Thanapong Sareein

Dielectric Properties of Y2NiMnO6 Ceramics at Various Sintering Times and Temperatures

Dielectric properties of hydrothermally decomposed Y2NiMnO6 ceramics prepared under several sintering conditions were investigated at room temperature. As the results, dielectric constants at 200 Hz were found about 928 and 23x103 for samples sintered at 1000 and 1400 oC, respectively. The dielectric permittivity for samples sintered at 1400 oC for different sintering times from 6 to 24 hours have yielded the best dielectric permittivity value of 104. On the other hand, low sintering temperature had resulted in smaller dielectric loss in comparison to larger dielectric loss generally found in the ceramics with high sintering temperature.

The Dielectric Property of Y2NiMnO6 Ceramics Sintered at High Temperature

The high dielectric permittivity of Y2NiMnO6 ceramics were measured by Agilent E4294A (Impedance Measurement) range of frequency 100 to 10 MHz in this research. In this sample ceramics, passing by a sintering temperature of 1400°C at 6 hours to 24 hours. The phase and microstructure of the deposited materials were investigated as a function of sintering temperature, using X-ray diffraction (XRD) and scanning electron microscopy (SEM). We found that the dielectric properties are very sensitive to the several sintered follow by time, and high temperature can be related to the change ordering of Ni2+ and Mn4+ ions.

Electrical Properties of Y2NiMnO6 Ceramics Sintered at High Temperature

In this work, impedance spectroscopy technique was used in order to investigate the electric properties of double perovskites of the Y2NiMnO6 ceramics, which were prepared by thermal decomposition technique at 800°C for 6 hours and then sintered at a high temperature of 1400°C for 6, 12, 18, and 24 hours. Consequently, the electric characterization of the Y2NiMnO6 ceramics was performed at 30°C °C in the frequency range from 102 Hz to 108 Hz. The results in the Rg with 10,000, 9,990, 6,400, and 1,700 (Ω) at sintering time, respectively. Dispersion was observed in the variation of impedance values with frequency. Possible reason for all the above observation was discussed.

Study Behavior of XPS Spectra of Ni, Mn, Y and O in Y2NiMnO6 Ceramics

Bulk Y2NiMnO6 samples were prepared by thermal decomposition technique at 800 °C for 6 hours. The effects of temperature on the structure of ceramics were investigated for different sintering temperatures in the range of 1000-1300 °C, while kept constant the sintering time of 12 hours. Structural characterization had been investigated via X-ray diffraction (XRD) on samples of different sintering temperatures. Results from the experiment had revealed that high temperature affected oxide in ceramic materials. Further analysis with X-ray photoelectron spectroscopy (XPS) technique had revealed an outstanding point of ceramics by investigating the Ni 2p, 2p3/2, Mn 2p1/2, 2p3/2, and Y 3d3/2, 3d5/2 at the surface of Y2NiMnO6 ceramics. The changes in relative intensity of XPS peaks and the shifts in their binding energy (eV) were observed in the results, while the effect of temperature on oxide in ceramics may be investigated with dielectric property in the future.

Effect of hybrid doping on dielectric behavior of barium titanate ceramics

ABSTRACT Hybrid-doped BaTiO3 ferroelectric polycrystalline ceramic samples were synthesized by solid state reaction. The concentration of La3+ was fixed 1 mol% while that of Sm3+ varied from 1 to 4 mol%. The effect of the replacement, which can be either lanthanum or samarium, in a cationic site on structural and physical properties of BaTiO3 was investigated. The dielectric permittivity changed significantly with temperature in a wide temperature rang. It was found that the dielectric behavior can be ascribed to the change in defect concentrations in different lattice locations in BaTiO3 structure.

The Grain Structure of Nd Doped Y2NiMnO6 Ceramics Sintered at High Temperature

The granular structure of ceramic material influences the electrical properties. Ceramics of YMNO (Y2NiMnO6) doped with Nd were produced by compression and sintering. Grain size was determined from SEM image analysis. Generally, As the Nd dopant concentration was increased, the grain size increased with sintering time. However, at the highest dopant levels of 30% and 20% Nd, a large range in grain size was observed with regions of defective growth. In contrast, a more uniform grain growth was seen for the 10% Nd doped ceramic at all sintering times.

Investigation of Luminescence Properties of Dy3+ Doped Alkaline Earth Oxides Barium Phosphate Glasses

In this work, the optical and luminescence properties of Dy2O3 doped barium phosphate glass with different alkaline earth oxides (MgO, CaO and SrO) have been investigated. The glass samples were prepared by the melt-quenching technique at the melting temperature of 1200 °C. The absorption spectra of glasses were recorded in the ultraviolet, visible and near infrared (UV-Vis-NIR) region. The absorption bands centered at 385, 424, 452, 472, 754, 803, 901, 1093, 1273 and 1683 nm, respectively have been observed. The emission spectra of glass samples centered at 482, 574, 662 and 751 nm, respectively have been observed with 350 nm excitation wavelength. The result of radioluminescence spectra were slightly different with photoluminescence spectra. The coordinate of emitting color (x, y) for 350 excitation wavelength is 0.3781 and 0.4252, respectively which is located in white light region of CIE diagram.

Complete Phase Change of Y2NiMnO6 Ceramics Doped with TiO2 at High Temperature

Determining the structure of ceramic materials is essential in order to fully characterize the electrical properties and improve existing materials. YMNO ceramics (Y2NiMnO6) prepared by compression and sintering were doped with TiO2 and analyzed using XRD and SEM. The calcined sample prior to sintering contained phases of the YMNO double perovskite and TiO2. Following sintering at 1400°C, the perovskite structure was replaced by Y2Ti2O7 fcc structure, and the grain size was found to increase with sintering time up to 18 hours. This sets a limit to the amount of TiO2 which can be used to successfully dope the YMNO ceramic.

Investigations on Luminescence Properties of Ce3+ Ion Doped Bismuth Borophosphate Glasses

Bismuth borophosphate glasses containing different doping cerium oxide have been synthesized at 1200 °C by melt-quenching technique. The doping concentration of the Ce3+ was varied from 0.05 mol% to 2.0 mol%. The glass samples were characterized through optical absorption and luminescence spectral measurements. UV-visible and near infrared absorption spectra of glass samples were not observed nevertheless the absorption edge was shift to the longer wavelength. The photoluminescence and radioluminescence spectra show emission bands around 367 nm under 317 nm excitation wavelength. Also, the highest emission intensity was found at 0.5 mol% CeF3 dopant for both of photoluminescence and radioluminescence.

Electrical Impedance Properties of Y 2 NiMnO 6 Ceramics for DC Bias at Atmosphere

The electrical impedance of Y2NiMnO6 ceramics sintered at 1400 °C for 6 to 24 hours were investigated. The electrical properties of Y2NiMnO6 ceramics were examined in dc bias from 0 volt to 1.5 volt at room temperature. At frequencies below 105 Hz the high electric impedance decreased significantly with longer sintering time, indicating that the grain and grain boundary effects. Increasing dc bias also reduced impedance at the lower frequencies, with polarisation affect at higher frequencies. This behaviour suggests a decrease in the relaxation time of the mobile charge carriers with increasing dc bias and describes a thermally activated relaxation phenomena in the Y2NiMnO6 ceramics.