Electrical Properties of Orthorhombic Iron Disilicide

1998 ◽  
Vol 545 ◽  
Author(s):  
Jun-Ichi Tani ◽  
Hiroyasu Kido
Keyword(s):  
Electrical Properties ◽  
Solid Solutions ◽  
Hole Concentration ◽  
Band Model ◽  
Measured Temperature ◽  
Iron Disilicide ◽  
Temperature Range ◽  
Order Of Magnitude ◽  
Mn Doped ◽  
Two Band Model

AbstractIn order to clarify the electrical properties of Cr-doped β-FeSi2(Fe1-xCrxSi2) and Mn-doped β--FeSi2(Fel-yMnySi2), the Hall effect and electrical resistivity of Fe1-xCrxSi2(0.01 ≦ x ≦ 0.05) and Fel-yMnySi2(0.01 ≦ y ≦ 0.10) have been measured in the temperature range between 80 and 300 K. fhe solid solutions Fel-xCrxSi2and Fel-yMnySi2are p-type over the measured temperature range. The observed features of RH of these solid solutions are explained by using the two-band model with the existence of two acceptor levels. The hole concentration of Fe1-xCrxSi2at 300 K ranges from 8.9×1018cm−3for x=0.01 to 1.1×1020cm−3for x=0.05, which is one order of magnitude higher than that of Fel-yMnySi2.

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.

Thermoelectric Properties of Doped Iron Disilicide

2000 ◽  
Vol 626 ◽  
Author(s):  
Jun-ichi Tani ◽  
Hiroyasu Kido
Keyword(s):  
Thermal Conductivity ◽  
Electrical Resistivity ◽  
Seebeck Coefficient ◽  
Thermoelectric Properties ◽  
Measured Temperature ◽  
Iron Disilicide ◽  
Measured Temperature Range ◽  
Temperature Range

ABSTRACTIn order to investigate the thermoelectric properties of Re-doped β-FeSi2 (Fe1-xRexSi2), Ir-doped β-FeSi2 (Fe1-xIrxSi2), and Pt-doped β-FeSi2 (Fe1-xPtxSi2), the electrical resistivity, the Seebeck coefficient, and the thermal conductivity of these samples have been measured in the temperature range between 300 and 1150 K. Fe1-xRexSi2 is p-type, while Fe1-xIrxSi2 and Fe1-xPt xSi2 are n-type over the measured temperature range. The solubility limits of dopant are estimated to be 0.2at% for Fe1-xRexSi2, 0.5at% for Fe1-xIrxSi2, and 1.9at% for Fe1-xPtxSi2. A maximum ZT value of 0.14 was obtained for Fe1-xPt xSi2 (x=0.03) at the temperature 847 K.

THE NORMAL STATE HALL EFFECT IN NdBa2-xLaxCu3O7-δ: EVIDENCE FOR HOLE LOCALIZATION BY LA DOPING

2009 ◽  
Vol 23 (31) ◽  
pp. 5779-5788
Author(s):  
S. R. GHORBANI ◽  
F. ABRINAEY
Keyword(s):  
Critical Temperature ◽  
Hall Effect ◽  
Hall Coefficient ◽  
Normal State ◽  
Doping Concentration ◽  
Narrow Band ◽  
Band Model ◽  
Measured Temperature ◽  
Temperature Range ◽  
La Doping

The transport properties of sintered samples of NdBa 2-x La x Cu 3 O 7-δ with 0 ≤ x ≤ 0.3 have been studied in the normal state by Hall effect measurements. The Hall coefficient, RH is positive in the normal state and increases with increasing La doping concentration over the whole temperature range from the critical temperature, Tc, up to room temperature. The results for the Hall coefficient as a function of temperature and doping concentration were analyzed within the phenomenological narrow band and Anderson models. A good agreement between models and data was obtained. As in the phenomenological narrow band model, the band widths increase with increasing doping concentration. As in the Anderson model, the Hall angle is proportional to T2 over the whole measured temperature range for all samples. The obtained results for both models supported the view that La doping introduces electronic disorder into the CuO 2 planes. The tendency towards localization is driven by electronic disorder. In addition to hole filling, the localization is another reason for the decreasing superconducting critical temperature in these samples.

scholarly journals Characterization of aerosol properties at Cyprus, focusing on cloud condensation nuclei and ice nucleating particles

2019 ◽  
Author(s):  
Xianda Gong ◽  
Heike Wex ◽  
Thomas Müller ◽  
Alfred Wiedensohler ◽  
Kristina Höhler ◽  
...  
Keyword(s):  
Size Range ◽  
Cloud Condensation Nuclei ◽  
Aerosol Particles ◽  
Particle Surface ◽  
Active Surface ◽  
Measured Temperature ◽  
Condensation Nuclei ◽  
Particle Surface Area ◽  
Temperature Range ◽  
Order Of Magnitude

Abstract. As part of the A-LIFE (Absorbing aerosol layers in a changing climate: aging, lifetime and dynamics) campaign, ground-based measurements were carried out in Paphos, Cyprus, for characterizing the abundance, properties and sources of aerosol particles in general, and cloud condensation nuclei (CCN) and ice nucleating particles (INP), in particular. New particle formation (NPF) events with subsequent growth of the particles into the CCN size range were observed. Aitken mode particles featured κ values of 0.21 to 0.29, indicating the presence of organic materials. Accumulation mode particles featured a higher hygroscopicity parameter, with a median κ value of 0.57, suggesting the presence of sulfate. A clear downward trend of κ with increasing supersaturation and decreasing dcrit was found. Super-micron particles originated mainly from sea spray aerosol (SSA) and partly from mineral dust. INP concentrations (NINP) were measured in the temperature range from −6.5 to −26.5 ℃, using two freezing array type instruments. NINP at a particular temperature span around 1 order of magnitude below −20 ℃, and about 2 orders of magnitude at warmer temperatures (T > −18 ℃). Few samples showed elevated concentrations at temperatures > −15 ℃, which suggests a significant contribution of biological particles to the INP population, which possibly could originate from Cyprus. Both measured temperature spectra and NINP probability density functions (PDFs) indicate that the observed INP (ice active in the temperature range between −15 and −20 ℃) mainly originate from long-range transport. There was no correlation between NINP and particle number concentration in the size range > 500 nm (N> 500 nm). Parameterizations based on N> 500 nm were found to overestimate NINP by about 1 to 2 orders of magnitude. There was also no correlation between NINP and particle surface area concentration. The ice active surface site density (ns) for the anthropogenically polluted aerosol encountered in this study is about 1 to 3 orders of magnitude lower than the ns found for dust aerosol particles in previous studies. This suggests that observed NINP-PDFs as those derived here could be a better choice for modelling NINP if the aerosol particle composition is unknown or uncertain.

scholarly journals О структуре энергетического спектра дырок в материалах A-=SUP=-IV-=/SUP=-B-=SUP=-VI-=/SUP=- под иным углом зрения

2019 ◽  
Vol 53 (7) ◽  
pp. 890
Author(s):  
Л.В. Прокофьева ◽  
П.П. Константинов
Keyword(s):  
Energy Spectrum ◽  
Hole Concentration ◽  
Small Addition ◽  
Band Model ◽  
Temperature Hysteresis ◽  
Charge Process ◽  
The Common ◽  
Heavy Doping ◽  
Two Band Model ◽  
Twofold Decrease

The twofold decrease in hole concentration of all PbTe <NaTe> samples at 77–450 K and the same effect achieved at 77 K and heavy doping only due to introduction in PbTe of tin small addition, supplemented by observation in indicated range of temperature hysteresis in hole concentration, are the grounds for developing an other approach to a study of the energy spectrum in A(IV)B(VI) materials, an alternative two-band model. It is based on the common for these materials phenomenon — compensation of current carriers as a reaction on electroactive doping. The appearance of compensation is associated with initial (at temperatures below 77 K) two-charge process — participation in a single doping act of the pair of electrons due to their mutual attraction. With a rise in temperature, as with introduction of tin, the situation is changed. The study of all aspects of transformation is a task for further research.

Novel electrical properties of Mn-doped LaCrO3 ceramics as NTC thermistors

2021 ◽  
pp. 159269
Author(s):  
Fang Guan ◽  
Zewei Dang ◽  
Xuan Chen ◽  
Shifeng Huang ◽  
Jianrong Wang ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Ntc Thermistors ◽  
Mn Doped

IONIZATION ENERGY AND IMPURITY BAND CONDUCTION OF SHALLOW DONORS IN n-GALLIUM ARSENIDE

1967 ◽  
Vol 45 (1) ◽  
pp. 119-126 ◽  
Author(s):  
J. Basinski ◽  
R. Olivier
Keyword(s):  
Ionization Energy ◽  
Impurity Band ◽  
Shallow Donor ◽  
Band Model ◽  
A Value ◽  
Transition Concentration ◽  
Temperature Electron ◽  
Two Band Model ◽  
Band Conduction ◽  
Made In

Hall effect and resistivity measurements have been made in the temperature range 4.2–360 °K on several samples of n-type GaAs grown under oxygen atmosphere and without any other intentional dopings. The principal shallow donor in this material is considered to be Si. All samples exhibited impurity-band conduction at low temperature. Electron concentrations in the conduction band were calculated, using a two-band model, and then fitted to the usual equation expressing charge neutrality. A value of 2.3 × 10−3 eV was obtained for the ionization energy of the donors, for donor concentration ranging from 5 × 1015 cm−3 to 2 × 1016 cm−3. The conduction in the impurity band was of the hopping type for these concentrations. A value of 3.5 × 1016 cm−3 was obtained for the critical transition concentration of the impurity-band conduction to the metallic type.

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