Electrical Properties of Sb-Doped BaPbO3 Ceramics

Sb-doped BaPbO3 ceramics were prepared by sol-gel method. The influence of Pb/Ba ratio and Sb concentration on the electrical properties of BaPb1+x-ySbyO3 (x=0.0, 0.1, 0.2 and 0≤y≤0.2) compositions were investigated. Holes and Pb vacancies were the major defects in lightly donor-doped BaPbO3, where the increase of donor concentration resulted in decrease of charge carriers (holes), leading to resistivity increasing. In the highly donor-doped conditions, the microstructure or solid solubility substituted defect structure as the main factor affecting the variety of resistivity. The lowest electrical resistivity of Sb-doped BaPbO3 was 2.69 × 10-4 /·cm when the Sb concentration y=0.12~0.13. Excess of Pb causes the born of barium vacancies. And, the observed PTCR behavior of BaPb1.2O3 involves the Barium vacancies in grain boundaries. 0.5 mol% Sb-doped BaPbO3 showed the best PTCR behavior and its Curie temperature was about 850°C.

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Varistor Properties of (Nb,Ba)-Doped TiO2

MRS Proceedings ◽

10.1557/proc-5-357 ◽

1981 ◽

Vol 5 ◽

Author(s):

M. F. Yan ◽

W. W. Rhodes

Keyword(s):

Electrical Properties ◽

Grain Boundaries ◽

Defect Structure ◽

Doped Tio2 ◽

Resistivity Data ◽

Oxidizing Atmosphere ◽

Device Applications

ABSTRACTA new varistor based on TiO2 ceramic was developed. TiO2 ceramics with the dopant ranges of 0 < Nb < 2% and 0 < Ba < 2% were prepared and their electrical properties were measured. In these dopant ranges, several compositions were discovered to have useful varistor properties with a voltagecurrent nonlinearity index of α > 3. It was found that Ba dopant which segregates at grain boundaries and an oxidizing atmosphere during cooling are necessary to produce varistor properties in (Nb,Ba)-doped TiO2. Nb was introduced to decrease the TiO2 lattice resistivity to a range useful for device applications. Resistivity data were measured as functions of dopant composition and sintering atmospheres. Data were analyzed in terms of the defect structure in TiO2.

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Investigation on microstructure and electrical properties of Bi doping Ca3Co4O9 nanoparticles synthesized by sol-gel process

International Journal of Engineering & Technology ◽

10.14419/ijet.v7i2.29.13121 ◽

2018 ◽

Vol 7 (2.29) ◽

pp. 31

Author(s):

Mohammed M A ◽

Izman Sudin ◽

Alias Mohd Noor ◽

Srithar Rajoo ◽

Uday M B ◽

...

Keyword(s):

Electrical Resistivity ◽

Electrical Properties ◽

Sol Gel ◽

Combustion Method ◽

Variable Pressure ◽

X Ray Diffraction ◽

Sol Gel Process ◽

Gel Combustion ◽

Bi Doping ◽

Increasing Temperature

In this study, nanoparticles of Bi doped Ca3-xCo4O9 [Ca3-xBixCo4O9 where x=0, 0.2, 0.4 and 0.6] were prepared by sol gel combustion method. The phase structures and microstructures of Bi doped Ca3-xCo4O9 powders preparation were investigated. The microstructural observations of different Bi doped Ca3-xCo4O9 powders were evaluated using X-ray diffraction analysis (XRD) and Variable Pressure Scanning Electron Microscope (VPSEM). The bulk Ca3-xBixCo4O9 samples were fabricated using uniaxial cold pressing technique. Electrical resistivity of bulk Ca3-xBixCo4O9 samples with different doping was measured using four-probe method from 300 to 700°K. The electrical resistivity was found to decrease with increasing temperature for the bulk Ca3-xBixCo4O9 samples. The electrical properties of Ca3-xBixCo4O9 are non-monotonic functions of x.

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Effect of CdTe Stoichiometry on the Electrical Properties of CdTe Films

MRS Proceedings ◽

10.1557/proc-426-385 ◽

1996 ◽

Vol 426 ◽

Author(s):

Gil Yong Chung ◽

Jin Soo Song ◽

Byung Tae Ahn

Keyword(s):

Electrical Resistivity ◽

Electrical Properties ◽

Solid Solubility ◽

Cdte Film ◽

Oxygen Flow ◽

Oxygen Doping ◽

Order Of Magnitude ◽

Cdte Films

AbstractCdTe films have been prepared by a close-spaced sublimation (CSS) process with screenprinted CdTe layers as a source. The electrical resistivity of the CdTe film deposited in O2 was about one order of magnitude lower than that of the film deposited in He. The Cd content in the CdTe films deposited in O2 was smaller than that in the CdTe films deposited in He. No oxygen was detected in the CdTe films deposited in O2. As the Cd/Te ratio decreased, the resistivity of the CdTe films decreased and reached at about 3×104 Ω2.cm. The resistivity decrease by oxygen flow was diminished when the CdTe composition was limited by solid solubility. The above results indicated that the resistivity decrease of CdTe films deposited in O2 was not by due to the oxygen doping but by due to the CdTe stoichiometry change.

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Structural, Magnetic and Electrical Properties of the Ternary Silicide Gd6Co1.67Si3 Derived from the Hexagonal Ho4Co3.07 (or Ho6Co4.61) Type Structure

Zeitschrift für Naturforschung B ◽

10.1515/znb-2006-0709 ◽

2006 ◽

Vol 61 (7) ◽

pp. 825-832 ◽

Cited By ~ 23

Author(s):

Etienne Gaudin ◽

François Weill ◽

Bernard Chevalier

Keyword(s):

Electrical Resistivity ◽

Electrical Properties ◽

Curie Temperature ◽

Powder Diffraction ◽

Title Compound ◽

Magnetic Ordering ◽

Impurity Phase ◽

Ferromagnetic Transition ◽

X Ray ◽

Ternary Silicide

The title compound was discovered as an impurity phase in many GdCoSi samples. It crystallizes in the hexagonal space group P63/m with a = 11.7787(5) and c = 4.1640(2) Å . Using X-ray powder diffraction, an ordered distribution between Co and Si was found but one site is not fully occupied by Co for steric reasons. Magnetization measurements reveal that Gd6Co1.67Si3 exhibits a ferromagnetic transition at TC = 294(2) K, a Curie temperature similar to that reported for pure gadolinium. This magnetic ordering has been confirmed by electrical resistivity investigations.

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Influence of Grain Formation on Electrical Properties of La0.67Sr0.33MnO3

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1107.255 ◽

2015 ◽

Vol 1107 ◽

pp. 255-260

Author(s):

Hui Wei Chin ◽

Kean Pah Lim ◽

S.A. Halim ◽

S.K. Chen ◽

S.W. Ng ◽

...

Keyword(s):

Grain Size ◽

Electrical Properties ◽

Grain Boundaries ◽

Grain Growth ◽

Sol Gel ◽

Hexagonal Structure ◽

Perovskite Manganites ◽

Shell Effect ◽

Exchange Effect ◽

Co Precipitation

In this work, polycrystalline perovskite manganites of La0.67Sr0.33MnO3 (LSMO) sample was prepared by two wet chemical methods: co-precipitation (CP) and sol-gel (SG) methods. Both samples were sintered at high temperature (1300 °C) for longer duration (24 hours) to investigate the effect of grains formation on its electrical properties. XRD results show that both samples were forming single LSMO phase with hexagonal structure (R-3c). SG sample shows smaller grain size (~220nm) however the CP sample (~4.45μm) was about 20-fold larger. Slower grain growth takes place in SG sample due to the triple junction effect where grain growth in nanocrystal is limited. Terrace patterns are noticed on the surface of CP sample which is suspected as the occurrence full crystallization or recrystallisation. TP of SG sample was shifted to lower temperature (298 K) due to the significant magnetically disordered layer across the grain boundaries which had weakened double exchange effect. SG sample displays higher extrinsic MR (-10.8%, 1 kG) and intrinsic MR (-25.1%, 10 kG) at 80 K due to the Core-Shell effect in the nanograin. However, grain boundaries (shell) effect is weakening in full crystallite CP sample. Hence, only intrinsic MR can be observed which is-15.6% at 10 kG applied field. Consequently, extrinsic MR is dominant in sol-gel sample however intrinsic MR is dominant in co-precipitation sample. Therefore, the grain size and microstructure formation affect the Tp, resistivity and magnetoresistive effect.

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