scholarly journals Microstructures and Electrical Conduction Behaviors of Gd/Cr Codoped Bi3TiNbO9 Aurivillius Phase Ceramic

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5598
Author(s):  
Huajiang Zhou ◽  
Shaozhao Wang ◽  
Daowen Wu ◽  
Qiang Chen ◽  
Yu Chen
Keyword(s):  
Activation Energy ◽  
Electrical Conduction ◽  
Impedance Spectrum ◽  
Element Distribution ◽  
Charge Carriers ◽  
High Resistivity ◽  
Aurivillius Phase ◽  
Conventional Solid State Reaction ◽  
Debye Relaxation ◽  
Conduction Activation Energy

In this work, a kind of Gd/Cr codoped Bi3TiNbO9 Aurivillius phase ceramic with the formula of Bi2.8Gd0.2TiNbO9 + 0.2 wt% Cr2O3 (abbreviated as BGTN−0.2Cr) was prepared by a conventional solid-state reaction route. Microstructures and electrical conduction behaviors of the ceramic were investigated. XRD and SEM detection found that the BGTN−0.2Cr ceramic was crystallized in a pure Bi3TiNbO9 phase and composed of plate-like grains. A uniform element distribution involving Bi, Gd, Ti, Nb, Cr, and O was identified in the ceramic by EDS. Because of the frequency dependence of the conductivity between 300 and 650 °C, the electrical conduction mechanisms of the BGTN−0.2Cr ceramic were attributed to the jump of the charge carriers. Based on the correlated barrier hopping (CBH) model, the maximum barrier height WM, dc conduction activation energy Ec, and hopping conduction activation energy Ep were calculated with values of 0.63 eV, 1.09 eV, and 0.73 eV, respectively. Impedance spectrum analysis revealed that the contribution of grains to the conductance increased with rise in temperature; at high temperatures, the conductance behavior of grains deviated from the Debye relaxation model more than that of grain boundaries. Calculation of electrical modulus further suggested that the degree of interaction between charge carriers β tended to grow larger with rising temperature. In view of the approximate relaxation activation energy (~1 eV) calculated from Z’’ and M’’ peaks, the dielectric relaxation process of the BGTN−0.2Cr ceramic was suggested to be dominated by the thermally activated motion of oxygen vacancies as defect charge carriers. Finally, a high piezoelectricity of d33 = 18 pC/N as well as a high resistivity of ρdc = 1.52 × 105 Ω cm at 600 °C provided the BGTN−0.2Cr ceramic with promising applications in the piezoelectric sensors with operating temperature above 600 °C.

DC Conductivity of Illite with Fly-Ash between 20 – 1050 °C

2015 ◽  
Vol 1126 ◽  
pp. 123-128 ◽  
Author(s):  
Ján Ondruška ◽  
Igor Štubňa ◽  
Viera Trnovcová ◽  
Tomáš Húlan ◽  
Libor Vozár
Keyword(s):  
Activation Energy ◽  
Phase Transformation ◽  
Fly Ash ◽  
Temperature Region ◽  
Dc Conductivity ◽  
Charge Carriers ◽  
Conduction Activation Energy ◽  
Main Charge ◽  
Temperature Dependences ◽  
A Current

The temperature dependence of the electrical DC conductivity of fly-ash and illite-based ceramics was measured in the temperature range of 20 – 1050 °C. The measurements were done for illite samples with no fly-ash and fired illite added and illite samples containing 10 wt. %, 20 wt. %, 30 wt. %, and 40 wt. % of fly-ash and 0 wt. %, 10 wt. %, 20 wt. %, and 30 wt. % of fired illite. Addition of fly-ash substantially influences temperature dependences of the DC conductivity and introduces a temperature region with a high conduction activation energy which precedes the dehydroxylation. At the lowest temperatures, the main charge carriers are H+ and OH− ions, while at higher temperatures K+ and Na+ ions also play a role. The phase transformation metaillite -> Al-Si spinel is characterized with a current peak at 940 °C.

Electrical and Optical Properties of Indium-Modified SeSbTe Thin Films for Low Power Memory Devices

2011 ◽  
Vol 324 ◽  
pp. 245-248
Author(s):  
Hassan Ghamlouche ◽  
Saleh Thaker Mahmoud ◽  
Naser Qamhieh ◽  
Ahmad I. Ayesh
Keyword(s):  
Thin Films ◽  
Activation Energy ◽  
Optical Properties ◽  
Low Power ◽  
Phase Change ◽  
Electrical Conduction ◽  
Crystallization Temperature ◽  
Memory Devices ◽  
Electrical And Optical Properties ◽  
Conduction Activation Energy

The electrical and optical characteristics of indium doped Se2Sb2Te6phase-change alloy are studied. It is found that adding indium to Se2Sb2Te6 alloy (In0.3Se2Sb2Te6) increased the crystallization temperature and reduced the electrical conduction activation energy. The capacitance-temperature measurements showed a drastic change in the capacitance of the modified film when the temperature approaches the crystallization temperature, and eventually the capacitance becomes negative and nonlinear. The negativity and nonlinearity in the capacitancevoltage dependence can be attributed to the growth of conductive crystalline islands by increasing the temperature.

Electrical Properties of Fresnoite Ba2TiSi2O8 Using Impedance Spectroscopy

2013 ◽  
Vol 795 ◽  
pp. 640-643 ◽  
Author(s):  
Rozana A.M. Osman ◽  
Mohd Sobri Idris
Keyword(s):  
Activation Energy ◽  
Solid State ◽  
Sintering Temperature ◽  
Second Harmonic ◽  
Conventional Solid State Reaction ◽  
Reaction Phase ◽  
Tetragonal Unit Cell ◽  
Phase Pure ◽  
Very High ◽  
Centrosymmetric Structure

Fresnoite with composition Ba2TiSi2O8 (B2TS2) was first found in 1965, adopting a non-centrosymmetric structure. It also reported to crystallize in a tetragonal unit cell with a=8.52Å and c=5.210Å leading to some possible application as hydrophone, transducer and second harmonic generation and low temperature co-fired ceramics (LTCC). B2TS2 were synthesized by conventional solid state reaction. Phase pure B2TS2 was obtained after heating the pellets at a final sintering temperature of 1230 °C in air at 92 h. Study found that Fresnoite B2TS2 is a type of materials which are not ferroelectric and instead show perfect dielectric insulator behaviour with resistance >106Ωcm at temperatures below 750°C and also shows nonideal debye respone. The activation energy for conduction of B2TS2 samples is very high, indicating that these materials are highly insulating.

Variable Range Hopping Resistivity in La2-xSrxCuO4 Nanoparticles Evaluated by Four Point Probe Method

2020 ◽  
Vol 860 ◽  
pp. 142-147
Author(s):  
Suci Winarsih ◽  
Faisal Budiman ◽  
Hirofumi Tanaka ◽  
Tadashi Adachi ◽  
Takayuki Goto ◽  
...  
Keyword(s):  
Temperature Dependence ◽  
Thermal Activation ◽  
Resistivity Measurement ◽  
Probe Method ◽  
Charge Carriers ◽  
High Resistivity ◽  
Variable Range Hopping ◽  
Variable Range ◽  
Hopping Model ◽  
Variable Range Hopping Model

We report the results of the resistivity measurement on La2-xSrxCuO4 nanoparticles with x = 0, 0.05, and 0.20 evaluated by the four-point probe method. The high resistivity value shows the predominance of the inter-grain part. The temperature dependence of the conductivity can be analyzed by variable range hopping model showing the charge carriers are formed by thermal activation. There is no superconducting behavior that could be observed in La2-xSrxCuO4 nanoparticles with x = 0.05 and 0.20.

Persistent photoconductivity in AlGaN films Grown by mocvd

1998 ◽  
Vol 512 ◽  
Author(s):  
A. Y. Polyakov ◽  
N. B. Smirnov ◽  
A. V. Govorkov ◽  
J. M. Redwing
Keyword(s):  
Activation Energy ◽  
Light Intensity ◽  
High Resistivity ◽  
Persistent Photoconductivity ◽  
Quasi Fermi Level ◽  
Decay Times ◽  
Long Time ◽  
Light Excitation ◽  
Si Doped ◽  
Kinetics Of

ABSTRACTPhotocurrent transients due to illumination by above-bandgap and subbandgap light were studied for Si doped and undoped films of AlGaN grown by MOCVD on sapphire and having compositions ranging from 0% to 60% of Al. It is shown that in Si doped layers the decay of photoconductivity takes extremely long time (hundreds and thousands seconds, depending on temperature, composition and illumination conditions). Both the kinetics of rise and fall of photoconductivity are best described by stretched exponents. The characteristic decay times are virtually temperature independent for temperatures below 270–290K and have activation energy of 0.14–0.26 eV (depending on composition) for higher temperatures. The decay times become longer with decreased light intensity and increase when above-bandgap light excitation is replaced by subbandgap light excitation (the photocurrent values from which the decay starts being equivalent). The results cannot be quantitatively explained by the effects of changing of the quasi-Fermi level position well known for DX-centers in AlGaAs. No persistent photoconductivity could be observed in high resistivity undoped AlGaN films with 5%, 15% and 25% of Al.

ELECTRICAL CONDUCTION IN SUBSTITUTED Li-FERRITES PREPARED BY MICROWAVE PROCESSING

2005 ◽  
Vol 19 (21) ◽  
pp. 1051-1055 ◽  
Author(s):  
MAMATA MAISNAM ◽  
SUMITRA PHANJOUBAM ◽  
H. N. K. SARMA ◽  
CHANDRA PRAKASH ◽  
L. RADHAPIYARI DEVI ◽  
...  
Keyword(s):  
Activation Energy ◽  
Lattice Constant ◽  
Electrical Conduction ◽  
Spinel Structure ◽  
Single Phase ◽  
Microwave Sintering ◽  
Microwave Processing ◽  
Conventional Sintering

Samples with representative formula Li 0.45 Ni 0.1 Mn 0.1 Fe 2.35 O 4 have been sintered by conventional sintering technique and microwave sintering technique. Both the samples showed single-phase with spinel structure. The lattice constant for the microwave sintered (MS) sample showed a lower value than the conventionally sintered (CS) sample. The density of the MS sample has been found to be higher than the CS sample. And MS sample showed a higher value of resistivity and activation energy compared to the CS sample. The possible mechanisms are discussed.

Optimization and modulation for the moderate and high temperature thermoelectric properties of PbSe via solid solution with PbS synthesized by HPHT

2020 ◽  
Vol 34 (17) ◽  
pp. 2050185 ◽  
Author(s):  
Baomin Liu ◽  
Hongan Ma ◽  
Qi Chen ◽  
Yao Wang ◽  
Guangyao Ji ◽  
...  
Keyword(s):  
Activation Energy ◽  
Solid Solution ◽  
Electrical Conduction ◽  
Figure Of Merit ◽  
Solution Treatment ◽  
Conduction Type ◽  
Base Materials ◽  
Solid Solution Treatment ◽  
Electron Microscopes ◽  
Synthesis Stage

PbS synthesized at the same condition with PbSe exhibits an opposite electrical conduction type from it. Via the solid solution of PbS into PbSe, we attempt to change the major carries kind of PbSe-base materials and improve the thermoelectric (TE) property of synthesis samples in corresponding temperature areas. Introduction of high pressure into the synthesis stage could reduce the reactive activation energy and improve the synthesis efficiency. Characterizations via the electron microscopes demonstrate that synthesis samples are made of multiscale grains. Finally, characterizations on the thermoelectrical properties of [Formula: see text] demonstrate that the solid solution treatment could modulate the electrical conduction type and the figure of merit effectively.

Charge Carriers Motion in P3HT:Capped ZnO Nanoparticles Blend Films; Impact of Capping Agents

2016 ◽  
Vol 1 ◽  
Author(s):  
Ayi Bahtiar
Keyword(s):  
Activation Energy ◽  
Solar Cells ◽  
Charge Carrier ◽  
Zno Nanoparticles ◽  
High Performance ◽  
Active Material ◽  
Charge Carriers ◽  
Capping Agents ◽  
Blend Films ◽  
Carrier Recombination

<p class="TTPAbstract">Blend of conjugated polymer poly(3-hexylthiophene) or P3HT and Zinc Oxide nanoparticles (ZnO-NP) has been intensively used as active material for high performance hybrid solar cells. However, agglomeration of ZnO-NP hinders efficient charge carrier<span lang="IN">s</span> transfer both from P3HT to ZnO-NP and <span lang="IN">their </span>transport within ZnO-NP which cause to low performance of solar cells. Capping of ZnO-NP is currently applied to avoid this agglomeration effect. In this study, we used three different capping agents to cap ZnO-NP, namely small semiconducting molecules squaraine, 2-naphthalene and insulating polymer polyvinylpyrrolidone. We <span lang="IN">conducted</span> temperature dependence of photoinduced infrared absorption spectroscopy to study charge carriers motion in the P3HT:capped ZnO nanoparticles blend films. The measurement was carried out with light irradiation of 532 nm and temperature ranging from 78 to 300 K.  The spectra were analyzed by a bimolecular carrier recombination method with Arrhenius activation energy. Two parallel charge carrier recombination processes are observed, namely polarons recombination along polymer chain (intra-chain) and inter-chain polarons recombination in the P3HT-chains. At low temperatures, polarons recombine along polymer chains (intra-chain) with activation energy between 19-23 eV for all samples. However, the inter-chain polaron motion is influenced by capping agents as shown by a variation in its activation energy ranging from 28 to 58 eV.</p>

scholarly journals Structural, Electrical, and Magnetic Study of SrNi2+(Li1+Fe3+)0.5Fe16O27 Ferrite

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
P. R. Arjunwadkar ◽  
M. Y. Salunkhe ◽  
C. M. Dudhe
Keyword(s):  
Solid State Reaction Method ◽  
Product Formation ◽  
Continuous Heating ◽  
High Resistivity ◽  
Conventional Solid State Reaction ◽  
Prolonged Heating ◽  
Mixed Valency ◽  
Site Preferences ◽  
Ferrite Structure ◽  
Ir Bands

W-type ferrite having chemical formula SrNi(LiFe)0.5Fe16O27 was prepared by using conventional solid state reaction method at little low temperature (1100°C). The prolonged and continuous heating resulted in better product formation and it has validated that the Lithium present in the compound facilitates the synthesis. Typical IR bands observed are assigned to the Fe–O bonds in S block of W ferrite structure and the band near 914.3 cm−1 is assigned to the stretching vibrations of Sr–O. High resistivity is found which suggested presence of very small amount of mixed valency cations on equivalent lattice apart from the little amount created due to the release of an electron by divalent Ni to become trivalent. The magnetic properties of compound do not differ much from those of the reported for SrNi2W ferrite except a little decrease in saturation magnetization at room temperature due to canting effect. The experimental observations support presumed site preferences to a greater extent and also the prediction that the Li present on 4fVI sub-lattice results in small canting effect of 12k cations. The low value of coercivity observed is attributed to the larger particle size resulting due to prolonged heating.

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