scholarly journals Semiconducting properties of nonstoichiometric TiO2-x ceramics

2012 ◽  
Vol 6 (2) ◽  
pp. 91-95 ◽  
Author(s):  
Agnese Pura ◽  
Kristaps Rubenis ◽  
Dmitrijs Stepanovs ◽  
Liga Berzina-Cimdina ◽  
Jurijs Ozolins
Keyword(s):  
Activation Energy ◽  
Electrical Conductivity ◽  
Electrical Properties ◽  
Room Temperature ◽  
High Vacuum ◽  
Titanium Oxides ◽  
Atmospheric Conditions ◽  
Semiconducting Properties ◽  
Two Stages ◽  
Extrusion Technology

Ceramics containing titanium oxides were prepared using extrusion technology and thermal treatment in two stages: sintering at normal atmospheric conditions at 1000 and 1200?C and annealing in high vacuum conditions at 950 and 1150?C. Electrical properties such as thermopower and electrical conductivity of cylindrical specimens have been studied at temperature range from the room temperature up to 350?C. Activation energy of the process has been determined from conductivity curves. Obtained thermopower values are in the range from 68 up to 105 mV at temperature gradient between the hot and cold ends of the samples at 300?C, while activation energy values are from 0.03 to 1.16 eV.

Electrochemical Studies of Nonstoichiometric TiO2-x Ceramic

2014 ◽  
Vol 604 ◽  
pp. 254-257
Author(s):  
Inga Narkevica ◽  
Madars Reimanis ◽  
Janis Kleperis ◽  
Jurijs Ozolins ◽  
Liga Berzina-Cimdina
Keyword(s):  
Electrical Conductivity ◽  
Water Treatment ◽  
Thermal Treatment ◽  
Titanium Oxide ◽  
High Vacuum ◽  
Oxide Ceramic ◽  
Electrochemical Studies ◽  
Two Stages ◽  
Extrusion Technology ◽  
Nonstoichiometric Titanium

TiO2 ceramic was prepared using extrusion technology and thermal treatment in two stages: sintering in air and subsequent annealing under high vacuum conditions. Sample thermal treatment in high vacuum conditions causes formation of nonstoichiometric titanium oxide ceramic. As a result electrical conductivity of the material significantly increases. Such a material can be used for electrode production for electrochemical water treatment.

scholarly journals Electrical properties of pure NiO and NiO:Au thin films prepared by using pulsed laser deposition

2019 ◽  
Vol 14 (29) ◽  
pp. 37-43 ◽  
Author(s):  
Raied K. Jamal
Keyword(s):  
Thin Films ◽  
Activation Energy ◽  
Electrical Properties ◽  
Transport Mechanism ◽  
Room Temperature ◽  
Pulsed Laser ◽  
Laser Deposition ◽  
Concentration Increase ◽  
Annealing Temperatures ◽  
P Type

The electrical properties of pure NiO and NiO:Au Films which aredeposited on glass substrate with various dopant concentrations(1wt.%, 2wt%, 3wt.% and 4wt.%) at room temperature 450 Coannealing temperature will be presented. The results of the hall effectshowed that all the films were p-type. The Hall mobility decreaseswhile both carrier concentration and conductivity increases with theincreasing of annealing temperatures and doping percentage, Thus,indicating the behavior of semiconductor, and also the D.Cconductivity from which the activation energy decrease with thedoping concentration increase and transport mechanism of the chargecarriers can be estimated.

Thermal Diffusivity and Conductivity of La0.7Ca0.3-xSrxMnO3 (x=0 to 0.10)

2012 ◽  
Vol 501 ◽  
pp. 319-323
Author(s):  
Hasan A. Alwi ◽  
Lay S. Ewe ◽  
Zahari Ibrahim ◽  
Noor B. Ibrahim ◽  
Roslan Abd-Shukor
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Grain Size ◽  
Transition Temperature ◽  
Thermal Diffusivity ◽  
Electrical Properties ◽  
Room Temperature ◽  
Electronic Contribution ◽  
Insulator Metal Transition ◽  
Thermal And Electrical Properties

We report the room temperature thermal conductivity κ and thermal diffusivity α of polycrystalline La0.7Ca0.3-xSrxMnO3 for x = 0 to 0.1. The samples were prepared by heating at 1220 and 1320oC. The insulator-metal transition temperature, TIM and thermal diffusivity increased with Sr content. Phonon was the dominant contributor to thermal conductivity and the electronic contribution was less than 1%. Enhancement of electrical conductivity σ and thermal diffusivity for x ≥ 0.08 was observed in both series of samples. The grain size of the samples (28 to 46 µm) does not show any affect on the thermal and electrical properties.

Electrical Properties of AlN-SiC Ceramics

2006 ◽  
Vol 317-318 ◽  
pp. 641-644
Author(s):  
Ryota Kobayashi ◽  
Junichi Tatami ◽  
Toru Wakihara ◽  
Takeshi Meguro ◽  
Katsutoshi Komeya
Keyword(s):  
Electrical Conductivity ◽  
Electrical Properties ◽  
Seebeck Coefficient ◽  
Gas Flow ◽  
Room Temperature ◽  
Xrd Analysis ◽  
Sic Ceramics ◽  
Sic Ceramic ◽  
Powder Compacts ◽  
Electrical Conductors

AlN-SiC ceramics with 0 to 75 mol% of AlN were fabricated through pressureless sintering of very fine AlN and SiC. Powder compacts with different amounts of AlN were fired at 2000°C for 1 h in Argon gas flow using an induction-heating furnace. The microstructure and phases present in the products were evaluated using SEM and XRD. The AlN-SiC ceramics had a porous structure with 30% porosity, and the grain size was increased with the addition of AlN. XRD analysis showed that 2H was a main phase in all samples, though 3C and 6H phases were found in 25 mol%AlN-75 mol%SiC ceramic. The electrical properties of the AlN-SiC ceramics were evaluated at various temperatures ranging from room temperature to 300°C. The electrical conductivity of the AlN-SiC ceramics depended on the amount of AlN and on the temperature. The 75 mol%AlN-SiC ceramic had higher electrical resistance, though the other samples were electrical conductors. The highest electrical conductivity was obtained with the 25 mol% AlN composition, which was 7 S/m at room temperature and 30 S/m at 300°C. The Seebeck coefficient for the AlN-SiC ceramics increased with rising temperatures. The AlN-SiC ceramics with 50 mol%AlN had the highest Seebeck coefficient of 220 2V/K at 300°C.

scholarly journals Preparation and Study of some Electrical Properties of PVA-Ni(NO3)2 Composites

2014 ◽  
Vol 40 ◽  
pp. 36-42 ◽  
Author(s):  
Sabah A. Salman ◽  
Nabeel A. Bakr ◽  
Mohammed H. Mahmood
Keyword(s):  
Activation Energy ◽  
Electrical Conductivity ◽  
Electrical Properties ◽  
Filler Content ◽  
Experimental Results ◽  
Casting Technique ◽  
Different Temperatures

The aim of this paper is to prepare and study the (D.C.) electrical conductivity of (PVA-Ni (NO3)2) composites at different temperatures. For that purpose, PVA films with Ni (NO3)2 salt additive were prepared with different concentrations‎ 2, 4, 6, 8 and 10 wt. % and with thickness of 45μm by using casting technique. The experimental results for PVA-Ni (NO3)2) ‎films show that the (D.C.) electrical‏ ‏conductivity increased with increasing ‎the filler content and the‏ ‏temperature, and the activation energy was ‎decreased with increasing the filler content‎.

scholarly journals DTA Evaluation of Spruce Wood Degradation Process

2017 ◽  
Vol 25 (40) ◽  
pp. 41-48
Author(s):  
Ivan Hrušovský ◽  
Peter Rantuch ◽  
Jozef Martinka ◽  
Simona Dzíbelová
Keyword(s):  
Activation Energy ◽  
Room Temperature ◽  
Degradation Process ◽  
Heating Rates ◽  
Wood Degradation ◽  
Wood Sawdust ◽  
Spruce Wood ◽  
Calculated Activation Energy ◽  
Two Stages ◽  
Calculated Activation

Abstract The decomposition stages of spruce wood sawdust were analyzed by means of sequential differential calorimetry. Two stages of decomposition were identified and activation energy of one stage was calculated using the Kissinger method. The DTA was conducted by means of SEDEX safety calorimeter. Sample was analyzed under three heating rates of 10, 20 and 45 °C/h in temperature range from room temperature to 400 °C. The calculated activation energy for the last and most clear decomposition peak was 122.63 KJ/mol. The results are comparable with the data calculated by J.V. Rissanen et al., who calculated activation energy for Spruce hemicellulose as 120 KJ/mol.

The influence of thermal treatment conditions on the properties of TiO2 ceramics

2014 ◽  
Vol 11 (2) ◽  
pp. 131-138
Author(s):  
Inga Narkevica ◽  
Jurijs Ozolins ◽  
Kristaps Rubenis ◽  
Janis Kleperis ◽  
Janis Locs ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Thermal Treatment ◽  
High Vacuum ◽  
Extrusion Process ◽  
Oxide Ceramics ◽  
Mechanical And Electrical Properties ◽  
Treatment Conditions ◽  
Extrusion Technology ◽  
Nonstoichiometric Titanium ◽  
Resistant Ceramic

The influence of thermal treatment conditions on titanium dioxide ceramics phase transformation, microstructure, physico-mechanical and electrical properties was studied. TiO2 ceramic was prepared using extrusion technology and thermal treatment in air and subsequent annealing under high vacuum conditions. It has been observed that intense TiO2 ceramic mass sintering occurs over the temperature ranging from 950 °C to 1100 °C. It is accompanied by crystallographic modification change from anatase to rutile. Ceramic sample annealing in vacuum causes formation of nonstoichiometric titanium oxide ceramics and as a result electrical conductivity of the material significantly increases. Using extrusion process relatively dense and mechanically resistant ceramic material can be obtained that can be used in different technological processes.

DEPENDENCE OF THE OPTICAL AND ELECTRICAL PROPERTIES OF CHEMICALLY ANNEALED VACUUM-DEPOSITED a-Si:H FILMS ON THE DEPOSITION RATE

2012 ◽  
Vol 27 (02) ◽  
pp. 1350015
Author(s):  
AHMED M. EL-NAGGAR
Keyword(s):  
Activation Energy ◽  
Electrical Properties ◽  
Deposition Rate ◽  
Room Temperature ◽  
Energy Gap ◽  
Dark Conductivity ◽  
Optical Parameters ◽  
Optical And Electrical Properties ◽  
Optical Energy Gap ◽  
Optical Energy

The influence of the deposition rate of chemically annealed vacuum-deposited a-Si : H films on its optical and electrical properties was studied. The optical parameters were studied using spectrophotometric measurements of the film transmittance in the wavelength range 200–3000 nm. It was found that with increasing the silicon deposition rate from 0.09 to 0.23 nm/s, the refractive index, n, decreases from 3.78 to 3.45 at 1.5 μm, and the optical energy gap, Eg, decreases from 1.74 to 1.66 eV, while the Urbach parameter, ΔE, increases from 77 to 99 meV. The dark conductivity was measured at temperatures descending from 480 to 170 K. It was found that the room temperature dark conductivity values decreased from 1.11 × 10-6 (Ω⋅ cm )-1 to 2.08 × 10-10 (Ω⋅ cm )-1 with increasing the deposition rate from 0.09 to 0.23 nm/s respectively, while the activation energy Ea increased from 0.53 to 0.84 eV with increasing deposition rate. As a result, a good quality a-Si : H film with optical energy gap of 1.74 eV, Urbach parameter of 77 meV, dark conductivity of 1.11 × 10-6 (Ω⋅ cm )-1, and activation energy of 0.53 eV was successfully prepared at a low deposition rate of 0.09 nm/s.

Chalcogenide Glasses

MRS Bulletin ◽  
1987 ◽  
Vol 12 (5) ◽  
pp. 36-39 ◽  
Author(s):  
P. Craig Taylor
Keyword(s):  
Activation Energy ◽  
Electrical Conductivity ◽  
Electrical Properties ◽  
Periodic Table ◽  
Chalcogenide Glasses ◽  
Charge Carriers ◽  
Arsenic Trisulfide ◽  
Glass Forming ◽  
Optical Gap ◽  
Arsenic Triselenide

Although there are some significant exceptions, most important glass-forming systems contain elements from the sixth, or chalcogenide, column of the periodic table (oxygen, sulfur, selenium, or tellurium). The glasses which contain oxygen are typically insulators, while those which contain the heavier chalcogen elements are usually semiconductors. Even though oxygen is technically a chalcogen element, the term “chalcogenide glass” is commonly used to denote those largely covalent, semiconducting glasses which contain sulfur, selenium, or tellurium as one of the constituents.The chalcogenide glasses are called semiconducting glasses because of their electrical properties. The electrical conductivity in these glasses depends exponentially on the temperature with an activation energy which is approximately one half of the optical gap. In this sense these glasses exhibit electrical properties similar to those in intrinsic crystalline semiconductors. The analogy is by no means perfect. The mobilities for the charge carriers in these glasses are very low (< 10 cm2/V-s) compared to crystalline semiconductors, and there are even discrepancies in determining the sign of the charge carriers from measurements of the Hall effect and the Seebeck effect.The first detailed studies of the chalcogenide glasses were performed about 30 years ago. For many years the prototype compositions have been selenium (Se), arsenic triselenide (As2Se3) or arsenic trisulfide (As2S3), and germanium diselenide (GeSe2) or germanium disulfide (GeS2).

The Influence of Annealing in Saturated Water Vapor on LiNbO3 Crystals Optical and Electrical Properties

2015 ◽  
Vol 230 ◽  
pp. 233-237 ◽  
Author(s):  
Aleksandr V. Yatsenko ◽  
A.S. Pritulenko ◽  
S.V. Yevdokimov ◽  
Dmytro Yu. Sugak ◽  
I.I. Syvorotka ◽  
...  
Keyword(s):  
Activation Energy ◽  
Electrical Conductivity ◽  
Water Vapor ◽  
Electrical Properties ◽  
Temperature Dependence ◽  
Optical Spectra ◽  
Optical And Electrical Properties ◽  
Saturated Water Vapor ◽  
Hydrogen Annealing ◽  
Saturated Water

The temperature dependence of the dark electrical conductivity of the LiNbO3(LN) crystals annealed in saturated H2O and D2O vapor in the range 293...400 K is investigated. It is found that the activation energy of the electrical conductivity is equal to (0.71 ± 0.02) eV and is close this value of LN samples, reduced in hydrogen. Annealing in ampoules with H2O vapor also lead to LN optical spectra changes such annealing in H2. The nature of this phenomenon is discussed.

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