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 Influence of rare-earth additives (La, Sm and Dy) on the microstructure and dielectric properties of doped BaTiO3 ceramics

2010 ◽  
Vol 42 (1) ◽  
pp. 69-79 ◽  
Author(s):  
Vesna Paunovic ◽  
Lj. Zivkovic ◽  
V. Mitic
Keyword(s):  
Phase Transformation ◽  
Room Temperature ◽  
Core Shell ◽  
Homogeneous Microstructure ◽  
Grain Sizes ◽  
Air Atmosphere ◽  
Fine Grain ◽  
Heavily Doped ◽  
Core Shell Structure ◽  
Diffuse Phase

A series of La/Mn, Sm/Mn and Dy/Mn codoped BaTiO3 samples were prepared by the conventional solid state procedure with dopant concentrations ranging from 0.1 up to 2.0 at%. The specimens were sintered at 1320?C and 1350?C in an air atmosphere for two hours. The low doped samples demonstrated a mainly uniform and homogeneous microstructure with average grain sizes ranging from 0.3 ?m to 5.0 ?m. The appearance of secondary abnormal grains in the fine grain matrix and core-shell structure were observed in highly doped La/BaTiO3 and Dy/BaTiO3 sintered at 1350?C. The low doped samples, sintered at 1350?C, display a high value of dielectric permittivity at room temperature, 6800 for Sm/BaTiO3, 5900 for Dy/BaTiO3 and 3100 for La/BaTiO3. A nearly flat permittivity-response was obtained in specimens with 2.0 at% additive content. Using a modified Curie-Weiss law the Curie-like constant C? and a critical exponent ? were calculated. The obtained values of ? pointed out the diffuse phase transformation in heavily doped BaTiO3 samples.

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.

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.

Rare Earth and Perovskite Composite Ceramics Applied for the Thermistor with Wide Temperature Range

2012 ◽  
Vol 512-515 ◽  
pp. 613-616 ◽  
Author(s):  
Bo Zhang ◽  
Qing Zhao ◽  
Ai Min Chang ◽  
Peng Jun Zhao ◽  
Fang Guan
Keyword(s):  
Wide Temperature Range ◽  
Perovskite Phase ◽  
Temperature Characteristic ◽  
Absolute Temperature ◽  
Composite Ceramics ◽  
Conventional Solid State Reaction ◽  
Temperature Range ◽  
Air Atmosphere ◽  
Wide Range ◽  
Ntc Thermistors

Different compositions (aY2O3+bCeO2)-0.4YCr0.5Mn0.5O3 (a+b=0.6) were prepared via a conventional solid-state reaction at 1200°C, and sintered under air atmosphere at 1600°C. XRD patterns analysis has revealed that for 0<a<0.6, the major phases present in the calcined bodies are Y2O3, CeO2 and orthorhombic perovskite YCr0.5Mn0.5O3 phase, respectively. SEM and EDAX observations confirm the obtaining of three-phased composite ceramics. The brighter regions are the Y2O3 and CeO2 phase, whereas the darker are perovskite phase. All the NTC thermistors prepared show a similar linear relationship between the ln of the resistance and the reciprocal of the absolute temperature, indicative of NTC characteristics. For 0≤a≤0.6, the plotting curves of resistance- temperature characteristic are none linear on the wide temperature range, exhibit two branches. The obtained B25/150 and B700/1000 constants of the thermistors are in the range 3600-4400K and 6700-12000K. The magnitude order of the resistivity at 25°C is of 106-107Ωcm and activation energies vary from 0.313 to 1.029 eV at low and high temperatures, respectively. These compounds, having good NTC characteristics in a wide range of temperatures, could be applied as potential candidates for NTC thermistors from ambient to 1100°C.

Study on characteristics of schottky temperature detector based on metal/n-ZnO/n-Si structures

2020 ◽  
Vol 12 ◽  
Author(s):  
Fang Wang ◽  
Jingkai Wei ◽  
Caixia Guo ◽  
Tao Ma ◽  
Linqing Zhang ◽  
...  
Keyword(s):  
High Temperature ◽  
Temperature Measurement ◽  
Temperature Response ◽  
Large Temperature ◽  
Mems Devices ◽  
Temperature Range ◽  
Response Characteristics ◽  
High Temperature Measurement ◽  
Temperature Detector ◽  
Schottky Structure

Background: At present, the main problems of Micro-Electro-Mechanical Systems (MEMS) temperature detector focus on the narrow range of temperature detection, difficulty of the high temperature measurement. Besides, MEMS devices have different response characteristics for various surrounding temperature in the petrochemical and metallurgy application fields with high-temperature and harsh conditions. To evaluate the performance stability of the hightemperature MEMS devices, the real-time temperature measurement is necessary. Objective: A schottky temperature detector based on the metal/n-ZnO/n-Si structures is designed to measure high temperature (523~873K) for the high-temperature MEMS devices with large temperature range. Method: By using the finite element method (FEM), three different work function metals (Cu, Ni and Pt) contact with the n-ZnO are investigated to realize Schottky. At room temperature (298K) and high temperature (523~873K), the current densities with various bias voltages (J-V) are studied. Results: The simulation results show that the high temperature response power consumption of three schottky detectors of Cu, Ni and Pt decreases successively, which are 1.16 mW, 63.63 μW and 0.14 μW. The response temperature sensitivities of 6.35 μA/K, 0.78 μA/K, and 2.29 nA/K are achieved. Conclusion: The Cu/n-ZnO/n-Si schottky structure could be used as a high temperature detector (523~873K) for the hightemperature MEMS devices. It has a large temperature range (350K) and a high response sensitivity is 6.35 μA/K. Compared with traditional devices, the Cu/n-ZnO/n-Si Schottky structure based temperature detector has a low energy consumption of 1.16 mW, which has potential applications in the high-temperature measurement of the MEMS devices.

Effects of Nb doping on thermoelectric properties of Zn4Sb3 at high temperatures

2009 ◽  
Vol 24 (2) ◽  
pp. 430-435 ◽  
Author(s):  
D. Li ◽  
H.H. Hng ◽  
J. Ma ◽  
X.Y. Qin
Keyword(s):  
Thermal Conductivity ◽  
Electrical Resistivity ◽  
High Temperatures ◽  
Thermoelectric Properties ◽  
Figure Of Merit ◽  
Thermoelectric Performance ◽  
Temperature Range ◽  
A Value ◽  
Nb Doping ◽  
Thermal Conductivities

The thermoelectric properties of Nb-doped Zn4Sb3 compounds, (Zn1–xNbx)4Sb3 (x = 0, 0.005, and 0.01), were investigated at temperatures ranging from 300 to 685 K. The results showed that by substituting Zn with Nb, the thermal conductivities of all the Nb-doped compounds were lower than that of the pristine β-Zn4Sb3. Among the compounds studied, the lightly substituted (Zn0.995Nb0.005)4Sb3 compound exhibited the best thermoelectric performance due to the improvement in both its electrical resistivity and thermal conductivity. Its figure of merit, ZT, was greater than the undoped Zn4Sb3 compound for the temperature range investigated. In particular, the ZT of (Zn0.995Nb0.005)4Sb3 reached a value of 1.1 at 680 K, which was 69% greater than that of the undoped Zn4Sb3 obtained in this study.

Preparation and Characterization of NTC NiMn2O4-La1-xCaxMnO3 (0≤x≤0.3) Composite Ceramics

2013 ◽  
Vol 716 ◽  
pp. 78-83 ◽  
Author(s):  
Hui Min Zhang ◽  
Fang Guan ◽  
Ai Min Chang ◽  
Li Jun Zhao
Keyword(s):  
Electrical Resistivity ◽  
Perovskite Structure ◽  
Spinel Structure ◽  
Thermal Constant ◽  
Inrush Current ◽  
Composite Ceramics ◽  
Sem Images ◽  
Conventional Solid State Reaction ◽  
Different Temperatures ◽  
Xrd Patterns

Composite ceramics made of spinel structure NiMn2O4 and CaO-doped perovskite structure LaMnO3 were prepared by a conventional solid state reaction and sintered at different temperatures. The XRD patterns have shown that the major phases presented in the sintered samples are NiMn2O4 compounds with the spinel structure, La1-xCaxMnO3 with the perovskite structure and NiO with a monoclinic structure. SEM images show that the density and grain size of the composite ceramics increases with sintered temperature increasing. The electrical resistivity of the composite ceramics at 25°C is found to change significantly depending on the CaO content, while the thermal constant B is still reasonably large in the range of 2400 to 3000 K. For the composition x = 0.1, the composite with a low electrical resistivity (ρ25°C=4.46Ω·cm) and moderate B value (B25/50=2762K) was obtained. These composites could be applied as potential candidates for NTC thermistors in the suppression of the inrush current.

Analysis of temperature dependent electrical characteristics of Au/n-GaAs/GaAs structures in a wide temperature range

Vacuum ◽  
2008 ◽  
Vol 83 (2) ◽  
pp. 276-281 ◽  
Author(s):  
A. Bengi ◽  
S. Altındal ◽  
S. Özçelik ◽  
S.T. Agaliyeva ◽  
T.S. Mammadov
Keyword(s):  
Wide Temperature Range ◽  
Electrical Characteristics ◽  
Temperature Dependent ◽  
Temperature Range

Structure and Electrical Characteristics of BaTiO3 and Ba0.99Er0.01TiO3 Ceramics

2018 ◽  
Vol 280 ◽  
pp. 127-133 ◽  
Author(s):  
F. A. Ismail ◽  
Rozana Aina Maulat Osman ◽  
Mohd Sobri Idris ◽  
N.A.M. Ahmad Hambali
Keyword(s):  
Perovskite Phase ◽  
Microstructural Analysis ◽  
Xrd Analysis ◽  
Solid State Reaction Method ◽  
X Ray Diffraction ◽  
Conventional Solid State Reaction ◽  
Grain Sizes ◽  
Capacitance Voltage ◽  
Ion Incorporation ◽  
Voltage Breakdown

Conventional solid state reaction method was used to prepare BaTiO3 and Ba0.99Er0.01TiO3 ceramics. Influence of Er3+ ion incorporation on their structural, microstructural and electrical properties was studied. The phase pure samples were obtained when heated at 1400 °C for overnight. The tetragonal perovskite phase of BaTiO3 and Ba0.99Er0.01TiO3 was confirmed by using X-ray Diffraction (XRD) analysis which is in agreement with results obtained from Rietveld refinement analysis. The lattice parameters and unit cell volume of BaTiO3 increased when doped with Erbium. Microstructural analysis of BaTiO3 and Ba0.99Er0.01TiO3 ceramics showed that the grain sizes of BaTiO3 and Ba0.99Er0.01TiO3 significantly decreased. The dielectric properties of BaTiO3 and Ba0.99Er0.01TiO3 were investigated as a function of temperature and frequency. It revealed that the Curie temperature (TC) increased by doping Er content from 110 °C to 120 °C. Ba0.99Er0.01TiO3 exhibited the high value of dielectric constant (ε=5929) at TC of 120 °C. The capacitance-voltage characteristic revealed that the voltage breakdown for both BaTiO3 and Ba0.99Er0.01TiO3 exceeded 30 V.

Sign in / Sign up

Export Citation Format

Share Document