高压烧结制备Tb掺杂n型(Bi1–xTbx)2(Te0.9Se0.1)3合金及其微结构和热电性能

采用高压烧结技术制备了稀土元素Tb掺杂的n型Bi2Te2.7Se0.3基纳米晶块体热电材料.将高压烧结成型的样品于633 K真空退火36 h.研究了Tb掺杂量对样品的晶体结构和热电性能的影响.结果表明,高压烧结制备的样品为纳米结构, Tb掺杂使样品的晶胞体积变大,功率因子增大,热导率降低,从而使ZT值提高.Tb掺杂量为x=0.004是最优的掺杂量,该掺杂量的高压烧结样品经退火处理后,于373 K时ZT值达到最大为0.99,并且在323-473 K范围内, ZT值均大于0.8,这对用于温差发电领域具有重要意义.     

Synthesis of terbium doped calcium phosphate nanocrystalline powders by citric acid sol–gel combustion method

Terbium doped calcium phosphate (Tb-doped CaP) nanocrystalline powders were synthesized by the citric acid sol–gel combustion method. The phase composition, morphology and luminescent property of Tb-doped CaP nanocrystalline powders were characterized by powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, fluorescence spectrophotometer and fluorescence microscopy. At 700 °C, Tb-doped CaP nanocrystalline powders are composed of HAP (main phase) and β-TCP (minor phase) with Tb doping content of 0.5–4%. SEM and TEM observations show that the 4% Tb-doped CaP nanocrystalline powders are about 50–150 nm spherical particles. The 4% Tb-doped CaP nanocrystalline powders exhibit the strongest emission at 548 nm (λ_excitation = 240 nm) and show strong green fluorescence under fluorescence microscopy.     

Electrical and ferromagnetic properties of Tb-doped indium-tin oxide films fabricated by sol-gel method

The electrical and ferromagnetic properties of (In_0.9−xTb_xSn_0.1)₂O₃ and (In_0.99−yTb_0.01Sn_y)₂O₃ films fabricated by sol-gel method have been investigated. All the films show room temperature ferromagnetism. The magnetic moment per Tb ion of (In_0.9−xTb_xSn_0.1)₂O₃ films first increases and then decreases with the increasing Tb content. The variation of conductivity with Tb content is coincident with that of the magnetic moment. Furthermore, the conductivity and magnetic moment variations with Sn content y in (In_0.99−yTb_0.01Sn_y)₂O₃ films also have the similar trend. These results imply that the ferromagnetism may originate from the carrier-mediated mechanism.     

Preparing nanometer scaled Tb-doped Y2O3 luminescent powders by the polyol method

Sub-micrometer Tb-doped Y₂O₃ luminescent powders were prepared from nitrate precursors using the polyol method. Just after precipitation, the powders consist of agglomerates with a spherical shape and a size ranging between 400 and 500 nm. Each agglomerate is composed of ultra-small crystallites (from 3 to 6 nm) of a bcc oxide phase whose luminescence presents original features in comparison with bulk materials. Powders were further calcinated at different temperatures and for annealing below 900 °C, highly crystalline samples with the classical green ⁵D₄→⁷F₅ luminescent transitions of Tb³⁺ ions are obtained. For optimized annealing temperatures, sintering between the agglomerates is avoided and a sub-micrometric powder with a narrow size distribution and a high luminescence is obtained.     

掺Tb-硅基发光材料制备过程中结构及发光性能

采用溶胶 凝胶技术,制备了不同退火温度下掺Tb3＋的SiO2玻璃,掺Tb3＋的凝胶玻璃在448,544,585,620 nm显示Tb3＋的5D4 7FJ(J=3,4,5,6)的特征发光光谱.通过不同退火温度下样品的激发光谱、发射光谱、红外光谱、远红外光谱及差热 热重谱研究了掺Tb3＋的硅基材料由凝胶向玻璃转变过程中的结构变化及对Tb3＋发光性能的影响.结果显示,在50～100 ℃退火温度下,凝胶大部分吸附水分子被除去,在150～500 ℃退火温度区,是凝胶向玻璃转变的主要结构变化区,并且其发光强度也明显增加,到800 ℃时趋于稳定.这些现象得出一个结论,Tb3＋的发光跃迁被O－H基强烈猝灭而随退火温度的升高而加强.