Wyniki wyszukiwania - Biblioteka Nauki

1

Electrical conductivity of Pd47Ni47Si6 amorphous membrane while hydrogen permeation

100%

Prochwicz W. , Stępień Z. M.

Materials Science Poland

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2013

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tom Vol. 31, No. 4

484--488

EN

Hydrogen diffusion through an amorphous membrane causes local disorders in the structure which can be detected through the measurement of changes of the electrical conductivity. Detecting these changes and comparing them directly with the amount of the permeated hydrogen provides information on the efficiency of separation, which can be used in hydrogen sensor and analyzer technology. This paper presents the results of electrical resistivity measurement of Pd47Ni47Si6 alloy amorphous membrane while hydrogen permeation flux was being changed along with the temperature. It was found that hydrogen changes the nature of the resistivity and the temperature coefficient of resistivity is negative, however, starting from the temperature of 365 K, its value becomes smaller. In order to explain this phenomenon thorough and detailed measurements of phase transitions were made with the use of differential scanning calorimetry and X-ray diffractometry. On the basis of the research an attempt was made to explain the recorded changes of electrical conductivity.

2

Magnetotelluric studies of the East-European Craton and adjacent regions

100%

Bubnov V. P. , Yakovlev A. G. , Aleksanova E. D. , Yakovlev D. V. , Berdichevsky M. N. , Pushkarev P. Y.

Acta Geophysica

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2007

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tom Vol. 55, no. 2

154-168

EN

Magnetotelluric method is widely applied to study the Russian part of the East-European Craton, as well as the Caucasus and the Urals: several thousand soundings were performed during the last few years. Their periods range is approximately from 0.003 to 3000 seconds, which allows to study the sedimentary cover and the consolidated crust. Resistivity cross-sections along several regional profiles which run across the tectonic structures of the East-European Craton and the adjacent folded systems were obtained, mainly using 1D and 2D interpretational tools. MT investigations provided important information about the structure and reservoir properties of sedimentary complexes, the state of active geodynamic regions, the graphitization and fluid regime of the consolidated crust, and the perme-able and fluid-saturated crustal zones.

3

4th Conference International Dielectric Society and 9th International Conference Dielectric and Related Phenomena. IDS & DRP 2006

100%

Zeszyty Naukowe. Chemia / Politechnika Łódzka

|

2006

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tom Z. 49

1-347

EN

Zawiera tylko streszczenia angielskie referatów z konferencji: 4th Conference International Dielectric Society and 9th International Conference Dielectric and Related Phenomena. IDS & DRP 2006 (03-07.09.2006 ; Poznań ; Poland). Konferencja obejmowała następujące zagadnienia: Glass transition; Johari-Goldstein β-relaxation; Dynamics under spatial confinement; Dynamics under applied pressure; Charge transport in disordered systems; Relaxation theories; Simulations of molecular dynamics; Nano-confined systems, ultrathin layers; Micro- and nanocomposites; Molecular dynamics of functional polymers; Special dielectrics for opto-electronics; Nanostructured dielectrics and electrets; Liquid crystalline and ferroelectric materials; Biological systems: biopolymers, biodielectrics; Molecular dynamics in aqueous systems; BDS in comparison with another spectroscopic techniques; Time-domain spectroscopy; Real-time dielectric spectroscopy - monitoring of structure evolution; Novel methodological developments. Wybrane pełne teksty referatów: Journal of Non-Crystalline Solids, Vol. 353, Iss. 47-51 (December 1, 2007).

4

Electrical and mechanical properties of nitrided sol-gel derived TiO2 and SiO2-TiO2 films

100%

Kościelska B. , Murawski L. , Wicikowski L.

Materials Science Poland

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2005

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tom Vol. 23, No. 1

93--100

EN

The results of measurements of electrical conductivity for titanium-nitride films prepared by the ammonolysis of sol-gel derived TiO2 and SiO2-TiO2 coatings are presented. Sol-gel derived films on silicon and quartz substrates were nitrided by ammonia treatment in the temperature range from 500 to 1200 C. The dc conductivity of nitrided films has been measured from 10 K to 900 K. It was found that conductivity is related to the amount of TiO2, which is converted to TiN during ammonolysis. In this way it is possible to change the electrical conductivity of samples by many orders of magnitude. The observed activation energy of the samples containing large amounts of TiN is below 0.1 eV. This indicates that the conductivity mechanism may be interpreted as electrons tunnelling between metallic TiN granules. The mechanical properties were evaluated by a nanoidentometric technique. The results of nanoidentometric measurements confirm an increase in microhardness and Young's modulus for nitrided SiO2-TiO2 films containing large amounts of TiN.

5

Dielectric and electrical properties of 0.5(BiGd0.05Fe0.95O3)-0.5(PbZrO3) composite

100%

Satpathy S. K. , Mohanty N. K. , Behera A. K. , Behera B.

Materials Science Poland

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2014

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tom Vol. 32, No. 1

59--65

EN

The 0.5(BiGd0.05Fe0.95O3)-0.5(PbZrO3) composite was synthesized by means of a high temperature solid-state reaction technique using high purity ingredients. Preliminary X-ray structural analysis confirms the formation of the composite. The dielectric constant and loss tangent have been studied. The impedance parameters have been measured using an impedance analyzer in a wide range of frequency (102–106 Hz) at different temperatures. The Nyquist plot suggests the contribution of bulk effect only and the bulk resistance decreases with a rise in temperature. Electrical impedance confirms the presence of grain effect and hopping mechanism in the electrical transport of the material. The dc conductivity increases with a rise of temperature. The frequency variation of ac conductivity shows that the compound obeys Jonscher’s universal power law and from Jonscher’s power law fit confirms the Small Polaron (SP) tunneling effect. Temperature dependence of dc and ac conductivity indicates that electrical conduction in the material is a thermally activated process.

6

Electrical conductivity of implant isolation in GaAs

100%

Synowiec Z.

Nukleonika

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1999

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tom Vol. 44, nr 2

349-356

EN

GaAs wafers with the Si doped epitaxial layers were bombarded by double energy of oxygen ions with 250 keV and 100 keV of 10[indeks górny]12 cm-2÷5x10[indeks górny]13 cm-2 doses followed by 500°C annealing process. Temperature dependence of the layer resistivity was evaluated in the temperature range 30÷423 K for the above structures to estimate the conduction mechanism in the material. Variable range hopping conductivity dominated at temperatures up to 300 K for high ion doses (5x10[indeks górny]13 cm-2) and up to 250°K for lower doses (10[indeks górny]13 cm-2). At higher temperatures, the resistivity data plotted indicated a transition from hopping to conduction through the extended states.

PL

Płytki GaAs z domieszkowanymi krzemem warstwami epitaksjalnymi bombardowano dwukrotnie jonami tlenu o energii 250 keV i 100 keV i o dawce od 10[indeks górny]12 cm-2 do 5x10[indeks górny]13 cm-2, a następnie wygrzewano w temperaturze 500°C. Dla oceny mechanizmu przewodnictwa w materiale powyższych struktur określono temperaturową zależność rezystywności warstw w temperaturze od 30 do 423 K. Przewodnictwo hoppingowe o zmiennym zasięgu dominowało do 300 K dla przypadku wysokich dawek jonów (5x10[indeks górny]13 cm-2) i do 250 K dla niższych dawek (10[indeks górny]12 cm-2). W wyższych temperaturach, wykreślone temperaturowe zależności rezystywności wskazują na przechodzenie od hoppingu do przewodnictwa po stanach rozciągłych.

7

A cyclic voltammetric and coulometric study of a modified electrode prepared by electrooxidative polymerization of nickel complex of 1,5-diaminonaphthalene in acetonitrile

100%

Yousef U. S. , Abdel-Azzem M.

Polish Journal of Chemistry

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1998

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tom Vol. 72, nr 12

2583-2597

EN

The electrooxydative polymerization of nickel complex of 1,5-diaminonaphthalene was performed in acetonitrile containing lithium perchlorate, using cyclic voltammetry and controlled potencial electrolysis. The film coated electrode showed an electroactive redox response in acidic solutions only. The stability of the redox response towards repetitive cyclic voltammetry was studied. The formal redox potential of the resulting film electrode was about 0.28 V vs. Ag/Ag(+) in 1.0 M acid chloride aqueous solution (ph=0). The electrical conductivity of the film was measured in 0,01 M KCl aqueous solution and was found as (2.2 (+/-) 0.02) 10(-4) S cm(-1). The morphology of the film and the factors affecting its electroactivity were studied in detail.

8

The Relationship Between Mechanical and Electrical Properties During Vulcanisation of SBR Based Rubber

100%

BOŠÁK O. , MINÁRIK S. , KUBLIHA M. , LABAŠ V.

Edukacja-Technika-Informatyka

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2015

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tom 6

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nr 2

192-197

EN

The aim of this paper is description of vulcanization process by monitoring of selected electrical and mechanical parameters. The experiments have shown that the vulcanization process can be qualitatively and quantitatively evaluated on the basis of measurements of mechanical (standard procedure in rubber industry) and also electrical parameters. The results obtained for model system SBR rubber mixture under conditions of linear heating are presented also.

9

Naval mine detection system based of FPGA circuit

100%

Wołoszyn M. , Łubkowski J. , Chomnicki M.

Computer Applications in Electrical Engineering

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2011

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tom Vol. 9

60--68

EN

Electrochemical processes take place in a metal object immersed into sea water even if an anticorrosive coating is applied [1]. As a result, flowing field appears around the object. There are naval mines between many other objects situated in the sea. Naval mines can be put in the seabed in order to be more difficult to detect by sonars. Such a mine is located on the line demarking two environments of different electrical conductivity. The results of a computer analysis of the influence of seabed’s electrical conductivity on the electric field’s disposition around a mine model are shown below. Also, a naval mine detection system based on the FPGA circuit is presented.

10

The Anodic Behavior of Silver in Concentrated Chloride Solutions

100%

Kołodziej B.

Polish Journal of Chemistry

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2000

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tom Vol. 74, nr 3

349-360

EN

The processes on the silver electrode during its anodic polarization in concentrated chloride solutions (1,5 - 5,0 M) are identified. The analysis of the potentiodynamic E-I relationships showed, that the anodic polarization depends on the concentration of Cl ions and runs through two steps (peaks A and B). The first step - peak A corresponds to: a/the irreversible electrode reaction involving the adsorption of the reaction product - AgCl in the solution, in which concentration of Cl was less than 2M and b/ the reversible electrode reaction involving the adsorption of the AgCl type species (n=3,4), when the concentration of Cl was more than 4 M. The second step - peak B corresponds to: a/the increase of the passive layer of AgCl showing high porosity and a low ohmic resistance - in the solution in which concentration of Cl was less than 2 M and b/the anodic process, which follows the dissolution-precipitation model, in which the electrochemical reaction of AgCl formation precedes the chemical precipitation of AgCl - in the solution with Cl was more than 4 M. On the basis of experimental functions the values of specific conductivity for the passive layer of AgCl at 4 M and 5 M chloride solutions were calculated. The structure differences of the passive AgCl layer forming in the chloride solutions have been shown by the microscope scanning analysis.

11

Synthesis, effect of γ-ray and electrical conductivity of uranium doped nano LiMn2O4 spinels for applications as positive electrodes in Li-ion rechargeable batteries

100%

El-Metwaly F. G. , Abou-Sekkina M. M. , Saad F. A. , Khedr A. M.

Materials Science Poland

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2014

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tom Vol. 32, No. 4

571--577

EN

LiMn2O4 is an attractive candidate cathode material for Li-ion rechargeable batteries, but it suffers from severe capacity fading, especially at higher temperature (55 ◦C) during charging/discharging processes. Recently, many attempts have been made to synthesize modified LiMn2O4. In this work, a new study on the synthesis of pure and U4+-doped nano lithium manganese oxide [LiMn2−xUxO4, (x = 0.00, 0.01, 0.03)] via solid-state method was introduced. The synthesized LiMn1.97U0.03O4 was irradiated by γ-radiation (10 and 30 kGy). The green samples and the resulting spinel products were characterized using thermogravimetric and differential thermal analysis (TG/DTA), X-ray diffraction (XRD), infrared (IR), and scanning electron microscopy (SEM) measurements. XRD and SEM studies revealed nano-sized particles in all prepared samples. Direct-current (DC) electrical conductivity measurements indicated that these samples are semiconductors and the activation energies decrease with increasing rare-earth U4+ content and γ-irradiation. ∆Ea equals to 0.304 eV for LiMn1.99U0.01O4, ∆Ea is 0.282 eV for LiMn1.97U0.03O4 and decreases to ∆Ea = 0.262 eV for γ-irradiated LiMn1.97U0.03O4 nano spinel. The data obtained for the investigated samples increase their attractiveness in modern electronic technology.

12

Stabilization of mechanical properties in silver alloys by addition of lanthanides

100%

Głuchowski W. , Rdzawski Z. M.

Journal of Achievements in Materials and Manufacturing Engineering

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2008

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tom Vol. 30, nr 2

129-134

EN

Purpose: Silver alloys intended for industrial application should characterise by high electrical conductivity (as pure silver) as well as high mechanical and functional properties, stable also at elevated temperature. The objective of this work was to investigate the mechanical properties stability of Ag-La (0.5%) and Ag-mishmetal (1 and 4%) alloys caused by severe plastic deformation compared to the Ag+(7.5 wt %)Cu alloy and pure Ag materials. Design/methodology/approach: Tests were made with the samples obtained by casting and further plastic working included KOBO® extrusion process and drawing. Wires were annealed in temperature range 50-500° C. The mechanical properties (at room temperature, elevated temperature and after annealing) and microstructure were examined. The values of yield strength obtained in a tension tests have been compared to the values calculated theoretically. Findings: Additive of rare earth metals contributed to fine structure obtaining, particles formed in grain boundaries stabilized microstructure at elevated temperature. Increase of mechanical properties of investigated alloys was connected with presence of fine precipitations in silver matrix, which confirmed susceptibility to precipitation hardening of silver-mishmetal alloys. Research limitations/implications: Ability of new alloys to precipitation hardening should be confirmed by further investigations, including solution heat treatment and ageing, also for materials prepared in vacuum furnace. Practical implications: Stability of mechanical properties at elevated temperature, gives possibility to use of new silver allays for producing elements designed to operate at elevated temperatures or exposed to rapid temperature changes. Increased mechanical properties and good tarnish resistance indicates possibility of new applications of investigated alloys in jewellery and medicine, after additional and essential investigations. Originality/value: The wire made from this material could be easily produced by the developed processing methods, without the need to use annealing operations.

PL

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13

Electrical characterization of polymer matrix - TiO2 filler composites through isothermal polarization / depolarization currents and I–V tests

100%

Stavrakas I. , Triantis D. , Hloupis G. , Moutzouris K.

Open Physics

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2014

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tom 12

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nr 4

286-291

EN

Specimens of polymer matrix - ceramic TiO2 filler composites were prepared. The contribution of the filler content on the electrical conductivity and energy storage properties of the samples was examined. I–V and Isothermal Polarization/Depolarization Current (IPC/IDC) measurements were conducted. Dc conductivity values directly calculated from the I–V curves exhibited excellent agreement with corresponding values derived from the IPC/IDC recordings. Standard models were employed for fitting the IPC/IDC data. In specific, the short and the very long depolarization times were fitted by use of power laws of different slopes, while the intermediate depolarization times were fitted as a sum of three exponential decays. The present study reveals a strong dependence of the depolarization and polarization processes, as well as of the dc conductivity, on the filler concentration.

14

Structural and electrical investigation of (Ag3AsS3)x(As2S3)1−x superionic glasses

100%

Studenyak I. , Neimet Y. , Cserháti C. , Kökényesi S. , Kazakevičius E. , Šalkus T. , Kežionis A. , Orliukas A.

Open Physics

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2012

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tom 10

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nr 1

206-209

EN

Structural studies of (Ag3AsS3)x (As2S3)1−x chalcogenide superionic glasses in the compositional range x = 0.3–0.9 were performed by scanning electron microscopy. Temperature and compositional dependences of transmission coefficient, electrical conductivity, and activation energy were investigated

15

A new organic metal with thedithiooxalato - bridged anion network β″-ET)2{[NMe3Ph]NaCr(C2S2O2)3(MeCN)}

100%

Zhilyaeva E. I. , Shilov G. V. , Bogdanova O. A. , Lyubovskaya R. N. , Lyubovskii R. B. , Lyubovskaya R. N. , Ovanesyan N. S. , Aldoshin S. M. , Train C. , Gruselle M.

Materials Science Poland

|

2004

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tom Vol. 22, No. 4

565--569

16

Optical and electrical characterization of BixSe1−x thin films

100%

Ibrahim M. M. , Fayek S. A. , Amin G. A. M. , Elnagar D. M.

Materials Science Poland

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2016

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tom Vol. 34, No. 2

460--469

EN

Bulk samples of the BixSe1-x system with (x = 0, 5, and 10) were prepared using conventional melt quenching technique. Thin films were then deposited by thermal evaporation technique under high vacuum conditions from the prepared bulk samples. Effect of Bi substitution on surface morphology, electrical and optical properties of BixSe1-x thin films was studied. X-ray diffraction studies showed the formation of nanocrystalline clusters at Bi concentration x = 10. Formation of these clusters resulted in a rough surface which was confirmed by AFM measurements. The film surface was smooth, with RMS roughness of 0.0124 nm for Bi5Se95. For Bi10Se90, the RMS roughness increased to 3.93 nm indicating the formation of Bi2Se3 clusters. A simple hot probe technique showed a transition from p-type to n-type due to Bi incorporation. Charge transport mechanisms were investigated by temperature dependent DC electrical conductivity measurements in the temperature range of 209 K to 313 K. Electrical activation energy (ΔE) of the films with different Bi concentrations was found to exhibit a notable change at the p to n transition. At low temperature, the conduction was in reasonable agreement with Mott’s condition of variable range hopping. Mott parameters and the density of localized states near Fermi level were evaluated and correlated with the structural changes resulting from Bi addition. In addition, a red shift of the optical absorption edge of the films under study caused by Bi-Se substitution was observed. Slight changes in the optical parameters were observed with the γ-irradiation. Addition of Bi atoms could be used to tailor the structural, electrical and optical properties of chalcogenide materials such as junctionless photovoltaic devices.

17

Electrical Conductivity of Heat Treated Polyacrylonitrile and Complexes of Polyacrylonitrile with Transition Metal Chlorides

100%

Al-Gurashi M.

Polish Journal of Chemistry

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2001

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tom Vol. 75, nr 5

689-698

EN

Polymerization of acrylonitrile (AN), without and in the presence of CuCl2, CoCl2, and NiCl2, formed polyacrylonitrile homopolymer (PAN) and polymer complexes of AN-CuCl2, AN-CoCl2 and AN-NiCl2, respectively. These polymer complexes were characterized using spectroscopic techniques. Electrical conductivity and cyclic voltammetry on untreated and heat treated polymers, carried out at different temperatures, showed that the conductivity increased with temperature, presumably due to conjugation and cyclization during heat treatment.

18

Przewodnictwo elektryczne szkieł tlenkowych

100%

Łukaszewicz T.

Zeszyty Naukowe Politechniki Białostockiej. Matematyka, Fizyka, Chemia

|

1998

|

tom Z. 18

201-218

PL

W pracy opisano jonowe i superjonowe przewodnictwo oraz mechanizm transportu jonów w jedno- i wieloalkalicznych szkłach krzemiankowych. Przedyskutowno tzw. mieszany efekt alkaliczny oraz zależność pomiędzy przewodnictwem i dyfuzją. Przedstawiono też przewodnictwo elektronowe szkieł tlenkowych i jego mechanizmy.

EN

In this paper ionic and superionic conduction and mechanism of ionic transport for single- and mixed- alkali silicate glasses are described. The 'mixed- alkali' effect and relationship beetwen conductivity and diffusion were discussed. Electronic conduction of oxide glasses and its mechanisms are presented too.

19

Synthesis, characterization and properties of nanocrystalline perovskite cathode materials

100%

Ghosh S. , Dasgupta S.

Materials Science Poland

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2010

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tom Vol. 28, No. 2

427--438

EN

A simple low temperature synthesis route has been presented of preparing nanosized, single phased LaFeO3, La(1-x)SrxFeO3 (x = 0.3, 0.5) and La(1-x)SrxCo0.2Fe0.8O3 (x = 0.2, 0.4) for cathode applications in ITSOFC. A soft chemical method has been applied, using tartaric acid as a template material and nitric acid as an oxidizing agent. Phase pure materials were obtained at temperatures ranging from 550 °C to 700 °C. The synthesized powders were characterized by TGA, XRD, SEM and FTIR analysis. The crystallite size was 45-50 nm, with the surface area of 14-20 m2/g. Electronic conductivity of the material was found to increase upon increasing Sr concentration and the sintering temperature. High electronic conductivities of 355 S/cm and 545 S/cm were obtained at 400 °C for La0.5Sr0.5Fe2O3 and La0.6Sr0.4Co0.2Fe2O3, respectively. Activation energy decreases with the increase in Sr concentration. The values of thermal expansion coefficients (TEC) of the materials are compatible with the TEC of the ceria-gadolinium oxide CGO interlayer between cathode layer and electrolyte.

20

Electrical and optical properties of new Pr3+-doped PbWO4 ceramics

100%

Groń T. , Piątkowska M. , Tomaszewicz E. , Sawicki B. , Urbanowicz P. , Duda H.

Materials Science Poland

|

2018

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tom Vol. 36, No. 4

530--536

EN

Polycrystalline samples of new scheelite-type tungstates, Pb1−3x xPr2xWO4 with 0.0098 ⩽ x ⩽ 0.20, where denotes cationic vacancies have been successfully prepared by a high-temperature solid-state reaction method using Pr2 (WO4)3 and PbWO4 as the starting reactants. The influence of the Pr3+ substitution in the scheelite framework on the structure and optical properties of prepared new ceramic materials has been examined using powder X-ray diffraction method (XRD) and UV-Vis-NIR spectroscopy. The results of dielectric studies of Pb1−3x xPr2xWO4 samples showed both low values of dielectric constant (below 14) and loss tangent (below 0.2). The electrical conductivity and thermoelectric power measurements revealed a low conductivity (∼2 × 10−9 S/m) and the sign change of thermoelectric power around the temperature of 366 K suggesting the p-n transition. These results are discussed in the context of vacancy, acceptor and donor levels as well as the Maxwell-Wagner model.