Anomalous Broad Dielectric Dispersion of 0.4PZN-0.3PSN-0.3PZN Relaxor Ceramics at Lower Temperatures

2006 ◽  
Vol 514-516 ◽  
pp. 216-220
Author(s):  
Juras Banys ◽  
Jan Macutkevic ◽  
Algirdas Brilingas ◽  
Vytautas Samulionis ◽  
K. Bormanis ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Dielectric Permittivity ◽  
Bias Field ◽  
Dielectric Dispersion ◽  
Dielectric Losses ◽  
Low Frequencies ◽  
External Bias ◽  
Very High ◽  
Maximum Permittivity

Dielectric properties of 0.4PbZn1/3Nb2/3O3-0.3PbSc1/2Nb1/2O3-0.3PbMg1/3Nb2/3O3- (0.4PZN- 0.3PSN-0.3PMN) ceramics are presented for 200 < T < 500 K and 20 Hz < ν < 1 MHz. Dielectric constant is very high (more 14000) in the vicinity of the peak. Anomalous broad dielectric relaxation have been observed near the temperature of the maximum permittivity, Tm (at 1 kHz). External bias field considerably lowers the value of dielectric losses at low frequencies due to decrease of polar nano regions contribution to the dielectric permittivity.

Tuning the mechanical and dielectric properties of zinc incorporated hydroxyapatite

2020 ◽  
Vol 16 ◽  
Author(s):  
Alliya Qamar ◽  
Rehana Zia ◽  
Madeeha Riaz
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Bone Growth ◽  
Healing Process ◽  
Secondary Phase ◽  
Chemical Precipitation ◽  
Hexagonal Structure ◽  
Precipitation Method ◽  
Low Frequencies ◽  
A Minor

Background: Hydroxyapatite is similar to bone mineral in chemical composition, has good biocompatibility with host tissue and bone. Objective: This work aims to tailor the mechanical and dielectric properties of hydroxyapatite with zinc sudstitution, to improve wearability of implant and accelerate the healing process. Method: Pure and zinc incorporated hydroxyapatite Ca10(PO4)6(OH)2 samples have been successfully prepared by means of the chemical precipitation method. Results: The results showed that hydroxyapatite(Hap) having hexagonal structure was the major phase identified in all the samples. It was found that secondary phase of β-tricalcium phosphate (β-TCP) formed due to addition of Zinc resulting in biphasic structure BCP (Hap + β-TCP). A minor phase of ZnO also formed for higher concentration of Zn (Zn ≥ 2mol%) doping. It was found that the Zn incorporation to Hap enhanced both mechanical and dielectric properties without altering the bioactive properties. The microhardness increased upto 0.87 GPa for Zn concentration equal to 1.5mol%, which is comparable to the human bone ~0.3 - 0.9 GPa. The dielectric properties evaluated in the study showed that 1.5 mol% Zn doped hydroxyapatite had highest dielectric constant. Higher values of dielectric constant at low frequencies signifies its importance in healing processes and bone growth due to polarization of the material under the influence of electric field. Conclusion: Sample Z1.5 having 1.5 mol% Zn doping showed the most optimized properties suitable for bone regeneration applications.

scholarly journals Sintering, Microstructure, and Dielectric Properties of Copper Borates for High Frequency LTCC Applications

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4017
Author(s):  
Dorota Szwagierczak ◽  
Beata Synkiewicz-Musialska ◽  
Jan Kulawik ◽  
Norbert Pałka
Keyword(s):  
Dielectric Properties ◽  
Dielectric Permittivity ◽  
High Frequency ◽  
Ceramic Materials ◽  
Sintering Behavior ◽  
Terahertz Time Domain Spectroscopy ◽  
Very High Frequency ◽  
X Ray ◽  
Low Dielectric ◽  
Very High

New ceramic materials based on two copper borates, CuB2O4 and Cu3B2O6, were prepared via solid state synthesis and sintering, and characterized as promising candidates for low dielectric permittivity substrates for very high frequency circuits. The sintering behavior, composition, microstructure, and dielectric properties of the ceramics were investigated using a heating microscope, X-ray diffractometry, scanning electron microscopy, energy dispersive spectroscopy, and terahertz time domain spectroscopy. The studies revealed a low dielectric permittivity of 5.1–6.7 and low dielectric loss in the frequency range 0.14–0.7 THz. The copper borate-based materials, owing to a low sintering temperature of 900–960 °C, are suitable for LTCC (low temperature cofired ceramics) applications.

Influence of firing profile on microstructural and dielectric properties of LTCC substrates

2017 ◽  
Vol 34 (3) ◽  
pp. 127-130 ◽  
Author(s):  
Alena Pietrikova ◽  
Tibor Rovensky ◽  
Juraj Durisin ◽  
Igor Vehec ◽  
Ondrej Kovac
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Dwell Time ◽  
Design Methodology ◽  
Peak Temperature ◽  
Dielectric Losses ◽  
Sintering Process ◽  
Alpha Radiation ◽  
Content Type ◽  
X Ray

Purpose The purpose of this paper is to analyse the influence of various firing profiles on microstructural and dielectric properties of low-temperature, co-fired ceramic (LTCC) substrates in a GHz frequency range. According these analyses, sintering process can be controlled and modified to achieve better performance of devices fabricated from LTCC substrates. Design/methodology/approach Samples from LTCC substrates GreenTape 951 and GreenTape 9K7 were sintered by four firing profiles. Basic firing profile recommended by the manufacturer was modified by increasing the peak temperature or the dwell time at the peak temperature. The influence of firing profile on microstructural properties was analysed according to measurements by X-ray diffractometer (application of the Cu K-alpha radiation and the Bragg-Brentano method), and the influence on dielectric properties (dielectric constant and dielectric losses) was analysed according to measurements by split cylinder resonator method at 9.7 and 12.5 GHz. Findings Rising of the peak temperature or extension of dwell time at this temperature has influence on all analysed properties of LTCC substrates. Size of crystallites can be changed by modification of firing profile as well as microdeformation. In addition, dielectric properties can be changed too by modification of the firing profile. Correlation between microdeformation and dielectric losses was observed. Originality/value The novelty of this work lies in finding the mutual relationship between changes in microstructural (size of grains and microdeformation) and dielectric properties (dielectric constant and dielectric losses) caused by different firing profiles.

scholarly journals Stable dielectric response of low-loss aromatic polythiourea thin films on Pt/SiO2 substrate

2016 ◽  
Vol 06 (01) ◽  
pp. 1650003 ◽  
Author(s):  
A. Eršte ◽  
L. Fulanović ◽  
L. Čoga ◽  
M. Lin ◽  
Y. Thakur ◽  
...  
Keyword(s):  
Thin Films ◽  
Dielectric Constant ◽  
Dielectric Properties ◽  
Dielectric Response ◽  
High Density Polyethylene ◽  
Dielectric Losses ◽  
Low Loss ◽  
Promising Candidate ◽  
Sio2 Substrate ◽  
Polar Polymer

We have investigated dielectric properties of aromatic polythiourea (ArPTU, a polar polymer containing high dipolar moments with very low defect levels) thin films that were developed on Pt/SiO2 substrate. The detected response is compared to the response of commercially available polymers, such as high density polyethylene (HDPE) and polypropylene (PP), which are at present used in foil capacitors. Stable values of the dielectric constant [Formula: see text] (being twice higher than in HDPE and PP) over broad temperature and frequency ranges and dielectric losses as low as in commercial systems suggest ArPTU as a promising candidate for future use in a variety of applications.

Processing and the Microstructure of SrTiO3-Based Bl Capacitors using Pb(Fe, W)O3 Ferroelectrics

1989 ◽  
Vol 155 ◽  
Author(s):  
Makoto Kuwabara
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Grain Boundaries ◽  
Strontium Titanate ◽  
Barrier Layer ◽  
High Dielectric Constant ◽  
Ferroelectric Materials ◽  
New Type ◽  
High Dielectric ◽  
Very High

ABSTRACTA preliminary experiment was conducted to prepare semiconducting strontium titanate-based internal barrier layer capacitors with ferroelectric Pb(Fe, W)O3 forming insulating layers along the grain boundaries. Processing, microstructure and the dielectric properties of this new type of BL capacitors are described. The idea to obtain this type of BL capacitors with a very high dielectric constant may be realized when the ferroelectric materials can uniformly be diffused along the grain boundaries by using a more sophisticated processing of the second firing.

The Microstructure and Dielectric Properties of SrTiO3 Modified 0.9Pb(Mg1/3Nb2/3)O3-0.1PbTiO3 Ceramics

2011 ◽  
Vol 687 ◽  
pp. 433-438
Author(s):  
Jing Song Liu ◽  
Tao Li ◽  
Hui Qin Li ◽  
You Chao Xu ◽  
Ji Qiang Yu
Keyword(s):  
Phase Transition ◽  
Dielectric Constant ◽  
Transition Temperature ◽  
Dielectric Properties ◽  
Spontaneous Polarization ◽  
Relaxor Behavior ◽  
Maximum Dielectric Constant ◽  
Lower Temperature ◽  
Region Size ◽  
Maximum Permittivity

The microstructure and dielectric properties of ferroelectric solutions which is formulated with (1-x)[0.9Pb(Mg1/3Nb2/3)O3-0.1PbTiO3]-x mol% SrTiO3(x=0, 1, 3 and 5) have been investigated. The ceramics was fabricated by a modified columbite route sintered at 1200 °C. The effects of dopants on microstructure, maximum dielectric constant (εm) and diffuseness of the phase transition, etc. have been studied. It is found that the maximum permittivity (εm) increases to 24968 for the ST-doped (1 mol %) sample, subsequently decreases with ST addition and its corresponding phase-transition-temperature (Tm) shifts to the lower temperature. The variation of εmis caused by the decrease of polar nano-region size, increase of the fluctuation of the component and the increase of the effective spontaneous polarization. The enhancement of relaxor behavior in the PMN-PT sample is explained by the decrease of FE/AFE coupling.

Effect of Al2O3 and MgO Additives on Dielectric Properties of BaZrxTi1-xO3-Based Ceramics

2014 ◽  
Vol 602-603 ◽  
pp. 714-718
Author(s):  
Hong Jun Feng ◽  
Hui Ming Ji ◽  
Xiao Lei Li ◽  
Jian Wang ◽  
Da Hao Wang
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Dielectric Loss ◽  
Raw Materials ◽  
Bias Field ◽  
Phase Shifters ◽  
Sem Images ◽  
Solid State Method ◽  
Tunable Capacitors ◽  
Lcr Meter

BaZrxTi1-xO3-based (BZT) ceramics with Al2O3 and MgO addtives were prepared by the conventional solid state method with BaCO3, ZrO2, TiO2, Al2O3 and MgO as raw materials and B2O3 and Li2CO3 as sintering additive. The morphologies were analysized by scanning electron microscopy (SEM). The dielectric constant and dielectric loss of ceramics were measured by LCR meter. The temperature dependences of dielectric constant were measured by high-low temperature incubator tank and LCR meter at 1 MHz and a temperature range-55 to 125 °C. The tunabilities were tested by C-T-V converter and LCR meter at 1 MHz at room temperature. The results show that with the increase of Zr/Ti, BZT ceramic dielectric constant increases, the loss increases, the Curie temperature moves to a lower temperature, and dielectric bias field coordination is relatively lower. The SEM images show that the grain size reaches about 1-2 μm when the sintering temperature is 1100 °C, and the addition of Al2O3 and MgO promote the grain growth and densification of the composite ceramics. The Curie peaks are broadened and depressed with the addition of Al2O3 and MgO. The tunability is improved to 9.59% under a DC electric field of 7.0 kV/cm after the addition of Al2O3. The dielectric constant and dielectric loss of BaZr0.25Ti0.75O3-30wt%Al2O3 and BaZr0.25Ti0.75O3-30wt%MgO are 586, 0.011 and 486, 0.003, respectively. The optimistic dielectric properties make it a promising candidate for the application of tunable capacitors and phase shifters.

scholarly journals Dielectric Properties of Modified Lead Zirconate Titanate

2021 ◽  
Vol 16 (2) ◽  
Author(s):  
R.K. Sharma ◽  
Gunjan Purohit ◽  
D. K. Tyagi
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Dielectric Loss ◽  
Lead Zirconate Titanate ◽  
Lead Zirconate ◽  
Dielectric Measurement ◽  
Low Frequencies ◽  
Loss Measurement ◽  
Zirconate Titanate ◽  
Paraelectric State

In this paper, the dielectric properties of modified i. e. alkali doped lead zirconate titanate Pb(Zr1- xTix)O3 has been studied. The composition Pb1-x (La1-zDz)x (Zry Ti1-y)1-x/4 O3;where x = 0.10, y = 0.70, z = 0.0, 0.1, 0.2, and 0.3, D= Na, K and Li has been prepared by conventional mixed oxide method at a temperature of 11000C. Dielectric constant and dielectric loss measurement of the sintered pellets has been measured. Dielectric measurement shows that the dielectric constant decreases with an increase in temperature. The results show that the dielectric loss is very small and decreases with frequency above 300°C. The increase in the dielectric constant observed at high temperatures and low frequencies is explained in the paraelectric state.

Electrical Properties in Large Frequency and Temperature Ranges of Sr0.6Ca0.4TiO3 Ceramics

2020 ◽  
Vol 13 (3) ◽  
pp. 201-210
Keyword(s):  
Dielectric Permittivity ◽  
High Temperatures ◽  
Complex Impedance ◽  
Impedance Measurement ◽  
Conductivity Measurement ◽  
Calcium Titanate ◽  
Lead Free ◽  
Dielectric Losses ◽  
Low Frequencies ◽  
Wide Range

Abstract: Lead-free Sr0.6Ca0.4TiO3 (SCT) ceramic was prepared by the solid state reaction route. X-Ray diffraction technique showed the phase purity and identified the orthorhombic perovskite structure of the material. Scanning Electronic Microscopy observation evidenced homogeneous morphology and dense microstructure for the ceramic. The dielectric and conductivity properties of the sample were studied using complex impedance measurement technique in a wide range of frequencies and temperatures: from 100 Hz to 1.8 GHz and from 25°C to 550°C. The ceramic exhibits a stable dielectric permittivity and low dielectric losses in frequency and temperature up to 200°C. This is very interesting in view of developing high-quality lead-free ceramic capacitors for applications requiring high temperatures; for example, in cars. The increase in dielectric permittivity for temperatures higher than 200°C may be related to oxygen vacancies that are heat-activated in the material. Dielectric losses show the existence of a dielectric relaxation at low temperatures and low frequencies. Conductivity measurement investigated at high temperatures show on one hand high AC conductivity values attributed to the high temperature jumping process and on the other hand two electrical conductivity mechanisms above 400° C in the material. Keywords: Strontium calcium titanate, Ceramic, Structure, Dielectric properties, Conductivity.

The Crystalline and Dielectric Properties of 0.38(Bi1−xLax)ScO3-0.62PbTiO3 Ferroelectric Ceramics

2005 ◽  
Vol 888 ◽  
Author(s):  
Yi Chen ◽  
Dejun Lan ◽  
Qiang Chen ◽  
Zhuo Xu ◽  
Xi Yue ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Solid State ◽  
Dielectric Permittivity ◽  
Curie Temperature ◽  
Ferroelectric Ceramics ◽  
Partial Replacement ◽  
State Process ◽  
Lanthanum Content ◽  
Lower Temperature

ABSTRACTTo investigate the effects of partially substitution of lanthanum for bismuth in the BiScO3-PbTiO3 (BSPT) ceramics, the 0.38(Bi1−xLax)ScO3-0.62PbTiO3 (BLSPTx) ceramics were prepared by using conventional solid state process. It was found that the partial replacement of lanthanum for bismuth do not affects the crystalline structure of the BSPT ceramics. With increasing of the lanthanum content, the grains of BLSPTx ceramics grown much bigger than those of BSPT ceramics when BLSPTx and BSPT ceramics were sintered at the same temperature. The temperature dependence of dielectric permittivity of BLSPTx ceramics shows that the Curie temperature (Tc) shifts toward lower temperature with the increasing of lanthanum content, and the BLSPTx samples for x=0.02 show the highest value of the dielectric constant at Tc.

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