Photocatalytic Activity of Nanosized TiO_2 Enhanced by co-doping with Fe^(3+) and Nd^(3+) Ions

In this study, nanosized TiO2 co-doped with Fe3+ and Nd3+ ions was synthesized via a sol-gel method. The metallic ion doped TiO2 was thoroughly characterized with XRD and UV-vis, and the photocatalytic activity was evaluated by degrading methylene blue (MB) solution. The results indicated that TiO2 crystalline size was reduced and phase transformation of anatase to rutile was suppressed as the content of doped Nd3+ ion increased in the co-doped TiO2. The UV-vis spectra of co-doped TiO2 seemed to simply overlay two spectra of single metal doped TiO2, and had significantly increased absorbance in the ranges of 400～500 nm, 565～600 nm and 730～765 nm as compared to pure TiO2. The photocatalytic activity of co-doped TiO2 was obviously enhanced, and raised about 30% compared to that of pure TiO2 as doped Nd3+ content was 0.15% and Fe3+ content was 0.05%, respectively. The enhanced catalytic activity was attributed to a synergistic effect of two doped ions, where doped Fe3+ ion inhibited the recombination of photogenerated electron and hole, and Nd3+ ion brought more surface carboxyl to promote the degradation reaction.

Spectroscopic analysis of trivalent Nd3+/Yb3+ions codoped in PZS host glasses as a new laser material at 1.06μm

This paper reports on the spectral results of Nd3＋/yb3＋ ions codoped 50P2Os-30ZnO-20SrO （PZS, in mol.%） glasses which were prepared by a melting technique. The glass transition temperature and spectroscopic properties of these glasses were estimated. From the absorption spectra, Judd-Ofelt （J-O） intensity parameters （Ωk）, were calculated. Using J-O intensity parameters, several radiative properties such as spontaneous transition probabilities （AR）, radiative branching ratios （fiR） and radiative lifetimes （rR） were determined for the exciting levels of the Nd3＋ ions. The large value of the stimulated integrated cross-section and the lifetimes of Nd3~ level revealed the potential of the present glasses as a candidate for generating laser emission at 1.06/am as continuous wave laser action and exploited for optical device fabrication. A broad emission band from 950 to 1100 nm was detected when the Nd3＋/yb3＋ was co-doped in PZS glasses excited by 805 nm lighting diode （LD）. The energy transfer process from Nd3＋--→Yb3＋ in co-doped phos- phate glasses was described in this paper.

Effects of Yb^3＋ in Er^3＋/Yb^3＋ Codoped Fluorophosphate Glasses

For the Er^3＋ /Yb^3＋ codoped fluorophosphate glasses, Judd-Ofelt theory is used to analyse the influence of YbF3 as not a sensitizer but an average component on the spectroscopic properties around 1530nm emission. The double roles of Yb^3＋, as a sensitizer and as an average component, are discussed. It is found that Yb^3＋ as an average component contributes to the increase of fluorescence lifetime, and Yb^3＋ as a sensitizer has the best sensitization when its concentration is 2.4 mol%.

Optical thermometry based on near-infrared luminescence from phosphors mixture

Luminescence ratiometric thermometry based on rare earth(RE)ions has attracted great interest for the potential applications in many fields.But the improvement of the measurement sensitivity and accuracy is significantly restricted due to the small energy gap between thermally coupled levels(TCL).Here,a strategy striving for good thermometric properties of luminescent materials was designed by using the phosphors mixture composed of NaY(WO_(4))_(2):Nd^(3+)-Yb^(3+)and NaY(WO_(4))_(2):Er^(3+),which were prepared by secondary sintering method.Under the excitation of 980 nm lase r,the near-infrared(NIR)emissions(710-920 nm)from Nd^(3+)ions are effectively strengthened when the temperature increases from 304 to773 K,whereas Er^(3+)NIR luminescence centered at around 1536 nm is thermally quenched.The remarkably different response of NIR emissions to the thermal variation allows us to map temperature through the ratiometric method.By optimizing the dopant concentration of rare earth(RE)ions,a maximum sensitivity of 5.14%/K together with a measurement uncertainty of about 0.1 K is acquired at304 K,which is superior to the previously reported RE luminescence-based temperature sensors,indicating that the approach developed here can pave the way for achieving optical thermometry with desired properties.