Studying Ionic Conductivity with Diffraction Techniques an Application to laF3

1988 ◽  
Vol 135 ◽  
Author(s):  
Andreas Belzner ◽  
Heinz Schulz
Keyword(s):  
Activation Energy ◽  
Ionic Conductivity ◽  
Nearest Neighbor ◽  
Fluoride Ion ◽  
Static Disorder ◽  
Ion Conductor ◽  
3 Dimensional ◽  
Thermal Vibrations ◽  
Temperature Factors

AbstractThe LaF3-structure has been reinvestigated using diffraction data measured with twinned crystals.LaF3 is fluoride ion conductor with essentially 3-dimensional conductivity. The conduction perpendicular to the c-axis is shown to occur on paths which include all three sets of fluorine positions in the structure and which connect symmetrically non-equivalent nearest neighbor positions only. This is confirmed by determination of anharmonic temperature factors. The temperature dependence of the harmonic thermal parameters indicates that thermal vibrations are described rather than static disorder. The magnitude of the temperature factors of fluorine is consistent with an intrinsic activation energy of 0.8 eV for fluorine conduction.

Phase Transitions in Lead(II) Fluoride Upon Milling

1997 ◽  
Vol 481 ◽  
Author(s):  
Georges DÉnÉ ◽  
M. Cecilia Madamba
Keyword(s):  
Activation Energy ◽  
Phase Transitions ◽  
High Temperature ◽  
High Temperature Phase ◽  
Fluoride Ion ◽  
Temperature Phase ◽  
Ambient Conditions ◽  
Ion Conductor ◽  
Frenkel Defects ◽  
High Temperature Polymorph

ABSTRACTPbF2 is known to exist under two different polymorphic structures. Orthorhombic α-PbF 2 is stable at ambient temperature. It has the PbC12 structure. Cubic β-PbF2 is obtained by heating α-PbF2. It does not transform back to α-PbF2 on cooling, and it seems to be infinitely stable in the metastable state under ambient conditions. β-PbF2 crystallizes in the fluorite (CaF2) type. Owing to the large number of potential interstitial sites, many F- Frenkel defects can be formed, which make β-PbF2 the highest performance fluoride ion conductor among binary fluorides. In this work, both phases of PbF2 have been ball milled. Milling α-PbF2 results in a partial transformation to microcrystalline β-PbF2. The energy required for obtaining the high temperature phase is probably provided in the mechanical form. Milling β-PbF2 leads to partial amorphization and formation of α-PbF2. In this case, milling transforms the high temperature polymorph to the low temperature form, by providing the energy required to overcome the activation energy that keeps PbF2 trapped in the high temperature β-form after cooling.

scholarly journals Akurasi Klasifikasi Pengguna terhadap Hotspot WiFi dengan Menggunakan Metode K-Nearest Neighbour

2021 ◽  
pp. 128-133
Author(s):  
Raemon S Saljumairi ◽  
Sarjon Defit ◽  
S Sumijan ◽  
Yusma Elda
Keyword(s):  
Test Data ◽  
Euclidean Distance ◽  
Nearest Neighbor ◽  
Access Point ◽  
Training Data ◽  
Test Results ◽  
K Nearest Neighbor ◽  
Accuracy Rate ◽  
3 Dimensional

The Current wireless technology is used to find out where the user is in the room. Utilization of WiFi strength signal from the Access Point (AP) can provide information on the user position in a room. Alternative determination of the user's position in the room using WiFi Receive Signal Strength (RSS). This research was conducted by comparing the distance between users to 2 or more APs using the euclidean distance technique. The Euclidean distance technique is used as a distance calculator where there are two points in a 3-dimensional plane or space by measuring the length of the segment connecting two points. This technique is best for representing the distance between the users and the AP. The collection of RSS data uses the Fingerprinting technique. The RSS data was collected from 20 APs detected using the wifi analyzer application, from the results of the scanning, 709 RSS data were obtained. The RSS value is used as training data. K-Nearest Neighbor (K-NN) uses the Neighborhood Classification as the predictive value of the new test data so that K-NN can classify the closest distance from the new test data to the value of the existing training data. Based on the test results obtained an accuracy rate of 95% with K is 3. Based on the results of research that has been done that using the K-NN method obtained excellent results, with the highest accuracy rate of 95% with a minimum error value of 5%

Least-square refinement of structure parameters from CBED integrated intensities: application to determination of temperature factors in Y BA2CU3O7

1992 ◽  
Vol 50 (2) ◽  
pp. 1456-1457
Author(s):  
Kjersti Gjønnes ◽  
Jon Gjønnes
Keyword(s):  
Least Square ◽  
Measured Intensity ◽  
Structure Information ◽  
Accurate Temperature ◽  
Least Square Fit ◽  
Case Application ◽  
Integrated Intensities ◽  
Temperature Factors ◽  
Narrow Bands

Electron diffraction intensities can be obtained at large scattering angles (sinθ/λ ≥ 2.0), and thus structure information can be collected in regions of reciprocal space that are not accessable with other diffraction methods. LACBED intensities in this range can be utilized for determination of accurate temperature factors or for refinement of coordinates. Such high index reflections can usually be treated kinematically or as a pertubed two-beam case. Application to Y Ba2Cu3O7 shows that a least square refinememt based on integrated intensities can determine temperature factors or coordinates.LACBED patterns taken in the (00l) systematic row show an easily recognisable pattern of narrow bands from reflections in the range 15 < l < 40 (figure 1). Integrated intensities obtained from measured intensity profiles after subtraction of inelastic background (figure 2) were used in the least square fit for determination of temperature factors and refinement of z-coordinates for the Ba- and Cu-atoms.

Under Pressure: Mechanochemical Effects on Structure and Ion Conduction in the Sodium-Ion Solid Electrolyte Na3PS4

2020 ◽  
Author(s):  
Theodosios Famprikis ◽  
O. Ulas Kudu ◽  
James Dawson ◽  
Pieremanuele Canepa ◽  
François Fauth ◽  
...  
Keyword(s):  
Ionic Conductivity ◽  
Mechanochemical Synthesis ◽  
Activation Volume ◽  
External Pressure ◽  
Sodium Ion ◽  
Variable Pressure ◽  
Ion Conductor ◽  
Ceramic Synthesis ◽  
Solid State Batteries ◽  
Fast Ion

<div> <p>Fast-ion conductors are critical to the development of solid-state batteries. The effects of mechanochemical synthesis that lead to increased ionic conductivity in an archetypical sodium-ion conductor Na<sub>3</sub>PS<sub>4</sub> are not fully understood. We present here a comprehensive analysis based on diffraction (Bragg, pair distribution function), spectroscopy (impedance, Raman, NMR, INS) and <i>ab-initio</i> simulations aimed at elucidating the synthesis-property relationships in Na<sub>3</sub>PS<sub>4</sub>. We consolidate previously reported interpretations about the local structure of ball-milled samples, underlining the sodium disorder and showing that a local tetragonal framework more accurately describes the structure than the originally proposed cubic one. Through variable-pressure impedance spectroscopy measurements, we report for the first time the activation volume for Na<sup>+</sup> migration in Na<sub>3</sub>PS<sub>4</sub>, which is ~30% higher for the ball-milled samples. Moreover, we show that the effect of ball-milling on increasing the ionic conductivity of Na<sub>3</sub>PS<sub>4</sub> to ~10<sup>-4</sup> S/cm can be reproduced by applying external pressure on a sample from conventional high temperature ceramic synthesis. We conclude that the key effects of mechanochemical synthesis on the properties of solid electrolytes can be analyzed and understood in terms of pressure, strain and activation volume.</p> </div>

Development of HPLC Method for the Purity Test by Design of Experiments and Determination of Activation Energy of Hydrolytic Degradation Reactions of Sofosbuvir

2020 ◽  
Vol 16 (7) ◽  
pp. 976-987
Author(s):  
Jakub Petřík ◽  
Jakub Heřt ◽  
Pavel Řezanka ◽  
Filip Vymyslický ◽  
Michal Douša
Keyword(s):  
Activation Energy ◽  
Design Of Experiments ◽  
Mobile Phase ◽  
Hydrolytic Degradation ◽  
Isoconversional Method ◽  
Hplc Method ◽  
Organic Modifier ◽  
Calculation Methods ◽  
Degradation Reactions

Background: The present study was focused on the development of HPLC method for purity testing of sofosbuvir by the Design of Experiments and determination of the activation energy of hydrolytic degradation reactions of sofosbuvir using HPLC based on the kinetics of sofosbuvir degradation. Methods: Following four factors for the Design of Experiments were selected, stationary phase, an organic modifier of the mobile phase, column temperature and pH of the mobile phase. These factors were examined in two or three level experimental design using Modde 11.0 (Umetrics) software. The chromatographic parameters like resolution, USP tailing and discrimination factor were calculated and analysed by partial least squares. The chromatography was performed based on Design of Experiments results with the mobile phase containing ammonium phosphate buffer pH 2.5 and methanol as an organic modifier. Separation was achieved using gradient elution on XBridge BEH C8 at 50 °C and a flow rate of 0.8 mL/min. UV detection was performed at 220 nm. The activation energy of hydrolytic degradation reactions of sofosbuvir was evaluated using two different calculation methods. The first method is based on the slope of dependence of natural logarithm of the rate constant on inverted thermodynamic temperature and the second approach is the isoconversional method. Results and Conclusion: Calculated activation energies were 77.9 ± 1.1 kJ/mol for the first method and 79.5 ± 3.2 kJ/mol for the isoconversional method. The results can be considered to be identical, therefore both calculation methods are suitable for the determination of the activation energy of degradation reactions.

Cathodoluminescence of SiO2/Si System

2009 ◽  
Vol 156-158 ◽  
pp. 487-492 ◽  
Author(s):  
M.V. Zamoryanskaya
Keyword(s):  
Activation Energy ◽  
Electron Beam ◽  
Rise Time ◽  
Silicon Oxide ◽  
Beam Current ◽  
Electron Beam Current ◽  
Electron Traps ◽  
Definition Of ◽  
Luminescent Centers

In this paper the new method for determination of luminescent centers concentration are discussed. While the possibility of electron traps determination and definition of its activation energy are suggested. The cathodoluminescent (CL) method was used. The determination of luminescent centers concentration in silicon oxide is based on the measurements of dependences of CL intensity on electron beam current. The presence and energy of activation of electron traps were studied by measurement of rise time and decay of luminescent band during the stationary irradiation of silica by electron beam.

Automated Fluoride Ion Determination

1977 ◽  
Vol 14 (1-6) ◽  
pp. 269-274 ◽  
Author(s):  
David C. Cowell
Keyword(s):  
Continuous Flow ◽  
Ion Concentration ◽  
Fluoride Ion ◽  
Selective Electrode ◽  
Automated Method ◽  
Electrode Response ◽  
Kinetics Of ◽  
Fluoride Ion Selective Electrode ◽  
Flow Techniques

An automated method is described, using standard continuous flow techniques, for the determination of urine fluoride ion concentration using a fluoride ion selective electrode. It is shown that the kinetics of the electrode response to changes in fluoride ion can be used for the accurate measurement of fluoride ion concentration in urine, and that equilibration of the electrode response is not a prerequisite for the measurement of fluoride ion. Recovery experiments are in the range 83 to 90%; in-batch precision is between 0·9 and 1·6% and carryover 2·5% or less.

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