Conductivity and Permittivity Studies in the Diluted Perovskite System [(NH3)(CH2)6(NH3)]FexZn1-xCl4, x=1, 0.8, 0.5, and 0

2002 ◽  
Vol 57 (11) ◽  
pp. 897-908 ◽  
Author(s):  
M. F. Mostafa ◽  
M. M. AbdelKader ◽  
S. S. Arafat
Keyword(s):  
Temperature Region ◽  
Room Temperature ◽  
Conduction Mechanism ◽  
High Temperature Region ◽  
Frequency Dependent ◽  
Arrhenius Relation ◽  
Zn Addition ◽  
Series Type ◽  
Type Conduction ◽  
Band Type

The dielectric permittivity and AC conductivity of the perovskite-like system [(NH3)(CH2)6(NH3)]FexZn1-xCl4 (HDAFxZ1-x), where x=1, 0.8, 0.5 and 0, were measured at different frequencies in the temperature range 100 K<T<430 K. At temperatures below 273 K, for x=1 the material exhibits a transition at (245±1) K, while for x=0 transitions at (155±5) K, (220±4) K and (255±2) K were found. A rotational-type transition in the range 295 - 305 K was found for the Fe-containing materials. Ferroelectric transitions were observed in the high temperature region for all four concentrations. Differential thermal scanning confirmed the existence of the phase transitions above room temperature. The conductivity decreases with Zn addition, an the conduction mechanism varies with the temperature and concentration. Extrinsic conduction prevails for T<150 K for all concentrations. At intermediate temperatures an Arrhenius relation with frequency dependent activation energy (ΔE=0.46 - 0.06 eV) is observed for Fecontaining materials. The frequency dependent conductivity for all materials has a linear response following the power law: σac=A(T) ·ωS(T) with the exponent s varying with temperature and composition. At high temperatures, for Zn-rich materials series type conduction with s ∼ 0.6±0.1 is identified, while for Fe-rich materials band type conduction prevails. In the low temperature region ionic hopping prevails.

scholarly journals Electrical Conduction in Some Nickelates

2011 ◽  
Vol 8 (1) ◽  
pp. 83-90
Author(s):  
Kanchan Gaur ◽  
Shalini Shalini ◽  
Satyendra Singh
Keyword(s):  
Temperature Region ◽  
Conduction Mechanism ◽  
Charge Carriers ◽  
Band Model ◽  
Orthorhombic Unit Cell ◽  
Dominant Conduction Mechanism ◽  
Higher Temperature ◽  
Lower Temperature ◽  
Lower Temperature Region ◽  
Band Type

This paper reports electrical conductivity (s) and Seebeck coefficient (s) study on rare-earth nickelates RNiO3 where R = Nd, Sm and Eu in the temperature range 400-1200 K. They have orthorhombic unit cell. The majority charge carriers are holes throughout the measurement. Both s and S variations show three regions. In higher temperature region (Above 1000K) dominant conduction mechanism is intrisic band type whereas below this temperature, hopping of holes from Ni3+ to Ni2+ centres takes place. In lower temperature region, the electrical conductions is taken over by acceptor type impurities. The conduction mechanism is explained on the basis of every band model. Break temperatures as well as mobility have also been evaluated.

STUDIES OF STRUCTURAL AND ELECTRICAL BEHAVIOR OF SAMARIUM BARIUM TUNGSTATE CERAMICS

2011 ◽  
Vol 01 (04) ◽  
pp. 465-470 ◽  
Author(s):  
N. K. SINGH ◽  
PRITAM KUMAR ◽  
O. P. ROY ◽  
R. N. P. CHOUDHARY
Keyword(s):  
Activation Energy ◽  
High Temperature ◽  
Temperature Region ◽  
Room Temperature ◽  
Pyrochlore Structure ◽  
Structure Type ◽  
High Temperature Region ◽  
Phase Compound ◽  
Barium Tungstate ◽  
Xrd Patterns

Polycrystalline samples of samarium barium tungstate [ Sm2(Ba0.5W0.5)2O7 : (SBW)] pyrochlore structure type oxides have been prepared by a solid-state reaction technique. X-ray diffraction (XRD) patterns of this compound at room temperature suggest the formation of a single phase compound with orthorhombic structure. Studies of the dielectric constant and dielectric loss of compound as a function of frequency (4 kHz–1 MHz) at room temperature, and as a function of temperature (23–350°C) at 20 and 50 kHz frequencies suggest that the compound does not have dielectric anomaly. The variation of dc resistivity suggests the semiconductor characteristics of the material. The value of activation energy (E a ~ 0.43 at 20 kHz and E a ~ 0.29 at 50 kHz) of the above mentioned compound has been calculated from the slope of the ln σac versus 1/T graph in the high temperature region (> 240°C). The low value of activation energy supports the superionic nature of the compounds in the high temperature region.

scholarly journals Synthesis and Characterization of Lithium-Ion Conductive LATP-LaPO4 Composites Using La2O3 Nano-Powder

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3502
Author(s):  
Fangzhou Song ◽  
Masayoshi Uematsu ◽  
Takeshi Yabutsuka ◽  
Takeshi Yao ◽  
Shigeomi Takai
Keyword(s):  
Room Temperature ◽  
Conduction Mechanism ◽  
Lithium Ion ◽  
X Ray Diffraction ◽  
Temperature Conductivity ◽  
Room Temperature Conductivity ◽  
X Ray ◽  
Nano Powder ◽  
Powder Addition

LATP-based composite electrolytes were prepared by sintering the mixtures of LATP precursor and La2O3 nano-powder. Powder X-ray diffraction and scanning electron microscopy suggest that La2O3 can react with LATP during sintering to form fine LaPO4 particles that are dispersed in the LATP matrix. The room temperature conductivity initially increases with La2O3 nano-powder addition showing the maximum of 0.69 mS∙cm−1 at 6 wt.%, above which, conductivity decreases with the introduction of La2O3. The activation energy of conductivity is not largely varied with the La2O3 content, suggesting that the conduction mechanism is essentially preserved despite LaPO4 dispersion. In comparison with the previously reported LATP-LLTO system, although some unidentified impurity slightly reduces the conductivity maximum, the fine dispersion of LaPO4 particles can be achieved in the LATP–La2O3 system.

Dielectric Breakdown of Polyimide Film in High Temperature Region

1976 ◽  
Vol 15 (9) ◽  
pp. 1813-1814 ◽  
Author(s):  
Masayuki Nagao ◽  
Goro Sawa ◽  
Masahiko Fukui ◽  
Masayuki Ieda
Keyword(s):  
High Temperature ◽  
Temperature Region ◽  
Dielectric Breakdown ◽  
Polyimide Film ◽  
High Temperature Region
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