THE ELECTRICAL PROPERTIES OF ALUMINA AT HIGH TEMPERATURES

1966 ◽  
Vol 44 (8) ◽  
pp. 1685-1698 ◽  
Author(s):  
T. Matsumura
Keyword(s):  
Electrical Conductivity ◽  
Electrical Properties ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Single Crystal ◽  
Transport Number ◽  
Ionic Transport ◽  
Mixed Conductor ◽  
Polycrystalline Alumina ◽  
Ionic Transport Number

The ionic transport number and the d-c. electrical conductivity of single-crystal and polycrystalline alumina have been studied between 1 000 °K and 1 750 °K at an oxygen partial pressure of 0.2 atm. The ionic transport number was determined by the galvanic-cell e.m.f. measurements; the electrical conductivity was measured by the three-terminal method.It was found that alumina is a mixed conductor, being predominantly an ionic conductor at temperatures below 1 100 °K and predominantly electronic at temperatures higher than 1 600 °K. The activation energies found for the electrical conductivity of the single-crystal and polycrystalline specimens are 0.8 eV and 2.4 eV respectively in the ionic range and 3.0 eV and 3.7 eV in the electronic range.

Electrical Properties of Donor and Acceptor Doped Gd2Ti2O7

1994 ◽  
Vol 369 ◽  
Author(s):  
Igor Kosacki ◽  
Harry L. Tuller
Keyword(s):  
Electrical Conductivity ◽  
Electrical Properties ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Conductivity Measurements ◽  
Donor And Acceptor ◽  
Mn Doped

The results of electrical conductivity measurements on Nb, W, and Mn-doped Gd2Ti2O7 are presented. A correlation between electrical conductivity, the oxygen partial pressure and type of dopants has been obtained. The source of the different PO2 dependence for Mn-doped material is discussed.

Ionic transport in LiNbO3

1991 ◽  
Vol 6 (4) ◽  
pp. 851-854 ◽  
Author(s):  
Apurva Mehta ◽  
Edward K. Chang ◽  
Donald M. Smyth
Keyword(s):  
Ionic Conductivity ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Ionic Transport ◽  
Ionic Transport Number ◽  
Cell Measurement ◽  
Experimental Validity ◽  
Pressure Independent ◽  
Temperature Equilibrium ◽  
Good Agreement

The high temperature equilibrium conductivity (950 °C–1050 °C) of congruent LiNbO3 can be resolved into two components: an electronic portion that is dependent on the oxygen partial pressure and an ionic portion that is pressure independent. It is shown that the two components can be obtained from an analysis of the total equilibrium conductivity measured as a function of oxygen partial pressure. The ionic transport number (fractional ionic conductivity) thus obtained is compared with that obtained from an oxygen concentration cell measurement. The two techniques are found to be in excellent agreement, confirming the experimental validity of the defect chemistry method. From the temperature dependence of the ionic conductivity, the activation energy (138 kJ/mol [1.43 eV]) for the ionic transport is obtained. The results are in good agreement with the value previously obtained for the oxygen chemical diffusivity.

Electrical Conductivity of Piezoelectric Strontium Bismuth Titanate Under Controlled Oxygen Partial Pressure

1999 ◽  
Vol 604 ◽  
Author(s):  
C. Voisard ◽  
P. Duran Martin ◽  
D. Damjanovic ◽  
N. Settier
Keyword(s):  
Electrical Conductivity ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Elevated Temperatures ◽  
Vacancy Concentration ◽  
Common Mechanism ◽  
Oxygen Vacancy Concentration ◽  
Reducing Conditions ◽  
Ionic Transport Number ◽  
Mn Doped

AbstractHysteresis free and linear piezoelectric behavior of SrBi4Ti4O15 (SrBIT) is very promising for precise sensors/actuators devices. Despite a quite low longitudinal piezoelectric coefficient (around 15 pC/N), its elevated ferroelectric phase transition temperature (540°C) allows its use above 300°C. Electrical conductivity at such temperatures should be kept as low as possible in order to avoid loss of piezoelectric properties or charge drifts. Under reducing conditions, however, the electrical conductivity may change considerably. The electrical conductivity of SrBi4Ti4O15 (SrBIT) has been measured under controlled oxygen partial pressure at elevated temperatures (700-900°C) from 1 atm down to 10−15atm. From 1 atm down to 10−15 atm pO2, above 700°C, the conductivity of SrBIT exhibits a -1/4 slope in log-log scale indicating n-type conductivity and an impurity controlled oxygen vacancy concentration. A conductivity minimum is observed around 0.2 atm for undoped SrBIT at 800°C. Acceptor doping (Mn) raises the minimum and flattens the conductivity curve with slope around -1/10 at 700°C, and -1/6 at 900°C. Ionic conductivity and defect ionization are discussed to account for this. Preliminary results indicate the possibility of a large, pO2 independent, region, down to 10−15atm pO2. The ionic transport number was found to be 0.42 at 800°C for undoped SrBIT and 0.75 for Mn doped SrBIT. The activation energies of undoped (1.35 eV) and Mn doped (1.44 eV) samples are close to each other as expected for a common mechanism

Defect Chemistry of “BaCuO2” II. Transport Properties and Nature of Defects

1995 ◽  
Vol 50 (11) ◽  
pp. 1059-1066 ◽  
Author(s):  
G. Chiodelli ◽  
U. Anselmi-Tamburini ◽  
M. Arimondi ◽  
G. Spinolo ◽  
G. Flor
Keyword(s):  
Electrical Conductivity ◽  
Charge Transport ◽  
Transport Properties ◽  
Carrier Mobility ◽  
Transport Number ◽  
Ionic Transport ◽  
Ionic Transport Number ◽  
Wide Range ◽  
Small Polarons ◽  
Cation Ratio

Abstract The charge transport properties of "BaCuO2" with 88:90 (Ba :Cu) cation ratio were characterized by thermopower, electrical conductivity and ionic transport number measurements in a wide range of temperature and oxygen partial pressure conditions. The nature of carriers is always represented by small polarons due to self-trapping of the electronic holes generated by the oxygen non-stoichiometry equilibrium. Some anomalies in carrier mobility as a function of temperature are shown not to be related to incomplete ionization of oxygen atoms on interstitial sites

Characterization of YBa2Cu4O8 high temperature electrical properties and thermodynamic stability

1991 ◽  
Vol 6 (10) ◽  
pp. 2054-2058 ◽  
Author(s):  
B-S. Hong ◽  
T.O. Mason
Keyword(s):  
High Temperature ◽  
Electrical Property ◽  
Electrical Properties ◽  
Seebeck Coefficient ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Pressure Range ◽  
Stability Range

Via in situ electrical property measurements (conductivity, Seebeck coefficient) over the temperature range 500–800 °C and oxygen partial pressure range 10−4-1 atm, the equilibrium transport properties and stability range of YBa2Cu4O8 were determined. YBa2Cu4O8 behaves like the intrinsically mixed-valent compound, magnetite (Fe3O4), with small variations in electrical properties with changes in oxygen partial pressure. The decomposition boundary to YBa2Cu3O6+y (or YBa2Cu3.5O7.5±z) and CuO occurs at log(po2, atm) = −1.24 × 104/T(K) + 11.01(773 ⋚ T(K) ⋚ 1073).

Composition-Dependent Electrical Conductivity of Ionic-Electronic Composite

1997 ◽  
Vol 500 ◽  
Author(s):  
M. Park ◽  
G. M. Choi
Keyword(s):  
Electrical Conductivity ◽  
Electrical Properties ◽  
Electromotive Force ◽  
Composition Dependence ◽  
Force Measurement ◽  
Ionic Transport ◽  
Charge Carriers ◽  
Stabilized Zirconia ◽  
Ionic Charge ◽  
Polarization Technique

ABSTRACTComposition. dependence of electrical conductivity of ionic-electronic composite was camined using yttria(8mol%) stabilized zirconia-NiO composites. The contributions of ectronic and ionic charge carriers to the electrical conductivity were determined by Hebb-Vagner polarization technique and electromotive force measurement of galvanic cell. Up to 6 sol% NiO addition, the conductivity decreased since the electronic NiO acted as an insulator in onic matrix. However the ionic transport was dominant until NiO content reaches 26 vol%. Mixed conduction was observed between 26 and 68 vol% of NiO. The effects of composition on he electrical properties were explained by the microstructure and thus by the distribution of two hases.

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