scholarly journals Structure, morphology, and microwave dielectric properties of SmAlO3 synthesized by stearic acid route

2020 ◽  
Vol 9 (5) ◽  
pp. 558-566 ◽  
Author(s):  
Jiamao Li ◽  
Chuimin Zhang ◽  
Hui Liu ◽  
Tai Qiu ◽  
Chuangang Fan
Keyword(s):  
Electron Microscopy ◽  
Dielectric Properties ◽  
Stearic Acid ◽  
Microwave Dielectric Properties ◽  
Solid State Reaction Method ◽  
Synthesis Temperature ◽  
Microwave Ceramics ◽  
Conventional Solid State Reaction ◽  
Microwave Frequencies ◽  
Transmission Electron

Abstract A rapid and facile approach was developed for the synthesis of ultrafine SmAlO3 powders through the combustion of stearic acid precursors. The obtained products were characterized by typical techniques including X-ray diffraction (XRD), Fourier Transform Infrared (FT-IR), thermogravimetric and differential thermal analysis (TG-DTA), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) to analyze the phase composition and microstructure. The dielectric characteristics of SmAlO3 microwave ceramics, using the as-obtained products as original materials, were also studied. Compared with the conventional solid-state reaction method, the synthesis temperature was dramatically reduced to 750 °C. The large-size sheet structure was composed of a number of micro/nano-scale crystallites, which were mostly irregular in shape due to the mutual growth and overlapping shapes of adjacent grains. The SmAlO3 ceramics with high density and uniform microstructure were obtained after sintering at 1500 °C for 4 h due to the favorable sintering activity of the as-synthesized powders. In addition, desired dielectric properties at microwave frequencies (dielectric constant εr = 20.22, quality factor Q·f = 74110 GHz, and a temperature coefficient of resonant frequency τf = −74.6 ppm/°C) were achieved.

scholarly journals Chemical synthesis of SmAlO3 by stearic acid route: structure, morphology and microwave dielectric properties

2020 ◽  
Author(s):  
J.M. Li ◽  
Chuimin Zhang ◽  
Hui Liu ◽  
Tai Qiu ◽  
Chuangang Fan
Keyword(s):  
Electron Microscopy ◽  
Dielectric Properties ◽  
Stearic Acid ◽  
Microwave Dielectric Properties ◽  
Solid State Reaction Method ◽  
Synthesis Temperature ◽  
X Ray Diffraction ◽  
Microwave Ceramics ◽  
Conventional Solid State Reaction ◽  
Microwave Frequencies

Abstract A rapid and facile approach was developed for the synthesis of ultrafine SmAlO3 powders through spontaneously combusting stearic acid precursors. The obtained products were characterized by typical techniques including X-ray diffraction (XRD), Fourier Transform Infrared (FT-IR), thermogravimetric and differential thermal analysis (TG-DTA), scanning electron microscopy (SEM) and electron microscopy transmission (TEM) to analyze the phase composition and microstructure. The dielectric characteristics of SmAlO3 microwave ceramics using the as-obtained products as original materials were also studied. Comparing with conventional solid-state reaction method, the synthesis temperature was dramatically reduced to 750 °C. Large size sheet structure was composed of a number of micro/nano-scale crystallites that were almost irregular in shape due to the mutual growth and overlapped shape of adjacent grains. The SmAlO3 ceramics with high density and uniform microstructure were obtained after sintering at 1500 °C for 4 h due to good sintering activity of the as-synthesized powders. In addition, desired dielectric properties at microwave frequencies (dielectric constant εr = 20.22, quality factor Q·f = 74110 GHz, and temperature coefficient of resonant frequency TCf = -74.6 ppm/°C) were achieved.

scholarly journals Synthesis and characterization of SmAlO3 by stearic acid route

2020 ◽  
Author(s):  
J.M. Li ◽  
Chuimin Zhang ◽  
Hui Liu ◽  
Tai Qiu ◽  
Chuangang Fan
Keyword(s):  
Electron Microscopy ◽  
Stearic Acid ◽  
Solid State Reaction Method ◽  
Synthesis Temperature ◽  
X Ray Diffraction ◽  
Microwave Ceramics ◽  
Conventional Solid State Reaction ◽  
Microwave Frequencies ◽  
Large Size ◽  
Ft Ir

Abstract A rapid and facile approach was developed for the synthesis of ultrafine SmAlO3 powders through the combustion of stearic acid precursors. The obtained products were characterized by typical techniques including X-ray diffraction (XRD), Fourier Transform Infrared (FT-IR), thermogravimetric and differential thermal analysis (TG-DTA), scanning electron microscopy (SEM) and electron microscopy transmission (TEM) to analyze the phase composition and microstructure. The dielectric characteristics of SmAlO3 microwave ceramics, using the as-obtained products as original materials, were also studied. Compared with the conventional solid-state reaction method, the synthesis temperature was dramatically reduced to 750 ℃. The large-size sheet structure was composed of a number of micro/nano-scale crystallites, which were mostly irregular in shape due to the mutual growth and overlapping shapes of adjacent grains. The SmAlO3 ceramics with high density and uniform microstructure were obtained after sintering at 1500 ℃ for 4 h due to the favorable sintering activity of the as-synthesized powders. In addition, desired dielectric properties at microwave frequencies (dielectric constant εr = 20.22, quality factor Q·f = 74110 GHz, and a temperature coefficient of resonant frequency τf = -74.6 ppm/℃) were achieved.

Influences of MnCO3 Doping on Processing Parameters and Dielectric Properties of ZnNb2O6 Microwave Ceramics

2007 ◽  
Vol 280-283 ◽  
pp. 23-26
Author(s):  
J. Luo ◽  
Z.Y. Pang ◽  
Y.S. Lin ◽  
Zhao Xian Xiong
Keyword(s):  
Dielectric Properties ◽  
Ceramic Body ◽  
Microwave Dielectric Properties ◽  
Microwave Frequency ◽  
Solid State Reaction Method ◽  
Processing Parameters ◽  
Microwave Ceramics ◽  
Conventional Solid State Reaction ◽  
Microwave Dielectric ◽  
Ceramic Microstructure

MnCO3 was added into ZnNb2O6 ceramics to obtain excellent microwave dielectric properties. The samples were prepared by conventional solid-state reaction method. The effects of the amount of MnCO3 on sintering temperatures, ceramic densities and contraction were systematically investigated. The crystalline structure of ceramic body was analyzed by XRD. The ceramic microstructure was observed by SEM. The dielectric properties of ZnNb2O6 ceramics were measured by a vector network analyzer at microwave frequency, which showed: er = 22.65, Q×f = 36700 GHz (loaded value) and tf = -40 ppm/°C.

Dielectric Properties of Ba(Mg0.2/3Zn0.8/3Nb2/3)O3 and Ba1-xSrx(Mg0.2/3Zn0.8/3Nb2/3)O3 Microwave Ceramics

2007 ◽  
Vol 336-338 ◽  
pp. 272-274
Author(s):  
S.S. Cheng ◽  
J. Luo ◽  
Zhao Xian Xiong
Keyword(s):  
Dielectric Properties ◽  
Solid State ◽  
Resonant Frequency ◽  
Solid State Reaction ◽  
Solid State Reaction Method ◽  
Zero Temperature ◽  
Microwave Ceramics ◽  
Conventional Solid State Reaction ◽  
Reaction Method ◽  
Zn Ions

Microwave ceramics of Ba(Mg0.2/3Zn0.8/3Nb2/3)O3 and Ba1-xSrx(Mg0.2/3Zn0.8/3Nb2/3)O3 were synthesized with conventional solid-state reaction method. Dielectric properties of the samples were studied as functions of compositions and sintering temperatures. Experimental results show that a higher Q×f value is reached by substituting Zn ions with Mg ions and a near-zero temperature coefficient of resonant frequency is obtained by replacing Ba ions with Sr ions.

Preparation and Microwave Dielectric Properties of xBaZn2Ti4O11-(1-x)BaNd2Ti4O12 Ceramics

2017 ◽  
Vol 726 ◽  
pp. 210-214
Author(s):  
Xu Wang ◽  
Ren Li Fu ◽  
Yue Xu ◽  
Yang Yang ◽  
Jun De Cai ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Microwave Dielectric Properties ◽  
Solid State Reaction Method ◽  
Phase System ◽  
Microwave Ceramics ◽  
Two Phase ◽  
Microwave Dielectric ◽  
X Band ◽  
High Dielectric

xBaZn2Ti4O11–(1-x)BaNd2Ti4O12 (x = 0.18–0.30) ceramics were prepared by solid-state reaction method and their microwave dielectric properties were investigated with the purpose of finding a microwave ceramics with high dielectric constant (εr), high quality factor (Q×f ) and zero temperature coefficient of resonant frequency (τf).The two phase system BaZn2Ti4O11–BaNd2Ti4O12 affected the unit cell volume and the microstructure, the microwave dielectric properties (εr, Q×f, τf). As increasing x from 0.18 to 0.30, the main phase composition was BaNd2Ti4O12. Therefore, the εr decreased from 64.9 to 60.3 and the Q×f values raised from 11,350GHz to 13,210GHz, and the τf values decreased from 7ppm/° to -5ppm/°.The 0.22BaZn2Ti4O11–0.78BaNd2Ti4O12 ceramics sintered at 1250°C for 4 h displayed the best dielectric constant εr,Q×f and τf, as 63.9, 12380 GHz and-0.1 ppm/° respectively.

Effect of V2O5 and ZnO Additives on the Sintering Temperature and Microwave Dielectric Properties of Ca[(Li1/3Nb2/3) 0.8Ti 0.2]O3-δ Ceramics

2011 ◽  
Vol 239-242 ◽  
pp. 77-80 ◽  
Author(s):  
Ji Hong Liao ◽  
Ying Dai ◽  
Ren Zhou Yang ◽  
Wen Chen
Keyword(s):  
Dielectric Properties ◽  
Sintering Temperature ◽  
Microwave Dielectric Properties ◽  
Solid State Reaction Method ◽  
Sintering Behavior ◽  
Conventional Solid State Reaction ◽  
Microwave Dielectric ◽  
Diffraction Peaks ◽  
Dielectric Ceramics ◽  
The Relationship

Low-temperature sintered Ca[(Li1/3Nb2/3)0.8Ti0.2]O3-δ (CLNT) microwave dielectric ceramics with V2O5 and ZnO additives were prepared by the conventional solid state reaction method. The sintering behavior and microwave dielectric properties of CLNT ceramics were investigated. The main diffraction peaks of all the specimens sintered at the temperature under 1150◦C split due to the coexistence of the non-stoichiometric phase and stoichiometric phase, which all possess CaTiO3-type perovskite structures. ZnO and V2O5 combined additives lowered the sintering temperature of CLNT ceramics from 1150◦C to 1090◦C. and the Qf values were improved from 18,210 GHz to 20,740 GHz. The CLNT ceramics with 4 wt% ZnO addition sintered at 1090◦C showed good microwave dielectric properties with εr ~39.7, Qf ~20,740 GHz, τf ~8.6 ppm/◦C. The relationship between dielectric properties and the sintering behavior was also discussed.

Effects of zinc substitution on the dielectric properties of Ca5Nb4TiO17 microwave ceramics

2013 ◽  
Vol 03 (04) ◽  
pp. 1320003 ◽  
Author(s):  
Chunchun Li ◽  
Xiaoyong Wei ◽  
Haixue Yan ◽  
Michael J. Reece
Keyword(s):  
Dielectric Properties ◽  
Sintering Temperature ◽  
Microwave Dielectric Properties ◽  
Solid State Reaction Method ◽  
Sintering Behavior ◽  
Potential Candidate ◽  
Strongly Correlated ◽  
Microwave Ceramics ◽  
Microwave Dielectric ◽  
Method Effects

Ca 5-x Zn x Nb 4 TiO 17 ceramics with 0 ≤ x ≤ 0.4 were prepared through a solid-state reaction method. Effects of zinc substitution on sintering behavior and microwave dielectric properties of Ca 5 Nb 4 TiO 17 ceramics were investigated. The sintering temperature was significantly lowered from 1480°C for pure Ca 5 Nb 4 TiO 17 to 1260°C for x = 0.4. The microwave dielectric properties are strongly correlated with the composition. It is worth noting that the temperature coefficient of resonant frequency (τf) displays a tendency toward positive value, ranging from −126.4 ppm/°C to −8.6 ppm/°C. A temperature stable microwave ceramic with dielectric constant of 52 and Q × f value of 9937 GHz is achieved at x = 0.4 and is a potential candidate for application as cores in dielectrically loaded antennas.

Preparation and Microwave Dielectric Properties of Ca(Sm0.5Nb0.5)O3 Ceramics

2012 ◽  
Vol 512-515 ◽  
pp. 1198-1202
Author(s):  
Jia Mao Li ◽  
Tai Qiu
Keyword(s):  
Dielectric Properties ◽  
Solid State ◽  
Cooling Rate ◽  
Sintering Temperature ◽  
Microwave Dielectric Properties ◽  
Solid State Reaction Method ◽  
Sintering Process ◽  
Conventional Solid State Reaction ◽  
Reaction Method ◽  
Microwave Dielectric

Microstructures and microwave dielectric properties of Ca(Sm0.5Nb0.5)O3 ceramics, prepared by a conventional solid-state reaction method, were systematically investigated by varying calcining temperature, sintering temperature and cooling rate. The XRD result showed that a single Ca(Sm0.5Nb0.5)O3 phase could be synthesized at a calcining temperature of 1200 °C. Optimized combination of microwave dielectric properties of εr = 22.36, Q×f = 18030 GHz and τf = -31.2 ppm/°C was obtained for furnace-cooled Ca(Sm0.5Nb0.5)O3 ceramics sintered at 1550 °C for 4 h. However, some microcracks were found from the microstructures of the furnace-cooled specimens. Further, the Q×f value could be increased by controlling the cooling rate during the sintering process due to the disappearance of microcracks in the final material. With a cooling rate of 2 °C/min, Ca(Sm0.5Nb0.5)O3ceramics exhibited an enhanced Q×f value of 37130 GHz.

scholarly journals The microstructure and dielectric properties of titanium oxide doped with nano CuO

2014 ◽  
Vol 04 (03) ◽  
pp. 1450025 ◽  
Author(s):  
Juan Li ◽  
Renli Fu ◽  
Yue Xu ◽  
Zhenxiao Fu ◽  
Hongjuan Su
Keyword(s):  
Dielectric Properties ◽  
Microwave Dielectric Properties ◽  
Solid State Reaction Method ◽  
Lattice Vibrations ◽  
Sintering Process ◽  
Conventional Solid State Reaction ◽  
Homogeneous Microstructure ◽  
Microwave Dielectric ◽  
Phonon Lifetime ◽  
Better Than

The TiO 2 ceramics doped with nano CuO were fabricated by the conventional solid-state reaction method. The crystal structure, microstructure, microwave dielectric properties and lattice vibrations of TiO 2 ceramics doped with nano CuO have been investigated. Nano CuO with higher sintering capability worked as flux former and effectively improved the sintering process of TiO 2 ceramics. The microwave dielectric properties of TiO 2 doped with nano CuO were much better than that doped with micron CuO at the same doping content. Raman spectra showed that the full width at half maximum of Eg mode of TiO 2 doped with micron CuO was larger than nano CuO doped ones, which indicated a poor crystalline and a short phonon lifetime. TiO 2 doped with 1 wt.% nano CuO , sintered at 950°C for 2 h had compact and homogeneous microstructure and possessed the following dielectric properties: εr = 106, Q × f = 24808, τf = 371 ppm/°C.

Effect of CuO-Bi2O3 Co-Doping on Microwave Dielectric Properties of Ba4Sm9.33Ti18O54 Ceramics

2011 ◽  
Vol 197-198 ◽  
pp. 548-551
Author(s):  
Zhi Lan Tang ◽  
Chun Ying Shen ◽  
Zhao Xi Li ◽  
Jian Yang ◽  
Tai Qiu
Keyword(s):  
Dielectric Properties ◽  
Microwave Dielectric Properties ◽  
Solid State Reaction Method ◽  
Liquid Phase Sintering ◽  
Sintering Behavior ◽  
Conventional Solid State Reaction ◽  
Co Doping ◽  
Microwave Dielectric ◽  
Bst Ceramics ◽  
Quality Factor Q

Ba4Sm9.33Ti18O54(BST) ceramics were prepared by conventional solid-state reaction method. The effect of CuO-Bi2O3co-doping on the sintering behavior and microwave dielectric properties of BST ceramics has been investigated. The results indicated that when the total addition of CuO-Bi2O3doping agent was 1.0wt%, the sintering temperature of BST ceramics was reduced to 1240°C as a result of liquid-phase sintering effect derived from CuBi2O4. When the total addition of CuO-Bi2O3was fixed at 1.0wt%, the microwave dielelctric properties of BST were improved by adjusting the mass percentage of Bi2O3. With the increase of Bi2O3amount from 20wt% to 80wt%, the dielectric constant (εr) decreased, the quality factor (Q•f) increased and the temperature coefficient of resonant frequency (τf) shifted from negative value to positive value. The excellent microwave dielectric properties of εr=82.51, Q•f=7878GHz and τf=+6.02ppm/ were obtained for the sample with Bi2O3amount of 80wt% when sintered at 1240°C for 3h.

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