Chunhui Su

Effect of Crystallization of Li2O-Al2O3-SiO2 Glasses on Luminescence Properties of Nd3+ Ions

Generally the preparation of lithium aluminosilicate (LAS) glasses is difficult on account of their high melting temperature. This research managed to prepare LAS glasses doped with Nd3+ ions by the conventional melting and quenching technique, at a relatively low melting temperature and by the use of some additives. Lithium aluminosilicate glasses were transformed to glass-ceramics by controlled nucleation and the crystallization process. The characterizations were performed by differential thermal analysis, X-ray diffraction, UV-Vis-NIR scanning spectrophotometry, and fluorescence spectrometry. The research focused on the photoluminescence spectra of the initial glass and the glass-ceramics under different heat-treatment schedules. Three main fluorescence bands centering at about 890, 1065, and 1330 nm were observed, which corresponded to the transitions of 4F3/2→4I9/2, and 4F3/2→4I11/2, and 4F3/2→4I13/2, respectively. Phase compositions of glass-ceramics were found to affect their fluorescent characteristics considerably. The fluorescent intensity increased markedly when Nd3+ ions entered the LixAlxSi1-xO2 β-eucryptite solid solution (SS). Quenching occurred when Nd3+ ions located at LixAlxSi3-xO6 β-eucryptite SS. Quenching disappeared after LixAlxSi3-xO6 β-eucryptite SS recrystallized into β-spodumene SS. The effectively induced cross section σin of Nd3+ ions located at the LixAlxSi1-xO2 β-eucryptite SS was 1.931 × 10−21 cm2 at 1065 nm.

Application of Stereology on Neodymium-Doped Yttrium Aluminum Garnet (Nd:YAG) Transparent Ceramics

Abstract Nd:YAG precursor powders were synthesized by homogeneous precipitation, and Nd:YAG transparent ceramics were prepared by vacuum sintering at 1700 °C for 5 h. The ceramic materials were characterized by light transmittance and field emission gun-environment scanning microscope. Using statistics and stereology theory, study was carried out on the quantitative relationships between light transmittance and stereological parameters in three-dimensional Euclidean space. It is found that the transmittance of Nd:YAG with 1 mm in thickness is about 45% and 58% in visible and near-infrared wavelength, respectively. The transmittance linearly increases with increasing equivalent sphere diameter and reaches the theoretical value of single crystal when the equivalent sphere diameter is 20 μm. The transmittance decreases with the increasing of mean specific area per unit volume of grain and discrete grains, and the transmittance decreases with increasing mean free distance of grains in Nd:YAG ceramics.

Controllable synthesis and photocatalytic activity of ZnO nanorods

ABSTRACT ZnO nanorods were successfully synthesized by a microwave-assisted chemical method. The as-prepared ZnO particles were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), high resolution TEM, X-ray photoelectron spectra (XPS), and X-ray diffraction (XRD). It is found that ZnO nanorods with diameters around 20–30 nm and lengths in the range of 60–80 nm were synthesized. The products showed good photocatalytic performance under UV light irradiation. The ZnO nanorods also showed excellent photostability and reusability under UV-visible light irradiation.

Study on crystallization and microstructure of Li2O-Al2O3-SiO2 glass ceramics

Abstract Lithium aluminosilicate (LAS) glasses are generally difficult to prepare because of their high melting temperature. In this study, the preparation of LAS glasses was achieved at a relatively low melting temperature. The batch containing MgO-ZnO-Li2O-Al2O3-SiO2 was melted in a platinum crucible at 1550°C for 2 h and was then followed by two- or three-step heat treatment processes for nucleation and crystal growth. The characterizations were carried out by differential thermal analysis, X-ray diffraction, infrared spectroscopy, scanning electron microscopy, and UV-Vis-NIR scanning spectrophotometry. The hexagonal stuffed β-eucryptite solid solution crystallized at 840–960°C. Most of the hexagonal β-eucryptite solid solution transformed into the tetragonal β-spodumene solid solution at 1100°C. Almost all the aluminum atoms entered into the tetrahedral sites in the aluminosilicate network of the β-eucryptite/β-quartz solid solution. All of the Al atoms did not belong to the aluminosilicate network of the β-spodumene solid solution. The glass ceramic with a mean grain size of 10–20 nm is transparent, the transmittance reaches ∼85% in the visible light wavelength.

Preparation and optical properties of Er3+: Na2O-Al2O3-SiO2 transparent glass-ceramics

Na2O-Al2O3-SiO2 glass-ceramics doped with Er3+ ions were synthesized by the conventional melt quenching technique at a low melting temperature. The samples were characterized by differential scanning calorimetry (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-vis-NIR scanning spectrophotometry, and fluorescence spectrometry. The results show that the main crystalline phase of glass-ceramics is nepheline.The best heat-treatment process is at 520 °C for 2 h. Because the up-conversion luminescence and near infrared luminescence properties of glass doped with Eu3+ are studied in detail.

Preparation and Luminescence Properties of Eu3+ doped Transparent Glass Ceramics Containing CaMoO4 crystals

Abstract. Eu doped transparent molybdate glass ceramics containing CaMoO4 were successfully fabricated by melt-quenching technique. The optimal heat-treated system for the glass sample was determined by DSC,XRD and SEM(710o for 2.5h). The grain size of the glass ceramics gradually increased with the increasing of heat treatment time. The UV-Vis-NIR spectra indicated that the sample transparency was approximately up to 80% in visible light range. The effect of different Eu doping concentration on the luminescence properties of the glass ceramics under the condition of the same heat treatment by fluorescence spectrum. The experimental result indicated that the Eu doping concentration was 5mol%, the sample has the maximum fluorescence intensity.

Study on the optical spectra of Nd:YAG ceramics

This document shows the desired format and appearance of a manuscript prepared for the Proceedings of the ICO20. It contains general formatting instructions and hints about how to use it. The (Y0.99Nd0.01)3Al5 O12 nano-sized powders were synthesized by low temperature combustion (LCS), using Nd2O3, Y2O3, Al(NO3) 3♦9H2O, ammonia water and citric acid as starting materials. This method effectively solves the problems caused by solid-state reaction at high temperature and hard agglomerates brought by chemical precipitation method. The powders were characterized by TG-DTA, XRD, TEM respectively. The study focused on the photoluminescence (PL) spectra of (Y0.99Nd0.01)3Al5 O12 ceramic green and sintered disks. The experiments show that the forming temperature of YAG crystal phase is 850°C and YAP crystal phase appearing during the calcinations transforms to pure YAG at 1050°C. The particle size of the powders synthesized by the LCS is in range 20-50nm depending on the thermal treatment. The effectively induced cross section (σin) with the value 4.03×10-19cm2 of (Y0.99Nd0.01)3Al5 O12 ceramics is about 44% higher than that of single crystal.