scholarly journals Fast Diffusion of Iron in Single Crystal Rutile and Iron Doped Rutile

1983 ◽  
Vol 24 ◽  
Author(s):  
J. Sasaki ◽  
N. L. Peterson ◽  
L. C. De Jonghe
Keyword(s):  
Electrical Conductivity ◽  
Ionic Conductivity ◽  
Pressure Dependence ◽  
Ionic Conduction ◽  
Complex Impedance ◽  
Fast Diffusion ◽  
Iron Ions ◽  
Impedance Measurements ◽  
Fe Content ◽  
Shear Structure

ABSTRACTTracer diffusion coefficients of Fe, DFe* in single crystals of rutile and of 0 –2.0% Fe doped rutile were measured. The oxygen pressure dependence of DFe* in pure rutile showed complicated behavior. The values of DFe* may consist of contributions from Fe2+ ions diffusing by an interstitial mechanism and from Fe3+ ions diffusing by an interstitialcy mechanism in cooperation with tetravalent titanium interstitial ions, Tii. The value of DFe* in Fe doped rutile attains a saturation value when the Fe content reaches about 0.1%, D*Fe decreases drastically when the Fe content exceeds about 0.35%. Complex impedance measurements of electrical conductivity indicate the existence of ionic conduction for Fe doped rutile containing less than 0.35% of Fe. The small ionic conductivity relative to the values of D*Fe suggests that only a small fraction of the iron ions are highly mobile. Above 0.35% Fe, the observed drastic decrease in D*Fe may result from the formation of a shear structure In highly doped rutile.

Electrical Conductivity and Structural Studies on the Binary System BiI3-Ag2SO4

2012 ◽  
Vol 584 ◽  
pp. 521-525
Author(s):  
S. Austin Suthanthiraraj ◽  
Ayesha Saleem
Keyword(s):  
Electrical Conductivity ◽  
Binary System ◽  
Ionic Conduction ◽  
Structural Characteristics ◽  
Complex Impedance ◽  
Present System ◽  
Rapid Melt Quenching ◽  
Ionic Nature ◽  
Electrochemical Devices ◽  
Silver Sulphate

A new solid-state pseudo binary system BiI3_-Ag2SO4 involving bismuth triiodide (BiI3) and a silver oxysalt namely silver sulphate (Ag2SO4) has been prepared using rapid melt-quenching technique. AC conductivity studies have been carried out on the nine different samples of the (BiI3)x –- (Ag2SO4)(1-x) system with compositions corresponding to x=0.1,0.2,0.3,0.4,0.5,0.6,0.7,0.8 and 0.9 mole fraction at temperatures ranging from room temperature (298 K) to 433K. The bulk resistance values estimated using complex impedance plots indicated that electrical conductivity of the synthesized solid specimens would vary from 2.9 x10-2 to 3.4 x10-6Scm-1 thus suggesting the present system to be ionic in nature. The extent of ionic conduction due to Ag + cation has also been analyzed using Wagner’s dc polarization technique whereas detailed structural characteristics of the various compositions derived from Fourier transform infrared (FTIR) spectroscopy and features of surface morphology of these samples obtained using scanning electron microscopy (SEM) have further supported the ionic nature of the chosen system and suggested possible application as a solid electrolyte in electrochemical devices.

Dehydration and decomposition of pyrophyllite at high pressures: electrical conductivity and X-ray diffraction studies to 5 GPa

1997 ◽  
Vol 34 (6) ◽  
pp. 875-882 ◽  
Author(s):  
Tara L. Hicks ◽  
Richard A. Secco
Keyword(s):  
Electrical Conductivity ◽  
South African ◽  
Pressure Dependence ◽  
High Pressures ◽  
Ionic Conduction ◽  
Temperature Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Temperature Dependence Of Conductivity

The dehydration and decomposition of South African pyrophyllite were studied in the pressure range 2.5–5.0 GPa and in the temperature (T) range 295–1473 K using both in situ electrical conductivity measurements and X-ray diffraction studies on the recovered samples. Activation energies for conduction (Qc) vary in the range 0.02–0.07 eV for T ≤ 500 K where the dominant conduction mode is electronic, and Qc is in the range 1.10–1.28 eV for T ≥ 500 K where ionic conduction dominates. Abrupt changes in the isobaric temperature dependence of conductivity mark the onset of dehydration and subsequent decomposition into kyanite plus quartz–coesite. At 2.5 GPa, South African pyrophyllite forms the dehydroxylate phase at 760 K with a pressure dependence of ~30 K/GPa and complete decomposition follows at 1080 K with a pressure dependence of ~41 K/GPa. The resulting pressure–temperature phase diagram is in very good agreement with many previous studies at 1 atm (101.325 kPa).

On the Sol-Gel Synthesis and Structure, Electronic and Ionic Conductivities and Impedance Behavior of Y, Fe Co-Doped SrTiO3 Mixed Conductor

2018 ◽  
Vol 281 ◽  
pp. 774-781
Author(s):  
Ke Shan ◽  
Feng Rui Zhai ◽  
Nan Li ◽  
Zhong Zhou Yi
Keyword(s):  
Electrical Conductivity ◽  
Ionic Conductivity ◽  
Ionic Conduction ◽  
Sol Gel ◽  
Ionic Conductivities ◽  
Wide Frequency Range ◽  
Mixed Conductor ◽  
Doping Amount ◽  
Impedance Characteristics ◽  
Sol Gel Synthesis

A single phase perovskite, YxSr1−xTi0.6Fe0.4O3-δ(x=0.06-0.09), was fabricated at 1350°C in air by sol-gel method. The effects of Y-and Fe-doping into SrTiO3on phase structure, electrical conductivity, ionic conductivity and its impedance behavior were investigated. The optimized Y0.07Sr0.93Fe0.4Ti0.6O3-δsample exhibits an electrical conductivity of 0.135 S·cm-1at 800 °C. Y-doping decreases the migration energy for oxygen ions, leading to a significant increase in ionic conductivity. The ionic conductivity of Y0.09Sr0.91Ti0.6Fe0.4O3-δsample varies from 0.0052 S· cm-1at 600°C to 0.02 S·cm-1at 800°C. Impedance characteristics over a wide frequency range of 0.01Hz-100 KHz reveal that the resistance of ionic conduction is predominantly influenced by grain boundary, the relaxation time of which decreases with increase of Y-doping amount.

ONE DIMENSIONAL NATURE OF IONIC CONDUCTIVITY IN SELF-FLUX GROWN RbTiOPO4 SINGLE CRYSTALS

2003 ◽  
Vol 17 (03) ◽  
pp. 373-382 ◽  
Author(s):  
C. V. KANNAN ◽  
S. GANESAMOORTHY ◽  
C. SUBRAMANIAN ◽  
P. RAMASAMY
Keyword(s):  
Ionic Conductivity ◽  
Ionic Conduction ◽  
Complex Impedance ◽  
Impedance Measurement ◽  
Dielectric Polarization ◽  
One Dimensional ◽  
Measured Activation Energy ◽  
Conduction Behavior ◽  
Measured Activation ◽  
Complex Impedance Measurement

The ionic conductivity of self-flux grown RbTiOPO 4 single crystal along the crystallographic a, b and c (polar) axes in the frequency range 100 Hz–10 MHz and in the temperature range 300–1140 K has been studied. The measured activation energy indicates the existence of super ionic conduction behavior in RTP crystals and also reveals that the DC electrical conduction and dielectric polarization are governed by the same mechanism. Complex impedance measurement shows the existence of non-Debye type of relaxation in the crystals.

scholarly journals Effect of chemical composition on the electrical conductivity of gneiss at high temperatures and pressures

Solid Earth ◽  
2018 ◽  
Vol 9 (2) ◽  
pp. 233-245 ◽  
Author(s):  
Lidong Dai ◽  
Wenqing Sun ◽  
Heping Li ◽  
Haiying Hu ◽  
Lei Wu ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Temperature Region ◽  
Ionic Conduction ◽  
Complex Impedance ◽  
Weight Percent ◽  
Spectroscopic Technique ◽  
Ultrahigh Pressure ◽  
Chemical Compositions ◽  
Metamorphic Belt ◽  
Lower Temperature

Abstract. The electrical conductivity of gneiss samples with different chemical compositions (WA = Na2O + K2O + CaO  =  7.12, 7.27 and 7.64 % weight percent) was measured using a complex impedance spectroscopic technique at 623–1073 K and 1.5 GPa and a frequency range of 10−1 to 106 Hz. Simultaneously, a pressure effect on the electrical conductivity was also determined for the WA = 7.12 % gneiss. The results indicated that the gneiss conductivities markedly increase with total alkali and calcium ion content. The sample conductivity and temperature conform to an Arrhenius relationship within a certain temperature range. The influence of pressure on gneiss conductivity is weaker than temperature, although conductivity still increases with pressure. According to various ranges of activation enthalpy (0.35–0.52 and 0.76–0.87 eV) at 1.5 GPa, two main conduction mechanisms are suggested that dominate the electrical conductivity of gneiss: impurity conduction in the lower-temperature region and ionic conduction (charge carriers are K+, Na+ and Ca2+) in the higher-temperature region. The electrical conductivity of gneiss with various chemical compositions cannot be used to interpret the high conductivity anomalies in the Dabie–Sulu ultrahigh-pressure metamorphic belt. However, the conductivity–depth profiles for gneiss may provide an important constraint on the interpretation of field magnetotelluric conductivity results in the regional metamorphic belt.

Structure and Ionic Conductivity of Lithio-Borate Thin Films

1990 ◽  
Vol 210 ◽  
Author(s):  
P. Dzwonkowski ◽  
M. Eddrief ◽  
C. Julien ◽  
M. Balkanski
Keyword(s):  
Thin Films ◽  
Ionic Conductivity ◽  
Solid Electrolyte ◽  
Ionic Conduction ◽  
Complex Impedance ◽  
Oxide System ◽  
Lithium Oxide ◽  
Process Conditions ◽  
Lithium Metaborate ◽  
Evaporation Technique

AbstractThin films of vitreous solid electrolyte in the boron-oxide/lithium oxide system have been grown using a thermal evaporation technique. Solid electrolyte films of composition B2O3-xLi2O with 0.5≤x≤5 are obtained from a mixture of lithium metaborate and lithium oxide in good proportion. Structure and ionic conduction are studied as a function of the glass modifier concentration and process conditions. The structure is investigated by the mid-infrared absorption spectroscopyof films deposited on a silicon wafer. Comparison with bulk materials whose structures are known shows that the films have a similar structure, and exhibit the transformation of boroxol rings into triborate or di-triborate units as the Li2O concentration increases. The ionic conductivity has been studied over wide frequency and temperatureranges using the complex impedance spectroscopy in a sandwiched geometry. The ionic conductivity increases with increasing Li content and exhibits a maximum value for B2O3-3Li2O.

Diffusion and Ion Conduction in Cation-Conducting Oxide Glasses

2016 ◽  
Vol 6 ◽  
pp. 59-106 ◽  
Author(s):  
Helmut Mehrer
Keyword(s):  
Ionic Conductivity ◽  
Pressure Dependence ◽  
Borate Glass ◽  
Ionic Conduction ◽  
Soda Lime ◽  
Tracer Diffusion ◽  
Oxide Glasses ◽  
Alkali Oxide ◽  
Alkali Ions ◽  
Temperature And Pressure

In this Chapter we review knowledge about diffusion and cation conduction in oxide glasses. We first remind the reader in Section 1 of major aspects of the glassy state and recall in Section 2 the more common glass families. The diffusive motion in ion-conducting oxide glasses can be studied by several techniques – measurements of radiotracer diffusion, studies of the ionic conductivity by impedance spectroscopy, viscosity studies and pressure dependent studies of tracer diffusion and ion conduction. These methods are briefly reviewed in Section 3. Radiotracer diffusion is element-specific, whereas ionic conduction is not. A comparison of both types of experiments can throw considerable light on the question which type of ions are carriers of ionic conduction. For ionic conductors Haven ratios can be obtained from the tracer diffusivity and the ionic conductivity for those ions which dominate the conductivity.In the following sections we review the diffusive motion of cations in soda-lime silicate glass and in several alkali-oxide glasses based mainly on results from our laboratory published in detail elsewhere, but we also take into account literature data.Section 4 is devoted to two soda-lime silicate glasses, materials which are commonly used for window glass and glass containers. A comparison between ionic conductivity and tracer diffusion of Na and Ca isotopes, using the Nernst-Einstein relation to deduce charge diffusivities, reveals that sodium ions are the carriers of ionic conduction in soda-lime glasses. A comparison with viscosity data on the basis of the Stokes-Einstein relation shows that the SiO2 network is many orders of magnitude less mobile than the relatively fast diffusing modifier cations Na. The Ca ions are less mobile than the Na ions but nevertheless Ca is considerably more mobile than the network.Section 5 summarizes results of ion conduction and tracer diffusion for single Na and single Rb borate glasses. Tracer diffusion and ionic conduction have been studied in single alkali-borate glasses as functions of temperature and pressure. The smaller ion is the faster diffusing species in its own glass. This is a common feature of all alkali oxide glasses. The Haven ratio of Na in Na borate glass is temperature independent whereas the Haven ratio of Rb diffusion in Rb borate glass decreases with decreasing temperature.Section 6 reviews major facts of alkali-oxide glasses with two different alkali ions. Such glasses reveal the so-called mixed-alkali effect. Its major feature is a deep minimum of the conductivity near some middle composition for the ratio of the two alkali ions. Tracer diffusion shows a crossover of the two tracer diffusivities as functions of the relative alkali content near the conductivity minimum. The values of the tracer diffusivities also reveal in which composition range which ions dominate ionic conduction. Tracer diffusion is faster for those alkali ions which dominate the composition of the mixed glass.Section 7 considers the pressure dependence of tracer diffusion and ionic conduction. Activation volumes of tracer diffusion and of charge diffusion are reviewed. By comparison of tracer and charge diffusion the so-called Haven ratios are obtained as functions of temperature, pressure and composition. The Haven ratio of Rb in Rb borate glass decreases with temperature and pressure whereas that of Na in Na borate glass is almost constant.Section 8 summarizes additional common features of alkali-oxide glasses. Activation enthalpies of charge diffusion decrease with decreasing average ion-ion distance. The Haven ratio is unity for large ion-ion distances and decreases with increasing alkali content and hence with decreasing ion-ion distance.Conclusions about the mechanism of diffusion are discussed in Section 9. The Haven ratio near unity at low alkali concentrations can be attributed to interstitial-like diffusion similar to interstitial diffusion in crystals. At higher alkali contents collective, chain-like motions of several ions prevail and lead to a decrease of the Haven ratio. The tracer diffusivities have a pressure dependence which is stronger than that of ionic conductivity. This entails a pressure-dependent Haven ratio, which can be attributed to an increasing degree of collectivity of the ionic jump process with increasing pressure. Monte Carlo simulations showed that the number of ions which participate in collective jump events increases with increasing ion content – i.e. with decreasing average ion-ion distance. For the highest alkali contents up to four ions can be involved in collective motion. Common aspects of the motion process of ions in glasses and of atoms in glassy metals are pointed out. Diffusion in glassy metals also occurs by collective motion of several atoms.Section 10 summarizes the major features of ionic conduction and tracer diffusion and its temperature and pressure dependence of oxide glasses.

Effect of MCl (M = Na, K) addition on microstructure and electrical conductivity of forsterite

2020 ◽  
Vol 92 (1) ◽  
pp. 10901
Author(s):  
Saloua El Asri ◽  
Hamid Ahamdane ◽  
Lahoucine Hajji ◽  
Mohamed El Hadri ◽  
Moulay Ahmed El Idrissi Raghni ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Electrical Conductivity ◽  
Single Phase ◽  
Sol Gel ◽  
Complex Impedance ◽  
Transmission Spectra ◽  
Electrical Measurements ◽  
Cation Type ◽  
Edx Analyses ◽  
The Fourier Transform

Forsterite single phase powder Mg2SiO4 was synthesized by sol–gel method alongside with heat treatment, using two different cation alkaline salts MCl as mineralizers (M = Na, K) with various mass percentages (2.5, 5, 7.5, and 10 wt.%). In this work, we report on the effect of the cation type and the added amount of used mineralizer on microstructure and electrical conductivity of Mg2SiO4. The formation of forsterite started at 680–740  °C and at 630–700  °C with KCl and NaCl respectively, as shown by TG-DTA and confirmed by XRD. Furthermore, the Fourier transform infrared (FTIR) transmission spectra indicated bands corresponding to vibrations of forsterite structure. The morphology and elemental composition of sintered ceramics were examined by SEM-EDX analyses, while their densities, which were measured by Archimedes method, increased with addition of both alkaline salts. The electrical measurements were performed by Complex Impedance Spectroscopy. The results showed that electrical conductivity increased with the addition of both mineralizers, which was higher for samples prepared with NaCl than those prepared with KCl.

scholarly journals Investigating the Factors Affecting the Ionic Conduction in Nanoconfined NaBH4

Inorganics ◽  
2021 ◽  
Vol 9 (1) ◽  
pp. 2
Author(s):  
Xiaoxuan Luo ◽  
Aditya Rawal ◽  
Kondo-Francois Aguey-Zinsou
Keyword(s):  
Ionic Conductivity ◽  
Ionic Conduction ◽  
Metal Hydrides ◽  
Ionic Conductivities ◽  
Effective Strategy ◽  
Li Ion Batteries ◽  
Large Cage ◽  
Factors Affecting ◽  
Li Ion ◽  
Mcm 41

Nanoconfinement is an effective strategy to tune the properties of the metal hydrides. It has been extensively employed to modify the ionic conductivity of LiBH4 as an electrolyte for Li-ion batteries. However, the approach does not seem to be applicable to other borohydrides such as NaBH4, which is found to reach a limited improvement in ionic conductivity of 10−7 S cm−1 at 115 °C upon nanoconfinement in Mobil Composition of Matter No. 41 (MCM-41) instead of 10−8 S cm−1. In comparison, introducing large cage anions in the form of Na2B12H12 naturally formed upon the nanoconfinement of NaBH4 was found to be more effective in leading to higher ionic conductivities of 10−4 S cm−1 at 110 °C.

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