共沉淀法YAG、Nd∶YAG纳米粉体的制备、结构与光谱性能研究

采用共沉淀方法,以氨水为沉淀剂,与硝酸盐的混合溶液反应得到YAG、Nd∶YAG前驱体,并在不同的温度下对前驱体进行锻烧。利用红外光谱(FT IR)、热重/差热分析(TG/DTA)、X射线衍射(XRD)、透射电镜(TEM)等技术对YAG前驱物及煅烧粉体进行表征,对Nd∶YAG粉体的发光性能进行了测试。结果表明,在800℃下煅烧YAG前驱体,得到纯YAG晶相,无YAP、YAM中间相的出现;XRD、TEM和比表面分析表明在800～1000℃煅烧所得粉体晶粒直径为40～100nm,具有较好的分散性。同时荧光测试表明Nd∶YAG粉体具有良好的发光性能。     

微通道反应-共沉淀法制备YAG纳米粉体

以碳酸氢铵为沉淀剂,采用微通道反应与共沉淀法相结合的方法制备出了钇铝石榴石纳米粉体。实验考查了溶液浓度、pH值、Nd3+掺杂等因素对合成纯相YAG纳米粉体的影响。结果表明增大沉淀剂浓度不利于纯相YAG粉体的制备,当沉淀剂浓度为0.4mol/L,Al 3+浓度范围为0.1～0.4mol/L的条件下均得到纯相YAG纳米粉体;采用优化的实验条件,体系pH值维持在8左右,以2%(原子分数)的Nd3+取代YAG中的Y3+,900℃保温4h得到纯相Nd∶YAG粉体,粉体平均粒径在40nm左右,分布均匀,呈近球形。     

共沉淀法制备Nd:YAG纳米粉体与机理探讨

以碳酸氢铵为沉淀剂采用共沉淀法和添加分散剂的方式．获得具有高烧结活性的碳酸盐前驱体,这种前驱体在较低的温度下烧结即可转变成相。同时借助DTA-TG、IR、XRD和TEM等测试手段对前驱体和YAG粉体进行表征。结果表明：在分散剂存在的情况下,此800℃左右煅烧2h前驱物直接转变为纯的YAG相,而无其它的杂质相,所得的YAG粉体的颗粒尺寸约20nm．是单分散的形貌近似球形的。此外不同温度下粉体的荧光性质表明,随着烧结温度的提高发光强度有所增加。     

微流体快速沉淀法制备Nd∶YAG纳米粉体

采用一种基于微流体快速均匀混合的沉淀方法,以碳酸氢铵(NH4HCO3)为沉淀剂制备前驱体。红外光谱(FT-IR)、X射线衍射(XRD)、透射电镜(TEM)和热分析(TG-DTA)等测试结果显示,该方法获得的前驱体经煅烧后可得到分散性好、形状规则、平均粒径为50nm的纯相Nd∶YAG纳米粉体。     

共沉淀法制备纯相钇铝石榴石(YAG)纳米粉体中的若干影响因素

探讨了影响生成纯相YAG纳米粉体的各种因素,并通过优化工艺参数,得到了纯相并具有单分散、无团聚、颗粒尺寸分布窄且近似球形特点的YAG纳米粉体.实验中,配制不同浓度的NH4HCO3水溶液作为沉淀剂,配制不同浓度的Y(NO3)3和NH4Al(SO4)2混合水溶液作为母液,在不同的的温度下,采用不同的滴定速度,得到不同的前驱体,前驱体在900℃以上的温度焙烧2h即可获得不同的粉体.主要采用X射线衍射(XRD)对这些粉体进行了物相分析,同时结合红外光谱法(F-IR)对部分前驱体进行了定性分析,用透射电子显微镜(TEM)对纯相粉体进行了形貌观察.结果表明,在共沉淀过程中,混合溶液和沉淀剂的浓度直接决定了是否生成YAG为主相的粉体,环境温度和滴定速度则对是否生成纯相粉体有较大的影响.     

两种沉淀剂对Pr:YAG纳米粉体的性能影响研究

分别采用碳酸氢铵和尿素为沉淀剂用沉淀法制备了Pr掺杂的YAG纳米粉体。并利用XRD、FT-IR、TEM等方法对样品进行了成分、粒度和形貌等性能分析,讨论了不同沉淀剂的反应机理。结果表明,碳酸氢铵沉淀法能够在较低温度下制备颗粒均匀、分散性良好的YAG纳米粉体;而尿素沉淀法所制备的粉体需要较高的煅烧温度,粉体粒径大、团聚较为严重。此外,Pr∶YAG纳米粉体的荧光强度随粉体粒径的增大而加强。     

YAG：Ce，Tb粉体的共沉淀法制备与发光性能

以NH4HC03溶液为沉淀剂，采用共沉淀法制备了前驱体，在氩气气氛中经1200℃煅烧2h合成了Y2.91-xCe0.06TbxAl5O12（YAG：Ce，Tb）粉体。利用X射线衍射仪、透射电子显微镜、荧光光谱仪对样品的结构、形貌及发光性能进行了表征。所得粉体为体心立方相YAG：Ce，Tb。粉体颗粒团聚成珊瑚虫形。YAG...     

共沉淀法制备YAG微粉及其烧结性能

本实验采用共沉淀方法制备YAG微粉,Al原子和Y原子分布均匀,在900℃煅烧2小时即可全部转变为YAG粉体.该粉体具有较好的烧结性能,在1500℃热压1小时可获得致密烧结体.     

加料方式对共沉淀法制备Nd∶YAG透明陶瓷的影响

以Nd2O3、Y2O3、NH4Al(SO4)2·12H2O为原料,NH4HCO3为沉淀剂,采用顺序、反序和并流3种不同共沉淀加料方式,在高滴加速率条件下制取了掺钕钇铝石榴石(Nd∶YAG)粉体,比较工艺操作,表征其相组成、显微形貌、粒度分布和烧结后陶瓷的透过率。结果表明,并流共沉淀工艺无需调节pH值,工艺操作最简单;经1 100℃煅烧,反序、并流法制备的粉体均为纯相YAG,顺序制备的粉体含有杂相,其中并流法制备的粉体粒径分布窄,颗粒呈类球形,粉体活性高。采用真空烧结技术于1 715℃下烧结制备了Nd∶YAG陶瓷,顺序、反序和并流样品在1 064 nm处透过率分别为68%,70%和75%。     

交叉共沉淀法制备Skutterudite纳米粉体的研究

探索了交叉共沉淀法制备纳米方钴矿化合物CoSb₃. 以钴和锑的氯化物为原料, NaOH和氨水为沉淀剂, 室温下调节pH=5~10, 经过滤、洗涤、超声分散和真空干燥后得到了Co(OH)₂和Sb₂O₃前驱体. 研究了还原热处理过程中还原气氛、温度、时间、原料配比对还原产物的相组成和粉体粒径的影响. 结果表明, 采用纯H₂为还原气氛, 500℃下还原3h, 当Sb/Co摩尔比为3.15时, 可得到粒径均匀、平均粒径约为100nm的单相CoSb₃粉体.     

Synthesis of YAG powder by alcohol-water co-precipitation method

Yttrium Aluminum Garnet (YAG) precursors were co-precipitated by using alcohol-water as the precipitant solvent. The effects of different volume ratios of alcohol to water (R) and ambient temperature (T) on the preparation of pure-phase YAG powders have been mainly studied. The results show that alcohol-water solvent with proper R (0.2-1.2) is effective for the uniform distribution of Al and Y elements in the precursor under low ambient temperature (5-20 °C). Pure-phase YAG powder can be obtained by calcining at 900 °C for 2 h under optimal conditions (R = 0.8; T = 15 °C). Moreover, the elliptical YAG powder calcined at 1000 °C for 2 h is well-crystallized with an average size of 30 nm, and a little agglomeration exists.     

撞击流共沉淀法制备YAG:Ce荧光粉过程的研究

采用Al(NO3)3、Y(NO3)3和Ce(NO3)3为母盐,碳酸氢铵为沉淀剂,利用撞击流共沉淀法制备YAG:Ce(Y3Al5O12:Ce)球形纳米粉体。利用XRD、FT-IR、SEM和荧光分光光度计对YAG前驱体及煅烧纳米粉体进行了表征,并分析了母盐溶液的浓度、溶液的滴加速度以及煅烧方法和温度对制备YAG纳米粉体的影响。结果表明母盐溶液的浓度、滴加速度及煅烧方法和温度对煅烧粉体的组成、分散性、形貌及发光性能有显著的影响。当初始原料浓度较低(c0=0.055mol/L)时,900℃可以获得纯YAG晶相,不形成任何中间相;初始浓度c0在1.0mol/L以上时,1000℃得到的YAG荧光粉中有YAM、YAP和CeO2杂质相存在;适当的提高加料速度,可以增加粉体的结晶度;采用Na2CO3-S-K2CO3助熔剂辅助煅烧,700℃时已完全转变为YAG相,与直接煅烧法相比,YAG相的完全转变温度降低了约300℃,荧光粉的发光强度比不加熔盐明显提高了。     

Preparation and characterization of Y3Al5O12 (YAG) nano-powder by co-precipitation method

YAG precursor was synthesized by a co-precipitation method from a mixed solution of aluminum and yttrium nitrates with aqueous ammonia as the precipitator. The structure, phase evolution and morphology of YAG precursor and the sintered powders were studied by means of IR, TG/DTA, XRD, TEM methods. It was found the precursor with approximate composition of Al(OH)₃·0.3[Y₂(OH)₅·(NO₃)₂·2H₂O] directly transformed to pure-YAG phase at 800 °C and no intermediate phases were detected. YAG nanocrystalline powders from sintering the precursor at different temperatures were less-aggregated and the diameters of the grains were about 40-100 nm. BET surface area of the particles decreased with increase of calcination temperature and the powder sintered at 800 °C can be used for fabrication of transparent YAG ceramics.     

共沉淀法制备YAG超细粉及透明陶瓷

研究了共沉淀法制备YAG透明陶瓷的工艺。采用Al(NO3)3和Y(NO3)3的混合溶液为母盐,以碳酸氢铵为沉淀剂,采用共沉淀法制备了化学组成为Y2(CO3)3·nH2O+NH4AlO(OH)HCO3的碳酸盐先驱沉淀物。使用透射电镜和X射线衍射对先驱沉淀物的形貌及煅烧过程的相转变进行了研究。结果表明先驱沉淀物在900℃煅烧2h后完全转变为YAG相。1100℃煅烧后得到的YAG粉体具有良好的烧结性能。使用0.5%(质量分数)的TEOS(正硅酸乙酯)作为烧结添加剂,1700℃真空烧结5h后,得到了透明YAG烧结体。     

Performance of diode-end-pumped Cr, Nd:YAG self-Q-switched and Nd:YAG/Cr:YAG diffusion bonded lasers

Self-passively Q-switching of a diode-pumped Cr,Nd:YAG, where the Cr⁴⁺ is used as a saturable absorber for the 1064 nm laser emission is reported. The maximum average output power was obtained using an output coupler of R=86%. The self-Q-switched diode pumped laser yielded 1.86-W average output power with low threshold pumping power (≈1.7-W), average slope efficiency of ≈34%, pulse duration of about 14–16 ns, and modulation frequency ranging from 2.4 to 73 kHz, depending on the input pumping power. These results are the highest reported for self-Q-switched lasers. Higher slope efficiency (42%) and shorter Q-switched pulses were obtained for a Q-switched Nd:YAG/Cr⁴⁺:YAG diffusion bonded laser. A comparison of the codoped Cr,Nd:YAG laser performance, with that of a diffusion bonded laser is reported and analyzed.     

碳酸氢铵-氨水-草酸共沉淀法制备微米稀土CeO2工艺的研究

以碳酸氢铵-氨水-草酸(AAO)为共沉淀剂对氯化铈进行了沉淀实验,研究了反应温度、物料浓度、搅拌速率、陈化时间等因素对草酸盐粒度的影响;探讨了较佳的条件:AAO共沉淀法,陈化时间60min,CeCl3浓度1.6mol/L,搅拌速率650r/min,反应时间3h,焙烧温度800℃,AAO的pH为5～6,制备了微米级氧化铈,为其工业化提供参考。     

Comparative study of synthesis and characterization of YAG:Yb3+ nanoparticles using different precipitator by co-precipitation method

Irregular club-shape nanoparticles of Yb3+ doped Y3Al5O12 were synthesized by the co-precipitation method using different precipitator, such as ammonium hydrogen carbonate, hexamethylene tetramine and urea. The reaction mechanism of different precipitator and the effect on the particle size and dispersion of Y3Al5O12:Yb3+ powders were investigated, and the influence of ammonium sulfate as the dispersant in the reaction system was also discussed. The results show that the large and agglomerated Y3Al5O12:Yb3+ powders were obtained from urea compared to that uniform particle size and dispersion one from ammonium hydrogen carbonate and hexamethylene tetramine. Moreover, ammonium sulfate is beneficial to enhance the dispersion of the particles for ammonium hydrogen carbonate and to form the club-shape morphology of Y3Al5O12:Yb3+ crystals for hexamethylene tetramine. The photoluminescence property investigation shows that the near-infrared emission intensity of the powders increased with the calcining temperature as well as the particle size and dispersion of as-prepared particles for all the precipitators.