Up-Conversion Luminescence Properties of Nd3+/Yb3+ Doped Lutetium-Based Oxyfluoride Glass Ceramic

Nd[Formula: see text]/Yb[Formula: see text] co-doped lutetium-based glass sample and glass ceramic sample were prepared with the molar ratios of 52SiO2-8Na2CO3-16Al2O3-33NaF-3LuF3-0.15Yb2O3-0.03Nd2O3 by the high temperature melting method in 1400∘C. Under the excitation of 980[Formula: see text]nm diode laser, up-conversion luminescence spectrum of glass sample and glass ceramic sample was measured and three stronger up-conversion luminescence peaks at the wavelength of 552[Formula: see text]nm, 656[Formula: see text]nm and 668[Formula: see text]nm were observed, and up-conversion luminescence strengths of glass ceramic sample are higher than those of glass sample. The two-photon absorption of three emission peaks was determined by the fitting curve graph of up-conversion emission power and LD wording current. Absorption spectrum of glass ceramic sample was obtained and spectral strength parameters were computed as [Formula: see text][Formula: see text]cm2, [Formula: see text][Formula: see text]cm2, [Formula: see text][Formula: see text]cm2 by adopting Judd–Ofelt theory, and the root mean square deviation between the theoretical oscillator strength and the experimental oscillator strength were calculated as [Formula: see text]. Transition probability, branching ratio of 4F[Formula: see text] to its lower level and lifetime of 4F[Formula: see text] level of Nd[Formula: see text] ions were calculated, and the results indicate that the prepared Nd[Formula: see text]/Yb[Formula: see text] co-doped glass ceramic sample is a kind of good up-conversion material.

Dielectric Properties and Microstructural Studies of Er2O3 Doped Potassium Sodium Niobate Silicate Glass-Ceramics

In this work, electrical and structural properties of ferroelectric glasses and glass-ceramics from K0.5Na0.5NbO3-SiO2 doped with 0.5-1.0 mol%Er2O3 system have been investigated. The influent of Er2O3 dopant was also compared with the original glass. The K0.5Na0.5NbO3 (KNN) powder was mixed with SiO2 in composition of 75KNN-25SiO2 and doped with Er2O3. Well-mixed powder was subsequently melted at 1300°C for 15 min in a platinum crucible using an electric furnace. The quenched glasses were then subjected to heat treatment at various temperatures for 4 h. From the study, KNN single phase in transparent glass was successfully prepared via incorporation method. The maximum Ԑr of about 360 at 10 kHz with a low tanδ of 0.07 could be obtained from the glass-ceramic sample of 75KNN–25SiO2 doped 0.5 mol% Er2O3 and heat treated at 600°C. It can be seen that the higher percent of Er2O3 can lower the dielectric loss of KNN glass-ceramics. This interesting value suggesting the opportunity of using them in electronic applications in the future.

Study of PbTiO3-Based Glass Ceramics Containing SiO2

Glass samples with composition 50PbO : 25TiO2 : (25-X) B2O3 : XSiO2 (with X = 0, 1.5, 2.5, 3.5, and 5 mol%) were prepared by conventional quenching technique. These glass samples were converted to glass ceramics by the two-stage heat treatment schedule. Formation of ferroelectric lead titanate phase in the glass ceramics was confirmed from the XRD. The density, CTE, and dielectric constant of the glass and glass-ceramic samples were measured. The glass-ceramic sample containing 2.5 mol% SiO2 exhibited the highest dielectric constant. The SEMs of glass-ceramic samples were studied. The P-E hysteresis loop studies also revealed the highest remnant polarization for this sample, which has a potential for being developed for practical applications.

HEAT TREATMENT EFFECT ON CaO–P2O5–SiO2–Fe2O3 GLASS-CERAMICS STRUCTURE

The heat treatment carried out at different temperatures between 1000 and 1200°C for the same time and under similar conditions leads to differences in the elemental composition and therefore in the ratio of the component elements on the sample surface. They are evidenced by changes in O1s core level XPS spectra. The ratio of bridging oxygen (BO) to non-bridging oxygen (NBO) in iron containing CaO – SiO 2– P 2 O 5 glasses changes differently for the glass ceramic sample resulting from heat treatment carried out at 1000°C and for those obtained at higher treatment temperatures.