Dielectric Properties of A, B-Site Mn-Doped LaTiO3+δ

2018 ◽  
Vol 921 ◽  
pp. 78-84
Author(s):  
Yan Chen ◽  
Qi Qi Yan ◽  
Yi Min Cui
Keyword(s):  
Dielectric Properties ◽  
Dielectric Response ◽  
Low Frequency ◽  
Solid State Reaction Method ◽  
Dielectric Constants ◽  
Conventional Solid State Reaction ◽  
Dielectric Characteristics ◽  
Low Dielectric ◽  
A Site ◽  
Mn Doped

A-site Mn-doped La1-xMnxTiO3+δand B-site doped LaMnxTi1-xO3+δ(x = 0.1, 0.2) composites were synthesized by conventional solid-state reaction method. The low-frequency complex dielectric properties of the composites were investigated as functions of temperature (77 K ≤ T ≤ 360 K) and frequency (100 Hz ≤ f ≤ 1 MHz), respectively. The dielectric constants of A-site doped samples are higher than that of B-site doped samples. The loss tangents of the low doped samples are much less than that of the high doped samples. The A-site doped composites exhibit intrinsic dielectric response with a dielectric constant of ~40 in the temperature below 250 K. Interestingly, the dielectric constants of B-site doped composites always increased in the temperature range from 77 to 360 K. And it is clearly observed that extraordinarily low dielectric loss tangents appear in LaMn0.1Ti0.9O3+δ, which are much lower than that of LaMn0.2Ti0.8O3+δ. These changes indicate that the doped content can affect the intrinsic dielectric characteristics significantly.

Temperature Dependence on Dielectric Response of La0.7Ba0.3Mn0.4Ti0.6O3 Ceramic

2015 ◽  
Vol 1107 ◽  
pp. 45-52
Author(s):  
Aaliyawani Ezzerin Sinin ◽  
Walter Charles Primus ◽  
Abdul Halim Shaari ◽  
Zainal Abidin Talib ◽  
Sinin Hamdan
Keyword(s):  
Dielectric Properties ◽  
Temperature Dependence ◽  
Low Frequency ◽  
Sintered Sample ◽  
Solid State Reaction Method ◽  
X Ray Diffraction ◽  
Conventional Solid State Reaction ◽  
Low Frequencies ◽  
X Ray ◽  
Lcr Meter

Ceramic sample of La0.70Ba0.30Mn0.40Ti0.60O3 oxide has been prepared by the conventional solid-state reaction method. The sintered sample was characterized by using x-ray diffraction (XRD) and low frequency LCR meter. XRD result shows that the sample has a cubic structure with the existence of impurity phase. The dielectric properties of La0.70Ba0.30Mn0.40Ti0.60O3 measured from room temperature to 200°C shows that the dielectric permittivity is temperature dependence with strong dispersion at low frequencies. A circuit model based on the universal capacitor response function is also being used to represent the dielectric properties of the sample.

Effect of Sintering Method on the Microstructure and Dielectric Properties of Lead-Free BCZT Ceramics

2017 ◽  
Vol 866 ◽  
pp. 263-266 ◽  
Author(s):  
Puripat Kantha ◽  
Teerapat Bunthod ◽  
Sasithron Jansrabua ◽  
Naris Barnthip ◽  
Siriporn Tigunta ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Solid State Reaction Method ◽  
Lead Free ◽  
Coarse Grained ◽  
Conventional Solid State Reaction ◽  
Low Dielectric ◽  
Maximum Dielectric Constant ◽  
Conventional Sintering ◽  
Long Time ◽  
Sintering Method

Lead-free ceramic powders based on Ba0.85Ca0.15Zr0.1Ti0.9O3 (BCZT) were successfully fabricated by the conventional solid-state reaction method. Two kinds of sintering methods: zero-time sintering (ZTS) and conventional sintering (CS) were applied to obtain BCZT ceramics. The microstructure and dielectric properties of BCZT ceramics sintered from the ZTS and the CS method were systematically studied. It was found that the coarse-grained samples with grain sizes ~ 19-21 μm were obtained from the ZTS and the CS method. The CS method with a long time of dwelling was helpful for improving the dielectric properties of lead-free BCZT ceramics. The maximum dielectric constant of 9926 and low dielectric loss of 0.0108 were obtained at CS with 8h.

A facile method for the preparation of aliphatic main-chain benzoxazine copolymers with high-frequency low dielectric constants

2018 ◽  
Vol 9 (21) ◽  
pp. 2913-2925 ◽  
Author(s):  
Ming Zeng ◽  
Jiangbing Chen ◽  
Qingyu Xu ◽  
Yiwan Huang ◽  
Zijian Feng ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
High Frequency ◽  
Main Chain ◽  
Polymerization Kinetics ◽  
Dielectric Constants ◽  
Low Dielectric

The effects of the reaction solvent on the preparation, polymerization kinetics, and high-frequency dielectric properties of aliphatic main-chain benzoxazine copolymers were investigated.

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.

Dielectric Properties of Sol - Gel Silica Glasses

1986 ◽  
Vol 72 ◽  
Author(s):  
G. V. Chandrashekhar ◽  
M. W. Shafer
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Elemental Carbon ◽  
Sol Gel ◽  
Fused Silica ◽  
Dielectric Constants ◽  
Low Dielectric Constant ◽  
Silica Glasses ◽  
Low Dielectric ◽  
Gel Technique

AbstractDielectric properties have been measured for a series of porous and fully densified silica glasses, prepared by the sol-gel technique starting from Si-methoxide or Si-fume. The results for the partially densified glasses do not show any preferred orientation for porosity. When fully densified (˜2.25 gms/cc) without any prior treatment of the gels, they have dielectric constants of ≥ 6.5 and loss factors of 0.002 at 1 MHz, compared to values of 3.8 and <0.001 for commercial fused silica. There is no corresponding anomaly in the d.c. resistivity. Elemental carbon present to the extent of 400–500 ppm is likely to be the main cause for this enhanced dielectric constant. Extensive cleaning of the gels prior to densification to remove this carbon were not completely successful pointing to the difficulty in preparing high purity, low dielectric constant glasses via the organic sol-gel route at least in the bulk form.

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.

B-O Bond Character and Microwave Dielectric Properties of (1-x)CaTiO3-xCa(Zn1/3Nb2/3)O3 Perovskite Ceramics

2009 ◽  
Vol 421-422 ◽  
pp. 69-72
Author(s):  
Jie Shen ◽  
Wen Chen ◽  
Jing Zhou ◽  
Jie Zhu ◽  
Qiong Lei
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Microwave Dielectric Properties ◽  
Dielectric Materials ◽  
Solid State Reaction Method ◽  
Dielectric Constants ◽  
Identical Result ◽  
Microwave Dielectric ◽  
Calculation Results ◽  
The Relationship

The relationship between the character of the B-site cation–oxygen bond and the microwave dielectric properties in perovskites dielectric materials was studied in this paper. The atomic net charge of CaTiO3 (CT) and Ca(Zn1/3Nb2/3)O3 (CZN) was calculated respectively. The calculating result implies that the covalency of B-O bonds in CZN is stronger than that in CT. This predicted that the dielectric constant and loss of the ceramics will decrease after CZN incorporated in CT. To confirme the prediction, (1-x)CT-xCZN microwave dielectric ceramics were prepared by solid state reaction method with ZnNb2O6 as precursor. The structure analysis in terms of tolerance factor gives an identical result as calculation. The microwave dielectric properties, such as dielectric constants, Q×f values and τf were studied as a function of composition. With x increasing from 0.2 to 0.8, the dielectric constant linearly decreases from 109 to 49.37, the Q×f value increases from 8,340 to 13,200 GHz, and τf decreases from 321 to -18 ppm/°C. The properties trends are consistent with the previous calculation results, and confirm the relationship between the character of B-O bond and dielectric properties.

Effects of Doping ZnO-2B2O3-7SiO2 Glass by Sol-Gel Method on BaO-Sm2O3-4TiO2 Ceramics

2011 ◽  
Vol 148-149 ◽  
pp. 1077-1080
Author(s):  
Zhong Yan ◽  
Jin Liang Huang ◽  
Yong Jun Gu ◽  
Li Hua Li ◽  
Xiao Wang
Keyword(s):  
Dielectric Properties ◽  
Sol Gel ◽  
Ceramic Powder ◽  
Tungsten Bronze ◽  
Solid State Reaction Method ◽  
Structure Type ◽  
Conventional Solid State Reaction ◽  
Gel Method ◽  
Sol Gel Method ◽  
Bst Ceramics

BaO-Sm2O3-4TiO2 (abbreviated BST) ceramic powder was prepared by the conventional solid-state reaction method. The effects of doping ZnO-2B2O3-7SiO2 (abbreviated ZBS) glass by sol-gel method on the sintering behaviors, microstructure, phase composition and dielectric properties of BST ceramics were investigated. The experimental results reveal that the main phase of samples doped with ZBS glass is tungsten bronze structure type BaSm2Ti4O12 phase, a litter Sm2Ti2O7 phase is also observed. The sintering tenperature of BST ceramics is remarkably reduced from 1350°C to 1050°C and the good dielectric properties of εr=60.2，tanδ=0.004，τf=-7.9ppm/°C were obtained for BST ceramics doped with 6wt% ZBS glass by sol-gel method sintered at 1050°C for 3h.

Microwave Dielectric Properties of A-Site Modified Pb(Mg1/2W1/2)O3

2007 ◽  
Vol 280-283 ◽  
pp. 1-4
Author(s):  
Jian Jiang Bian ◽  
Hong Bo Gao ◽  
Xiao Wu Wang
Keyword(s):  
Dielectric Properties ◽  
Structural Difference ◽  
Microwave Dielectric Properties ◽  
Dielectric Constants ◽  
Sintering Behavior ◽  
Microwave Dielectric ◽  
Increase With Increase ◽  
A Site ◽  
Perovskite Type ◽  
Perovskite Type Structure

The sintering behavior, microstructure and microwave dielectric properties of A-site modified Pb(Mg1/2W1/2)O3 with Ca2+, Ba2+and La3+ were investigated in this paper. It is discovered that a series of single-phase perovskite type solid solutions with A-site vacancies were formed for Pb1-3/2xLax(Mg1/2W1/2)O3 (0 £ x £ 2/3)). The solid solution took cubic perovskite type structure (Fm3m)with random distribution of A-site vacancies when 0 < x < 0.5, and tetragonal or orthorhombic structure with the ordering of A-site vacancies when 0.5 £ x £ 2/3. However, the solid solubility of Ba(Mg1/2W1/2)O3 and Ca(Mg1/2W1/2)O3 in Pb(Mg1/2W1/2)O3 is limited to 15 and 5 mol%, respectively, in spite of no structural difference between the end member. It was also found that the A-site substitution with Ca2+, Ba2+and La3+ for Pb2+ has no influences on the degree of B-site ordering between Mg2+ and W6+. However, the antiferroelectric Tc decreases with increase in the content of A-site substitution. The dielectric constants and temperature coefficient of resonant frequency of La3+ modified Pb(Mg1/2W1/2)O3 are much lower than that of. Ca2+and Ba2+ modified Pb(Mg1/2W1/2)O3, and decrease with increasing La content. However, its Q×f values is much higher than that of Ca2+and Ba2+ modified Pb(Mg1/2W1/2)O3, and increase with increase in La content. Relatively good combination microwave dielectric properties were obtained for Pb1-3/2xLax(Mg1/2W1/2)O3 with x=0.56: er=28.7, Q×f=18098, and tf=-5.8ppm/oC.

Synthesis and dielectric properties of tungsten-based complex perovskites

2003 ◽  
Vol 18 (11) ◽  
pp. 2600-2607 ◽  
Author(s):  
D.D. Khalyavin ◽  
Jiaping Han ◽  
A.M.R Senos ◽  
P.Q. Mantas
Keyword(s):  
Dielectric Properties ◽  
Temperature Variation ◽  
Single Phase ◽  
Low Frequency ◽  
Double Perovskites ◽  
Dielectric Measurements ◽  
Anomalous Temperature ◽  
Conventional Solid State Reaction ◽  
Thermally Activated ◽  
Second Phases

Ba2MeWO6 (Me=Mg, Ni, Zn) double perovskites were prepared by the conventional solid-state reaction in a wide temperature range. Single-phase ceramics were obtained only at low temperatures approximately 1200°C, whereas a small amount of second phases existed in the samples sintered at higher temperatures. All the compounds are characterized by the cubic perovskite structure (space group Fm3m) with a complete NaCl type ordering between B-site ions. Anomalous temperature variation of the dielectric loss tangent found in the Ba2NiWO6 perovskite is supposed to be connected with a dielectric relaxation due to electronic hopping within thermally activated Ni3+-6W(6-1/6)+/W5+-6Ni(2+1/6)+ clusters. Dielectric measurements showed that the other two perovskites—Ba2ZnWO6 and Ba2MgWO6—exhibit a positive value of the temperature coefficient of permittivity. Such temperature variation is assumed to be caused by a considerable influence of the second polar mode involving B-site ion vibrations on the low-frequency dielectric properties.

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