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Wpływ domieszkowania halogenkami metali alkalicznych na właściwości warstw perowskitowych w ogniwach słonecznych

Szwanda Agata, Starowicz Zbigniew, Janicki Jarosław, Fryczkowski Ryszard

Polish Journal of Materials and Environmental Engineering

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2023

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Vol. 6 (26)

66--78

EN

Perovskite cells are a new generation of solar cells that have gained significant attention in the field of photovoltaics due to their unique properties and potential benefits. Perovskites are a class of materials that have a characteristic crystal structure known as the perovskite structure. The typical chemical formula of perovskite is ABX3, where 'A' and 'B' are cations that differ in size, and 'X' is an anion, most often halogen. Doping with alkali metals in perovskite materials has shown a significant improvement in the efficiency of the solar cell, which is confirmed by numerous scientific studies. The addition of ru-bidium bromide and other alkali metals, such as lithium, sodium and potassium, affects the microstructure, electronic and optical properties of perovskites, which is crucial for the efficiency and stability of solar cells. The paper presents research results on doping with alkali metals for inorganic perovskite cells based on CsPbBr3. The process of doping with alkali metals was carried out in various stages of creating a Perovskite cell. The work presents the influence of the dopant on the structure of the perovskite and the obtained cell, as well as its optical and electrical properties. The conducted research indicates a positive effect of the addition of rubidium bromide, both in the phase of creating the lead bromide layer and during the application of cesium bromide. The most promising is the admixture of 9% rubidium bromide in the cesium bromide layer. In this way, the applied dopant is located in the perovskite structure, changing its optical and electrical properties.

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Effect of KCl on the optical and structural properties of CaZnO3 perovskite thin films

Al-Saqa Read Hashim, Jassim Ismail Kalil, Uonis Mohammad Mahmood

Ochrona przed Korozją

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2023

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nr 8

243--246

EN

The primary goal of this study is to determine whether the produced CaZnO3 perovskite compound may be used in the production of solar cells and diodes. CaZnO3 perovskite thin films have been prepared and examined using scanning electron microscopy (SEM), X-ray spectroscopy, and UV spectroscopy. The films were made using the chemical spray pyrolysis deposition (CSPD) method; they were prepared from a mixture of 0.6 g of CaCl2 and ZnCl2 with 1.2 g of KOH, and CaZnO3 thin films were deposited on a glass substrate at a temperature of 150°C. Optical properties such as transmittance (T), absorbance (A), reflectance (R), the refractive index (n), and extinction coefficient (k) were studied. The energy gap varied from 3.19 eV for films without KCl to 3.22 eV for films with KCl, indicating that the presence of KCl had an impact on the energy gap; furthermore, the average particle’s diameter for films with KCl was about 112.28 nm and decreased to 53.86 nm when KCl was removed from the solutions to obtain pure in CaZnO3 perovskite thin films.

PL

Wpływ KCl na właściwości optyczne i strukturalne cienkich warstw perowskitu CaZnO3 Głównym celem badania było określenie, czy wytworzony perowskitowy związek CaZnO3 może zostać wykorzystany do produkcji ogniw fotowoltaicznych i diod. Przygotowano cienkie warstwy perowskitu CaZnO3, które zostały zbadane za pomocą skaningowego mikroskopu elektronowego (SEM), spektrometru rentgenowskiego i spektrometru UV. Warstwy zostały wykonane przy użyciu metody chemicznego osadzania pirolitycznego (CSPD); przygotowano je z mieszaniny 0,6 g CaCl2 i ZnCl2 z 1,2 g KOH, cienkie warstwy CaZnO3 osadzono na szklanym podłożu w temperaturze 150°C. Zbadano właściwości optyczne, takie jak transmitancja (T), absorbancja (A), współczynnik odbicia (R), współczynnik załamania światła (n) i współczynnik ekstynkcji (k). Przerwa energetyczna wynosiła od 3,19 eV w wypadku warstw bez KCl do 3,22 eV dla warstw z KCl, co świadczy o tym, że obecność KCl miała wpływ na przerwę energetyczną. Średnica cząstek w warstwach zawierających KCl wynosiła średnio 112,28 nm i zmniejszyła się do 53,86 nm, gdy z roztworów usunięto KCl w celu uzyskania czystych postaci cienkich warstw CaZnO3.

3

Pochodne 9,9'-bifluorenylidenu dla zastosowań w ogniwach perowskitowych

Pająk Agnieszka Katarzyna, Lipiński Marek, Schab-Balcerzak Ewa

Przegląd Elektrotechniczny

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2022

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R. 98, nr 2

95--97

PL

W pracy przedstawiono dwie pochodne 9,9’-bifluorenylidenu, różniące się długością łańcucha alkoksylowego, które zastosowano jako związki transportujące ładunki dodatnie (HTM) w perowskitowych ogniwach fotowoltaicznych o budowie FTO/b-TiO2/m-TiO2/perowskit/HTM/Au. Dodatkowo przygotowano ogniwa referencyjne bez HTM i zawierające jako HTM spiro-MeOTAD (C81H68N4O8). Najwyższą sprawność (7,33%), wyższą niż ogniwa referencyjnego (4,40%), uzyskano dla związku z grupami etoksylowymi.

EN

The article presents two 9,9’-bifluorenylidene derivatives differing in the length of the alkoxy chain, which were applied as hole transporting materials (HTM) in perovskite solar cells with structure FTO/b-TiO2/m-TiO2/perovskite/HTM/Au. Additionally, the reference cells without HTM and based on spiro-MeOTAD (C81H68N4O8) as HTM were also prepared. The highest efficiency (7.33%), being higher compare to the reference cell (4.40%), was reached for compound with ethoxyl groups.

4

Simulation investigation of perovskite-based solar cells

Łuszczek Maciej, Łuszczek Grzegorz, Świsulski Dariusz

Przegląd Elektrotechniczny

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2021

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R. 97, nr 5

99--102

EN

Three models of thin-layer lead-halide perovskite solar cells with different electron-transport layers (T iO2, SnO2, ZnO) were investigated by the simulation method. The perovskite layer thickness was optimized for all the systems. The analysis of the standard photovoltaic cell performance parameters at various operating temperatures was performed. The best performance was achieved for the system with the SnO2 conductive layer.

PL

Przeprowadzono badania symulacyjne trzech modeli ołowiowo-halogenkowych perowskitowych ogniw słonecznych z róznymi warst- ˙ wami odpowiedzialnymi za transport elektronowy (T iO2, SnO2, ZnO). Dla wszystkich układów dokonano optymalizacji grubosci warstwy perowskitu. ´ Przeanalizowano standardowe parametry okreslaj ˛ ´ ace wydajnos´c ogniw fotowoltaicznych w ró ´ znych temperaturach pracy. Najwi ˛ ˙ eksz ˛a sprawnos´c´ uzyskano dla układu z warstw ˛a przewodz ˛ac ˛a SnO2.

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Ca4−xLa2+xTi5−xBxO17 (B = Al, Ga) dielectric ceramics for microwave applications

Muhammad Raz, Khesro Amir

Materials Science Poland

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2020

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Vol. 38, No. 1

73--78

EN

In this study, Ca4−xLa2+xTi5−xBxO17(B = Al, Ga; x = 0, 1) ceramics were processed via a mixed oxide solid state sintering route and characterized using XRD, SEM, EDS and Vector Network Analyzer. Phase analysis of the samples showed single phase formation for the sample x = 0 while secondary phases formed for Ca4−xLa2+xTi5−xBxO17 (B = Al, Ga; x = 1) ceramics. Ca4La2Ti5O17 exhibited ∈r = 74, Q×fo = 14,116 GHz and τf = 157 ppm/°C. The substitution of Ga or Al for Ti at the B-site of Ca4La2Ti5O17 ceramics significantly improved the microwave dielectric properties i.e. Ca3La3Ti4GaO17 and Ca3La3Ti4AlO17 have ∈r = 44, Q×fo = 16,128 GHz and τf = 7.3 ppm/°C and ∈r =46, Q×fo= 13,754 GHz and τf = −2 ppm/°C, respectively. The microwave dielectric properties of these materials are suitable for high frequency microwave applications.

6

Synthesis of SrTiO3 by the Calcination of SrCO3 and TiO2 Mixtures Intensively Ground by Means of High Energy Milling

Rocha-Rangel Enrique, Pech-Rodríguez Wilian J., López-Hernández Juan, Calles-Arriaga Carlos A., Armendáriz-Mireles Eddie N., Castillo-Robles José A., Rodríguez-García José A.

Archives of Metallurgy and Materials

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2020

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Vol. 65, iss. 2

621--626

EN

A SrTiO3 electroceramic with perovskite structure was produced by the calcination of a mixture of SrCO3 and TiO2 intensively grounded by high energy milling. For this purpose, raw materials were mixed in stoichiometric amounts in a planetary type mill; the obtained powder mixture was calcined for 2 h at temperatures between 800 and 1300°C. Samples resulting from the calcination were characterized by XRD, FTIR, SEM analysis and electrical measurements. From XRD, it was determined that the SrTiO3 formed presents the cubic structure of perovskite. The complete reaction for SrTiO3 compound formation occurs at 1200°C. Micrograph observations indicate the presence of a homogeneous microstructure with tiny grain size. The measured values of electrical resistivity were within the typical range of insulating materials.

7

FTIR and Raman spectroscopic study of a complex perovskite: Ca0.91-xCe0.09Rb0.04Csx [(Zr0.50Ti0.45)Al0.05]O3, x=0.2 to 0.4, dedicated for radioactive waste confinement

Hasnat K., Kamel N., Moudir D., Mouheb Y., Kamariz S., Arabi A.

Advances in Materials Science

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2020

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Vol. 20, nr 2(64)

81--94

EN

Perovskite is able to sequester simultaneously, in its structure, both actinides and alkaline-earth elements. This study is an attempt to synthesize a complex perovskite Ca0.91-xCe0.09Rb0.04Csx [(Zr0.50Ti0.45)Al0.05]O3 (0.2≤x≤0.4), doped in the same time, with Ce, Cs and Rb. The synthesis is conducted by sintering at 1150°C during 16h. XRX analysis confirms the perovskite formation. SEM observations show a less porous microstructure. FTIR analysis reveals TiO6, Ti-O-Ti, Ti-O and Zr-O vibrations. Raman spectroscopy indicates many orthorhombic perovskite active modes, as: Ti-O6 and Ti-O3 torsions, ZrO7, CaO8 vibrations, the totally symmetric oxygen, and the O-octahedron cage rotation.

8

Thin film hybrid structures perovskite and silicon photovoltaic cells

Kołodziej A., Kołodziej M., Kołodziej T.

Science, Technology and Innovation

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2018

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Vol. 2, no. 1

27--30

EN

The world economy needs new breakthrough in the technological and material efficiency and costs in the manufactured solar cells. The authors present new studies on triple junction photo voltaic structures using nano-technological solutions. The system of the amorphous a-Si:H sandwich with the scattered light particles, the plasmonic nano Si in the a-Si:H matrix structure and the silicon-germanium sandwich on the multi ZnO layer electrode- reflector was made and studied in detail.

9

Wpływ dodatku palladu do perowskitu LaFeO3 na aktywność katalityczną w utlenianiu węglowodorów

Kucharczyk B., Szczygieł B., Winiarski J., Kokot vel Kokocińska P.

Przemysł Chemiczny

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2018

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T. 97, nr 10

1684--1688

PL

Perowskity La1-xPdxFeO3 (x = 0-0,25) wytworzono przez wysokotemperaturową kalcynację (750°C) mieszaniny azotanów lantanu, żelaza i palladu. Przedstawiono charakterystykę katalizatorów zawierających różne ilości Pd (powierzchnia właściwa BET, XRD, SEM). Otrzymane perowskity zastosowano jako warstwę aktywną katalizatorów monolitycznych do utleniania metanu i n-heksanu. Częściowe zastąpienie La w perowskicie przez Pd zwiększało aktywność katalizatora w procesie utleniania obydwu węglowodorów. W utlenianiu metanu i heksanu wzrost aktywności katalizatora z perowskitem LaFeO3 następował przy zastąpieniu 0,15 mola i 0,1 mola La przez Pd. Aktywność perowskitu La1-xPdxFeO3 rosła ze wzrostem zawartości Pd.

EN

La, Fe and Pd nitrates were mixed together in various proportions and calcinated at 750°C to obtain La1-xPdxFeO3 (x = 0-0.25) perovskites supported on a steel substrate and then used as an active catalyst layer for oxidn. of MeH and hexane. A partial replacement of La with Pd in the perovskite resulted in an increase in their catalytic activity. The activity increased with increasing Pd content in perovskite.

10

Kompozytowe elektrody dla ogniw SPCFC

Skubida W., Cichy K., Świerczek K.

Materiały Ceramiczne

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2018

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T. 70, nr 2

138--151

PL

Celem niniejszej pracy było opracowanie kompozytowych elektrod dla ogniw SPCFC (ang. symmetrical proton ceramc fuel cell). W pracy zaprezentowano wyniki badań strukturalnych dwóch związków zsyntezowanych metodą wysokotemperaturowej reakcji w fazie stałej: materiału elektrolitowego Ba0,9La0,1Zr0,25Sn0,25In0,5O3−δ oraz elektrodowego SrFe0,75Mo0,25O3-δ. Niezależnie od warunków syntezy, oba tlenki przyjęły strukturę krystaliczną perowskitu prostego (grupa przestrzenna Pm-3m). Na drodze wysokotemperaturowych pomiarów dyfrakcyjnych wykazano również, że symetria Pm-3m dla obu związków utrzymuje się w całym analizowanym zakresie temperatur, tj. od 25 °C do 900 °C. Wartości współczynników rozszerzalności termicznej wyniosły dla elektrolitu i elektrody odpowiednio 12,4(2)∙10-6 K-1 i 18,5(4)∙10-6 K-1. Przedstawione zostały również wyniki elektrochemicznych pomiarów przewodnictwa gęstego spieku materiału elektrolitowego (ponad 95% gęstości teoretycznej) oraz ogniwa z kompozytowymi elektrodami w układzie symetrycznym, skonstruowanego w oparciu o badane materiały ceramiczne. Badania przeprowadzono w atmosferach nawilżonego powietrza syntetycznego i mieszaniny

EN

The main aim of this work was to develop composite electrodes for SPCFC (Symmetrical Proton Ceramic Fuel Cell). The paper presents the results of structural studies of two compounds synthesized by the solid state high-temperature reaction: electrolyte Ba0.9La0.1Zr0.25Sn0.25In0.5O3-δ and electrode SrFe0.75Mo0.25O3-δ. Regardless of the synthesis conditions, both oxides adopted the cubic perovskite crystalline structure (space group Pm-3m). By means of high-temperature diffraction measurements, it was also shown that Pm-3m symmetry for both compounds is maintained throughout the analyzed temperature range, i.e. from 25 °C to 900 °C. The values of coefficients of thermal expansion were calculated to be 12.4(2)∙10-6 K-1 and 18.5(4)∙10-6 K-1 for the electrolyte and the electrode, respectively. The results of electrochemical measurements of conductivity of dense electrolyte material sinter (above 95% of theoretical density) and a cell with composite electrodes in a symmetrical system constructed on the basis of studied ceramics are also presented. The tests were carried out in atmospheres of humidified synthetic air and Ar/H2 mixture. The total cell conductivity was 3.80•10-4 S•cm-1 at 500 °C.

11

Features of distribution of uranium and thorium in red mud

Gu H., Wang N., Yang Y., Zhao C., Cui S.

Physicochemical Problems of Mineral Processing

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2017

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Vol. 53, iss. 1

110--120

EN

Natural radioactive elements such as uranium and thorium restrict the use of red mud as building materials or additives, and may cause environmental problems. The distribution features of U and Th in red mud was studied from micro and macro analysis, using EPMA, LA-ICP-MS, and methods of mineralogy and beneficiation. Based on the micro-area scanning analysis, main chemical compositions in red mud, such as Ca, Al, Si, Na, and K are dispersive while Fe and Ti mainly tend to concentrate in granular phases. Based on the in-situ analysis, the distribution of main elements and most trace elements in micro-zone of red mud was homogeneous. In micro-zone area, the variation tendency of thorium content was similar with Y in red mud samples. By means of the methods of mineralogy and beneficiation, red mud samples were separated into different fractions. U and Th tend to be enriched in the low density fraction of the red mud. Th presented a high concentration in the finest particle size fractions of the red mud. Neither U or Th was regularly distributed in various magnetic red mud fractions. Thorium fingerprint peaks were determined in perovskite by EDX under TEM, which is proposed to be one of the radioactivity sources in Bayer red mud.

12

Searching of new, cheap, air- and thermally stable hole transporting materials for perovskite solar cells

Gawlinska K., Iwan A., Starowicz Z., Kulesza-Matlak G., Stan-Glowinska K., Janusz M., Lipinski M., Boharewicz B., Tazbir I., Sikora A.

Opto-Electronics Review

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2017

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Vol. 25, No. 4

274--284

EN

In this work, two thermal- and air-stable, hole transporting materials (HTM) in perovskite solar cells are analyzed. Those obtained and investigated materials were two polyazomethines: the first one with three thiophene rings and 3,3’-dimethoxybenzidine moieties (S9) and the second one with three thiophene rings and fluorene moieties (S7). Furthermore, presented polyazomethines were characterized by Fourier transform infrared spectroscopy (FTIR), UV–vis spectroscopy, atomic force microscopy (AFM) and thermogravimetric analysis (TGA) experiments. Both polyazomethines (S7 and S9) possessed good thermal stability with a 5% weight loss at 406 and 377°C, respectively. The conductivity of S7 was two orders of magnitude higher than for S9 polymer (2.7 × 10⁻⁸ S/cm, and 2.6 × 10⁻¹⁰ S/cm, respectively). Moreover, polyazomethine S9 exhibited 31 nm bathochromic shift of the absorption band maximum compared toS7. Obtained perovskite was investigated by UV–vis and XRD. Electrical parameters of perovskite solar cells (PSC) were investigated at Standard Test Conditions (STC). It was found that both polyazomethines protect perovskite which is confirmed by ageing test where Voc did not decrease significantly for solar cells with HTM in contrast to solar cell without hole conductor, where Voc decrease was substantial. The best photoconversion efficiency (PCE = 6.9%), among two investigated in this work polyazomethines, was obtained for device with the following architectures FTO/TiO₂/TiO₂ + perovskite/S7/Au. Stability test proved the procreative effects of polyazomethines on perovskite absorber.

13

Microstructure and dielectric properties of La2O3 doped Ti-rich barium strontium titanate ceramics for capacitor applications

Zhang C., Chen F., Ling Z., Jian G., Li Y.

Materials Science Poland

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2017

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Vol. 35, No. 4

806--815

EN

Microstructure and dielectric properties of La2O3 doped Ti-rich barium strontium titanate ceramics, prepared by solid state method, were investigated with non-stoichiometric level and various La2O3 content, using XRD, SEM and LCR measuring system. With an increase of non-stoichiometric level, the unit cell volumes of perovskite lattices for the single phase Ti-rich barium strontium titanate ceramics increased due to the decreasing A site vacancy concentration V″A. The unit cell volume increased and then decreased slightly with the increasing La2O3 content. Relatively high non-stoichiometric level and high La2O3 content in Ti-rich barium strontium titanate ceramics contributed to the decreased average grain size as well as fine grain size distribution, which correspondingly improved the temperature stability of the relative dielectric constant. The relative dielectric constant єrRT, dielectric loss tanδRT and the maximum relative dielectric constant єrmax decreased and then increased with the increasing non-stoichiometric level. With the increase of La2O3 doping content, the relative dielectric constant єrRT increased initially and then decreased. The maximum relative dielectric constant єrmax can be increased by applying low doping content of La2O3 in Ti-rich barium strontium titanate ceramics due to the increased spontaneous polarization.

14

Search of methods for synthesizing photo-catalytically active layered perovskite-like phases of REE and transition elements

Dryuchko A. G., Storozhenko D. O., Bunyakina N. V.

Journal of New Technologies in Environmental Science

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2017

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Vol. 1, nr 4

158--164

EN

Complex layered perovskite-like oxides ALnTiO4, A2Ln2Ti3O10, ALnNb2O7, ALnTa2O7 (A - Li, Na, K, Rb, Cs, H; Ln - La, Nd) are crystalline compounds where layers of the perovskite structure are alternating with layers having different type of structure. Recently, the said phases have attracted significant attention due to their photo-catalytic properties [1, 2]. They can also be used as precursors to obtain other perovskite-like compounds by means of ion exchange or certain topochemical transformations. It was found that alkaline forms of such perovskites in the aqueous medium can perform replacement of cations by protons and hydration (rooting of water molecules in the interlayer space). These effects lead to substantial changes in physical and chemical properties of photo-catalysts. The composition of layered perovskite oxides may include several different metals [1-5], and depending on their nature and stoichiometry, these objects can display a wide range of physical and chemical properties. Normally, perovskite-like oxides are semiconducting materials.

15

Electrical and Thermal Properties of Na1-xLixNbO3 (x = 0.08, 0.1 and 0.2) Ceramics Near the Morphotropic Phase Boundary Region

Konieczny K., Czaja P.

Archives of Metallurgy and Materials

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2017

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Vol. 62, iss. 2A

539--544

EN

Na1-xLixNbO3 ceramics (for x = 0.08, 0.1, 0.2) were fabricated by the conventional solid state reaction method. The influence of LiNbO3 on the microstructure, electric, thermal properties of Na1-xLixNbO3 ceramics was studied and a significant influence of doped Li ions on the electrical properties was observed. The electrical properties were improved and are described as the best for x = 0.1 (near a morphotropic phase boundary) Na1-xLixNbO3 solid solutions. After crossing the morphotropic phase boundary for x = 0.2, the electric properties are getting worse. These types of solid compounds show some interesting properties suitable for practical applications.

16

The role and position of iron in 0.8CaZrO3-0.2CaFe2O4

Szczerba J., Śnieżek E., Stoch P., Prorok R., Jastrzębska I.

Nukleonika

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2015

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Vol. 60, No. 1

147--150

EN

The aim of the study was to characterize the 0.8CaZrO3-0.2CaFe2O4 composite structure with particular emphasis on the role and position of iron in the function of sintering temperature. The paper presents the results of 57Fe Mössbauer effect at room temperature. It was found that the increase of sintering temperature causes an increase in the amount of incorporated iron ions in the CaZrO3-crystal structure. Based on Mössbauer spectroscopy analysis, it was found that three different environments of Fe3+ ions were observed in the obtained materials. Two of them corresponded to CaFe2O4 phase and one was associated with the substitution of Zr4+ by Fe3+ in the CaZrO3 structure.

17

Hydrothermal synthesis and characterization of polycrystalline gadolinium aluminum perovskite (GdAlO3, GAP)

Girish H. N., Basavalingu B., Shao G. Q., Sajan C. P., Verma S. K.

Materials Science Poland

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2015

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Vol. 33, No. 2

301--305

EN

Gadolinium aluminum perovskite (GdAlO3, GAP) is a promising high temperature ceramic material, known for its wide applications in phosphors. Polycrystalline gadolinium aluminum perovskites were synthesized using a precursor of co-precipitate gel of GdAlO3 by employing hydrothermal supercritical fluid technique under pressure and temperature ranging from 150 to 200 MPa and 600 to 700 degrees C, respectively. The resulted products of GAP were studied using the characterization techniques, such as powder X-ray diffraction analysis (XRD), infrared spectroscopy (IR), scanning electron microscopy (SEM) and energy dispersive analysis of X-ray (EDX). The X-ray diffraction pattern matched well with the reported orthorhombic GAP pattern (JCPDS-46-0395).

18

Effects of partial Co replacement by Fe in Sr0.775Y0.225CoO3-δ on its magnetic property, oxygen deficiency and crystal structure

Sutjahja I. M., Berthalita F., Mustaqima M., Nugroho A. A., Tjia M. O.

Materials Science Poland

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2015

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Vol. 33, No. 3

579--587

EN

A study has been conducted on the effects of partial, 10 % Co substitution by Fe in the perovskite Sr0.775Y0.225CoO3-δ compound. The XRD data show that the resulted samples of Fe-free and Fe-doped compounds exhibit good 314 single phase quality with a tetragonal I4/mmm crystal structure. The measured M-T curves display the typical feature of ferromagnetic (FM) transition at 335 K for the Fe-free sample, while showing significantly degraded FM ordering for the 10 % Fe-doped sample. The oxygen deficiency determined from our 10 % Fe doped sample is found to decrease by only 0.025. Further detailed analysis of the XRD data also reveals distinctly different structural changes in the Co–O slabs compared to the 50 % Fe-doped sample which exhibits a complete suppression of FM order. The results of this study, thus, have revealed the close relations among the changes induced by Fe doping in the magnetic ordering of crystal, and its oxygen content as well as the associated local structure in the Co–O layers responsible for the magnetic properties in the compound.

19

Aktywność katalityczna mieszanych tlenków metali La-Mn (La-Co) o strukturze perowskitu w spalaniu rozcieńczonego metanu

Miniajluk N., Trawczyński J., Zawadzki M., Chomiak M.

Przemysł Chemiczny

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2014

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T. 93, nr 6

873-877

PL

Badano aktywność katalityczną mieszanych tlenków La-Mn i La-Co o strukturze typu perowskitu w spalaniu rozcieńczonego metanu. Stwierdzono, że materiały nieosadzone charakteryzowały się wysoką aktywnością katalityczną, podczas gdy odpowiadające im próbki osadzone na La-Al22O3 wykazywały mniejszą aktywność w tym procesie. Materiały La-Mn wykazywały lepiej rozwiniętą powierzchnię właściwą oraz większą aktywność katalityczną niż materiały La-Co. Największą aktywność wykazywały materiały, w których część lantanu zastąpiono strontem. Określono korelację pomiędzy aktywnością katalityczną badanych materiałów a udziałem tlenu sieciowanego na ich powierzchni.

EN

Six perovskite type oxides (both bulk and supported) were synthesized by the citrate-assisted sol-gel method and examd. by X-ray diffraction anal., N adsorption at low temp., X-ray photoelectron spectroscopy and temp.-programmed redn. with H2, and then used as catalyst in dild. Methane combustion. All oxides showed surface area 7.3-79.3 m2/g and were catalytically active. The chem. compn. of the prepd. oxides and their oxidn. state showed the presence of the lattice, adsorbed and hydroxyl or carbonate oxygens. A correlation between the CH4 conversion at 520°C on the studied oxides and share of lattice oxygen on the surface was found.

20

Correlation between structural and electrical properties in highly porous (Y,Sr)(Ti,Nb)O3−δ SOFC anodes

Miruszewski T, Trawiński B., Gałka M., Morzy J, Bochentyn B, Karczewski J., Gdaniec P, Gazda M., Kusz B.

Materials Science Poland

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2014

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Vol. 32, No. 3

331--340

EN

In order to find a relationship between structural and electrical properties, niobium and yttrium doped SrTiO3 ceramics were prepared via solid-state reaction. The samples were sintered in hydrogen and air conditions. The samples were also fabricated with a pore-former to obtain highly porous specimens. The electrical properties of Nb-doped SrTiO3 samples and yttrium and niobium co-doped SrTiO3 were compared. The comparable electrical properties were observed and discussed according to previous literature reports. It was noticed that the synthesis in a reducing hydrogen atmosphere can increase the solubility of dopants. Moreover, the samples sintered in air presented lower conductivity level and worse structural properties than the samples sintered in hydrogen. The explanation of obtained results was also suggested and discussed.