ABSTRACT The electrical conductivity and the electrochemical properties of dense La0.85Sr0.15MnO3... more ABSTRACT The electrical conductivity and the electrochemical properties of dense La0.85Sr0.15MnO3 − δ (LSM) films, prepared using Pulsed Laser Deposition (PLD) have been investigated. The nano-structure of the LSM films has been characterized using scanning electron microscopy (SEM). The oxygen transport properties of the films were studied using electrochemical impedance spectroscopy (EIS) on symmetrical cells. Electrical conductivity measurement were carried out in an oxygen partial pressure range from 1 to 0.0032 atm, and a temperature range from 950 to 700 °C. The electrical conductivity at 800 °C was 116 S cm− 1 and did not vary with the pO2. Impedance spectra were recorded in the temperature range from 600 to 950 °C in the oxygen partial pressure range from 0.06 to 1.00 atm. At 900 °C and 1.00 atm the area specific resistance was 30.6 Ω cm2 and an activation energy of 2.7 eV was found. The ASR increased with decreasing pO2. Based on the impedance spectra an oxide ion conductivity of 5.0 × 10− 1 S cm− 1 was found at 900 °C and pO2 = 1.00 atm. The characteristic length, at which the oxide transport reaction switch from being limited by bulk diffusion to that of surface exchange, was estimated to be approximately 220 and 130 nm at 700 and 900 °C, respectively.
Perovskites are materials of very versatile properties. They may be used in various ways and stru... more Perovskites are materials of very versatile properties. They may be used in various ways and structures. In this work the results of investigation of the Zr0.84Y0.16Ox electrolyte on La0.6Sr0.4FeO3 perovskite support are presented. The perovskite support was fabricated by iso-axially die-pressing of La0.6Sr0.4FeO3 powders and sintering at 1150 • C. The Zr0.84Y0.16Ox layer was deposited on La 0.6 Sr 0.4 FeO 3 by a combination of colloidal suspension and polymer precursor methods. In this way the dense electrolyte layer was prepared at as low temperature as 400 • C. This method may be also useful for high-Tc superconductor layers deposition. The chemical interaction between the electrolyte layer and perovskite support was investigated by X-ray diffraction. It was shown that no reaction occurs between cathode and electrolyte until 900 • C. Above 1200 • C, parameters of the La 0.6 Sr 0.4 FeO 3 unit cell increase. It suggests that the reaction between Zr0.84Y0.16Ox and La0.6Sr0.4FeO3 is accompanied by substitutional changes in the La 0.6 Sr 0.4 FeO 3 .
This study reports the interfacial stability of doped (La 0.8 Sr 0.2) 0.95 Cr 0.7 Fe 0.3 O 3 (LSC... more This study reports the interfacial stability of doped (La 0.8 Sr 0.2) 0.95 Cr 0.7 Fe 0.3 O 3 (LSCF) and 10Sc1CeSZ system in oxidizing and reducing atmosphere for the application of oxygen transport membrane (OTM) device. Role of oxygen partial pressure (PO 2) on the interfacial stability of LSCF with 10Sc1CeSZ is studied under OTM fabrication conditions (1400°C, PO 2 ~ 0.21-10-10 atm). Interfacial stability corresponding to the interaction between LSCF and 10Sc1CeSZ decreases with decrease in PO 2. Interfacial study of LSCF with 10Sc1CeSZ shows absence and presence of strontium zirconate (SrZrO 3) at the interface in oxidizing (PO 2 ~ 0.21 atm) and reducing atmosphere (PO 2 ~ 10-10 atm) at 1400°C respectively. Mechanism for the formation of SrZrO 3 is reported.
ABSTRACT The electrical conductivity and the electrochemical properties of dense La0.85Sr0.15MnO3... more ABSTRACT The electrical conductivity and the electrochemical properties of dense La0.85Sr0.15MnO3 − δ (LSM) films, prepared using Pulsed Laser Deposition (PLD) have been investigated. The nano-structure of the LSM films has been characterized using scanning electron microscopy (SEM). The oxygen transport properties of the films were studied using electrochemical impedance spectroscopy (EIS) on symmetrical cells. Electrical conductivity measurement were carried out in an oxygen partial pressure range from 1 to 0.0032 atm, and a temperature range from 950 to 700 °C. The electrical conductivity at 800 °C was 116 S cm− 1 and did not vary with the pO2. Impedance spectra were recorded in the temperature range from 600 to 950 °C in the oxygen partial pressure range from 0.06 to 1.00 atm. At 900 °C and 1.00 atm the area specific resistance was 30.6 Ω cm2 and an activation energy of 2.7 eV was found. The ASR increased with decreasing pO2. Based on the impedance spectra an oxide ion conductivity of 5.0 × 10− 1 S cm− 1 was found at 900 °C and pO2 = 1.00 atm. The characteristic length, at which the oxide transport reaction switch from being limited by bulk diffusion to that of surface exchange, was estimated to be approximately 220 and 130 nm at 700 and 900 °C, respectively.
La 0.6 Sr 0.4 FeO 3 (LSF) is a promising material for cathode support application because its the... more La 0.6 Sr 0.4 FeO 3 (LSF) is a promising material for cathode support application because its thermal expansion coefficient (TEC) is matching with typical electrolytes and it has sufficient level of ionic and electronic conductivity. In this paper, the LSF was used as a support for fabrication dense and nanocrystalline film of (Ce 0.8 Gd 0.2 O 1.95) CGO. The LSF support was fabricated by iso-axial pressing of powder, which was prepared using modified Pechini method. Several fabrication parameters were altered in order to obtain support with required density, conductivity and strength. This included different sintering temperatures, addition of pore former and variation of compaction pressure. The LSF powders were examined by X-ray diffractometry and did not show any other phases. The electrical conductivity and density of LSF supports were investigated in order to select optimal support for CGO film deposition. The electrical measurements indicated that porosity highly influence the electronic conductivity of LSF. A low temperature and cost-effective method, called net shape technique, was used to deposit CGO film on LSF. Impedance spectroscopy measurements (IS) of obtained structure showed that electrical conductivity of CGO film and calculated activation energy is in good agreement with literature data. SEM images indicated that the film has no cracks and is about 4 m thick.
... b Institut fur Anorganische und Analytische Chemie, Corrensstr. 28/30, D-48149 Münster, Germa... more ... b Institut fur Anorganische und Analytische Chemie, Corrensstr. 28/30, D-48149 Münster, Germany. Received 30 June 2010; revised 13 August 2010; accepted 30August 2010. Available online 9 September 2010. Abstract. A ...
Two methods for detailed characterization of the process of oxygen exchange between the gas phase... more Two methods for detailed characterization of the process of oxygen exchange between the gas phase and a mixed conducting solid oxide are discussed. First, the use of solid electrolyte probes for measuring the change in oxygen activity over the surface of a mixed conductor is presented and advantages of the technique discussed. Secondly, the use of thin film model electrodes is treated. Studies of thin films applied by PLD on both sides of a YSZ single crystal are presented for three different film materials; La0.85Sr0.15MnO3, La0.6Sr0.4Fe0.8Co0.2O3 and La0.6Sr0.4CoO3. Varia-tions in electrode performance with film structure is elucidated and the rate of the exchange process on the films is compared to that observed on bulk samples.
ABSTRACT The electrical conductivity and the electrochemical properties of dense La0.85Sr0.15MnO3... more ABSTRACT The electrical conductivity and the electrochemical properties of dense La0.85Sr0.15MnO3 − δ (LSM) films, prepared using Pulsed Laser Deposition (PLD) have been investigated. The nano-structure of the LSM films has been characterized using scanning electron microscopy (SEM). The oxygen transport properties of the films were studied using electrochemical impedance spectroscopy (EIS) on symmetrical cells. Electrical conductivity measurement were carried out in an oxygen partial pressure range from 1 to 0.0032 atm, and a temperature range from 950 to 700 °C. The electrical conductivity at 800 °C was 116 S cm− 1 and did not vary with the pO2. Impedance spectra were recorded in the temperature range from 600 to 950 °C in the oxygen partial pressure range from 0.06 to 1.00 atm. At 900 °C and 1.00 atm the area specific resistance was 30.6 Ω cm2 and an activation energy of 2.7 eV was found. The ASR increased with decreasing pO2. Based on the impedance spectra an oxide ion conductivity of 5.0 × 10− 1 S cm− 1 was found at 900 °C and pO2 = 1.00 atm. The characteristic length, at which the oxide transport reaction switch from being limited by bulk diffusion to that of surface exchange, was estimated to be approximately 220 and 130 nm at 700 and 900 °C, respectively.
Perovskites are materials of very versatile properties. They may be used in various ways and stru... more Perovskites are materials of very versatile properties. They may be used in various ways and structures. In this work the results of investigation of the Zr0.84Y0.16Ox electrolyte on La0.6Sr0.4FeO3 perovskite support are presented. The perovskite support was fabricated by iso-axially die-pressing of La0.6Sr0.4FeO3 powders and sintering at 1150 • C. The Zr0.84Y0.16Ox layer was deposited on La 0.6 Sr 0.4 FeO 3 by a combination of colloidal suspension and polymer precursor methods. In this way the dense electrolyte layer was prepared at as low temperature as 400 • C. This method may be also useful for high-Tc superconductor layers deposition. The chemical interaction between the electrolyte layer and perovskite support was investigated by X-ray diffraction. It was shown that no reaction occurs between cathode and electrolyte until 900 • C. Above 1200 • C, parameters of the La 0.6 Sr 0.4 FeO 3 unit cell increase. It suggests that the reaction between Zr0.84Y0.16Ox and La0.6Sr0.4FeO3 is accompanied by substitutional changes in the La 0.6 Sr 0.4 FeO 3 .
This study reports the interfacial stability of doped (La 0.8 Sr 0.2) 0.95 Cr 0.7 Fe 0.3 O 3 (LSC... more This study reports the interfacial stability of doped (La 0.8 Sr 0.2) 0.95 Cr 0.7 Fe 0.3 O 3 (LSCF) and 10Sc1CeSZ system in oxidizing and reducing atmosphere for the application of oxygen transport membrane (OTM) device. Role of oxygen partial pressure (PO 2) on the interfacial stability of LSCF with 10Sc1CeSZ is studied under OTM fabrication conditions (1400°C, PO 2 ~ 0.21-10-10 atm). Interfacial stability corresponding to the interaction between LSCF and 10Sc1CeSZ decreases with decrease in PO 2. Interfacial study of LSCF with 10Sc1CeSZ shows absence and presence of strontium zirconate (SrZrO 3) at the interface in oxidizing (PO 2 ~ 0.21 atm) and reducing atmosphere (PO 2 ~ 10-10 atm) at 1400°C respectively. Mechanism for the formation of SrZrO 3 is reported.
ABSTRACT The electrical conductivity and the electrochemical properties of dense La0.85Sr0.15MnO3... more ABSTRACT The electrical conductivity and the electrochemical properties of dense La0.85Sr0.15MnO3 − δ (LSM) films, prepared using Pulsed Laser Deposition (PLD) have been investigated. The nano-structure of the LSM films has been characterized using scanning electron microscopy (SEM). The oxygen transport properties of the films were studied using electrochemical impedance spectroscopy (EIS) on symmetrical cells. Electrical conductivity measurement were carried out in an oxygen partial pressure range from 1 to 0.0032 atm, and a temperature range from 950 to 700 °C. The electrical conductivity at 800 °C was 116 S cm− 1 and did not vary with the pO2. Impedance spectra were recorded in the temperature range from 600 to 950 °C in the oxygen partial pressure range from 0.06 to 1.00 atm. At 900 °C and 1.00 atm the area specific resistance was 30.6 Ω cm2 and an activation energy of 2.7 eV was found. The ASR increased with decreasing pO2. Based on the impedance spectra an oxide ion conductivity of 5.0 × 10− 1 S cm− 1 was found at 900 °C and pO2 = 1.00 atm. The characteristic length, at which the oxide transport reaction switch from being limited by bulk diffusion to that of surface exchange, was estimated to be approximately 220 and 130 nm at 700 and 900 °C, respectively.
La 0.6 Sr 0.4 FeO 3 (LSF) is a promising material for cathode support application because its the... more La 0.6 Sr 0.4 FeO 3 (LSF) is a promising material for cathode support application because its thermal expansion coefficient (TEC) is matching with typical electrolytes and it has sufficient level of ionic and electronic conductivity. In this paper, the LSF was used as a support for fabrication dense and nanocrystalline film of (Ce 0.8 Gd 0.2 O 1.95) CGO. The LSF support was fabricated by iso-axial pressing of powder, which was prepared using modified Pechini method. Several fabrication parameters were altered in order to obtain support with required density, conductivity and strength. This included different sintering temperatures, addition of pore former and variation of compaction pressure. The LSF powders were examined by X-ray diffractometry and did not show any other phases. The electrical conductivity and density of LSF supports were investigated in order to select optimal support for CGO film deposition. The electrical measurements indicated that porosity highly influence the electronic conductivity of LSF. A low temperature and cost-effective method, called net shape technique, was used to deposit CGO film on LSF. Impedance spectroscopy measurements (IS) of obtained structure showed that electrical conductivity of CGO film and calculated activation energy is in good agreement with literature data. SEM images indicated that the film has no cracks and is about 4 m thick.
... b Institut fur Anorganische und Analytische Chemie, Corrensstr. 28/30, D-48149 Münster, Germa... more ... b Institut fur Anorganische und Analytische Chemie, Corrensstr. 28/30, D-48149 Münster, Germany. Received 30 June 2010; revised 13 August 2010; accepted 30August 2010. Available online 9 September 2010. Abstract. A ...
Two methods for detailed characterization of the process of oxygen exchange between the gas phase... more Two methods for detailed characterization of the process of oxygen exchange between the gas phase and a mixed conducting solid oxide are discussed. First, the use of solid electrolyte probes for measuring the change in oxygen activity over the surface of a mixed conductor is presented and advantages of the technique discussed. Secondly, the use of thin film model electrodes is treated. Studies of thin films applied by PLD on both sides of a YSZ single crystal are presented for three different film materials; La0.85Sr0.15MnO3, La0.6Sr0.4Fe0.8Co0.2O3 and La0.6Sr0.4CoO3. Varia-tions in electrode performance with film structure is elucidated and the rate of the exchange process on the films is compared to that observed on bulk samples.
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Papers by Paweł Płończak