Effect of alkaline-earth metal composition on spectroscopic properties of Er3+ in fluorophosphate glasses

Optical spectroscopic properties of Er3+-doped alkaline-earth metal modified fluoropho sphate glasses have been investigated experimentally for developing broadband fiber and planar amplifiers. The results show a strong correlation between the alkaline-earth metal content and the spectroscopic parameters such as absorption and emission cross sections, full widths at half-maximum and Judd-Ofelt intensity parameters. It is found that strontium ions could have more influences on the Judd-Ofelt intensity parameters and the absorption and emission cross sections than other alkaline-earth metal ions such as Mg2+, Ca2+, Ba2+. The sample containing 23 mol% strontium fluoride exhibits the maximum emission cross section of 7.58 x 10(-21) cm(2), the broadest full width at half-maximum of 65 nm and the longer lifetime of 8.6 ms among the alkaline-earth metal modified fluorophosphates glasses studied. The Judd-Ofelt intensity parameter Omega(6)s, the emission cross sections and the full widths at half-maximum in the Er3+-doped fluorophosphate glasses studied are larger than in the silicate and phosphate glasses.

碱金属和碱土金属氟化物对掺Er^3＋氟磷酸盐玻璃光谱性质的影响

研究了碱金属和碱土金属离子修饰的掺Er^3＋氟磷酸盐玻璃的光谱性质，讨论了碱金属和碱土金属对铒氟磷玻璃的吸收和发射截面、荧光半高宽，Judd-Ofelt强度参数和上转换发光强度等光谱性质的影响，并与一些传统氧化物玻璃系统进行了比较．研究表明碱金属K^＋和碱土金属Sr^2＋掺杂高的玻璃更适宜用作光放大器基质．含12mol％K^＋的氟磷玻璃展现出7．83×10^-21cm^2的高发射截面和最小的荧光上转换强度；含23mol％Sr^2＋的氟磷玻璃则有7．58×10^-21cm^2的高发射截面、65nm的荧光半高

SrF2 hierarchical flowerlike structures: Solvothermal synthesis, formation mechanism, and optical properties

We present a solvothermal route to the synthesis of SrF2 hierarchical flowerlike structures based on thermal decomposition of single source precursor (SSP) of strontium trifluoroacetate in benzylamine solvent. These flowerlike superstructures are actually composed of numerous aggregated nanoplates, and the growth process involves the initial formation of spherical nanoparticles and subsequent transformation into nanoplates. which aggregated together to form microdisks and finally flowerlike superstructures. The results demonstrate the important role of benzylamine in the formation of well-defined SrF2 superstructures, not only providing size and shape control to form nanoplates but also contributing to the self-assembly behavior of nanoplates to build into flower-like superstructures. Additionally, the photoluminescence properties of the obtained SrF2 superstructures are studied.

Hydrothermal synthesis of SrCO3 : Eu3+/Tb3+ microneedles and their luminescence properties

SrCO3:Eu3+ /Tb3+ microneedles that grow along the a-axis were successfully prepared through a large-scale and facile hydrothermal method without any template and further annealing treatment. X-ray diffraction (XRD), scanning electron microscopy (SEM), and photoluminescence (PL) spectra as well kinetic decays, were used to characterize the samples. The preferential growth along a-axis for SrCO3:Eu3+/Tb3+ microneedles has been proposed through analysis of the XRD patterns of samples obtained at different hydrothermal treatment time. Under ultraviolet excitation, the SrCO3:Eu3+ and SrCO3:Tb3+ microncedle samples show a strong red and green emission corresponding to the D-5(0)-F-7(j) (J = 1, 2, 3, 4) transitions of Eu3+ and the D-5(4)-(7) F-j (J = 6, 5, 4, 3) transitions of Tb3+, respectively, which have potential applications in lighting fields.

Thermoluminescence studies of LiBa2B5O10 : RE3+ (RE = Dy, Tb and Tm)

LiBa2B5O10:RE3+ (RE = Dy, Tb and Tm) was synthesized by the method of high-temperature solid-state reaction and the thermoluminescence (TL) properties of the samples under the irradiation of the gamma-ray were studied. The result showed that Dy3+ ion was the most efficient activator. When the concentration of Dy3+ was 2 mol%, LiBa2B5O10:Dy3+ exhibited a maximum TL output. The kinetic parameter of LiBa2B5O10:0.02Dy was estimated by the peak shape method, for which the average activation energy was 0.757 eV and the frequency factor was 1.50 x 10(7) s(-1). By the three-dimensional (3D) TL spectrum, the TL of the sample was contributed to the characteristic f-f transition of DY3+. The dose-response of LiBa2B5O10:0.02Dy to gamma-ray was linear in the range from 1 to 1000 mGy. In addition, the decay of the TL intensity of LiBa2B5O10:0.02Dy was also investigated.

DNA network structures on various solid substrates investigated by atomic force microscopy

We have fabricated DNA network structures on glass and sapphire substrates. As a comparison, we also formed the network structure on mica substrate. For titanate strontium substrate, however, DNA network can not be obtained even if it is wet-treated by Na2HPO4 solution to make it hydrophilic. We also discuss the factors that affect the DNA networks formed on various substrates.

Synthesis, characterization and crystal structure of a new layered heterometallic coordination polymer {[(CuL) Sr-2(H2O)center dot Sr-2(H2O)(7)]center dot 2H(2)O center dot 0.5CH(3)OH}(n)

A copper-strontium heterometallic coordination polymer was synthesized and characterized by elemental analysis and IR spectra. The crystal structure was determined by single-crystal X-ray diffraction analyses. The title complex is a 2 D coordination polymer with the chemical formula [[(CuL)(2)Sr (H2O) center dot Sr-2 ((HO)-O-2)(7)]center dot 2H(2)O center dot 0.5CH(3)OH](n), where H4L = N-(2-hydroxybenzamido)-N'-(3-carboxylsalicylidene) ethylenediamine. Its structural unit is comprised of two adjacent units, which polymerized with each other to form a new layered heterometallic coordination polymer.

Local structure and valences of samariurn in SrB4O7 : Sm and SrB6O10 : Sm prepared in-air

The coordination numbers for the samarium atoms and the Sm-O bond distances in SrB4O7:Sm and SrB6O10:Sm prepared in air were determined by means of Sm-L-3 edge EXAFS. The coordination. was found to be nine-folded for both these hosts and the bond distance was 2.40-2.42 Angstrom in SrB4O7:Sm and 2.42-2.44 Angstrom in SrB6O10:Sm. For SrB4O7:Sm the coordination number is coincident with that of the strontium. atoms suggesting the substitution of the samarium atoms at the strontium sites. The coordination number of the strontium atoms in SrB6O10 was also suggested to be nine assuming the same type of substitution. The valences of samarium were determined from the luminescent spectra. Both divalent and trivalent ions were present in both SrB4O7:Sm and SrB6O10:Sm, while the fraction of Sm2+ was higher in the former than in the latter. This difference has been assigned to the difference in rigidity between the B-O networks in these structures.