@article { ISI:000254698300034, title = {Novel hydroxide precursors to prepare NaNbO3 and KNbO3}, journal = {Ceramics International}, volume = {34}, number = {3}, year = {2008}, month = {APR}, pages = {671-673}, publisher = {ELSEVIER SCI LTD}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND}, abstract = {

Firstly, fresh niobium, hydroxide was precipitated from NbF5 solution using an aqueous ammonium hydroxide under basic conditions. Then a simple procedure of mixing potassium (or sodium) and niobium hydroxides together and heating at a low temperature (\<400 degrees C) produced KNbO3 (KN) or NaNbO3 (NN) powders. This is the lowest temperature so far reported for the formation of these phases. The phase content and lattice parameters are determined by X-ray diffraction (XRD). The average particle size and morphology were studied by scanning electron microscopy (SEM). (c) 2007 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

}, keywords = {chemical preparation, niobates, Perovskites, powders, X-ray methods}, issn = {0272-8842}, doi = {10.1016/j.ceramint.2006.12.014}, author = {Muthurajan, H. and Kumar, H. H. and Samuel, V. and Gupta, U. N. and Ravi, V.} } @article { ISI:000309370500015, title = {Carbon dioxide reforming of methane over ruthenium substituted strontium titanate perovskite catalysts}, journal = {Indian Journal of Chemistry Section A-Inorganic Bio-Inorganic Physical Theoretical \& Analytical Chemistry}, volume = {51}, number = {9-10, SI}, year = {2012}, month = {SEP}, pages = {1339-1347}, publisher = {NATL INST SCIENCE COMMUNICATION-NISCAIR}, address = {DR K S KRISHNAN MARG, PUSA CAMPUS, NEW DELHI 110 012, INDIA}, abstract = {

Strontium titanate (SrTiO3) doped with varying amounts of ruthenium (7.9, 15.6 and 31 wt\%) have been prepared by the citrate gel synthesis method. Structural and textural characterizations reveal that at lower concentrations, a major part of Ru is incorporated in the lattice of SiTiO3. The content of surface Ru (outside lattice) increases with increasing amounts of the doped Ru. The surface Ru reduced at lower temperatures compared to Ru incorporated into the lattice. The reduction of the lattice substituted Ru occurs only at temperatures above the collapse of the perovskite structure. The catalyst sample with 7.9 wt\% of Ru shows good conversions in the dry reforming of methane with CO2. The conversion of CO2 is in excess compared to methane under the studied reaction conditions. As a result, H-2/CO ratio of the product gases which should have been equivalent to unity is lower than the stoichiometric value. This ratio is particularly low when lower reaction temperatures (873-973 K) were used. Similar was the case when high space velocities were used. Low methane conversion and reverse water gas shift reaction are the causes for the low H-2/CO ratios.

}, keywords = {Carbon dioxide reforming, Catalysts, Citrate gel method, Doped catalysts, Dry reforming, Methane reforming, Perovskites, Reverse water gas shift, Ruthenium doped catalysts, Strontium titanate, Syngas}, issn = {0376-4710}, author = {Gurav, Hanmant R. and Bobade, Richa and Das, Vineetha Lakshmi and Chilukuri, Satyanarayana V.} } @article { ISI:000347498500064, title = {Effect of pt incorporation in LaBO3 (B = Mn, Fe, Co) perovskites on water gas shift activity}, journal = {Journal of Molecular Catalysis A-Chemical}, volume = {395}, year = {2014}, month = {DEC}, pages = {506-513}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Pt incorporated perovskites LaBO3 (B = Mn, Co, Fe) were synthesised and characterised to understand the charge state of Pt in these materials. At the temperature range used in this study, Pt could be stabilised in ionic form in Co and Fe perovskites but not in LaMnO3. Consequent to incorporation of Pt in +2 and +4 oxidation states, reduction in B site ion charge state occurred, enhancing oxygen vacancies. Pt doped Co and Fe perovskites showed high activity for CO conversion under water gas shift conditions but the activity characteristics were found to be different for the two catalysts; LaCo1-xPtxO3-delta showed methanation whereas the Fe counterpart was active in water gas shift reaction. It was also observed that methanation could be decreased and water gas shift enhanced in case of Pt doped Co perovskite when compared to Pt impregnated perovskite or mixed oxides. (C) 2014 Elsevier B.V. All rights reserved.

}, keywords = {Methanation, Perovskites, Pt doping, Water gas shift reaction, XANES}, issn = {1381-1169}, doi = {10.1016/j.molcata.2014.09.015}, author = {Rajesh, Thattarathody and Upadhyay, Anuj and Sinha, Anil K. and Deb, Sudip K. and Devi, R. Nandini} } @article { ISI:000347498500067, title = {Resistance to ionic pt insertion in oxygen excess LaMnO3 perovskite lattices and its effect in water gas shift reaction}, journal = {Journal of Molecular Catalysis A-Chemical}, volume = {395}, year = {2014}, month = {DEC}, pages = {534-542}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Pt doped and impregnated LaMnO3 perovskites are synthesized at different temperatures and Pt and Mn states are compared in an attempt to get insight into extent of lattice incorporation of Pt in perovskite. Various characterization studies indicate that oxygen excess system like LaMnO3 presents substantial resistance to B site doping with Pt. This behavior is different from other oxygen deficient perovskites like LaCoO3 and LaFeO3 in which lattice incorporation stabilizes the active species against sintering. Water gas shift reaction was used as a probe reaction to understand the effect of this difference in the activity. In case of LaMnO3, failure in lattice substitution leads to sintering and deactivation at high synthesis temperatures (\>= 700 degrees C) in both impregnated and doped samples. In doped samples, however, a strong interaction of Pt species with a persistent amorphous phase prevents sintering at lower synthesis temperature thereby enhancing the activity when compared to impregnated sample. The study reveals a possible mechanism in which only Pt(0) species is active with perovskite playing a minimal role in this system due to the resistance to lattice incorporation. (C) 2014 Elsevier B.V. All rights reserved.

}, keywords = {Oxygen excess, Perovskites, Water gas shift reaction, XPS, XRD}, issn = {1381-1169}, doi = {10.1016/j.molcata.2014.08.042}, author = {Rajesh, Thattarathody and Devi, R. Nandini} } @article {48353, title = {Addressing challenges in sealing of scalable multifiber module for O-2 enrichment using LSCF membranes}, journal = {International Journal of Applied Ceramic Technology}, volume = {19}, year = {2022}, month = {MAY}, pages = {1561-1571}, type = {Article}, abstract = {

Scalable and multifiber modules in oxygen separation face huge challenges due to difficulty in integrating all the necessary components, especially in sealing the fibers in a gas tight module. Here, we report our findings on design and fabrication of a multifiber La0.6Sr0.4Co0.2Fe0.8O3-delta (LSCF)-based module, which can be scaled up. The focus is on sealing ceramic-metal interfaces by layering of sealants of varying thermal properties. We have also incorporated the use of dead ended fibers to minimize ceramic-metal interfaces in the hot zones and present a new method for dead ending by flame melting. Pressurizing the air inlet feed from either bore side or shell side is detrimental to the structural integrity of the fibers. A thorough characterization of the fresh and spent fibers is also carried out using X-ray tomography and electron microscopy, which indicates effect of temperature and pressure on the fibers.

}, keywords = {Characterization, permeability, Perovskites}, issn = {1546-542X}, doi = {10.1111/ijac.13967}, author = {Jogdand, Shunottara M. and Bedadur, Prachiti R. and Torris, Arun and Agrawal, Ravi and Kharul, Ulhas K. and Devi, R. Nandini} } @article {48802, title = {Unleashing methylammonium-guanidinium lead iodide hybrid perovskite spherulitic microstructures: a structural and morphological investigation}, journal = {MRS Communications}, volume = {13}, year = {2023}, month = {JUN}, pages = {406-415}, type = {Article}, abstract = {

Perovskites can offer an attractive replacement option for existing commercial solar technologies. Herein microstructure plays an important role in improving the efficiency and stability of solar cells. Previously unidentified spherulitic microstructures of self-assembled polycrystalline perovskites are explored in this report. For this an intermediate phase of a promising guanidinium (GUAI)-rich perovskite has been investigated for its structural and morphological properties. This study infuses new insight into the evolution of perovskite microstructure from heterogeneity to homogeneity, as a result unravels the structure of perovskite embryonic spherulites, lamellar arrangements, transcrystalline nature, novel spherulites bridging, hole nucleation, impingement, and defects.

}, keywords = {Microstructure, Morphology, Nucleation \& growth, Perovskites, Phase transformation, X-ray diffraction (XRD)}, issn = {2159-6859}, doi = {10.1557/s43579-023-00375-w}, author = {Mukul, Monika and Kaliaperumal, Selvaraj and Rani, Mamta and Tripathi, Surya Kant} }