Spectroscopic study of local thermal effect in transparent glass ceramics containing nanoparticles

Local thermal effect influencing the fluorescence of triply ionized rare earth ions doped in nanocrystals is studied with laser spectroscopy and theory of thermal transportation for transparent oxyfluoride glass ceramics containing nanocrystals. The result shows that the local temperature of the nanocrystals embedded in glass matrices is much higher than the environmental temperature of the sample. It is suggested that the tempera,ture-dependent thermal energy induced by the light absorption must be considered when the theory of thermal transportation is applied to the study of local thermal effect.

Spectroscopic study of thulium doped transparent glass ceramics

A systematic investigation on fluorescence spectroscopy of trivalent thulium doped in oxyfluoride glass ceramics containing LaF3 nanocrystals has been carried out in a spectral range from 400 to 900 nm under the direct excitation of 1D2 level at a low temperature. Specific optical transitions related to the fluorescence emissions are studied based on experimental measurements in frequency and time domain. Fluorescence emissions from the ions in crystal phase are distinguished from what in glass phase and their spectroscopic properties are explored. The dynamical process shows that the temporal decay of fluorescence emission consists of two parts： a rapid decay from the ions in glass phase and a slower decay from the ions in crystal phase.

Near-white light-emitting Dy^(3+)-doped transparent glass ceramics containing Ba_2LaF_7 nanocrystals

Glass ceramics Ba2LaFT：xDy3＋ are obtained through the conventional melt-quenching technique, and their lu- minescent properties are investigated. Under 350 nm excitation, the emission spectra consists of a strong blue- yellow band as well as a weak red emission centered at 660 nm, which are attributed to the 4F9/2 →6H15/2, 4F9/2→6H13/2 and 4F9/2 → 6Hll/2 transitions of the Dy3＋ ion, respectively. The corresponding Commission Internationale de L＇Eclairage （CIE） chromaticity coordinate for a sample of 2 mol.% Dy203 after being heat-treated at 690℃ is （0.313, 0.328）. It is concluded that the formed materials may have the possibility of applications for white light-emitting diodes （LEDs）.

Fabrication of patterned transparent conductive glass via laser metal transfer for efficient electrical heating and antibacteria

Vapor deposition and three-dimensional(3D)printing technology are considered to be conventional methods to achieve patterned metal film preparation through the assistance of masks and high temperature.Therefore,there are still some challenges in fabricating metal films in template-free and normal temperature environment.In this work,we report a flexible and rapid laser metal transfer(LMT)technique for fabricating the various metal films(Cu,Ni,Sn,Al,Fe,and Ag)with different patterns without templates on arbitrary substrates(glass,polyimide(PI)films,and aluminum nitride(AlN)ceramic).Especially,the obtained transparent conductive glass displays high transmittance(more than 90%)and adjustable resistances(≈5Ω).According to the Joule effect,the interface resistance between Cu particles and copper oxide coating produces the high temperature approximately 280℃ at 2 V in a short time(≈60 s)and remains stable at 120℃ over 12 h.At last,the multifunctional glass with Cu patterns also shows excellent bactericidal activity(≈95%).This work demonstrates that laser metal transfer is an exceeding effective means of fabricating the micro/nano structures with potential applications in functional devices.

Effect of KOH treatment on structural and photovoltaic properties of ZnO nanorod arrays

ZnO nanorod arrays （NRs） were synthesized on the fluorine-doped SnO2 transparent conductive glass （FTO） by a simple chemical bath deposition （CBD） method combined with alkali-etched method in potassium hydroxide （KOH） solution. X-ray diffraction （XRD）, scanning electron microscopy （SEM） and current-voltage （I-V） curve were used to characterize the structure, morphologies and optoelectronic properties. The results demonstrated that ZnO NRs had wurtzite structures, the morphologies and photovoltaic properties of ZnO NRs were closely related to the concentration of KOH and etching time, well-aligned and uniformly distributed ZnO NRs were obtained after etching with 0.1 mol/L KOH for 1 h. ZnO NRs treated by KOH had been proved to have superior photovoltaic properties compared with high density ZnO NRs. When using ZnO NRs etched with 0.1 mol/L KOH for 1 h as the anode of solar cell, the conversion efficiency, short circuit current and open circuit voltage, compared with the unetched ZnO NRs, increased by 0.71%, 2.79 mA and 0.03 V, respectively.

Plant Cultivation Device in Intelligent Agricultural Greenhouse

This paper mainly introduces the design and research of plant cultivation device in intelligent agricultural greenhouse.The device can automatically ventilate and control the temperature when the carbon dioxide content is insufficient.At the same time,the light color can be selected according to the plant properties,and the light and dark time can be controlled to provide a suitable growth environment for plants,which makes up for the shortcomings of the existing ordinary greenhouse.With China's strong support for agriculture,automatic agriculture is developing rapidly,and has a broad market prospect.

Luminescent properties of Ce^(3+)-doped transparent oxyfluoride glass ceramics containing BaGdF＿5 nanocrystals

The transparent oxyfluoride glass ceramics containing Ba Gd F5 nanocrystals were prepared with a composition of 42 Si O2-12Na2O-16Al2O3-24 Ba F2-4Gd2O3-2Ce F3（mol.%） by thermal treatment technology. The typical DSC curve, X-ray diffraction（XRD） and transmission electron microscopy（TEM） patterns were measured. The transmission spectra and luminescent properties were investigated. The decay times of the Gd^3＋ ions at 312 nm excited with 275 nm for the Ce^3＋ ions doped glass and glass ceramics specimens and the energy transfer process between Gd^3＋ ions and Ce^3＋ ions were also studied. The XRD analysis and the TEM images confirmed the generation of the spherical Ba Gd F5 nanocrystals. Compared with the PG specimen, the intensity of the luminescence spectra of the glass ceramics specimens was apparently enhanced with the heat treatment temperature increasing, and a blue shift in the excitation spectra and the emission spectra of glass ceramics specimens was obviously observed. In the fluorescence decay curves of the Gd^3＋ ions, it could be obviously observed that the fluorescent intensity decays in the Ce^3＋ ions doped glass and glass ceramics specimens decreased rapidly with the increase of the heat treatment temperature. In addition, the energy transfer efficiency from Gd3＋ions to Ce^3＋ ions was also calculated.

Enhancement of up-conversion luminescence properties in Yb^(3+)/Tm^(3+)/Er^(3+) tri-doped transparent oxyfluoride tellurite glass ceramics

Optically transparent Er3＋/Tm3＋/Yb3＋ tri-doped oxyfluoride tellurite based nano-crystallized glass ceramics with the batching composition of 73TeO2-15ZnO-7ZnF2-3YF3-1.5YbF3-0.3ErF3-0.2TmF3 （mol%） is prepared by a conventional melting quenching and the subsequent heat treatment processes. The sizes of grown nano-crystals in glass matrix appear to be smaller than 100 nm from the scanning electron mi- croscope measurement. Visible up-conversion luminescence of the as melted glass and glass ceramics is investigated. The three-color up-conversion luminescence intensities by 980-nm pumping are increased significantly due to the heat treatment, and the blue intensity increases with a higher magnitude than other wavelengths after heat treatment.

Impact of Yb^(3+)/Er^(3+) ions on crystallization of phosphosilicate glass melts

Transparent glass ceramics were prepared from the phosphosilicate system by melt-quenching devitrification（MQD） method, i.e., nanocrystals spontaneously form during cooling of the melts. Introduction of 2.5 wt.% Yb2O3 and 0.5 wt.% Er2O3 into the glass melt induced the change of type and concentration of crystals. The comparison of rheological and thermodynamic properties of both undoped and Yb^3＋/Er^3＋ doped melts showed that addition of Yb^3＋/Er^3＋ oxides caused increase of liquid fragility, and degree of medium-range order. In addition, the thermodynamic barriers for nucleation ΔG＊ as a function of reduced temperature T/Tm were calculated with an assumption of wetting angle θ=90o, Yb^3＋/Er^3＋ doped melt tended to firstly nucleate as compared to undoped melt at small undercooling.