氨水反滴共沉淀法制备Nd:YAG透明陶瓷粉体

以氨水为沉淀剂,硝酸盐为初始原料,采用反向滴定共沉淀法制备Nd∶YAG前驱体,将前驱体在不同温度下进行煅烧。采用XRD、IR、TG/DS等测试手段对样品进行表征,结果表明:前驱体在900℃下煅烧2 h就完全生成纯YAG相,没有中间相出现。最终得到分散性较好,平均尺寸在60 nm左右的粉体。     

基于铈钆共掺杂YAG单晶荧光片的高光效白光LED

为了满足高功率白光发光二极管(Light-Emitting Diode, LED)对荧光体的高性能要求,对白光LED用Ce_xGd∶YAG单晶荧光材料的制备和光学、电学、热学特性进行了研究。采用提拉法生长了Ce_xGd∶YAG(x=0.02, 0.04, 0.06, 0.08)单晶,并借助于X射线衍射(XRD)、吸收光谱、发射光谱等对晶体的光谱特性进行了表征,同时也测试分析了相对荧光强度随温度的变化关系、基于不同Ce³⁺浓度Ce_xGd∶YAG单晶的白光LED性能参数。结果表明Ce_xGd∶YAG单晶在450 nm的蓝光激发下,产生一个500～650 nm的宽峰发射,在100℃高温下,其荧光光强比商用荧光体粉末高出10%。当Ce³⁺浓度为6%时,采用Ce_xGd∶YAG单晶荧光片的白光LED光效高达153 lm/W,是Ce∶YAG和树脂荧光材料白光LED的两倍多。Ce_xGd∶YAG单晶荧光片,具有更高更稳定的荧光光强,制作...     

Investigation of structural perfection and faceting in highly Er‐doped Yb3Al5O12 crystals

The undoped Yb₃Al₅O₁₂ (YbAG) single crystals and doped with 1.5, 10 and 30 at% erbium were grown by the Czochralski method. The YbAG crystals offer efficient emission of laser beam of 2.94 µm and 1.55 µm important for practical applications in communication and medicine. The crystals were investigated by various synchrotron X‐ray diffraction methods including white beam topographic methods, monochromatic beam topography and recording of the rocking curves. The experiments were performed at E2 and F1 experimental stations in HASYLAB. The investigations proved a good crystallographic perfection of the crystals, in most cases revealing only segregation fringes and growth facets. The crystallographic identification of the facets was performed together with direct evaluation of growth front radius from the transmission section topographs. Relative lattice parameter changes connected with erbium segregation were found to be less than 2 × 10^‐5 inside the segregation fringes and 8 × 10^‐5 in the facets. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Conversion of yttrium-aluminum garnet to soluble forms as a result of mechanochemical treatment

Summary The changes in the solubility and in the phase composition of yttrium-aluminum garnet (YAG) as a result of its mechanochemical treatment for 2 h in a planetary ball mill together with H₃BO₃ and Na₂CO₃ (mole ratio H₂BO₃/Na₂CO₃=4) in ratios (H₃BO₃+Na₂CO₃)/YAG=2,4, and 9 are studied. At a ratio of 9, the yield of yttrium in the water solution obtained upon treatment of the activated mixture at 90 °C (50 cm³ water/g sample) reaches 85%. Its content in the same solution is above 93% relatively to the sum Y+Al.

---

Umwandlung von Yttrium-Aluminium-Granat in lösliche Formen durch mechanochemische Behandlung

Zusammenfassung Die Änderungen bezüglich Löslichkeit und Phasenzusammensetzung von Yttrium-Aluminium-Granat (YAG) als Ergebnis einer zweistündigen mechanochemischen Behandlung in einer Kugelmühle zusammen mit H₃BO₃ und Na₂CO₃ (Molverhältnis H₃BO₃/Na₂CO₃=4) bei (H₃BO₃+Na₂CO₃)/YAG-Verhältnissen von 2, 4 und 9 wurden untersucht. Bei einem Verhältnis von 9 erreicht die Ausbeute an Yttrium in der wäßrigen Lösung nach Behandlung der aktivierten Mischung bei 90 °C (50 cm³ H₂O pro Gramm) 85%. Relativ zur Summe Y+Al beträgt der Yttriumgehalt 93%.

     

Quantum magnonics: The magnon meets the superconducting qubit

The techniques of microwave quantum optics are applied to collective spin excitations in a macroscopic sphere of a ferromagnetic insulator. We demonstrate, in the single-magnon limit, strong coupling between a magnetostatic mode in the sphere and a microwave cavity mode. Moreover, we introduce a superconducting qubit in the cavity and couple the qubit with the magnon excitation via the virtual photon excitation. We observe the magnon–vacuum-induced Rabi splitting. The hybrid quantum system enables generation and characterization of non-classical quantum states of magnons.     

The vanadate garnet Ca2NaCd2V3O12: a single‐crystal X‐ray diffraction study

Single crystals of the vanadate garnet Ca₂NaCd₂V₃O₁₂ (dicalcium sodium dicadmium trivanadate) were synthesized using the floating‐zone method and the crystal structure was investigated using single‐crystal X‐ray diffraction. We considered the effectiveness of substitution of the Y‐site cation with reference to previous structural studies of vanadate garnets. The structures of vanadate garnets are subject to geometric constraints similar to those of silicate garnets. These constraints force the tetrahedral–dodecahedral shared edge length in vanadate garnets to become shorter than the unshared dodecahedral edge length, as in ugrandite (uvarovite, grossular and andradite) garnets. However, the vanadate garnet Ca₂NaCd₂V₃O₁₂ exhibits the normal structural feature, similar to pyralspite (pyrope, almandine and spessartine) garnets, namely that the dodecahedral–dodecahedral shared edge length is shorter than the unshared dodecahedral edge length. With increasing ionic radius of the Y‐site cation, the atomic coordinates x, y and z of oxygen adopt values which satisfy Pauling's third rule.     

Gd3+ to Ce3+ energy transfer in multi-component GdLuAG and GdYAG garnet scintillators

Optical and luminescence properties were studied in the Ce³⁺ doped yttrium and lutetium aluminum garnets (YAG, LuAG) admixed by Gd³⁺ and Ga³⁺ ions. The single crystalline films were grown by liquid phase epitaxy. Energy transfer from Gd³⁺ sensitizer to Ce³⁺ activator ions was established. This energy transfer was observed in a broad range of Gd concentrations which may point to longer range interaction between Gd³⁺ and Ce³⁺ ions.

     

钇复合氧化物颜料的制备与表征

通过尿素分解法,把三价铬离子掺入到钇铝石榴石Y₃Al₅O₁₂中,采用共沉淀法制备出绿色颜料。扫描电镜测试表明产物颗粒直径在200 nm左右,用XRD测试复合氧化物的结晶相行为,确定主相是钇铝石榴石相,用紫外可见漫反射光谱测试掺杂离子的配位状态和电子跃迁行为,用色度学测试氧化物颜色特征。将复合氧化物颜料颗粒与高分子聚丙烯共混,熔体纺丝,并通过北京同步辐射X射线CT对制得的纤维加以测试,结果表明复合氧化物颜料在高分子基质中得到良好的分散。这种颜料性能稳定,对环境友好,为实现无水印染技术奠定基础,减少纺织印染工业中所排放的污水。     

微下拉法生长Tb3AlxGa5-xO12磁光晶体及其性能表征

Tb₃Ga₅O₁₂晶体是一种具有良好磁光性能的主流商用材料,但生长过程中存在严重的氧化镓挥发问题,导致晶体难以满足高功率应用的发展需求,而菲尔德常数较大的Tb₃Al₅O₁₂晶体的不一致熔融特性使该晶体难以生长,因此亟需探索新型高质量磁光晶体以满足高功率应用需求。基于此,本文采用微下拉法在高纯氩气和二氧化碳混合气氛下生长了Tb₃Al_xGa_5-xO₁₂(TAGG)系列高掺铝磁光晶体。摇摆曲线测试结果表明TAGG磁光晶体拥有高结晶质量。透过光谱和磁光特性测试结果表明,与传统Tb₃Ga₅O₁₂晶体相比,TAGG磁光晶体具有更高的透过率和更大的菲尔德常数,是一种非常有潜力的可应用于高功率激光系统的低成本磁光材料。     

Curie temperatures of Y3Fe5O12/Gd3Fe5O12 superlattices

The magneto-optical Kerr effects (MOKE) of epitaxial Y₃Fe₅O₁₂/Gd₃Ga₅O₁₂ (YIG/GGG) garnet superlattices grown on (1 1 1)GGG previously by pulsed laser deposition (PLD) were measured. A series of superlattices were investigated with the thickness of the ferrimagnetic YIG layer varied from six unit cells to only one unit cell while keeping the Curie paramagnetic GGG fixed at one unit cell. It was demonstrated that the ellipsometric technique employing photoelastic modulators (PEM) is sensitive enough to measure the MOKE signals of these ultrathin oxide samples. The Curie temperatures, determined by MOKE, are fit with a power law, yielding a shift exponent λ = 3.1 ± 1.2.