scholarly journals SYNTHESIS AND ELECTRICAL CONDUCTIVITY OF SOLID SOLUTIONS OF THE SYSTEM PbF2–NdF3–SnF2

2020 ◽  
Vol 86 (5) ◽  
pp. 24-37
Author(s):  
Pohorenko Yuliia ◽  
Omel’chuk Anatoliy ◽  
Nagornyi Anton
Keyword(s):  
Activation Energy ◽  
Electrical Conductivity ◽  
Solid Solutions ◽  
Basic Structure ◽  
Elementary Cell ◽  
Initial Structure ◽  
Temperature Range ◽  
The Individual ◽  
Increasing Temperature ◽  
Transfer Numbers

In the system PbF2–NdF3–SnF2 are formed solid solutions of the heterovalent substitution Pb0,86-хNdхSn1,14F4+х (0 < x ≤ 0,17) with structure of β–PbSnF4. At x > 0,17 on the X-ray diffractograms, in addition to the basic structure, additional peaks are recorded to the reflexes of the individual NdF3. For single-phase solid solutions, the calculated parameters of the crystal lattice are satisfactorily described by the Vegard rule. The introduction of ions of Nd3+ into the initial structure leads to an increase in the parameter с of the elementary cell from 51.267 Å for x = 0,03 to 51.577 Å for x = 0.17. The replacement of a part of leads ions to neodymium ions an increase in electrical conductivity compared with Pb0.86Sn1.14F4. The slight replacement (3.0 mol. %) of Pb2+ ions by Nd3+ in the structure of Pb0.86Sn1.14F4 causes an increase in the electrical conductivity at T> 530 K (6.88·10-2 S/cm compared to 2.41·10-2 S/cm for the initial sample compound Pb0.86Sn1.14F4). In the region of lower temperatures, the electrical conductivity of the samples of this composition decreases, and below that temperature, on the contrary, slightly reduces the electrical conductivity, approaching the values characteristic of β-PbSnF4. The activation energy of the conductivity thus increases over the entire temperature range. A further increase in the concentration of Nd3+ ions in the synthesized samples causes an increase in their fluoride-ion conductivity throughout the temperature range. It should be noted that samples with a content of 10-15 mol% NdF3 at T>500 K have comparable conductivity values. At lower temperatures, the higher the conductivity, the higher the concentration of the substituent. The highest conductivity and the lowest activation energy have the sample Pb0.69Nd0.17Sn1.14F4.17 (σ373=3.68·10-2 S/сm, Ea=0,1 eV). The fluorine anions in synthesized phases are in three structurally-equivalent positions. The charge transfer is provided by the highly mobile interstitial fluorine anions, whose concentration increases with increasing temperature and concentration of NdF3. The transfer numbers for fluorine anions are not less than 0.99, practically independent of the concentration of neodymium trifluoride.

scholarly journals SYNTHESIS AND ELECTRICAL CONDUCTIVITY OF SOLID SOLUTIONS OF THE SYSTEM RbF-PbF2-SnF2

2019 ◽  
Vol 85 (5) ◽  
pp. 60-68
Author(s):  
Yuliay Pogorenko ◽  
Anatoliy Omel’chuk ◽  
Roman Pshenichny ◽  
Anton Nagornyi
Keyword(s):  
Activation Energy ◽  
Electrical Conductivity ◽  
Temperature Dependence ◽  
Solid Solutions ◽  
Basic Structure ◽  
Elementary Cell ◽  
Initial Structure ◽  
Fluoride Ions ◽  
Temperature Range ◽  
Order Of Magnitude

In the system RbF–PbF2–SnF2 are formed solid solutions of the heterovalent substitution RbxPb0,86‑xSn1,14F4-x (0 < x ≤ 0,2) with structure of β–PbSnF4. At x > 0,2 on the X-ray diffractograms, in addition to the basic structure, additional peaks are recorded that do not correspond to the reflexes of the individual fluorides and can indicate the formation of a mixture of solid solutions of different composition. For single-phase solid solutions, the calculated parameters of the crystal lattice are satisfactorily described by the Vegard rule. The introduction of ions of Rb+ into the initial structure leads to an increase in the parameter a of the elementary cell from 5.967 for x = 0 to 5.970 for x = 0.20. The replacement of a part of leads ions to rubium ions an increase in electrical conductivity compared with β–PbSnF4 and Pb0.86Sn1.14F4. Insignificant substitution (up to 3.0 mol%) of ions Pb2+ at Rb+ at T<500 K per order of magnitude reduces the conductivity of the samples obtained, while the nature of its temperature dependence is similar to the temperature dependence of the conductivity of the sample β-PbSnF4. By replacing 5 mol. % of ions with Pb2+ on Rb+, the fluoride ion conductivity at T> 450 K is higher than the conductivity of the initial sample Pb0,86Sn1,14F4 and at temperatures below 450 K by an order of magnitude smaller. With further increase in the content of RbF the electrical conductivity of the samples increases throughout the temperature range, reaching the maximum values at x≥0.15 (σ573 = 0.34–0.41 S/cm, Ea = 0.16 eV and σ373 = (5.34–8.16)•10-2 S/cm, Ea = 0.48–0.51 eV, respectively). In the general case, the replacement of a part of the ions of Pb2+ with Rb+ to an increase in the electrical conductivity of the samples throughout the temperature range. The activation energy of conductivity with an increase in the content of RbF in the low-temperature region in the general case increases, and at temperatures above 400 K is inversely proportional decreasing. The nature of the dependence of the activation energy on the concentration of the heterovalent substituent and its value indicate that the conductivity of the samples obtained increases with an increase in the vacancies of fluoride ions in the structure of the solid solutions.

Semiconducting Molybdenum Pyrochlores for high Temperature Applications

1998 ◽  
Vol 512 ◽  
Author(s):  
V. Ponnambalam ◽  
U. V. Varadaraju
Keyword(s):  
Activation Energy ◽  
Electrical Resistivity ◽  
High Temperature ◽  
Low Temperature ◽  
Solid Solutions ◽  
Power Factor ◽  
Charge Carriers ◽  
Temperature Range ◽  
Maximum Power Factor ◽  
Increasing Temperature

ABSTRACTThe solid solutions (Y1-xYbx)2Mo2O7 were prepared and the systematic changes in the electrical resistivity (ρ=l/σ), thermopower (S) and power factor (S2σ) have been studied in the temperature range 300–900 K. The lattice parameters ‘a’ and ‘c’ are smaller for higher Yb3+ content phases due to smaller Yb3+ radius and a small tetragonality is observed for all the phases. Semiconducting behaviour is seen for all compositions with systematic increase in activation energy with increasing Yb content. All compositions show negative thermopower indicating electrons are the majority charge carriers in the temperature range of measurements. The calculated power factor values S2σ increase with increasing temperature in the low temperature region and a maximum power factor of ∼0.76×10−7 Wcm−1K−2 is observed at 650K.

scholarly journals CONDUCTIVITY OF SOLID SOLUTIONS Pb0,86 xSmxSn1,14F4+x

2021 ◽  
Vol 87 (1) ◽  
pp. 13-22
Author(s):  
Yuliia Pohorenko ◽  
Anatoliy Omel’chuk ◽  
Anton Nagornyi
Keyword(s):  
Activation Energy ◽  
Electrical Conductivity ◽  
Solid Solutions ◽  
Initial Phase ◽  
Electronic Conductivity ◽  
Initial Structure ◽  
Fluoride Ions ◽  
Conducting Phase ◽  
Cell Parameters ◽  
Order Of Magnitude

In the PbF2 – SmF3 – SnF2 system, he­tero­valent substitution solid solutions Pb0.86-xSmxSn1,14F4+x (0 < x ≤ 0.15) with the structure β-PbSnF4 are formed. The unit cell parameters of solid solutions are satisfactorily described by Vegard’s rules. The electrical conductivity of the obtained samples decreases in the entire temperature range compared to Pb0.86Sn1.14F4  due to the introduction of SmF3 (at x≤0.08) in the initial structure. It brings them closer to the values of the electrical conductivity of β-PbSnF4. However, at temperatures above 520 K, the electrical conductivity of solid solutions is almost twice higher than that of the initial phase Pb0.86Sn1.14F4 (σ553 = 0.054 and 0.023 S/cm, respectively). The elect­rical conductivity of solid solutions increases with the Sm3+ content, reaching maximum values at x = 0.1. The Pb0.76Sm0.10Sn1.14F4.10 phases have the highest electrical conductivity and the lowest activation energy (σ373 = 1.08 • 10-2 S/cm). The substitution of Pb2+ ions by Sm3+ ions in the fluoride-conducting phase Pb0,86Sn1,14F4 helps to increase the electrical conductivity by almost an order of magnitude compared to the initial phase and by two orders of magnitude compared to β-PbSnF4. The ionic conductivity activation energy increases in the low-temperature region generally with increasing the SmF3 content and decreases proportionally at temperatures above 430 K. The nature of the dependence of the activation energy on the concentration of the heterovalent substituent and its value indicate that the conductivity of the obtained samples is provided by highly mobile interstitial fluoride ions in the structure of solid solutions. The Hebb-Wagner polarization saturation method was used to determine the electronic conductivity of the samples. It is 2 orders of magnitude lower than the ionic one. The fluorine ion transfer numbers are 0.99 and do not depend on the substituent content.

scholarly journals INVESTIGATION OF ELECTRICAL CONDUCTION IN VANADATE BASED GLASSES

2013 ◽  
Vol 22 ◽  
pp. 255-260 ◽  
Author(s):  
R. V. BARDE ◽  
S. A. WAGHULEY
Keyword(s):  
Activation Energy ◽  
Electrical Conductivity ◽  
Electrical Conduction ◽  
Arrhenius Equation ◽  
Localized States ◽  
Melt Quenching ◽  
Temperature Range ◽  
Dc Electrical Conductivity ◽  
Glassy Systems

The binary glassy systems 60V2O5-(40-x)P2O5 –xB2O3 were prepared by melt quenching technique. The mole of B2O3 was varies from 5 to 20 mol % with constant mol % of V2O5 during preparation of glass samples. The dc electrical conductivity of samples was measured in temperature range 303-473 K and found to be higher for sample 60 V2O5-20P2O5 –20B2O3 . Using the Arrhenius equation of conductivity, the activation energy of conduction is estimated. The conduction in these glasses is takes place by phonon-assisted hopping between the localized states.

Electrophysical properties of the (SnSe)1−x–(SmSe)x solid solutions at high and low temperature

2019 ◽  
Vol 34 (01) ◽  
pp. 2050008
Author(s):  
V. A. Abdurahmanova ◽  
N. M. Abdullaev ◽  
Sh. S. Ismayilov
Keyword(s):  
Activation Energy ◽  
Electrical Conductivity ◽  
Low Temperature ◽  
Solid Solutions ◽  
Low Temperatures ◽  
Electrophysical Properties ◽  
Type Specimens ◽  
Text Type ◽  
Donor Type ◽  
Text Density

The temperature range of [Formula: see text] = 77–770 K in the system alloys: Holl coefficient [Formula: see text], thermo-emf [Formula: see text], electric conductivity [Formula: see text], measured [Formula: see text]-density of components and analyzed. It has been established that samarium additive atoms contain donor-type properties and the effectiveness increases with the temperature increase: up to 40% proportional to [Formula: see text] K in [Formula: see text]-type specimens, whereas in [Formula: see text]-type samples this increase is higher and covers the contents of pH varying from [Formula: see text] to [Formula: see text]. An electrical conductivity of compounds increased due to the carrier activation with further increase of temperature. The activation energy of carriers at low temperatures ([Formula: see text] K) is [Formula: see text] eV for [Formula: see text] mol.% and [Formula: see text] mol.% compounds at [Formula: see text] = 77–320 K and for [Formula: see text] mol.% and [Formula: see text] mol.% compounds are [Formula: see text] eV. [Formula: see text] const at [Formula: see text]–400 K for [Formula: see text] mol.% and [Formula: see text] mol.% compounds, and passing with minimum increases at [Formula: see text] = 400–500 K.

scholarly journals Fluoride ion conductivity of solid solutions KxPb0.86-xSn1.14F4-x

2021 ◽  
pp. 31-31
Author(s):  
Yuliia Pohorenko ◽  
Roman Pshenychnyi ◽  
Tamara Pavlenko ◽  
Anatoliy Omel’chuk ◽  
Volodymyr Trachevskyi
Keyword(s):  
Electrical Conductivity ◽  
Impedance Spectroscopy ◽  
Solid Solutions ◽  
Ion Conductivity ◽  
19F Nmr ◽  
Fluoride Ion ◽  
Fluoride Ions ◽  
Order Of Magnitude ◽  
Increasing Temperature

The electrical conductivity of solid solutions with tetragonal syngony formed in 0.86(xKF - (1-x)PbF2) - 1.14SnF2 systems has been studied by 19F NMR and impedance spectroscopy. It was found that the Pb0.86Sn1.14F4 phase is characterized by better values of fluoride-ion conductivity than the ?-PbSnF4 compound. It was found that the substitution of Pb2+ ions by K+ up to ? = 0.07 in the structure of Pb0.86Sn1.14F4 contributes to increase in electrical conductivity by an order of magnitude relative to the original Pb0.86Sn1.14F4. The sample of the composition K0.03Pb0.83Sn1.14F3.97 has the highest electrical conductivity (?600 = 0.38 S cm-1, ?330 = 0.01 S cm-1). The fluoride anions in the synthesized samples of KxPb0.86-xSn1.14F4-x solid solutions occupy three structurally nonequivalent positions. It is shown that with increasing temperature, there is a redistribution of fluorine anions between positions in the anion lattice, which results in an increase in the concentration of highly mobile fluoride ions, which determine the electrical conductivity of samples.

scholarly journals Electrical Conductivity Studies of Composites Based on (Cu1–xAgx)7GeSe5I Solid Solutions

2020 ◽  
Vol 65 (1) ◽  
pp. 55
Author(s):  
A. I. Pogodin ◽  
M. M. Luchynets ◽  
V. I. Studenyak ◽  
O. P. Kokhan ◽  
I. P. Studenyak ◽  
...  
Keyword(s):  
Activation Energy ◽  
Electrical Conductivity ◽  
Impedance Spectroscopy ◽  
Solid Solutions ◽  
Frequency Range ◽  
Total Electrical Conductivity ◽  
Cationic Substitution ◽  
Nyquist Plots ◽  
Ionic Components ◽  
Frequency Dependences

Polymer composites based on (Cu1−xAgx)7GeSe5I solid solutions are produced. The electrical conductivity of the composites is measured by impedance spectroscopy in the frequency range from 20 Hz to 2×106 Hz and in the temperature interval 292–338 K. The frequency dependences of the total electrical conductivity are obtained, the Nyquist plots are constructed, and their analysis is performed. The effect of Cu+ →Ag+ cationic substitution on the total electrical conductivity and the activation energy, as well as on the electronic and ionic components of the electrical conductivity of composites based on (Cu1−xAgx)7GeSe5I solid solutions is studied on the basis of compositional dependences.

Electrical Conductivity of Some Copper Manganites

2003 ◽  
Vol 217 (6) ◽  
pp. 667-676 ◽  
Author(s):  
F. M. Ismail ◽  
F. F. Hamad ◽  
H. S. Faraj
Keyword(s):  
Activation Energy ◽  
Electrical Conductivity ◽  
Copper Content ◽  
Impurity Content ◽  
Temperature Range

AbstractThe a.c. conductivity as a function of temperature was measured for ten prepared samples. The measurements were carried out in the temperature range 25–340°C. The sample CuMn2O4 prepared either from oxide or carbonate contains the least impurity content, while the sample Cu1.5Mn1.5O4 from oxide origin and Cu1.6Mn1.4O4 from carbonate origin contain the highest impurity content. The activation energy ΔE1 values for the oxide origin samples are nearly the same of those obtained from carbonate origin. The variation of ΔE2 values with concentration of copper content (x) appears to be consistent.

Charge Transport and Relaxation in Triglycine Sulphate (TGS)

1997 ◽  
Vol 52 (8-9) ◽  
pp. 621-628 ◽  
Author(s):  
W. Osak
Keyword(s):  
Phase Transition ◽  
Activation Energy ◽  
Electrical Conductivity ◽  
Relaxation Time ◽  
Low Temperatures ◽  
Relaxation Times ◽  
Crystallographic Direction ◽  
Triglycine Sulphate ◽  
Temperature Range ◽  
Space Charge Limited Currents

Abstract Charging currents, J-V characteristics and electron conductivity have been measured in triglycine sulphate along three crystallographic directions: a, b and c. The measurements have been taken in a wide temperature range between −196°C and 80 °C. It is found that the charging currents have short relaxation times in the directions: a and c and a long relaxation time along the ferroelec-tric b axis. The J-V characteristics in the direction of the a and c axes have the shapes characteristic for linear dielectrics with space charge limited currents. The J-V characteristic for the b axis depends on the temperature: In the region of the phase transition the Fridkin-Kreher formula (J ∝ V4/3) is satisfied; for low temperatures characteristic agrees with SCLC theory for linear dielectrics with Gaussian traps energy distribution. The d.c. conductivity along the c axis is much higher than along the a and b axes. In the investigated temperature range, the electrical conductivity has an activation character. For −100 °C < T < −193 °C there is: σ ∝ (1/T) exp (− E/kT) . The activation energy depends both on the crystallographic direction and on the temperature-range. For low temperatures, T < −100 °C, the activation energies are very small (of the order of a few hundreds eV).

The Peculiarities of the Electrical Conductivity of LiNbO3 Crystals, Reduced in Hydrogen

2013 ◽  
Vol 200 ◽  
pp. 193-198 ◽  
Author(s):  
Aleksandr V. Yatsenko ◽  
A.S. Pritulenko ◽  
S.V. Yevdokimov ◽  
Dmytro Yu. Sugak ◽  
I.M. Solskii
Keyword(s):  
Activation Energy ◽  
Electrical Conductivity ◽  
Electrical Properties ◽  
Impedance Spectroscopy ◽  
Lithium Niobate ◽  
Low Frequency ◽  
Spectroscopy Method ◽  
Surface Layers ◽  
Temperature Range ◽  
Conductivity Mechanism

The low-frequency impedance spectroscopy method has been used to investigate the electrical conductivity peculiarities of lithium niobate (LN) crystals reduced in hydrogen. It has been found that the activation energy value of the dark electrical conductivity of such crystals in a temperature range of 288...370 К is equal to 0.68±0.02 eV. It has been demonstrated that the multiple heating of «black» LN crystals up to a temperature of about 420 K results in surface layers with modified electrical properties to occur in the crystal’s polar faces. The electrical conductivity mechanism of LiNbO3 crystals reduced in the hydrogen-containing atmosphere, and the causes of the instability of these properties are discussed.

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