Showing 3 results for Glass-Ceramic
A. M. Molavi, S. M. Mirkazemi, A. Beitollahi,
Volume 32, Issue 1 (6-2013)
Abstract
The effects of temperature, time and atmosphere on microstructure and magnetic properties of NiFe2O4 glassceramic were investigated utilizing differential thermal analysis, X-ray diffraction, vibrating sample magnetometer and scanning electron microscope techniques. Various compositions were studied in the Na2O-NiO-Fe2O3-B2O3-SiO2 system to obtain amorphous phase. The sample heat-treated in graphite bed at 510°C for 1 hr showed higher magnetization than the one heattreated in the air under the same condition. XRD analysis showed the presence of nickel ferrite and some non-magnetic phases such as sodium borate and silicate phases in the heat treated samples. The maximum magnetization of samples reduced by increasing the holding time from 1hr to 3 hr at 510°C. Increment of temperature to 700°C increased the amount of NiFe2O4 and maximum magnetization.
H. Amiri, S. M. Mirkazemi, A. Beitollahi ,
Volume 34, Issue 2 (7-2015)
Abstract
In this investigation, the effect of heat treatment on magnetic properties of glass and nano-structured cobalt-ferrite glass-ceramic was studied. The glass was synthesized in the system of Na2O-Fe2O3-CoO-B2O3-SiO2. Based on DTA results, heat treatment was done at different times and temperatures. X-ray diffraction pattern of glass-ceramic showed the crystallization of CoFe2O4 and some nonmagnetic phases. The highest magnetization of 11.8 emu/g was obtained for the sample heat-treated for 2 hr at 670C in graphite bed. Average crystallite size of CoFe2O4 in this sample was 50 nm. Scanning Electron Microscopy (SEM) confirmed the formation of cobalt ferrite nanoparticles in the glass matrix.
M. Illbeigi, A. R. Fazlali, M. Kazazi, A. H. Mohammadi,
Volume 36, Issue 1 (6-2017)
Abstract
In this research, new lithium ion conductor glass-ceramics with NASICON-type structure (Li1+x+yAlxCryGe2-x-y (PO4)3, x+y=0.5) were synthesized using melt-quenching method and converted to glass-ceramics through heat treatment. Influence of addition of different concentrations of aluminum and chromium in LiGe2(PO4)3 glass-ceramic was investigated for ionic conduction improvement. Substitution of Ge4+ ions in NASICON structure by Al3+ and Cr3+ ions induced more Li+ ions in A2 vacant sites to obtain charge balance and also changed the unit cell parameters. These two factors led to ionic conductivity improvement of synthesized glass-ceramics. The glass-ceramics were characterized and the amorth structures were investigated by X-ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), Energy-Dispersive X-ray spectroscopy (EDX), Differential Scanning Calorimetry (DSC) and Complex Impedance Spectroscopy (CIS). The highest lithium ion conductivity of 8.82×10-3 S/cm was obtained for x=0.4 and y=0.1 (Li1.5Al0.4Cr0.1Ge1.5(PO4)3) crystallized at 850 oC for 8 h with minimum activation energy of 0.267 eV.
