scholarly journals Microstructural and dielectrical characterization of Ho doped BaTiO3 ceramics

2014 ◽  
Vol 11 (1) ◽  
pp. 35-46 ◽  
Author(s):  
Milos Marjanovic ◽  
Dragana Dimitrijevic ◽  
Vesna Paunovic ◽  
Zoran Prijic
Keyword(s):  
Grain Size ◽  
Curie Temperature ◽  
Dopant Concentration ◽  
Sem Analysis ◽  
Curie Constant ◽  
Conventional Solid State Reaction ◽  
Homogeneous Microstructure ◽  
Dielectric Characteristics ◽  
Curie Temperature Tc

The Ho doped BaTiO3 ceramics, with different Ho2O3 content, ranging from 0.01 to 1.0 wt % Ho, were investigated regarding their microstructural and dielectric characteristics. Doped BaTiO3 were prepared using conventional solid state reaction and sintered at 1380?C for four hours. SEM analysis of Ho/BaTiO3 doped ceramics showed that the low doped samples exhibit mainly fairly uniform and homogeneous microstructure with the grain size ranged from 20-40 ?m. In the samples with the higher dopant concentration the abnormal grain growth is inhibited and the grain size ranged between 2-10 ?m. Measurements of dielectric properties were carried out as a function of temperature up to 180 ?C at different frequencies. The samples doped with 0.01wt % of Ho, exhibit the high value of dielectric permittivity (?r = 2160) at room temperature. A nearly flat permittivity-response was obtained in specimens with higher additive content. Using a Curie-Weiss law and modified Curie-Weiss law the Curie constant (C), Curie temperature (Tc) and a critical exponent of nonlinearity (g) were calculated. The Curie temperature of doped samples were ranged from 128 to 130?C. The Curie constant for all series of samples decrease with increase of dopant concentration and the lowest values were observed on samples doped with 0.01 wt % of holmium.

scholarly journals Ho2O3 additive effects on BaTiO3 ceramics microstructure and dielectric properties

2012 ◽  
Vol 44 (2) ◽  
pp. 223-233 ◽  
Author(s):  
Vesna Paunovic ◽  
Vojislav Mitic ◽  
Miroslav Miljkovic ◽  
Vera Pavlovic ◽  
Ljiljana Zivkovic
Keyword(s):  
Grain Size ◽  
Room Temperature ◽  
Dopant Concentration ◽  
Sem Analysis ◽  
Rare Earth Ions ◽  
Multilayer Ceramic Capacitors ◽  
Conventional Solid State Reaction ◽  
Dielectric Characteristics ◽  
Air Atmosphere ◽  
Curie Temperature Tc

Doped BaTiO3-ceramics is very interesting for their application as PTCR resistors, multilayer ceramic capacitors, thermal sensors etc. Ho doped BaTiO3 ceramics, with different Ho2O3 content, ranging from 0.01 to 1.0 wt% Ho, were investigated regarding their microstructural and dielectric characteristics. The samples were prepared by the conventional solid state reaction and sintered at 1320? and 1380?C in an air atmosphere for 4 hours. The grain size and microstructure characteristics for various samples and their phase composition was carried out using a scanning electron microscope (SEM) equipped with EDS system. SEM analysis of Ho/BaTiO3 doped ceramics showed that in samples doped with a rare-earth ions low level, the grain size ranged from 20-30?m, while with the higher dopant concentration the abnormal grain growth is inhibited and the grain size ranged between 2- 10?m. Dielectric measurements were carried out as a function of temperature up to 180?C. The low doped samples sintered at 1380?C, display the high value of dielectric permittivity at room temperature, 2400 for 0.01Ho/BaTiO3. A nearly flat permittivity-response was obtained in specimens with higher additive content. Using a Curie-Weiss low and modified Curie-Weiss low the Curie constant (C), Curie temperature (Tc) and a critical exponent of nonlinearity (?) were calculated. The obtained value of ? pointed out that the specimens have almost sharp phase transition.

Synthesis and Characterization of BaTiO3-(Bi0.5Na0.5)TiO3 Solid Solution Based Dielectric Ceramics

2012 ◽  
Vol 512-515 ◽  
pp. 1160-1164
Author(s):  
Guo Feng Yao ◽  
Xiao Hui Wang ◽  
Long Tu Li
Keyword(s):  
Solid Solution ◽  
Dielectric Properties ◽  
Solid State ◽  
Curie Temperature ◽  
Solid Solutions ◽  
Solid State Reaction ◽  
Synthesis And Characterization ◽  
Conventional Solid State Reaction ◽  
Dielectric Ceramics

BaTiO3-(Bi0.5Na0.5)TiO3 (BTBNT) solid solution ceramics with the Curie temperature higher than 150°C were prepared, which were promising for X9R MLCCs application. (Bi0.5Na0.5)TiO3 (BNT) was first synthesized by the conventional solid state reaction and then it was mixed with BaTiO3 (BT) with increasing BNT content from 0 to 12 mol%. BaTiO3-(Bi0.5Na0.5TiO3 solid solutions were obtained after calcining at 1100°C. The structural and dielectric properties of BTBNT and Nb-doped BTBNT ceramics were investigated.

scholarly journals Synthesis and characterization of titanium dioxide doped nickel oxide dielectric materials

2021 ◽  
Vol 6 (1) ◽  
pp. 31-35
Author(s):  
Nurul Ainon Bakar ◽  
Muhammad Azwadi Sulaiman ◽  
Julie Juliewatty Mohamed
Keyword(s):  
Grain Size ◽  
Dielectric Loss ◽  
Nickel Oxide ◽  
Dielectric Materials ◽  
Solid State Reaction Method ◽  
Sem Analysis ◽  
Calcination Process ◽  
High Dielectric Loss ◽  
High Dielectric

Nickel oxide (NiO) belongs to the transition metal oxide family, having good dielectric constantwith the range of 103 – 105, but it has high dielectric loss. In this research, the effect of titaniumdioxide (TiO2) addition into NiO was investigated. Generally, TiO2 was used in the application ofelectrical ceramic, catalysts, electric conductors and chemical intermediates. Ni1-xTixO1+x wasprepared via solid-state reaction method with 6 different TiO2 compositions. The preparation startedwith the powder mixing process for 24 hours and followed by calcination process at 950 °C for 4hours. Then, the calcined powders were compacted into 6 mm pellet shape under pressure of 250MPa pressure. Three pellets were made for each TiO2 composition. Those pellets were sintered at1250 °C for 5 hours. XRD results showed that pure NiO at 0.01 and 0.02 mole % of TiO2compositions produced single NiO crystalline phase, while 0.03, 0.05 and 0.10 mol % of TiO2showed the TiO2, instead of NiO phases. SEM analysis showed that increasing TiO2 concentrationmake the grain size increase, with 0.02 mole % of TiO2 gave the largest grain size, shows that 0.02mole % is the optimum TiO2 concentration for grain size enlargement. Furthermore, the bulkdensity of Ni1xTixO1+xpellet was reduces at higher TiO2 concentration. In dielectric test, the additionof 0.03 mole % of TiO2 gave the highest dielectric constant with value of 4.51 x 1014 and 0.05 mole% of TiO2 gives the result of lowest dielectric loss (0.53).

Texture Evolution In Fe-1%Si as a Function of High Magnetic Field

2005 ◽  
Vol 105 ◽  
pp. 151-156 ◽  
Author(s):  
Tricia A. Bennett ◽  
R.A. Jaramillo ◽  
David E. Laughlin ◽  
J.B. Wilgen ◽  
R. Kisner ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Grain Size ◽  
Field Strength ◽  
Curie Temperature ◽  
High Magnetic Field ◽  
Texture Component ◽  
Texture Evolution ◽  
Goss Texture ◽  
Drastic Increase ◽  
Curie Temperature Tc

The effect of a 1.5T, 15T and 30T magnetic field on texture evolution in Fe-1%Si was investigated by annealing samples for 1 hour at 787°C, (27° above the Curie temperature, Tc = 760°C). The intensity of the Goss texture component increased with increasing field strength accompanied by a drastic increase in grain size.

Preparation and Characterization of Fe Doped Bi2Ga4O9 Ceramics

2014 ◽  
Vol 552 ◽  
pp. 283-285
Author(s):  
Huan Huan Chen ◽  
Xiao Yan Zhang ◽  
Xi Wei Qi ◽  
Zhao Jie Zhou ◽  
Gui Fang Sun
Keyword(s):  
Grain Size ◽  
Solid Phase ◽  
Sem Analysis ◽  
Phase Method ◽  
Second Phase ◽  
Doping Content ◽  
Fe Doping ◽  
Sintering Process ◽  
Solid Phase Method

A series of Fe-doped Bi2(FexGa1-x)4O9 (x=0.1,0.2,0.3,0.4,0.5) ceramics were synthesized by solid-phase method with sintering process. The influences of Fe doping content on phase, morphology, dielectric properties are discussed. XRD results show that there is no second phase in Fe-doped Bi2(FexGa1-x)4O9 ceramics. The SEM analysis indicates the grain size of as-prepared doped samples are relatively uniform and estimated to be about 1–4μm. The permittivity of as-prepared doped samples increases and the dielectric loss decrease compared to pure Bi2Ga4O9 ceramics.

Effect of Sintering Temperature on Properties of Multiferroic BaFe12O19/MgFe2O4/BaTiO3 Composites

2016 ◽  
Vol 846 ◽  
pp. 410-415
Author(s):  
M.F.A. Zolkepli ◽  
Rozidawati Awang ◽  
Zalita Zainuddin
Keyword(s):  
Grain Size ◽  
Solid State ◽  
Electrical Properties ◽  
Sintering Temperature ◽  
Xrd Analysis ◽  
Sem Analysis ◽  
Solid State Reaction Technique ◽  
Conventional Solid State Reaction ◽  
Different Temperatures ◽  
Tetragonal Batio

In this paper, the structural, magnetic and electrical properties of multiferroic BaFe12O19/MgFe2O4/BaTiO3 composites have been studied. BaFe12O19/MgFe2O4/BaTiO3 composites were synthesized by using the conventional solid state reaction technique and sintered at different temperatures. XRD analysis confirmed the existence of hexagonal BaFe12O19, cubic spinel MgFe2O4 and tetragonal BaTiO3 for ferrites and ferroelectric phases, respectively. The suitable sintering temperature for preparing BaFe12O19/MgFe2O4/BaTiO3 composites is between 1000 °C and 1050 °C. SEM analysis showed that as a whole the grain size increases and the pores is reduced with sintering temperature; thus the sample became denser. The coercive field and saturation magnetization decreases when sintering temperature is increased. Resistance of the samples decrease from 103 kW to 19 kW while the capacitance increases from 0.8 nF to 4.0 nF with sintering temperature.

Characterization of Doped Titanium Oxide Varistor Powder Processed with Latex Binder

2015 ◽  
Vol 1115 ◽  
pp. 133-136
Author(s):  
Shahida Begum ◽  
Ida Rasyada ◽  
Arvin Panimeerselvam
Keyword(s):  
Grain Size ◽  
Silicon Oxide ◽  
Ceramic Materials ◽  
Sem Analysis ◽  
Electrical Performance ◽  
Green Density ◽  
Micro Hardness ◽  
Radial Shrinkage ◽  
Average Grain Size

In the processing of semiconducting electro ceramic materials the use of appropriate binder can lead to improve characteristics of powder which will reduce density gradient in the green body during compaction. The binder system is anticipated to have an influence on the grain growth and microstructure which in turn affect the electrical performance. To investigate this phenomenon, TiO2 powder doped with tungsten oxide (WO3), silicon oxide (SiO2) and bismuth oxide (Bi2O3) was processed with and without various percent of latex binder. The prepared samples were characterized by evaluating the physical properties like green density, fired density, axial and radial shrinkage, micro hardness and compressive strength. It was observed that TiO2 processed with latex binder exhibited higher green density and less axial and radial shrinkage compared to powder processed without binder. However, the binder level did not have any significant influence on the other characteristics of varistor discs. SEM analysis indicated that the average grain size was also influenced by the percent of binder used and but the higher average grain size was obtained for discs without any binder.

scholarly journals Electrical characteristics of Er doped BaTiO3 ceramics

2017 ◽  
Vol 49 (2) ◽  
pp. 129-137 ◽  
Author(s):  
Vesna Paunovic ◽  
Vojislav Mitic ◽  
Milos Djordjevic ◽  
Milos Marjanovic ◽  
Ljubisa Kocic
Keyword(s):  
Electrical Resistivity ◽  
Temperature Response ◽  
Sem Analysis ◽  
Electrical Characteristics ◽  
Conventional Solid State Reaction ◽  
Homogeneous Microstructure ◽  
Temperature Range ◽  
Grain Sizes ◽  
Air Atmosphere ◽  
Er Doped

In this study, the electrical resistivity (?) and PTC effect of Er doped BaTiO3 ceramics are investigated. The concentrations of Er2O3 in the doped samples vary from 0.01 to 1.0 at% Er. The samples are prepared by the conventional solid state reaction, and sintered at 1320? and 1350?C in air atmosphere for 4 hours. The SEM analysis shows that all of measured samples are characterized by polygonal grains. The uniform and homogeneous microstructure with grain sizes from 20 to 45?m is the main characteristic of the low doped samples (0.01 and 0.1 at% Er). For the samples doped with the higher dopant concentration (0.5 and 1.0 at%) the average grains sizes have been ranged from 5 to 10 ?m. The electrical resistivity is measured in the temperature range from 25?C to 170?C, at frequencies 1 kHz, 10 kHz and 100 kHz. The electrical resistivity values, measured at frequency of 1 kHz and room temperature, have been ranged from 1.62?104 ?cm to 4.24?104 ?cm, for samples sintered at 1320?C and from 1.43?104 ?cm to 1.94?104 ?cm, for samples sintered at 1350?C. A nearly flat and stable electrical resistivity-temperature response is characteristic for all samples at the temperature range from 25?C to 120?C. Above this temperature, the electrical resistivity increases rapidly. At 170?C the value of electrical resistivity is ranged 9.84?104 ?cm -1.62?105 ?cm, for Tsin=1320?C, and 6.11?104 ?cm 1.32?105 ?cm, for Tsin=1350?C. The electrical resistivity decreases with concentration increment up to 0.5 at%, while above 0.5 at% it increases. Also, with increasing frequency, ? decreases for a few orders of magnitude.

scholarly journals Tuning the Room Temperature Ferromagnetism in Fe5GeTe2 by Arsenic Substitution

2D Materials ◽  
2021 ◽  
Author(s):  
Andrew May ◽  
Jiaqiang Yan ◽  
Raphael Hermann ◽  
Mao-Hua Du ◽  
Michael A McGuire
Keyword(s):  
Magnetic Properties ◽  
Curie Temperature ◽  
Room Temperature ◽  
Room Temperature Ferromagnetism ◽  
Fine Tuning ◽  
The Individual ◽  
Curie Temperature Tc ◽  
Antiferromagnetic Behavior ◽  
Magnetic Sublattices

Abstract In order to tune the magnetic properties of the cleavable high-Curie temperature ferromagnet Fe5-xGeTe2, the effect of increasing the electron count through arsenic substitution has been investigated. Small additions of arsenic (2.5 and 5%) seemingly enhance ferromagnetic order in polycrystalline samples by quenching fluctuations on one of the three magnetic sublattices, whereas larger As concentrations decrease the ferromagnetic Curie temperature (TC) and saturation magnetization. This work also describes the growth and characterization of Fe4.8AsTe2 single crystals that are structurally analogous to Fe5-xGeTe2 but with some phase stability complications. Magnetization measurements reveal dominant antiferromagnetic behavior in Fe4.8AsTe2 with a Neel temperature of TN ≈42K. A field-induced spin-flop below TN results in a switch from negative to positive magnetoresistance, with significant hysteresis causing butterfly-shaped resistance loops. In addition to reporting the properties of Fe4.8GeTe2, this work shows the importance of manipulating the individual magnetic sublattices in Fe5-xGeTe2 and motivates further efforts to control the magnetic properties in related materials by fine tuning of the Fermi energy or crystal chemistry.

scholarly journals Microstructure and magnetic properties of soft nickel ferrite

2015 ◽  
Vol 39 (1) ◽  
pp. 59-64 ◽  
Author(s):  
Mahabub Alam Bhuiyan ◽  
Sheikh Manjura Hoque ◽  
Shamima Choudhury
Keyword(s):  
Grain Size ◽  
Magnetic Properties ◽  
Curie Temperature ◽  
Sintering Temperature ◽  
Great Influence ◽  
Complex Permeability ◽  
Scanning Electron Micrographs ◽  
Academy Of Sciences ◽  
Curie Temperature Tc ◽  
Microstructure And Magnetic Properties

Polycrystalline NiFe2O4 samples were prepared from analytical grade powder of NiO and Fe2O3 by conventional double sintering technique. The samples were sintered at 1000 - 1400°C. The scanning electron micrographs (magnification ´ 10000) of the samples revealed that the grain size increases and the porosity decreases with the increase in sintering temperature. These changes in microstructure, grain size and porosity with sintering temperature have great influence on the magnetic properties of NiFe2O4. Complex permeability (u’) over the frequency range from 1 kHz to 13 MHz for the samples at different sintering temperatures (1000-1400°C) has been observed. Variation of permeability with the applied temperature has been observed at various sintering temperature from which Curie temperature have been calculated. Decreased value of Curie temperature (Tc) has been found with the increase of sintering temperature.Journal of Bangladesh Academy of Sciences, Vol. 39, No. 1, 59-64, 2015

Sign in / Sign up

Export Citation Format

Share Document