Structural and Dielectric Properties of LiV 3 O 8 Ceramic Powders Structural and Dielectric Properties of LiV 3 O 8 Ceramic Powders (original) (raw)
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Analysis of structural, thermal and dielectric properties of LiTi 2 (PO 4 ) 3 ceramic powders
Lithium titanium phosphate (LiTi 2 (PO 4) 3) ceramic powders have been prepared by a solid state reaction method at five different temperatures (800 8C, 900 8C, 1000 8C, 1100 8C and 1200 8C for 5 h each). The XRD profiles have shown that the sample sintered at 1100 8C (optimized) has displayed well-defined features. XRD peaks are in good agreement with the JCPDS Card No. 35-0754 confirming the rhombohedral structure in a space group of R ¯ 3c. The SEM images of the five samples sintered have been examined. EDAX and Raman spectra have been obtained for the LiTi 2 (PO 4) 3 ceramic powder sintered at 1100 8C for analysis. Thermal properties for the as prepared precursor LiTi 2 (PO 4) 3 sample, have been analyzed from the TG-DTA profiles. Besides this, dielectric constant, dielectric loss and conductivities (s ac and s dc) have also been studied for the LiTi 2 (PO 4) 3 ceramic powder.
Analysis of structural and thermal properties of Li 2 TiO 3 ceramic powders
Li 2 TiO 3 ceramic powders have been developed by a solid state reaction method and those have been sintered at four different temperatures (600 8C, 700 8C, 800 8C and 900 8C) towards the optimization of sintering temperature that has been found to be at 800 8C based on the nature of the XRD profiles. The sample sintered at 800 8C has shown a good crystallinity situation from its XRD peaks and the sample is found to be in monoclinic structure which is in accordance with the reported data of JCPDS 33-0831. The SEM images for samples sintered at 600 8C, 700 8C, 800 and 900 8C, EDAX peaks, FTIR profile have been measured for the temperature optimized (800 8C) sample for understanding the structural details of Li 2 TiO 3 ceramic powders. Besides these, dielectric constant, dielectric loss and a.c. conductivities have been measured for the temperature optimized sample. In order to strengthen the observations made in the XRD profiles at four different temperatures, Raman spectra of those four sintered ceramic powders have also been studied. In respect of the thermal properties, only for the as synthesized (precursor) sample, simultaneous measurement of TG-DTA profiles has been carried out for analysis.
We have developed novel cathode materials in the chemical composition of Li2ZnSiO4, Li1.5Zn1.5SiO4, Li1Zn2Sio4, Li0.5Zn2.5SiO4 and Zn2SiO4 by a sol-gel method. Structural and thermal properties of these materials have been carried out from the measurement of their XRD, FTIR, and TG-DTA profiles. For the Zn2SiO4 sample, the optimized synthesis temperature has been found to be 900◦C and maintaining this temperature; the remaining other samples have also been developed for their analysis. The ac conductivity, dielectric constant, dielectric loss values have been obtained and their trends have been explained on the basis of the distribution of Li+ ions in them because of their display of Maxwell- Wagner interfacial- type polarization.
Dielectric properties of the La3+ doped ceramic system
Solid State Communications, 1997
A process for obtaining Sro.3_3y/zLa,Bao,7Nbz06 (LSBN) ceramics at different concentrations of the La3+ cation and different sintering times is presented. The dielectric properties of the LSBN system where Sr2+ ions are substituted by La3+ cations follow the pattern of a modification by cationic substitution for a constant Sr/Ba ratio. This behavior of the dielectric properties indicate that the La3+ cations occupy the A1 as well as the A2 sites which favors the formation of the LSBN system up to y c 0.05. For higher values the dielectric properties of the ceramic start to deteriorate. Copyright 0 1997 Published by Elsevier Science Ltd
Journal of The American Ceramic Society, 2010
Dense LaLuO3 ceramics were prepared by the conventional solid-state reaction route. Their room-temperature (RT) crystal structure and microwave (MW) dielectric properties were investigated. Rietveld refinements performed on X-ray diffraction data show the RT crystal symmetry to be best described by the centrosymmetric orthorhombic Pnma space group [a=6.01888 (9) Å, b=8.37489 (12) Å, and c=5.81841 (8) Å, Z=4]. This space group assignment was further corroborated by Raman spectroscopy analysis. At RT and MW frequencies, LaLuO3 ceramics sintered at 1525°C/4 h exhibit a relative permittivity, ɛr=22.4, a quality factor, Qu×f=14 400 GHz (at 5.14 GHz), and temperature coefficient of resonant frequency, τf=−7.5 ppm/°C. ɛr corrected for porosity was calculated as 23.9.
Dielectric and optical spectroscopy of new polycrystalline ceramic for device applications
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The polycrystalline double perovskite Li2GdFeTiO6 was synthesized through the solid-state mixed oxide method and its preliminary crystal structure was investigated by the XRD technique. The structure of the material was identified to be tetragonal with space group P4bm using POWD and MATCH software. The morphology of the sample was investigated through a scanning electron microscope (SEM) and the average grain size was found to be 3.82 μm using the intercept technique. The investigation of the perovskite phase and various vibrational modes were carried out through FTIR spectroscopic technique. The bandgap (Eg = 1.73 eV) and visible light sensitivity of the material were identified by UV–Visible spectroscopic operation carried in the range 200–700 nm. The dielectric and related properties were investigated as a function of frequency and temperature using an impedance analyzer (LCR meter). Room-temperature dielectric investigation suggests it may be useful for storage application. The...
Microwave dielectric properties of Li2ZnTi3O8 ceramics prepared by reaction-sintering process
Journal of Materials Science: Materials in Electronics, 2014
Li 2 ZnTi 3 O 8 (LZT) microwave dielectric ceramics prepared by reaction-sintering process were investigated. Li 2 CO 3 , ZnO and TiO 2 powders were mixed, pressed and sintered directly into ceramic pellets without any calcination stage involved. Pure LZT phase was obtained after sintering at temperatures above 1,100°C for 2 h. LZT ceramic with the maximum bulk density of 3.81 g/cm 3 (96.2 % of the theoretical value) and excellent microwave dielectric properties of e r = 25.8, Q 9 f = 78,216 GHz and s f = -10.5 ppm/°C was obtained after sintering at 1,100°C for 2 h. The results show that the reaction-sintering process is a simple and effective method to produce LZT ceramics.
Low-Temperature Sintering and Microwave Dielectric Properties of Li2ATi3O8 (A5Mg, Zn) Ceramics
New temperature-stable low-loss ceramic–glass composites based on Li2ATi3O8 (A5Mg, Zn) ceramics have been prepared by the conventional solid-state ceramic route. The effect of lithium magnesium zinc borosilicate (LMZBS) glass addition on the sinterability, phase purity, microstructure, and microwave dielectric properties of Li2MgTi3O8 (LMT) and Li2ZnTi3O8 (LZT) dielectric ceramics has been investigated for low-temperature co-fired ceramic applications. The LMT13 wt% of LMZBS glass sintered at 9251C/4 h has er524.5, Quf544,000 GHz, and tf5(1)0.2 ppm/1C. Addition of LZT ceramics with 3 wt% of LMZBS glass sintered at 9001C/4 h has er523.2, Quf531,300 GHz, and tf5()15.6 ppm/1C. The LMT and LZT ceramic–glass composites do not react with the commonly used silver electrode material.
Crystal Structure and Microwave Dielectric Properties of LaLuO3 Ceramics
Dense LaLuO3 ceramics were prepared by the conventional solid-state reaction route. Their room-temperature (RT) crystal structure and microwave (MW) dielectric properties were investigated. Rietveld refinements performed on X-ray diffraction data show the RT crystal symmetry to be best described by the centrosymmetric orthorhombic Pnma space group [a56.01888 (9) A ˚ , b58.37489 (12) A ˚ , and c55.81841 (8) A ˚ , Z54]. This space group assignment was further corroborated by Raman spectroscopy analysis. At RT and MW frequencies, LaLuO3 ceramics sintered at 15251C/4 h exhibit a relative permittivity, er522.4, a quality factor, Quf514 400 GHz (at 5.14 GHz), and temperature coefficient of resonant frequency, sf57.5 ppm/1C. er corrected for porosity was calculated as 23.9.