10 results on '"Liu, Chao"'
Search Results
2. Formation and optical properties of ZnSe and ZnS nanocrystals in glasses.
- Author
-
Xia, Mengling, Liu, Chao, Zhao, Zhiyong, Ai, Bing, Yin, Qiaoyun, Xie, Jun, Han, Jianjun, and Zhao, Xiujian
- Subjects
- *
OPTICAL properties , *ZINC selenide , *ZINC compounds , *GLASS , *NANOPARTICLES - Abstract
ZnSe and ZnS nanocrystals (NCs) were precipitated in glasses through heat-treatment. High resolution transmission electron microscope image confirmed that ZnSe NCs were formed in the silicate glasses, and the X-ray diffraction patterns confirmed that ZnS NCs were precipitated in the borosilicate glasses. Absorption shoulders of the ZnSe NCs and ZnS NCs appeared at ~ 2.76 eV and ~ 3.78 eV, corresponding to the bandgap energies of bulk ZnSe and ZnS crystals, respectively. Instead of the intrinsic emissions, broad-band visible photoluminescence from the surface defects or color centers in the glasses was observed from these ZnSe or ZnS NCs. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
3. Absorption and photoluminescence of PbS QDs in glasses
- Author
-
Liu, Chao, Kwon, Yong Kon, and Heo, Jong
- Subjects
- *
ABSORPTION spectra , *PHOTOLUMINESCENCE , *QUANTUM dots , *LEAD sulfide , *OPTICAL properties of semiconductors , *PRECIPITATION (Chemistry) , *TEMPERATURE effect , *EFFECT of radiation on semiconductors , *GLASS - Abstract
Abstract: Optical properties of PbS quantum dots (QDs) precipitated inside the oxide glass matrix were investigated. Photoluminescence (PL) from the PbS QDs showed peak wavelengths located at 1170–1680nm with widths of 150–550nm. Radii of QDs in glasses were 2.3–4.7nm depending upon the thermal treatment. Peak wavelengths of PL bands shifted as much as 70nm as the temperatures and excitation irradiances increased. Calculated effective local temperatures indicated that these shifts of PL spectra were associated with local heating induced by the temperatures and laser beam. [Copyright &y& Elsevier]
- Published
- 2009
- Full Text
- View/download PDF
4. Up-conversion and photon avalanche in oxy-fluoride nano-structured glasses doped with Ho3+
- Author
-
Liu, Chao and Heo, Jong
- Subjects
- *
NANOSTRUCTURED materials industry , *EMISSIONS (Air pollution) , *GLASS , *PHOTONS - Abstract
Abstract: Transparent nano-crystalline glass–ceramics (nano-structured glasses) were prepared from oxy-fluoride precursor glass doped with HoF3 and their luminescence properties were investigated. Visible blue, green and red emissions were observed, and the relative intensity of the green and red emission was strongly dependent on HoF3 concentration. Under 750 nm pumping, the intense green emission due to the photon avalanche process was observed at room temperature from nano-structured glass doped with high (0.5mol%) concentration of HoF3. [Copyright &y& Elsevier]
- Published
- 2006
- Full Text
- View/download PDF
5. Optical properties of CdSe quantum dots in silicate glasses
- Author
-
Xu, Kai, Liu, Chao, Chung, Woon Jin, and Heo, Jong
- Subjects
- *
OPTICAL properties , *CADMIUM selenide , *QUANTUM dots , *GLASS , *PRECIPITATION (Chemistry) , *ABSORPTION , *PHOTOLUMINESCENCE - Abstract
Abstract: CdSe quantum dots (QDs) were precipitated in silicate glasses under various durations and temperatures of heat-treatment. Absorption and photoluminescence (PL) spectra of the QDs showed the quantum confinement effect from CdSe QDs. When the glass was heat-treated for 10h, estimated average QD sizes increased from 5.2nm when the glass was heat-treated at 490°C and to 6.9nm when it was treated at 500°C. When the glass was heat-treated at 480°C, estimated average QD sizes were 4.9nm after 20h and 5.3nm after 30h. The PL peak position was independent of the excitation wavelengths; this result indicates that the size distribution of CdSe QDs was narrow. [ABSTRACT FROM AUTHOR]
- Published
- 2010
- Full Text
- View/download PDF
6. Crystallization and optical properties of Eu2+: CsCaCl3 nanocrystals in glasses.
- Author
-
Zhang, Yudong, Ye, Ying, Li, Kai, Zhang, Wenchao, and Liu, Chao
- Subjects
- *
OPTICAL properties , *OPTICAL glass , *QUANTUM efficiency , *RARE earth metals , *GLASS - Abstract
Narrow-band blue luminescence materials are desirable in full color display with wide color gamut. Divalent rare earth europium doped luminescence materials show excellent optical properties as promising backlit materials in display. However, narrow-band blue luminescence materials are still lacking. Herein, novel blue emitting Eu2+: CsCaCl 3 NCs are precipitated in the glasses, and effects of EuCl 3 doping concentration and heat-treatment conditions on the growth behavior and optical properties of Eu2+: CsCaCl 3 NCs precipitated in glasses are investigated. Doping concentration of EuCl 3 in glass and the heat-treatment condition can effectively regulate the Eu2+/Eu3+ molar ratio in glasses, size of Eu2+: CsCaCl 3 NCs, and effective doping concentration of Eu2+ ions in CsCaCl 3 NCs formed in the glasses. Besides, effect of phase separation on glass transmittance is explored to improve the glass optical properties. Upon incorporation of Eu2+ ions into CsCaCl 3 NCs in glasses, blue photoluminescence at 435 nm with full width at half maximum of 22 nm and color purity of ∼97.2 % is realized, and concomitantly, photoluminescence lifetimes are extended and quantum efficiency are significantly improved. These results demonstrate that Eu2+: CsCaCl 3 NCs doped glasses are promising blue emitting materials. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
7. Optical properties of CdTe quantum dots in silicate glasses containing CaO.
- Author
-
Wu, Hanwei, Zhang, Wenchao, Li, Kai, and Liu, Chao
- Subjects
- *
OPTICAL properties , *QUANTUM efficiency , *GLASS , *QUANTUM dots , *CHEMICAL stability , *SILICATES - Abstract
Embedding CdTe QDs into glass can improve the thermal and chemical stability of QDs, which facilitates their wide and endurable applications. However, the small tunable spectral range of photoluminescence, low quantum efficiency, and large full width at half maximum limit their wide applications. In this work, effect of introduction of CaO into glass matrix on the formation and optical properties of CdTe QDs is investigated. High concentration of CaO in glasses increases the solubility of Te in glasses, and consequently hinders the precipitation of CdTe QDs in glasses. By adjusting the heat-treatment temperature, average diameters of CdTe QDs are tuned in the range of 2.5–9.0 nm and their photoluminescence bands are tuned from 550 to 800 nm. More importantly, the absolute photoluminescence quantum yield is boosted up to 41.9 %. Results reported in this work indicate that CdTe quantum dots embedded in glasses are promising for applications in light-emitting devices. • High CaO concentration promote the dissolution of Te in the glass. • Photoluminescence of CdTe QDs doped glass is tuned from 550 nm to 800 nm. • PLQY of CdTe QDs doped glasses reaches 41.9 %. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
8. Growth kinetics and optical properties of PbSe quantum dots in dual-phase lithium-aluminum-silicate glass ceramic.
- Author
-
Shao, Xin, Wang, Jing, Han, Jianjun, Liu, Chao, Ruan, Jian, and Zhao, Xiujian
- Subjects
- *
GLASS-ceramics , *QUANTUM dots , *OPTICAL properties , *LEAD selenide crystals , *HEAT treatment , *GLASS , *GLASS recycling - Abstract
Lead selenide quantum dots (QDs) were precipitated in lithium-aluminum-silicate glass-ceramics. Their optical properties and the crystallization behavior of both glass host and PbSe QDs were investigated. When the glasses heat-treated at 480–520 °C for 10 h, the absorption bands from PbSe QDs were tuned from 1051 to 2016 nm, and the PL bands from 1165 to 2095 nm. Upon the dwelling time 10 h, the crystallization of glass host required relatively higher heating temperature (∼490 °C) than the formation of PbSe QDs (∼480 °C). With the heat treatment at 490 °C for10 h, the PLQY from PbSe QDs in glass-ceramics reached ∼38.7 %. Phase separation induced the glass crystallization and had a significant effect on the distribution of PbSe QDs. To study the growth kinetics of PbSe QDs, the glasses were heat treated at 480 °C and 500 °C for various durations. The average diameters of PbSe QDs (D) showed exponential relationship to the growth time (t), described by the equation D(t)∼ t x. In rapid growth stage, the growth exponents x is ∼ 0.56 at 480 °C and ∼ 0.47 at 500 °C, and then decrease to ∼ 0.13 and ∼ 0.10, respectively. The formation of a large number of LiAlO 2 crystals in glass hindered the diffusion of semiconductor ions, which is the main reason for the decreasing in the growth rate of PbSe QDs. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
9. Effects of Na2O on the optical properties of CdSe QDs embedded in glasses.
- Author
-
Jiang, Rongqing, Wu, Hanwei, Li, Kai, Zhang, Wenchao, Guo, Yunlan, Wang, Jing, and Liu, Chao
- Subjects
- *
OPTICAL properties , *GLASS , *PHASE separation , *GLASS structure , *PHOTOLUMINESCENCE , *HIGH temperatures - Abstract
• High Na 2 O concentration reduces the solubility of Se in the glass. • High Na2O concentration promotes the precipitation of CdSe QDs in glass. • Absorption and photoluminescence of CdSe QDs is tuned in the visible range. • Narrow band photoluminescence of CdSe QDs in glass is realized. In this work, effects of Na 2 O concentration on the precipitation of CdSe QDs in glasses is investigated. It is found that increase in concentration of Na 2 O reduces the connectivity of the network of glass and decreases the solubility of Se in the glass, leading to the formation of Se-related clusters and lower temperature for the precipitation of CdSe QDs. For glasses containing lower concentration of Na 2 O, defect-related photoluminescence (PL) is suppressed and the overall PL changes from dual band to narrow band with tunable wavelength in the visible range. For glasses containing higher concentration of Na 2 O, only dual band PL is observed due to the phase separation upon high temperature heat-treatment. Results reported in this work demonstrate that modulation of the PL properties of QDs in glasses can be accessed by adjusting the composition and structure of glasses. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
10. Precipitation and optical properties of PbSexS1-x quantum dots in glasses.
- Author
-
Liu, Juan, Liu, Jingjing, Zhang, Wenchao, Li, Kai, and Liu, Chao
- Subjects
- *
QUANTUM dots , *QUANTUM confinement effects , *OPTICAL properties , *CRYSTAL glass , *GLASS - Abstract
Lead chalcogenide quantum dots have particular optoelectronic properties induced by the quantum confinement effects and have promising potentials towards applications in infrared spectral range. Modulation of the optoelectronic properties of lead chalcogenide quantum dots is mainly based on the thermal treatment. In this work, precipitation and optical properties of alloyed PbSe x S 1-x quantum dots in glasses are investigated. Composition, size, absorption, and photoluminescence properties of PbSe x S 1-x quantum dots are modulated by chalcogen elements in glasses and thermal treatment. By adjusting the concentration of ZnSe and ZnS in the glasses, average diameters of the PbSe x S 1-x quantum dots are tuned in the range of 8.1–16.1 nm, their absorption peak wavelengths are tuned in the range of 724–2497 nm, and photoluminescence bands are tuned in the range of 1016–2165 nm with full width at half maximum in the range of 167–517 nm. Fraction of Se in the PbSe x S 1-x quantum dots precipitated in glasses is dependent on the concentrations of ZnSe and ZnS in the glass and heat-treatment temperature. Increase in concentration of S in the glasses results in the reduction of relative fraction of Se in the PbSe x S 1-x quantum dots formed in glasses. More importantly, high heat-treatment temperature promotes the enrichment of Se in PbSe x S 1-x quantum dots, and Se fraction in PbSe x S 1-x quantum dots increases from 0.69 to 0.89, from 0.53 to 0.85, from 0.47 to 0.79, and from 0.45 to 0.76 for those precipitated in glasses with ZnSe/(ZnSe+ZnS) molar ratios of 0.545, 0.375, 0.286, and 0.231, respectively. Increase in ZnSe/(ZnSe+ZnS) molar ratios in glasses also leads to reduction in diameter of PbSe x S 1-x quantum dots formed in glasses. These alloyed PbSe x S 1-x quantum dots also exhibit improved photoluminescence quantum yields and enhanced resistance to thermal quenching of photoluminescence. [Display omitted] [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.