值约为1:1.1;Urbach能量逐渐减小,即玻璃中带裂变和缺陷形成的趋势越小.     

La2Mo2O9掺杂钛酸铋钠铁电陶瓷的微观结构与光电性能

铁电陶瓷的极化内建电场可分离光生载流子并有效降低载流子间的复合率,但是其高带隙限制了对光的吸收。本文以具有良好铁电性能的Bi_0.5Na_0.5TiO₃(BNT)陶瓷为基体,通过掺杂La₂Mo₂O₉降低光学带隙,提高光电流密度。样品使用传统固相法制备,随后分析了此陶瓷的XRD、拉曼、光吸收、光电流、铁电和介电性质。结果表明,La₂Mo₂O₉掺杂能显著提高光吸收强度,随其含量增加,光学带隙值先明显下降,然后缓慢增加。在掺杂含量为0.7%(摩尔分数)时,陶瓷的带隙值最低为1.57 eV,远低于纯BNT陶瓷的2.9 eV,对应的最大光电流密度和开路电压为71.06 nA/cm²和4.40 V,得到的最大输出功率为312.7 nW/cm²,并且随时间增加变化不大,同时保持很好的铁电性能。研究结果表明,La₂Mo₂O₉改性BNT铁电陶瓷是一种非常有前景的铁电光伏材料。     

不同Al2O3/SiO2比的MgO-Al2O3-SiO2微晶玻璃制备及性能研究

本文采用烧结法制备MgO-Al₂O₃-SiO₂(MAS)微晶玻璃，研究不同Al₂O₃/SiO₂质量比对MAS微晶玻璃的微观结构和理化性能的影响，采用X射线衍射、差热分析、红外光谱、扫描电子显微镜对基础玻璃与微晶玻璃的结构和表面形貌进行表征，并对微晶玻璃的密度、力学性能、耐蚀性、热学性能和介电性能进行测试分析。结果表明：随着Al₂O₃/SiO₂质量比从0.52增大至0.64,基础玻璃的玻璃化转变温度T_g增大、析晶峰值温度T_p减小，促使样品析出α-堇青石晶相；样品密度在2.52～2.60 g/cm³波动，介电常数ε_r由1.73增加到4.51,热膨胀系数由4.46×10^-6℃^-1降低到2.38×10^-6℃^-1,介电损耗tan...     

Al2O3含量对PbO-CaO-B2O3-SiO2系玻璃析晶行为与烧结性能的影响

PbO-CaO-B₂O₃-SiO₂系玻璃粉体是耐高过载低温共烧陶瓷(LTCC)生瓷带的主要组成部分。玻璃粉体的析晶行为影响烧结性能,进而决定基板的使用性能。本文研究了Al₂O₃含量对PbO-CaO-B₂O₃-SiO₂系玻璃析晶行为与烧结性能的影响。结果表明:向PbO-CaO-B₂O₃-SiO₂系玻璃中引入Al₂O₃可抑制玻璃析晶,防止高膨胀晶相的析出,并提高玻璃烧结密度;不含Al₂O₃的PbO-CaO-B₂O₃-SiO₂玻璃粉体析晶峰温度为862 ℃,烧结过程中析出方石英晶相,20~200 ℃的平均线膨胀系数高达260.8×10^-7 ℃^-1;引入2.1%(质量分数)Al₂O₃可显著抑制玻璃析晶,700 ℃烧结后膨胀系数降低至72.9×10^-7 ℃^-1,介电常数显著增大,由6.30提高至7.02。     

ZnO-B2O3玻璃对Li2Zn3Ti4O12-CaTiO3复合陶瓷低温烧结及性能的影响

采用传统固相反应法制备0.94Li₂Zn₃Ti₄O₁₂-0.06CaTiO₃(LZT-CT)复合陶瓷,采用高温熔融法制备ZnO-B₂O₃(ZB)玻璃;以ZB玻璃为烧结助剂,研究了添加不同质量分数(x=0.5%、1.0%、1.5%、2.0%和2.5%)的ZB玻璃对LZT-CT复合陶瓷的烧结特性、物相组成、微观结构以及微波介电性能的影响。结果表明:ZB玻璃能有效地将LZT-CT复合陶瓷的烧结温度从1 175 ℃降低到875 ℃,并促进了LZT-CT复合陶瓷的致密化。当ZB玻璃掺量x≤2.5%时,LZT-CT复合陶瓷中除了LZT、CT相,没有出现其他新相。随着ZB玻璃添加量增加,复合陶瓷的体积密度、介电常数(ε_r)、品质因数(Q×f)均先增加后减小,谐振频率温度系数(τ_f)变化不大,在(-2.25~4.51)×10^-6/℃波动。当ZB玻璃掺量为2.0%时,LZT-CT复合陶瓷在875 ℃烧结2 h,获得最大体积密度(4.22 g/cm³)以及优异的微波介电性能,ε_r=23.9,Q×f=58 595 GHz,τ_f=-0.14×10^-6/℃。     

Bi2O3-B2O3-BaO系玻璃的光学折射率与带隙

研究了Bi2O3-B2O3-BaO三元系统的玻璃形成区,给出了该三元系统玻璃形成范围.采用熔融淬冷法制备了60Bi2O3-(40-x)B2O3-xBaO(x=5,10,15,20)和65Bi2O3-25B2O3-10BaO(以摩尔计)的5组高Bi2O3含量的Bi2O3-B2O3-BaO玻璃样品.测试了玻璃样品的折射率和吸收光谱,根据经典的Tauc方程计算了间接允许光学带隙和直接允许光学带隙,计算了样品的能量带隙,并估算了它们之间的关系.研究结果表明;随着BaO含量的增加,玻璃样品折射率逐渐增大,但Ba2 对玻璃折射率的影响要远小于Bi3 ;玻璃样品的紫外吸收增强,光学带隙和能量带隙逐渐减小,光学带隙和能量带隙的比值约为1:1.2.     

混合碱效应对Li2O-Al2O3-SiO2系玻璃结构和热膨胀性能的影响

本文用传统高温熔融法熔制Li₂O-Al₂O₃-SiO₂系高铝玻璃,改变碱金属氧化物n(Li₂O)/n(Na₂O)的摩尔比,运用阿基米德排水法、热膨胀仪、DSC、傅里叶变换红外光谱和拉曼光谱等测试手段和仪器,探究了混合碱金属效应对Li₂O-Al₂O₃-SiO₂系玻璃结构和热膨胀性能的影响。结果显示:随着n(Li₂O)/n(Na₂O)比例增大,混合碱金属效应对Li₂O-Al₂O₃-SiO₂系玻璃的密度和热膨胀系数的影响一致,表现为先增大后减小,当R=0.25(R=n(Li₂O)/[n(Li₂O)+n(Na₂O)],摩尔比)时,出现极值,此时密度达到最大2.447 4 g/cm³,热膨胀系数达到最大7.811 7×10^-6/℃;对玻璃特征温度的影响随着温度的升高而逐渐减弱至消失;对玻璃的析晶能力有一定的提升作用;对玻璃三维骨架结构中的硅氧四面体Qⁿ的影响也各不相同。     

Na2O-Al2O3-SiO2-P2O5玻璃的结构和析晶性能研究

采用熔融-淬冷法制备了不同(Al₂O₃+P₂O₅)含量的碱铝硅酸盐玻璃,通过拉曼光谱、X射线衍射光谱、扫描电镜研究了其结构特征和析晶性能。发现随着(Al₂O₃+P₂O₅)含量减少,玻璃中Na₂O含量增加,玻璃化转变温度从685 ℃降低到622 ℃,当减少至摩尔分数为22%时,出现析晶峰且起始析晶温度降低。拉曼光谱表明Q⁴_P对应的拉曼峰强度变低且逐渐向低波数方向移动,说明Na₂O作为网络修饰体使硅酸盐玻璃结构逐步解聚,玻璃的析晶能力逐渐增强。结果表明:当(Al₂O₃+P₂O₅)摩尔分数为22%时热处理后的样品存在晶型转变,700 ℃热处理时以NaAlSiO₄霞石晶体为主,900 ℃时转变为以Na_6.8Al_6.3Si_9.7O₃₂霞石晶体为主。当(Al₂O₃+P₂O₅)的摩尔分数为21%和20%时,热处理后的样品能稳定析出Na₃PO₄和Na_6.8Al_6.3Si_9.7O₃₂晶体。热处理后的样品析出了耐酸侵蚀性较差的富磷相和Na₃PO₄晶体,导致化学稳定性变差。     

Bi2O3/B2O3比及β-锂霞石粉对MEMS封接玻璃结构与性能的影响

针对微机电系统(MEMS)封接玻璃的性能要求,本文制备了Bi₂O₃-B₂O₃-ZnO-BaO-CuO系无铅玻璃粉,采用拉曼光谱仪、X射线衍射仪、热膨胀仪、烧结影像仪、扫描电子显微镜等测试手段分别表征了Bi₂O₃和B₂O₃物质的量比(n(Bi₂O₃)/n(B₂O₃))和β-锂霞石粉掺量变化对玻璃结构、热学性能、封接温度及微观形貌的影响。结果表明:随着n(Bi₂O₃)/n(B₂O₃)的增大,玻璃结构中[BiO₃]三角体和[BiO₆]八面体单元含量逐渐增多,[BO₄]四面体向[BO₃]三角体转变,导致玻璃网络连接强度减弱、结构变疏松;随着n(Bi₂O₃)/n(B₂O₃)的增大,玻璃热膨胀系数逐渐增大,特征温度和封接温度逐渐降低,但后期变化放缓;随着β-锂霞石粉外掺量的增加,复合玻璃粉的热膨胀系数明显降低,而特征温度和封接温度没有明显升高,但复合玻璃粉的流动性变差。     

Zn2+掺加的包覆型Fe2O3/SiO2颜料的制备及其呈色性能

包覆型Fe₂O₃/SiO₂颜料由于包覆完整性并不理想,该颜料高于800 ℃时呈色会产生变黑、变暗的问题。采用溶胶-凝胶法制备包覆型Fe₂O₃/SiO₂颜料,研究催化剂浓度、反应温度、硅/铁质量比等因素对包覆型Fe₂O₃/SiO₂颜料呈色性能的影响。在此基础上,通过掺加Zn²⁺,进行了Zn²⁺掺加的包覆型Fe₂O₃/SiO₂颜料的呈色性能研究。研究表明,当催化剂(氨水)浓度为0.75 mol/L,反应温度为40 ℃,硅/铁质量比m(SiO₂)/m(Fe₂O₃)为0.20,铁/锌摩尔比n(Fe)/n(Zn)为4时,制备得到的Zn²⁺掺加的包覆型Fe₂O₃/SiO₂颜料的呈色耐热性能获得明显提升,样品在850 ℃煅烧后仍然呈现出明亮的红橙色色调。     

Emission Analysis of Pr3 +& Tm3 +: B2O3-BaO-LiF/AlF3 Glasses

We report here on the preparation and emission properties of Pr³⁺(4f²) and Tm³⁺ (4f¹²) ions doped in newly developed to transparent glassy matrices of BBLi (= B₂O₃-BaO-LiF) BBAl (= B₂O₃-BaO-AlF₃). Under an UV source (355 nm), both the Tm³⁺: BBLi and Tm^{3 +}: BBAl glasses have shown bright blue emission at 452 nm. With regard to both the Pr³⁺: BBL and Pr³⁺: BBAl glasses red emission have been noticed upon excitation with blue excitation wavelength (445 nm).These results have also been obtained from the measurement of their emission spectra. For such emission bands, decay curves have been recorded to obtain their lifetimes. We have prepared optical glasses with good transparency and stability. From the measurement of XRD spectra, amorphous nature of these glasses have been confirmed. Between the two glasses studied, glass containing Li has demonstrated an extended UV transmission and also it has revealed an improved NIR transmission ability compared to the other glass with LiF.     

Absorption and Emission Spectral Analysis of Sm3 : Bi2O3-B2O3-Li2O Glasses

In order to enhance UV-transmission ability of B₂O₃ based glass, a suitable quantity of Bi₂O₃ and Li₂O salts have been added and hence the UV cut-off wavelength of Bi₂O-B₂O₃-Li₂O glass (abbreviated as BBL glass) has been found to be 268 nm. In this newly developed glass a luminescent rare earth ion namely Sm³⁺ (1 mol.%) has been incorporated to examine its absorption, excitation, emission and lifetimes of different measured emission bands. Under an UV-source, it has displayed a bright orange emission color. Apart from understanding its various optical properties, different physical properties of the un-doped reference glass have been investigated. The XRD profile of this glass has confirmed its amorphous nature. The measured excitation spectrum has shown a bright excitation band at 483 nm with which, the Sm³⁺ glass has been excited and thus obtained four emission bands at 563 nm, 598 nm, 648 nm and 709 nm respectively. An energy level diagram has been shown to explain the emission process involved in the glass system investigated in the present work.

Communicated by Prof. Jinzo Kobayashi     

Li2B4O7-Bi2O3-WO3玻璃的光学性能研究

采用熔融淬冷方法制备了(100-x)Li2B4O7-x(Bi2O3·WO3)(5≤x≤20)玻璃.采用比重计测定了玻璃密度,分光光度计测量了玻璃的吸收光谱,V棱镜折射仪测量了玻璃折射率.结果表明,随着Bi2 O3·WO3含量的增加,玻璃样品的密度和摩尔体积增大,而氧堆积密度减小;玻璃的吸收光谱中截止波长逐渐向长波方向移动,玻璃的间接跃迁光学带隙、Urbach能和费米能逐渐减小,折射率增大.光学性能的变化和玻璃网络中部分桥氧转变为非桥氧有关.     

Nb2O5对Nd3+掺杂锗酸盐玻璃光谱性能的影响

蓝光激光器在彩色激光显示、高密度光储存、海洋资源探测、水下通信以及生物科技等领域具有广泛的应用前景。目前较为成熟的Yb³⁺掺杂光纤激光器倍频后仅能获得~490 nm蓝绿光,因此如何得到接近450 nm的纯蓝光激光器是目前急需解决的问题。Nd³⁺:⁴F_3/2→⁴I_9/2能级跃迁产生的0.9 μm光经倍频后可获得~450 nm光,并可应用于蓝光激光器,但该跃迁产生的光所占荧光分支比较低。本文系统研究了1%(质量分数)Nd₂O₃掺杂50GeO₂-(20-x)PbO-15BaO-15ZnO-xNb₂O₅(x%=0%,2.5%,5%,10%,15%,摩尔分数)玻璃的吸收光谱、荧光光谱和荧光寿命,计算了相应的Judd-Ofelt强度参数以及增益带宽。研究发现,Nb₂O₅的加入会使Nd³⁺在900 nm荧光峰的吸收截面、发射截面、有效线宽和荧光分支比增加。当Nb₂O₅浓度为10%(摩尔分数)时,Judd-Ofelt强度参数Ω₂=5.91×10^-20 cm²,光谱质量参数χ=1.01,荧光分支比为42.9%。综上所述,Nb₂O₅能提高Nd³⁺ 0.9 μm的荧光分支比,从而倍频获得纯蓝光(450 nm),有利于蓝光激光器的发展及应用。     

Structural and optical properties of MoO3 and V2O5 thin films prepared by Spray Pyrolysis

MoO₃ and V₂O₅ thin films were prepared on glass substrates by Spray Pyrolysis technique at a substrate temperature of 423 K. The precursor solutions were obtained by varying the concentrations of MoCl₅ and VCl₃ in bi-distilled water. The structural investigation conducted by X-ray diffraction showed that MoO₃ and V₂O₅ thin films were polycrystalline with orthorhombic structure. The optical properties studied in the 300–2500 nm range suggest that the thin film behaviours are related to bound electronic states. The optical band gaps have been estimated from slopes of ln(hν) versus hν plots of MoO₃ and V₂O₅ films were 3.35 and 2.44 eV, respectively. The electrical conductivity was measured using four probes method.