Sonja Skuban

Conductivity and dielectric behaviour of indium substituted zinc ferrites prepared by coprecipitation method

This paper presents the results concerning dielectric behavior and conductivity of the nanosized Zn1−xInxFe2O4 powders (x = 0, 0.15, 0.2, and 0.3), obtained by coprecipitation method. The frequency dependence of dielectric permittivity and conductivity of the samples is determined in the frequency range of 1–105 Hz, at temperatures from 300–350 K, while the temperature dependence of conductivity was recorded at 100 Hz, 10 kHz and 100 kHz. The ac conductivity was found to follow universal dielectric response, which is typical for charge transport by hopping or tunneling processes. Analyzing the variation of the parameter n (as a measure of the degree of correlation between conductivity and frequency), with the temperatures we discuss the possible conduction mechanism in investigated samples. Qualitatively, non-overlapping small polarons (NSPT) are usually associated with increase in n with increasing temperature, while correlated barrier hopping (CBH) shows a decrease in n with increasing T.

Thermal stability of the amorphous system Ge20As14(SexS1−x)52I14

Results of thermal investigations of the amorphous five-component chalcogenide system Ge20As14(SexS1−x)52I14 are presented. Differential thermal analysis (DTA), derivative differential thermal analysis (DDTA), and dilatometry were employed to determine the temperatures of softening and partial crystallization of the samples. Thermal treatment of the samples at 1000°C and recording of the corresponding thermogravimetric (TG) and derivative thermogravimetric (DTG) curves allowed an elucidation of the full mechanism of their decomposition, which proceeds via seven characteristic phase transitions.ZusammenfassungChalkogenidsystemes Ge20As14(SexS1−x)52I14 dargelegt. DTA, DDTA und Dilatometrie wurden zur Bestimmung des Erweichungspunktes und der Temperatur für eine partielle Kristalisation der Proben eingesetzt. Thermische Behandlung bei 1000°C und die Aufzeichnung der entsprechenden TG-und DTG-Kurven erlaubte es, ihren über sieben charakteristische Phasenumwandlungen verlaufenden Zersetzungsmechanismus voll zu klären.

Dielectric Properties of Iron‐ and Sodium‐Fumarate

The behaviour of dielectric parameters such as relative dielectric constant (e′), relative loss factor (e″) and ac conductivity of well known pharmaceutical materials Fe(II)‐fumarate and sodium‐fumarate have been studied as a function of temperature (range 303 K to 483 K) and frequency (range 0.1 Hz to 100 kHz).

Correlation Between Dielectric Properties And Crystal Structure Of Sodium Maleate

The behavior of dielectric parameters: such as permittivity (e′), loss factor (e″), loss tangent (tan δ) and ac conductivity has been studied as a function of frequency (range 0.1 Hz to 100 kHz). The analysis of the variation of e″ with frequency indicates to the structural change at the frequency of 30 kHz which corresponds to the reorientation frequency of the main chain as in similar polymer structures.