Er~(3 ),Yb~(3 )∶YAl_3(BO_3)_4晶体的光谱性质研究

采用助熔剂法生长了Er3 ,Yb3 共掺的YAl3 (BO3 ) 4 晶体 ,测量了晶体的室温吸收谱。由此吸收谱 ,根据Judd Ofelt理论计算了Er3 在Er3 ,Yb3 ∶YAl3 (BO3 ) 4 晶体中的强度参数、自发辐射几率、积分发射截面等参数。强度参数为Ω2 =2 .4 4× 10 -2 0 cm2 、Ω4=2 .0 0× 10 -2 0 cm2 、Ω6=6 .10× 10 -2 0 cm2 。研究了晶体的荧光特性 ,并在 976nm激光泵浦下得到了上转换绿色荧光。     

Na3La2(BO3)3的晶体结构

以Na2CO3-H3BO3-NaF为助熔剂,使用顶部籽晶法生长出Na3La2(BO3)3透明单晶.测定了Na3La2(BO3)3的晶体结构,该晶体属正交晶系,空间群:mm2(No.38),晶胞参数为a＝0.51580(10)nm,b=1.1350(2)nm,c=0.73230(15)nm,α＝β＝γ＝90°,V＝0.42871(15)nm3,密度:.053g/cm3.晶体结构中的硼氧基团是平面的BO3基团,BO3基团相互独立,且与Na(1)O6、Na(2)O8、Na(3)O6和La(1)O9配位多面体连结形成三维网络骨架结构.讨论了Na3La2(BO3)3的晶体结构与倍频效应的关系.     

Reaction of ethyl diazoacetate with Co3(CO)9(μ3-CCl): Isolation and X-ray structures of Co3(CO)9(μ3-CCO2Et), Co3(CO)9(μ3-CCH2CO2Et), and [Co3(CO)9(μ3-CCHCO2Et)]2

The reaction between the tricobalt cluster Co₃(CO)₉(₃-CCl) (1) and AlCl₃, followed by treatment with ethyl diazoacetate, N₂CHCO₂Et, affords a complex mixture of products in low yields. Column chromatography has allowed the isolation of the four cluster compounds Co₃(CO)₉(₃-CH) (2), Co₃(CO)₉(₃-CCO₂Et) (3), Co₃(CO)₉(₃-CCH₂CO₂Et) (4), and [Co₃(CO)₉(₃-CCHCO₂Et)]₂ (5). Clusters 4 and 5 are new and have been fully characterized in solution by IR and ¹H NMR spectroscopy. The molecular structures of clusters 3–5 have also been determined by single-crystal X-ray diffraction analysis. Co₃(CO)₉(₃-CCO₂Et) crystallizes in the triclinic space group P , a = 8.8393(5), b = 14.727(1), c = 15.272(1) Å, = 93.361(6), = 105.509(5)°, = 100.336(6)°, V = 1872.6(2) ų, Z = 4, and d _calc = 1.823 g/cm³. Co₃(CO)₉(₃-CCH₂CO₂Et) crystallizes in the monoclinic space group P2₁/n, a = 9.3806(7), b = 9.2617(8), c = 22.455(2) Å, = 94.483(7)°, V = 1944.9(3) ų, Z = 4, and d _calc = 1.803 g/cm³. [Co₃(CO)₉(₃-CCHCO₂Et)]₂ crystallizes in the monoclinic space group C2/c, a = 21.585(2), b = 8.7977(7), c = 20.784(1) Å, = 104.807(6)°, V = 3815.8(5) ų, Z = 4, and d _calc = 1.835 g/cm³. Plausible pathways leading to the formation of clusters 2, 4, and 5 are discussed.     

(K,Na)3La2(BO3)3固溶体系的晶体结构

本文合成了一系列的(K,Na)3La2(BO3)3硼酸盐,通过自发结晶得到了组分为K1.34,Na1.66La2(BO3)3的单晶.单晶X射线结构分析表明该晶体与Na3La2(BO3)3同构,并且当K+取代Na+的数量小于2/3时,晶体结构仍为Na3La2(BO3)3构型.该晶体的基本结构单元为孤立的(BO3)3-基团.一个单胞中含有6个BO3基团,其中两个沿c方向一致平行排列,而剩余的4个BO3基团的排列方向与c方向呈一定的角度,从而减小了BO3基团对非线性效应的贡献.粉末倍频测试该晶体的有效非线性系数约为KDP的2.4倍.此外,研究表明用适量的Rb+,Li+取代Na+时,固溶晶体结构也不发生改变.     

双掺Er~(3+)/Yb~(3+)∶Sr_3La_2(BO_3)_4晶体的生长与光谱特性

采用提拉法生长了尺寸为20mm×30mm的Er3+/Yb3+∶Sr3La2(BO3)4晶体,研究了Er3+/Yb3+∶Sr3La2(BO3)4晶体的吸收光谱和荧光光谱。根据Judd-Ofelt理论分析并计算了辐射跃迁几率、辐射寿命、荧光分支比等光谱参数,获得的唯象参数为:Ω2=15.59×10-20cm2,Ω4=2.25×10-20cm2,Ω6=1.49×10-20cm2。在Er3+/Yb3+∶Sr3La2(BO3)4晶体中Er3+在1533nm处发射跃迁截面为7.88×10-21cm2,Er3+的4I13/2→4I15/2能级跃迁的荧光寿命和辐射寿命分别为0.728ms和4.24ms,结果表明Yb3+对Er3+有敏化作用,提高了对泵浦光的吸收能力,Er3+/Yb3+∶Sr3La2(BO3)4晶体可望作为1.55μm波段的一种有潜力的激光材料。     

(Nd3+,Yb3+):Ca3(VO4)2晶体的极化研究

本文回顾了(Nd3+,Yb3+):Ca3(VO4)2晶体的研究历程,通过对晶体结构和对晶体激光性能研究年代的对比,认为高的泵浦阈值是由于晶体中存在的对泵浦光和激光散射很强的畴壁结构未被发现而造成的.讨论了极化的原理、建立了极化装置,采用Laue定向法和X射线定向仪定向法结合解决了(Nd3+,Yb3+):Ca3(VO4)2这种大晶格常数(c＝3.8029nm)晶体的定向问题.把晶体的抛光面放入0.5mol;的温度为30℃的硼酸中腐蚀样品1h,用显微镜可以观察到畴结构.在～1100℃和电流密度为～10μA/mm2的条件下极化2h即可完成极化.变黑的极化样品可以通过把晶体放入马福炉中升温至850℃,保持1h,然后降至室温即可消除.     

Na3La9O3(BO3)8的晶体结构

以Na2CO3-H3BO3为助熔剂,用顶部籽晶法生长出Na3La9O3(BO3)8单晶.测定了Na3La9O3(BO3)8晶体结构,结果表明:该晶体属六方晶系,空间群:P62m,晶胞参数为a=b=0.89229(13)nm,c=O.87366(17)nm,α=β=90°,γ=120°,Z=1,V=0.60240(17)nm3,密度为5.066g/cm3.晶体结构中的硼氧基团是平面的BO3基团,BO3基团相互独立,通过与Na(1)O6、La(1)O9和La(2)O8的配位多面体连结形成层状结构,所有层平行于(001)面.描述了Na3La9O3(BO3)8晶体在非线性光学材料领域的应用前景.     

Na3La2(BO3)3晶体生长及光谱特性

本文以起始摩尔比为1:1的Na2CO3:H3BO3,并添加5;质量分数的NaF为助熔剂,用顶部籽晶法生长出φ35mm×5mm的透明Na3La2(BO3)3单晶.该晶体属正交晶系,空间群:Amm2,晶胞参数为a=0.51580(10)nm,b=1.1350(2)nm,c=0.73230(15)nm,α=β=γ=90°.测量了Na3La2(BO3)3晶体在室温下的透过光谱,紫外截止波长约为200nm.该晶体常温下稳定,不吸潮,但却易溶于稀酸.     

新型稀土发光材料Sr_(3-x)MgSi_3O_(10)∶Tb_x~(3+)的合成及性质

采用凝胶-燃烧法,在活性炭弱还原气氛下合成了新型荧光粉Sr3-xMgSi3O10∶Tb3x+,通过热分析仪、红外光谱、X射线粉末衍射、X射线能量色散谱仪及荧光分光光度计等对产物的形成过程、结构、组成及发光性质进行了分析和表征。结果表明:干凝胶起火燃烧得前驱物,经900℃还原热处理即可得目标产物,其晶体结构与Sr2MgSi2O7相似,同属四方晶系。Sr3-xMgSi3O10∶Tb3x+的激发光谱为一位于200～300nm的宽带,主激发峰在249nm左右;发射光谱由491nm,544nm,586nm,624nm等一系列窄带发射峰组成,归属于Tb3+的5D4到7FJ(J=6,5,4,3)的跃迁。主发射峰位于544nm,对应于Tb3+的5D4→7F5的能级跃迁,导致一种黄绿光发射。研究发现:还原温度及Tb3+掺杂浓度对发光强度有着重要的影响,并对浓度猝灭机制进行了探讨。     

Regiospecific CO substitution in (μ-H)Ru3(μ3− η3-CHCHCMe)(CO)9 by 4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione(bpcd). X-ray structure of (μ-H)Ru3(μ3−η3-CHCHCMe)(CO)7(bpcd)⋅MeOH

The triruthenium cluster ( -H)Ru₃( ₃–³-CHCHCMe)(CO)₉ reacts with the diphosphine ligand 4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione (bpcd) in the presence of Me₃NO to afford ( -H)Ru₃( ₃– ³-CHCHCMe)(CO)₇(bpcd) in moderate yield. This new cluster has been isolated and characterized in solution by IR and NMR (¹H, ³¹P) spectroscopies, and the solid-state structure has been established by X-ray crystallography. ( -H)Ru₃( ₃– ³-CHCHCMe)(CO)₇(bpcd) MeOH crystallizes in the triclinic space group P , a = 11.2426(8) Å, b = 11.7141(8) Å, c = 16.195(1) Å, = 102.041(5)°, = 95.128(5)°, = 102.553(6)°, V = 2008.4(3) ų, Z = 2, d _calc. = 1.733 g/cm³; R = 0.0488, R _w = 0.0546 for 2212 observed reflections with I > 3 (I). The X-ray structure reveals that the bpcd ligand is bound exclusively to the Ru₃ core at the ruthenium center coordinated by the terminal CH unit of the -allylic ₃– ³-CHCHCMe moiety.     

Ba(Zn(1-x)/3Nix/3Nb2/3)O3微波介质陶瓷的微观结构

本文采用传统的固相陶瓷烧结工艺,利用Ni2+取代Ba(Zn1/3Nb2/3)O3 的B位Zn2+形成固溶体来研究其微观结构.XRD表明,系统的主晶相为立方钙钛矿的BZNN,并有少量第二相如Ba5Nb4O15、BaNb2O6等存在.随Ni2+含量增加,系统晶格常数a减小;而随烧结温度升高,a逐渐增大.系统在1500 ℃下烧结时为固相烧结;当烧结温度为1550 ℃时,系统由固相烧结转变为液相烧结.较低温度下烧结时,在低角度区有很微弱的1∶ 2有序相产生;烧结温度升高,无序相增加,有序相消失.     

Nd~(3+)掺杂的Sr_3Y_2(BO_3)_4晶体光谱特性研究

采用提拉法生长出25mm×40mm的Nd3+∶Sr3Y2(BO3)4晶体,测试了该晶体的吸收光谱、荧光光谱及荧光寿命。结果表明:Nd3+∶Sr3Y2(BO3)4晶体在807nm附近有最强的吸收峰,其半峰宽(FWHM)为16nm,宽的吸收半峰宽适合于LD泵浦;从荧光光谱得到发射波长分别为910.8nm、1065.2nm和1399nm的荧光峰。根据吸收和荧光光谱,计算了晶体的吸收截面和发射截面。采用J-O理论计算了Nd3+在Sr3Y2(BO3)4中的强度参数、各能级的振子强度、自发辐射几率、荧光分支比等参数。计算结果表明,其强度参数Ω2=3.816×10-20cm2,Ω4=10.895×10-20cm2,Ω6=12.44×10-20cm2,辐射寿命为104μs,量子效率η=49.7%,荧光分支比β1(0.88μm)=0.429,β2(1.06μm)=0.461,β3(1.35μm)=0.107,β4(1.88μm)=0.003。     

Nd~(3+)、Eu~(3+)、Tb~(3+)掺杂纳米TiO_2的制备及光催化性能的研究

采用溶胶-凝胶法制备了掺杂1 mol%Nd3+、Eu3+、Tb3+的TiO2纳米光催化剂,通过X射线衍射、比表面积、紫外-可见吸收光谱等对制备的光催化剂进行了表征,并通过甲基橙的光催化降解研究了样品的光催化性能。结果表明,稀土离子的掺杂能有效抑制TiO2纳米粒子的生长,进而增大比表面积,并且掺杂纳米TiO2光催化剂紫外-可见吸收带边都有一定的红移;掺杂纳米TiO2光催化剂的活性优于未掺杂纳米TiO2光催化剂,其中Eu3+/TiO2的光催化活性为最强。     

Nonlinear-laser (χ(2) + χ(3)) effects in acentric cubic Bi4Ge3O12 and NaClO3 crystals

The effects of the self-frequency summing of IR-pumping and Stokes and anti-Stokes generation have been revealed in stimulated Raman scattering in (χ⁽²⁾ + χ⁽³⁾)-nonlinear Bi₄Ge₃O₁₂ and NaClO₃ crystals. The recorded components of Raman-induced parametric generation have been identified.     

CaYO(BO3)3晶体坩埚下降法生长

本文首次报道了Ca4YO(BO3)3(YCOB)晶体的坩埚下降法生长.在1600～1650℃炉温下,固液界面处的纵向温度梯度为40～60℃/cm,以0.2～0.6mm/h的生长速率,在近封闭的Pt坩埚中生长出了直径达25mm、长度超过50mm的完整透明YCOB晶体.介绍了生长工艺和原料制备,观察发现晶体中的主要宏观缺陷是包裹体.分析了包裹体生成的原因.     

紫外低吸收YAl3(BO3)4晶体生长

本文对用于紫外低吸收YAB晶体生长的助熔剂体系进行了筛选,测定了YAB-Li2B4O7-AlBO3体系的结晶关系.采用顶部籽晶熔盐法生长紫外低吸收YAl3(BO3)4晶体,测定了晶体的真空紫外透过截止波长,结果表明其真空紫外吸收边达到165 nm.     

Reaction of bis(dimethoxyphosphino)dimethylhydrazine (dmpdmh) with Ru3(CO)12: Evidence for facile ligand fragmentation in Ru3(CO)10(dmpdmh) to give Ru4(CO)12[μ-N(Me)N(Me)], Ru3(CO)11[P(OMe)3], and Ru3(CO)9[μ-P(OMe)3]

Thermolysis of the cluster Ru₃(CO)₁₂ with the bis(phosphanyl)hydrazine ligand (MeO)₂PN (Me)N(Me)P(OMe)₂ (dmpdmh) in toluene at 75°C furnishes the known clusters Ru₄(CO)₁₂ [-N(Me)N(Me)] (2) and Ru₃(CO)₁₁[P(OMe)₃] (3), in addition to the new cluster Ru₃ (CO)₁₀(dmpdmh) (1) and the phosphite-tethered cluster Ru₃(CO)₉[-P(OMe)₃] (4). The simple substitution product Ru₃(CO)₁₀(dmpdmh), a logical intermediate to clusters 2–4, was synthesized by treating Ru₃(CO)₁₂ with Me₃NO in CH₂Cl₂ at room temperature, and independent thermolysis reactions using cluster 1 was shown to yield clusters 2–4. The solid-state structure of clusters 2 and 4 were unequivocally established by X-ray diffraction analysis. Ru₄(CO)₁₂[-N(Me)N(Me)] crystallizes in the orthorhombic space group Pnna (#52), a = 12.913(1), b = 13.3238(6), c = 12.5690(8) Å, V = 2162.5(2) ų, Z = 4, and d _calc = 2.452 g/cm³. Ru₃(CO)₉[-P(OMe)₃] crystallizes in the triclinic space group P a = 9.586(1), b = 14.354(1), c = 14.997(2) Å, = 89.82(1)°, = 98.36(1)°, = 92.010(8)°, V = 2040.4(4) ų, Z = 4, and d _calc = 2.212 g/cm³. The coordination of the dimethylazo linkage to the four ruthenium atoms in 2 and the phosphorus atom and one of the oxygen atoms of the methoxy groups to the three ruthenium centers in 4 are confirmed by X-ray analysis.     

n(Sm~(3+))/n(S_2O_3~(2-))对液相自组装法制备Sm_2S_3薄膜的影响

采用液相自组装法,以氯化钐(SmCl3.6H2O)和硫代硫酸钠(Na2S2O3.5H2O)为原料,在不同n(Sm3+)/n(S2O23-)(物质的量比)条件下,于硅基板上制备了α-Sm2S3光学薄膜。利用X射线衍射仪(XRD)、光电子能谱分析(XPS)、原子力显微镜(AFM)和紫外-可见吸收光谱仪(UV-Vis)对Sm2S3薄膜的物相组成、表面形貌和光学性能进行了表征。结果表明:所制备的Sm2S3薄膜为α-Sm2S3,在一定范围内,随着n(Sm3+)/n(S2O23-)的增加,α-Sm2S3薄膜的结晶性先增强后降低,并表现出(105)晶面取向生长的特征。紫外透射光谱分析表明,当n(Sm3+)/n(S2O23-)=1∶2时,Sm2S3薄膜在可见光范围内透过率高达85%,禁带宽度为4.12 eV。     

Na3La2(BO3)3:Tb3+的合成及其光谱特性

采用固相反应法合成了一系列掺Tb3+的Na3La2(BO3)3多晶粉末,Tb3+的最大掺杂浓度约为30mo1;.在室温下测试了Na3La2(BO3)3:Tb3多晶粉末的红外光谱、发射光谱、激发光谱和荧光寿命.结果表明:在253 nm紫外光的激发下,Tb3+在487 nm、545 nm、583 nm和621 nm处有一组发射峰,分别对应于Tb3的5D4→7FJ(J=6,5,4,3)的跃迁.研究了荧光发射强度与Tb3+浓度之间的关系,掺杂浓度小于30mo1;时,荧光发光强度随Tb3+掺杂浓度的增加而增强.