@article { ISI:000232801900001, title = {Characterization of barium titanate: BaTiO3 (BT) ceramics prepared from sol-gel derived BT powders}, journal = {Journal of Electroceramics}, volume = {15}, number = {2}, year = {2005}, month = {NOV}, pages = {103-108}, publisher = {SPRINGER}, type = {Article}, address = {VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS}, abstract = {

Sol-gel synthesis was attempted at room temperature by adding drop wise a clear solution (made by reacting BaCO3 with glacial acetic acid) to an equi-molar solution of titanium tetrabutoxide in isopropanol (IPA) and acetic acid. The gelation occurred within 30 minutes. The as-dried gel was calcined at 750 degrees C/6 h in air to obtain carbon free BaTiO3 powders. The resulting BT powders were further pressed into pellets and sintered at 1280 degrees C/4 h in air to get dense ceramics (density similar to 94\%). XRD and SEM techniques were used for phase and microstructure analysis respectively. The room temperature relative permittivity (e) of 1280 increased to 7200 (at Curie temperature of 127 degrees C) at 1 kHz frequency. The dissipation factor (tan delta) similar to 1.6\% was observed in these samples. Also, the ferroelectric properties such as spontaneous polarization (Ps similar to 13 mu C/cm(2)), coercive field (E-c similar to 4.0 kV/cm) and dielectric strength (similar to 34 kV/cm) are estimated for these samples. These performance parameters are compared with the available standard data from the literature.

}, keywords = {barium titanate, ferroelectricity, Microstructure, relative permittivity, sol-gel processing}, issn = {1385-3449}, doi = {10.1007/s10832-005-1460-7}, author = {Deshpande, S. B. and Godbole, P. D. and Khollam, Y. B. and Potdar, H. S.} } @article { ISI:000225497800035, title = {Synthesis and characterization of microwave-hydrothermally derived Ba1-xSrxTiO3 powders}, journal = {Materials Letters}, volume = {59}, number = {2-3}, year = {2005}, month = {JAN}, pages = {293-296}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Submicron-sized, spherical, stoichiometric strontium substituted barium titanate: Ba0.75Sr0.25TiO3 (BST) powders are prepared by microwave-hydrothermal (MH) route under the MH conditions of 200 degreesC, 200 psi, and 30 min in strongly alkaline conditions (pH\>12) using potassium titanyl oxalate (KTO) and nitrates of Ba and Sr as the starting precursors and KOH as the mineralizer. The characterization studies by XRD, XRF and SEM indicated that stoichiometric cubic BST powders (a(0)=3.992 A) were obtained by adjusting MH conditions mentioned earlier and keeping the (Ba+Sr)/Ti ratio in starting solution slightly in excess (similar to1.06). (C) 2004 Elsevier B.V. All rights reserved.

}, keywords = {barium-strontium titanate, dissolution-recrystallization, Microstructure, microwave-hydrothermal synthesis, mineralizer, SEM, XRD, XRF}, issn = {0167-577X}, doi = {10.1016/j.matlet.2004.10.006}, author = {Deshpande, S. B. and Khollam, Y. B. and Bhoraskar, Y. B. and Date, Sadgopal K. and Sainkara, S. R. and Potdar, H. S.} } @article { ISI:000239359100012, title = {Dielectric properties of BaTiO3 ceramics prepared from powders with bimodal distribution}, journal = {Journal of Industrial and Engineering Chemistry}, volume = {12}, number = {4}, year = {2006}, month = {JUL}, pages = {584-588}, publisher = {KOREAN SOC INDUSTRIAL ENGINEERING CHEMISTRY}, type = {Article}, address = {A-803 TWIN BLDG, 275-3, YANGJAE-DONG, SEOCHO-KU, SEOUL 137-130, SOUTH KOREA}, abstract = {

BaTiO3 (BT) powders having bimodal distribution were synthesized successfully through a simple classical solid-state reaction route using cheap BaCO3 and TiO2 as starting materials. These powders were further processed in the form of green pellets to obtain dense BT ceramics having densities of similar to 94 similar to 96 \% after sintering in air at 1350 and 1400 degrees C/4 h in air. The room temperature dielectric constant (epsilon(RT)) of similar to 1500 at 1 KHz frequency was increased to : 10000 at a Curie temperature (T-C) similar to 126 degrees C, showing a very sharp transition from a polar tetragonal to a non-polar cubic structure. The dielectric loss factor (tan 6) was similar to 1.5 \%. SEM studies revealed the presence of dense microstructures having a distribution of smaller grains (size: 2 similar to 3 gm) surrounded by larger grains (\>= 35 mu m). The ferroelectric hysteresis loop measurements on these samples gave values of spontaneous polarization (P-s) of similar to 12.0 mu C/cm(2), a coercive field (E-C) of similar to 2 similar to 2.5 kV/cm, and a dielectric strength (E-b) of similar to 48.0 kV/cm. DC-resistivity as high as 1.5 x 10(9) Omega-cm was obtained in these samples. All these results are quite comparable with reported ferroelectric/dielectric data and are discussed elaborately in this paper.

}, keywords = {BaTiO3, dielectric-ferroelectric properties, Microstructure, Sintering, stoichiometry}, issn = {1226-086X}, author = {Deshpande, S. B. and Potdar, H. S. and Patil, M. M. and Deshpande, V. V. and Khollam, Y. B.} } @article { ISI:000236922600002, title = {Room temperature synthesis of mesoporous aggregates of anatase TiO2 nanoparticles}, journal = {Materials Chemistry and Physics}, volume = {97}, number = {2-3}, year = {2006}, month = {JUN}, pages = {207-212}, publisher = {ELSEVIER SCIENCE SA}, type = {Article}, address = {PO BOX 564, 1001 LAUSANNE, SWITZERLAND}, abstract = {

The controlled hydrolysis reaction of titanium tetrabutoxide in presence of acetic acid in isopropanol, i.e. in non-aqueous media was adopted in the present work for the synthesis of nanocrystalline titania followed by aging at ambient conditions for longer duration. The powder XRD shows that the as-dried precursor (without any aging) is non-crystalline in nature. However, room temperature aging for longer duration \> 120 days not only helped to develop crystallinity in TiO2 nanoparticles but also led to the formation of their self-assembly towards mesoporous aggregates creating sponge like TiO2 nano-structure having high surface area similar to 250m (2) g(-1)and narrow pore size distribution of 4-5 nm. TEM observations revealed the generation of spherical TiO2 nanoparticles (4-5 nm) assembled to form stable spongy scaffold having porous network structure with pore size 5-6 nm. Also, presence of a pronounced hysteresis loop in BET isotherm is indicative of a 3D-intersection network of the pores of size 4-5 nm. Further heat-treatment to the aged precursor at 400 degrees C/2 h in air modify pore network structure due to sintering of TiO2 particles as is observed in TEM studies and lowering thereby the surface area to 125 m(2) g(-1) (c) 2005 Elsevier B.V. All rights reserved.

}, keywords = {Microstructure, porous materials, sol-gel processing, titania}, issn = {0254-0584}, doi = {10.1016/j.matchemphys.2005.02.014}, author = {Deshpande, S. B. and Potdar, H. S. and Khollam, Y. B. and Patil, K. R. and Pasricha, R. and Jacob, Nalini E.} } @article { ISI:000234528800001, title = {Studies on shrikhand rheology}, journal = {Journal of Food Engineering}, volume = {74}, number = {2}, year = {2006}, month = {MAY}, pages = {169-177}, publisher = {ELSEVIER SCI LTD}, type = {Article}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND}, abstract = {

Shrikhand, a popular Indian dessert made from yogurt, is manufactured on an industrial scale using several chemical engineering unit operations such as mixing, filtration and heat transfer. Understanding the rheology of shrikhand is not only relevant for designing large scale mixers but can also provide quantitative means for linking the microstructure of shrikhand to its perception of texture, consistency and taste. We show here that shrikhand exhibits a combination of several rheological properties such as weak gel-like viscoelasticity, an apparent yield stress, thixotropy and long structural recovery time scales. For instance, the elastic modulus is always higher than the loss modulus over the measurable frequency range and that both moduli show only weak frequency dependence that is a characteristic of gel-like consistency. Forward and reverse rate sweep tests show a distinct hysteresis loop, which is a signature of thixotropic character. In an attempt to trace the origins of these rheological properties in shrikhand we characterized its microstructure and showed that there exist two different microstructures: one composed of crystallites of milk fats having a length scale of similar to 50-100 mu m, and the other composed of aggregates of colloidal cascin micelles of similar to 0.5-10 mu m size. Our studies show that while the temperature sensitivity of the viscoelastic parameters is dominated by the semicrystalline milk fat microstructure, the shear sensitivity is largely dictated by the protein network. (c) 2005 Elsevier Ltd. All rights reserved.

}, keywords = {Microstructure, Rheology, shrikhand}, issn = {0260-8774}, doi = {10.1016/j.jfoodeng.2005.02.029}, author = {Kulkarni, C. and Belsare, N. and Lele, Ashish K.} } @article { ISI:000252474200009, title = {Low voltage varistor ceramics based on SnO2}, journal = {Bulletin of Materials Science}, volume = {30}, number = {6}, year = {2007}, month = {DEC}, pages = {583-586}, publisher = {SPRINGER}, type = {Article}, address = {233 SPRING STREET, NEW YORK, NY 10013 USA}, abstract = {

The nonlinear current (I)-voltage (V) characteristics of tin dioxide doped with either Nb2O5 and CoO or Sb2O3 and CoO show promising values of nonlinear coefficient (alpha) values (similar to 11) with low breakdown voltages (E-B, similar to 40 V mm(-1)). The pentavalent antimony or niobium acts as donor and increases the electronic conductivity. The crucial parameter for obtaining low breakdown voltage is the grain size, which depends upon sintering duration and temperature of these oxide ceramics.

}, keywords = {Chemical synthesis, electronic materials, Microstructure, tin oxide, X-ray diffraction}, issn = {0250-4707}, doi = {10.1007/s12034-007-0092-8}, author = {Dhage, S. R. and Ravi, V. and Yang, O. B.} } @article { ISI:000270770900015, title = {Doping-induced microstructural, textural and optical properties of In2Ti1-xVxO5+delta semiconductors and their role in the photocatalytic splitting of water}, journal = {Materials Chemistry and Physics}, volume = {117}, number = {2-3}, year = {2009}, month = {OCT}, pages = {399-407}, publisher = {ELSEVIER SCIENCE SA}, address = {PO BOX 564, 1001 LAUSANNE, SWITZERLAND}, abstract = {

The physicochemical properties of V-doped indium titanates (In2Ti1-xVxO5-delta, 0.0 \<= x \<= 0.2) were investigated by using XPS, powder XRD, UV-vis, SEM and luminescence spectroscopy techniques. The Rietveld refinement of XRD data revealed that even though the V-containing samples were isostructural with In2TiO5 (orthorhombic space group Pnma), a systematic x-dependent variation was noticeable in the Ti-O bond lengths in [TiO6] octahedral units, cell parameters and in the value of delta. XPS results confirmed the coexistence of V5+ and V4+ states, leading thereby to an enhancement in oxygen non-stoichiometry in the doped samples. A loading-dependent progressive shift from 400 to 750 nm was also observed in the onset of the absorption edge, indicating a significant narrowing of the band gap. Furthermore, the samples with higher V-content were comprised of the grain clusters having larger size and an irregular shape. The UV-vis. photoluminescence and thermoluminescence studies indicate that the doping-induced lattice defects may give rise to certain closely spaced acceptor/donor energy levels in between the band gap of host matrix. The indium titanates are found to serve as stable photocatalysts for water splitting under visible light, where oxygen was the major reaction product. The role of microstructural and morphological properties in the photocatalytic activity is discussed. (C) 2009 Elsevier B.V. All rights reserved.

}, keywords = {In2Ti1-xVxO5+delta photocatalysts, Luminescence spectroscopy, Microstructure, Optical properties, Structure-activity relationship, water splitting}, issn = {0254-0584}, doi = {10.1016/j.matchemphys.2009.06.013}, author = {Shah, Pallavi and Bhange, Deu S. and Deshpande, Aparna and Kulkarni, Mukund S. and Gupta, Narendra M.} } @article { ISI:000288529500015, title = {Role of lattice defects and crystallite morphology in the UV and visible-light-induced photo-catalytic properties of combustion-prepared TiO2}, journal = {Materials Chemistry and Physics}, volume = {126}, number = {3}, year = {2011}, month = {APR}, pages = {546-554}, publisher = {ELSEVIER SCIENCE SA}, address = {PO BOX 564, 1001 LAUSANNE, SWITZERLAND}, abstract = {

The physico-chemical, photo-physical and micro-structural properties responsible for the strikingly different photocatalytic behavior of combustion-prepared TiO2 (c.TiO2) and Degussa P25 (d.TiO2) samples are elucidated in this study. Electron microscopy and selected area electron diffraction micrographs revealed that the two samples exhibited different morphologies. The grains of c.TiO2 were spherical and comprised of 5-6 nm size primary particle. On the other hand, d.TiO2 consisted of large (0.5-3.0 mu m) size and irregular shape aggregates having primary particles of 15-40 nm cross-sectional diameter. The ESR study revealed that the presence of certain defect states in c.TiO2 helped in stabilization of O-. and Ti3+-OH type species during room-temperature UV-irradiation. No such paramagnetic species were however formed over d.TiO2 under similar conditions. C1s and Ti 2p XPS spectra provide evidence for the presence of some lattice vacancies in c.TiO2 and also for the bulk Ti4+ -\> Ti3+ conversion during its UV-irradiation. Compared to d.TiO2, c.TiO2 displayed considerably higher activity for discoloration of methyl orange but very poor activity for splitting of water, both under UV and visible light radiations. This is attributed to enhanced surface adsorption of dye molecules over c.TiO2, because of its textural features and also the presence of photo-active ion-radicals. On the other hand, the poor activity of c.TiO2 for water splitting is related to certain defect-induced inter-band charge trapping states in the close vicinity of valence and conduction bands of c.TiO2, as revealed by thermoluminescence spectroscopy. Further, the dispersion of nanosize gold particles gave rise to augmented activity of both the catalysts, particularly for water splitting. This is explained by the promotional role of Au-0 or Au-0/TiO2 interfacial sites in the adsorption and charge-adsorbate interaction processes. (C) 2011 Elsevier B.V. All rights reserved.

}, keywords = {Band-structure, Interfaces, Microstructure, Nanostructures, Semiconductors}, issn = {0254-0584}, doi = {10.1016/j.matchemphys.2011.01.029}, author = {Deshpande, Aparna and Madras, Giridhar and Gupta, N. M.} } @article { ISI:000301990100016, title = {Factors affecting the production of H-2 by water splitting over a novel visible-light-driven photocatalyst GaFeO3}, journal = {International Journal of Hydrogen Energy}, volume = {37}, number = {6}, year = {2012}, month = {MAR}, pages = {4897-4907}, publisher = {PERGAMON-ELSEVIER SCIENCE LTD}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND}, abstract = {

A d(10) photocatalyst, GaFeO3 having a band gap of similar to 2.7 eV, exhibits significant activity for the overall splitting of water under visible light (\>395 nm) irradiation, in the absence of sacrificial reagent or a noble metal co-catalyst. The doping of an anion led to considerable enhancement in activity, the S-doped catalysts displaying better activity compared to the samples containing nitrogen. Even though the H-2/O-2 yields were affected by preparation-dependent grain morphology, no direct relationship was observed between the photoactivity of a sample and its specific surface area. The techniques of HRTEM, SEM, XPS, Laser Raman, UV-visible and photoluminescence spectroscopy have enabled to demonstrate that, besides the grain morphology, certain lattice imperfections and microstructure may also play a crucial role in water splitting activity of a photocatalyst. The factors responsible for catalyst deactivation are examined. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

}, keywords = {GaFeO3, hydrogen production, Microstructure, Photocatalyst, water splitting}, issn = {0360-3199}, doi = {10.1016/j.ijhydene.2011.12.068}, author = {Dhanasekaran, P. and Gupta, N. M.} } @article { ISI:000300474900013, title = {Probing influence of mesophasic transformation on performance of self-emulsifying system: effect of ion}, journal = {Molecular Pharmaceutics}, volume = {9}, number = {2}, year = {2012}, month = {FEB}, pages = {318-324}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

Self-emulsifying systems are mixtures of oils and surfactants, ideally isotropic, sometimes including cosolvents, which emulsify under conditions of gentle agitation, similar to those which would be encountered in the gastrointestinal tract. The process of self-emulsification has remained the center of attraction for most researchers. Controlled hydration of self-emulsifying systems shows formation of an intermediate gel phase which upon rupture forms an emulsion. Current work was undertaken to understand and explore the microstructural properties of intermediate gel phase which are believed to influence the performance (droplet size) of the final formulation. The effect of additives on microstructural properties of intermediate gel phase has also been investigated. Microstructural elucidation of hydrated samples of intermediate regimes was done by using techniques such as small angle X-ray scattering, differential scanning calorimetry and rheology. Samples from intermediate regimes showed formation of local lamellar structure which swelled with hydration. In the present work, the effect of addition of salt form of naproxen (sodium and potassium) and naproxen (base) on microstructural properties of intermediate regimes was investigated. Systems containing naproxen salts formed larger droplets whereas naproxen base formed smaller ones. Microstructural properties of intermediate lamellar structures were well correlated with performance of the final formulation. The current studies indicate that by controlling the properties of intermediate regimes optimized formulations with desired performance can be tailor-made.

}, keywords = {emulsion, lamellar structure, liquid crystal, Microstructure, Naproxen, self-emulsifying system}, issn = {1543-8384}, doi = {10.1021/mp200541r}, author = {Patil, Sharvil S. and Venugopal, Edakkal and Bhat, Suresh K. and Mahadik, Kakasaheb R. and Paradkar, Anant R.} } @article { ISI:000324311200017, title = {Influence of initial particle size on the magnetostriction of sintered cobalt ferrite derived from nanocrystalline powders}, journal = {Journal of Magnetism and Magnetic Materials}, volume = {346}, year = {2013}, month = {NOV}, pages = {96-102}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

The role of initial particle size on the magnetostriction coefficient of sintered cobalt ferrite derived from nanocrystalline powders is studied. Nanoparticles of cobalt ferrite with different sizes in the range 3-80 nm are synthesized by an autocombustion method using metal nitrates and glycine. It has been observed that the initial particle size of the starting powders has a strong influence on the magnetostrictive behavior of sintered cobalt ferrite. Highest magnetostrictive strain and strain derivative are obtained for sintered ferrite derived from nanoparticles of size \< 5 nm. The results show that higher magnetostriction coefficient for sintered cobalt ferrite can be achieved by compacting nanocrystalline particles of very small size. (C) 2013 Elsevier B.V. All rights reserved.

}, keywords = {Cobalt ferrite, magnetic properties, Magnetostriction, Microstructure, Nanocrystalline, Particle size}, issn = {0304-8853}, doi = {10.1016/j.jmmm.2013.07.016}, author = {Mohaideen, Kamal Khaja and Joy, Pattayil Alias} } @article { ISI:000329554400013, title = {Studies on the effect of sintering conditions on the magnetostriction characteristics of cobalt ferrite derived from nanocrystalline powders}, journal = {Journal of the European Ceramic Society}, volume = {34}, number = {3}, year = {2014}, month = {MAR}, pages = {677-686}, publisher = {ELSEVIER SCI LTD}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND}, abstract = {

The effect of sintering conditions on the magnetostriction characteristics of sintered cobalt ferrite derived from nanocrystalline powders is studied. It is observed that the magnetostriction coefficient as well as the slope of the magnetostriction as a function of field depends on the microstructure of the sintered product. There is a direct correlation between the magnetostriction characteristics and density as well as porosity of the sintered products. Intragranular pores are found to be strongly influencing the magnetostriction characteristics. Similarly, correlation is found between the magnetostriction parameters and the Curie temperature, indicating the role of cation distribution which affects the magnetic anisotropy. Sintering the compacts made from nanocrystalline powders at 1450 degrees C for a very short duration is found to give high values of magnetostriction coefficient. However, higher values of magnetostriction at low magnetic fields are obtained for samples sintered at lower temperatures for longer duration and having relatively lower density. (C) 2013 Elsevier Ltd. All rights reserved.

}, keywords = {Cobalt ferrite, Magnetostriction, Microstructure, Nanocrystalline, Sintering}, issn = {0955-2219}, doi = {10.1016/j.jeurceramsoc.2013.09.018}, author = {Mohaideen, Kamal Khaja and Joy, Pattayil Alias} } @article { ISI:000369679500020, title = {Synthesis and self-assembly of dumbbell shaped ZnO sub-micron structures using low temperature chemical bath deposition technique}, journal = {Materials Chemistry and Physics}, volume = {169}, year = {2016}, month = {FEB}, pages = {152-157}, publisher = {ELSEVIER SCIENCE SA}, address = {PO BOX 564, 1001 LAUSANNE, SWITZERLAND}, abstract = {

We report well dispersed horizontal growth of ZnO sub-micron structures using simplest technique ever known i.e. chemical bath deposition (CBD). A set of samples were prepared under two different cases A) dumbbell shaped ZnO grown in CBD bath and B) tubular ZnO structures evolved from dumbbell shaped structures by dissolution mechanism. Single phase wurtzite ZnO formation is confirmed using X-ray diffraction (XRD) technique in both cases. From the morphological investigations performed using scanning electron microscopy (SEM), sample prepared under case A indicate formation of hex bit tool (HBT) shaped ZnO crystals, which observed to self-organize to form dumbbell structures. Further these microstructures are then converted into tubular structures as a fragment of post CBD process. The possible mechanism responsible for the self-assembly of HBT units to form dumbbell structures is discussed. Observed free excitonic peak located at 370 nm in photoluminescence (PL) spectra recorded at 18 K indicate that the micro/nanostructures synthesized using CBD are of high optical quality. (C) 2015 Elsevier B.V. All rights reserved.

}, keywords = {Electron microscopy (STEM, Microstructure, Nanostructures, Optical properties, Photoluminescence spectroscopy, Raman spectroscopy and scattering, TEM and SEM)}, issn = {0254-0584}, doi = {10.1016/j.matchemphys.2015.11.042}, author = {Borade, P. and Joshi, K. U. and Gokarna, A. and Lerondel, G. and Walke, P. and Late, Dattatray J. and Jejurikar, S. M.} } @article {46918, title = {Microstructure and yielding of capillary force induced gel}, journal = {Rheologica Acta}, volume = {59}, year = {2020}, month = {MAY}, pages = {291-306}, type = {Article}, abstract = {

We have investigated the rheology and structure of a gel formed from a mixture of non-Brownian particles and two immiscible liquids. The suspension of particles in a liquid undergoes gelation upon the addition of a small content of second, wetting liquid which forms liquid bridges between particles leading to a sample spanning network. The rheology of this gel primarily exhibits a yield stress at low shear rates followed by a linear variation of shear stress at high shear rates. The apparent yield stress extracted from the flow curves increases rapidly with volume fraction of the second liquid before saturation, while it exhibits a monotonic increase with increasing particle concentration. Rescaling of the yield stress curves using suitable shift factors results in an empirical expression for the yield stress showing squared dependence on liquid fraction and a rapid increase with particle fraction above a certain value, both combined in a highly non-linear manner. The microstructural variations with changing secondary liquid content and particle fractions are captured using three-dimensional X-ray tomography technique. The microstructure is observed to show increased local compactness with increased liquid content and increased spatial homogeneity with increased particle fractions. The images from X-ray tomography are analysed to obtain the distributions of particle-particle bonds (coordination number) in the system which serve to explain the observed yield stress behaviour in a qualitative manner.

}, keywords = {Capillary force, Flow curve, gel, Microstructure, Rheology, Yield stress}, issn = {0035-4511}, doi = {10.1007/s00397-020-01189-6, Early Access Date = MAR 2020}, author = {Huprikar, Sameer and Usgaonkar, Saurabh and Lele, Ashish K. and Orpe, Ashish V.} } @article {47096, title = {Role of Nd3+ concentration on the microstructure and scintillation behaviour of langbeinite sulphate}, journal = {Materials Letters}, volume = {284}, year = {2021}, month = {FEB }, pages = {128997}, type = {Article}, abstract = {

Langebeinite (K2Ca2(SO4)(3)) ceramics doped with increasing concentrations of Nd3+ ions (0.01-0.04 mol\%) was prepared by wet chemical precipitation and calcination at 800 degrees C. Thermal studies revealed high temperature stability of the phosphors. UV-VIS-NIR spectroscopic analysis of phosphors reveal strong absorption peaks representing f -\> f transitions. Direct bandgap derived from Kubelka-Munk plot was found to be similar to 5.66 eV. FTIR studies reveal tetrahedral symmetry of the SO42 ions. SEM micrographs reveal the formation of phosphors with wide particle size distribution and elemental composition was analysed using EDX studies. Scintillation studies representing a single high intensity peak around 784 nm is ascribed to I-4(9/2) -\> F-4(5/2) + H-2(9/2) transition. Langbeinite phosphor with 0.02 mol\% of Nd3+ exhibited maximum emission intensity indicating optimal concentration for scintillation studies favouring the development of NIR emitting phosphors. (c) 2020 Elsevier B.V. All rights reserved.

}, keywords = {Ceramics, Langebeinites, Luminescence, Microstructure, Neodymium, Scintillation}, issn = {0167-577X}, doi = {10.1016/j.matlet.2020.128997}, author = {Poornima, Velswamy and Mohan, Subramaniam and Uma, Tiruchirappalli Sivagnanam} } @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} }