Qiu Sun
Harbin Institute of Technology
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Publication
Featured researches published by Qiu Sun.
Applied Physics Letters | 2007
Gang Chen; Yuqiang Liu; Y. G. Zhang; Gabriel Somesfalean; Z. G. Zhang; Qiu Sun; Fuping Wang
Room temperature bright white upconversion (UC) luminescence in Yb3+–Tm3+–Er3+ ions doped Y2O3 nanocrystals was obtained under single-wavelength diode laser excitation of 976nm. The white light consists of the blue, green, and red UC radiations which correspond to the transitions G41→H63 of Tm3+, H11∕22∕S3∕24→I15∕24, and F9∕24→I15∕24 of Er3+ ions, respectively. The UC mechanisms were proposed based on spectral, kinetic, and pump power dependence analyses. The calculated color coordinates display that white light can be achieved in a wide range of pumping powers, which promises their potential applications in the field of displays, lasers, photonics, and biomedicine.
Applied Physics Letters | 2006
Guanying Chen; Y. G. Zhang; Gabriel Somesfalean; Z. G. Zhang; Qiu Sun; Fei Wang
To develop fluorescent labels for multicolor imaging, rare-earth-ion-doped ZrO2 nanocrystals were prepared by a complex precursor method. Laser excitation of 976nm induced single fluorescent bands of green and red upconversion (UC) in ZrO2:Er3+ and ZrO2:Er3++Yb3+ nanocrystals, respectively. A suppression ratio (SR) parameter was introduced, defined as the UC intensity ratio of the main band to all the other detected impurity bands, and SR values in the order of 10–100 were experimentally obtained, demonstrating the excellent monochromaticity of the UC labels. Thus, the two-color UC labels obtained are potentially ideal to be used for biological multicolor imaging.
Applied Physics Letters | 2008
Guangyu Chen; Haichun Liu; Gabriel Somesfalean; Y. Q. Sheng; Huijuan Liang; Z. G. Zhang; Qiu Sun; Fuping Wang
We report on an innovative route to increase the upconversion (UC) green radiation by two orders of magnitude in Y2O3:Er3+ nanocrystals through tailoring Er3+ ions’ local environment with Li+ ions under diode laser excitation of 970nm. Theoretical investigations based on the steady-state rate equations indicate that such enhancement arises from a combining effect of the tailored lifetime of the intermediate I11∕24(Er) state, the suppressed cross relaxation H11∕22(Er)+I15∕24(Er)→I9∕24(Er)+I13∕24(Er) process, and the enlarged nanocrystal size induced by the Li+ ions. The proposed route here may constitute a promising step to solve the low efficiency problem in UC materials.
Optics Letters | 2007
Guanying Chen; Gabriel Somesfalean; Z. G. Zhang; Qiu Sun; Fei Wang
Room-temperature ultraviolet emission of Tm(3+) ions at 298 ((1)I(6)-->(3)H(6)), 364 ((1)D(2)-->(3)H(6)), and 391 nm ((1)I(6)-->(3)H(5)) was obtained in Y(2)O(3):Yb(3+)-Tm(3+) by continuous-wave diode laser excitation of 980 nm. Power dependence analysis demonstrates that five- and six-photon upconversion processes populate the (1)D(2) and (1)I(6) states, respectively. We believe that the (1)D(2) population originates from the cross relaxation (1)G(4)+(3)F(4)-->(3)H(4)+(1)D(2) of the Tm(3+) ions, while subsequent energy transfer from Yb(3+) to Tm(3+) excites the (1)D(2) state to the upper (1)I(6) state. High multiphoton-induced ultraviolet emission is also expected for other trivalent rare-earth ions similar to Tm(3+).
Journal of Materials Chemistry C | 2016
Mao Ye; Tao Li; Qiu Sun; Zhikai Liu; Biaolin Peng; Chuanwei Huang; Peng Lin; Shanming Ke; Xierong Zeng; Xiang Peng; Lang Chen; Haitao Huang
A negative electrocaloric effect (ECE) in 4 mol% Eu-doped PbZrO3 antiferroelectric (AFE) thin films prepared by using a sol–gel method is investigated via indirect measurements. Temperature dependent P–E hysteresis loops were measured. A giant negative electrocaloric temperature change of over 6.6 K was observed. These results raised hopes for the enhancement of the cooling efficiency in combination with positive ECE.
Applied Physics Letters | 2015
Mao Ye; Haitao Huang; Tao Li; Shanming Ke; Peng Lin; Biaolin Peng; Manfang Mai; Qiu Sun; Xiang Peng; Xierong Zeng
The dielectric and ferroelectric nonlinearity of Nb-doped PbZrO3 relaxor ferroelectric thin films was investigated. The ac field dependence of the permittivity of relaxor ferroelectric thin films is demonstrated to be described by a Rayleigh type relation. Both reversible and irreversible components of dielectric permittivity decrease linearly with the logarithm of the frequency of the ac field. The irreversible Rayleigh coefficient α′(T) shows a peak around the “freezing temperature” Tf, which is probably according to the transition from polar nano-regions (PNRs) to dipole-glass state in relaxor ferroelectrics. The results demonstrate that the models describing the interaction of domain walls and randomly distributed pinning centers in ferroelectric materials can be extended to the displacement of nanoscale walls in relaxors.
International Journal of Advanced Applied Physics Research | 2014
Shanming Ke; Mao Ye; Peng Lin; Haitao Huang; Biaolin Peng; Qiu Sun; Fuping Wang; Xiang Peng; Xierong Zeng
A series of 400-nm-thick sandwich structured Pb(1+x)ZrO3/(Pb,Eu)ZrO3/Pb(1+x)ZrO3(PZO/PEZO/PZO) antiferroelectric thin films with different Pb excess content (x) (x=0%, 10%, 20%, and 30%) in the PZO precursors have been successfully deposited on Pt(111)/Ti/SiO2/Si substrates by a sol–gel method. The effects of Pb excess content on the dielectric properties, and energy storage performance of the PZO/PEZO/PZO thin films have been investigated in detail. It is found that all the films show a unique perovskite phase structure. With increasing Pb excess content in the PZO precursors, P-E hysteresis loop changes from slanted to square shape. Meanwhile, a larger antiferroelectric to ferroelectric switching field (EAF) and ferroelectric to antiferroelectric switching field (EFA) are observed in the films with higher Pb excess content. When increasing Pb excess content from 0% to 30%, the energy storage density of the sandwich structured films is remarkably improved from 11.4 to 14.8 J/cm 3 at 1000 kV/cm.
Chemical Physics Letters | 2007
Gang Chen; Yuqiang Liu; Z. G. Zhang; B. Aghahadi; Gabriel Somesfalean; Qiu Sun; Fuping Wang
Optics Communications | 2011
Xiangqun Chen; Zhikai Liu; Qiu Sun; Mao Ye; Fuping Wang
Journal of the American Ceramic Society | 2012
Mao Ye; Qiu Sun; Xiangqun Chen; Zhaohua Jiang; Fuping Wang