Disparity in electrical and magnetic properties of isostructural oxygen-deficient perovskites BaSrCo2O6−δ and BaSrCoFeO6−δ

Hona, Ram Krishna; Ramezanipour, Farshid

doi:10.1007/s10854-018-9471-8

Cited by 14 publications

(12 citation statements)

References 36 publications

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“…As a result, the average structure looks similar to that of a typical perovskite 70,88 ( Figure 6.2), but with partial occupancy on the oxygen positions (Table 6.1). This is in sharp contrast to the structure of CaSrFe2O6-δ (δ=1), 4 ( Figure 6.2) which is known to contain an ordered array of defects, that appear in alternating layers, converting the octahedral geometry into tetrahedra in those layers.…”

Section: Crystal Structurementioning

confidence: 67%

“…Oxygen contents of each material was determined by iodometric titration as explained elsewhere. 88,120,130 Electrocatalytic performances of the materials were measured in a three-electrode We note that further substitution of Sr by Ca, beyond CaSrMn2O6, does not change the polyhedral connectivity. The completely substituted product, that contains only Ca on the A-site, contains the same type of corner-sharing connectivity as CaSrMn2O6, although the corner-sharing MnO6 octahedra are somewhat distorted, leading to orthorhombic symmetry.…”

Section: Methodsmentioning

confidence: 97%

“…83 Not surprisingly, the nature of the B-site cation also affects the structure and properties. 75,88 For example, both Ca2Mn2O5 119 and Ca2Cr2O5 122 have defect-ordered structures, but the type of ordering in these two compounds is different. Ca2Mn2O5 contains only one type of B-site coordination, namely square pyramidal MnO5 units.…”

Section: Methodsmentioning

confidence: 99%

“…The crystal structure of oxygen-deficient perovskites also depends on the arrangement of defects that are generated due to oxygendeficiency. 4,[84][85][86][87] The defects can be distributed in a disordered 76,[88][89] or ordered fashion. 4, 12, 73-75, 84-87, 90 One of the common structures, resulting from the ordering of defects, is brownmillerite-type structure.…”

Section: Introductionmentioning

confidence: 99%

“…83 The arrangement of oxygen-vacancies in the crystal lattice is also important. The defects, generated due to oxygen deficiency, can be arranged in ordered 4,72,86,89 or disordered [88][89] manner, leading to different structure and properties. 4,90 One of the common types of defect-order results in the brownmillerite structure, which contains alternating BO6 octahedra and B'O4 tetrahedra.…”

Section: Introductionmentioning

confidence: 99%

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Oxygen deficient perovskites: effect of structure on electrical conductivity, magnetism and electrocatalytic activity.

Hona¹

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Oxygen evolution reaction …………………………………………....19 CHAPTER 2. TRANSFORMATION OF STRUCTURE, ELECTRICAL CONDUCTIVITY AND MAGNETISM IN AA'Fe2O6-δ, A=Sr, Ca and A'= Sr..…... 21 Introduction ………………………………………………………………….. 21 Experimental ……... …………………………………………………………. 23 Results and discussion ………………………………………………………. 25 Crystal structure ……………………………………………………... 25 Magnetic structure …………………………………………………… 33 Electrical Properties ………………………………………………..… 36 Conclusion ………………………………………………………………...…. 43 CHAPTER 3. UNRAVELING THE ROLE OF STRUCTURAL ORDER IN TRANSFORMATION OF ELECTRICAL CONDUCTIVITY IN Ca2FeCoO6-δ, CaSrFeCoO6-δ and Sr2FeCoO6-δ …………………………………………………..….. 44 ix Introduction ………………………………………………………………...…. 44 Experimental ………………………………………………………………..…. 46 Results and discussion …………………………………….…………………. 48 Crystal structure ………………………………………….…………… 48 X-ray photoelectron spectroscopy …………………………………… 61 Electrical conductivities ……………………………………...………. 65 Conclusion …………………………………………………………………….. 73 CHAPTER 4. MAGNETIC STRIUCTURE OF CaSrFeCoO5 ………………..……… 75 Introduction …………………………………………………………….……….75 Experimental section ……………………………………………….………….. 77 Results and discussion ………………………………………………………….……. 78 Conclusion ……………………………………………………………….…………… 86 CHAPTER 5. ELECTRICAL PROPERTIES OF ORDERED OXYGEN-DEFICIENT PEROVSKITE Ca2Fe0.5Ga1.5O5…………..…..……………………………………….. 87 Introduction …………………………………………….……………………. 87 Materials and methods ………………………………….……………………. 90 Results and discussion ……………………………………...……….…………91 Crystal structure …………………………………………….….……… 91 x Electrical properties ………………………………..………….……… 94 Conclusion ……………………………………………..…………..…………. 99 CHAPTER 6. ENHANCED ELECTRICAL PROPERTIES OIN BaSrFe2O6-δ (δ=0.5): A DISORDERED DEFECT-PEROVSKITE………………………..………………..…. 100 Introduction …………………………………………………….…………… 100 Experimental……… ………………………………………..……………….. 102 Results and discussion …………………………………………..…………… 103 Crystal structure …………………………………………………...…. 103 Magnetic properties ………………………………………...…………109 Electrical properties ………………………………………………….. 111 Conclusion ……………………………………………….………………….. 115 CHAPTER 7. CHARGE-TRANSPORT PROPERTIES OF Ca2FeGaO6-δ AND CaSrFeGaO6-δ: THE EFFECT OF DIFECT-ORDERED .……………………...…….. 117 Introduction ………………………………………………………………….. 117 Experimental …………………………………………….………………….. 120 Results and discussion ………………………………..……………………… 121 Crystal structure ……………………………………………….…….. 121 Microstructure and X-ray photoelectron spectroscopy studies…………125 Electrical properties ………………………………….………………. 127 Conclusion ………………………………………………………..…………. 133 xi CHAPTER 8. DISPARITY IN ELECTRICAL AND MAGNETIC PROPERTIES OF ISOSTRUCTURAL OXYGEN-DEFICIENT PEROVSKITES BaSrCo2O6-δ AND BaSrCoFeO6-δ ………..………….……………………………………………..…….. 134 Introduction ……………………………………………………….…………. 134 Experimental……… …………………………………….….………………… Results and discussion …………………………………….……...………….. Crystal structure and crystallite morphology …….………….………… X-ray photoelectron spectroscopy (XPS) and iodometric titration ….…141 Magnetic properties ……………………………………………....…… Electrical conductiviti...

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Section: Crystal Structurementioning

confidence: 67%

Section: Methodsmentioning

confidence: 97%