Abstract: | The present work is an attempt to probe the elastic properties in some dielectric ceramics, by using ultrasonic pulse echo overlap technique. The base Ba6-xSm8+2xTi18O54 and Ca5Nb2TiO12 are very important dielectrics ceramics used for microwave communication as well as for substrate materials. Ultrasonic is one of the most widely used and powerful techniques to measure elastic properties of solids. The ultrasonic technique is nondestructive in nature and the measurements are relatively straightforward to perform. One unique advantantage of the ultrasonic technique is that both static and dynamic properties can be measured simultaneously. The velocity and attenuation coefficients of the ultrasonic waves propagating through a medium are related to the microscopic structure of the material and they provide valuable information about the structural changes in the system. Among the various ultrasonic techniques, the pulse echo overlap method is the most accurate and precise one. In the present case the decreased elastic properties of Cas-XMg,Nb2TiO12 and Cas-,ZnNb2TiO12 ceramics can be attributed to their mixture phases beyond x = 1. Moreover, the abrupt change in elastic properties observed for x >1 can also be correlated to the structural transformation of the materials from their phase pure form to mixture phases for higher extent of substitution of the concerned material . Ca4(ANb2Ti)012 (A = Mg, Zn) is the strongest compound with the maximum values for elastic properties . This could be due to the possible substitution of Mg/Zn ions with lesser radius [25] than Ca2+ in perovskite B-site of Ca(Cali4Nb2i4Tili4) O3 material to contribute more ordering and symmetry to the system [20]. All other compositions (x > 1) contain mixed-phases and for such mixed-phase samples, the mechanical properties are difficult to explain. |
URI: | http://dyuthi.cusat.ac.in/purl/916 |
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Dyuthi-T0069.pdf | (2.189Mb) |
Abstract: | A brief account of the several methods used for the production of thin films is presented in this Chapter. The discussions stress on the important methods used for the fabrication of a-si:H thin films. This review' also reveals ‘that almost all the general methods, like vacuum evaporation, sputtering, glow discharge and even chemical methods are currently employed for the production of a-Si:H thin films. Each method has its own advantages and disadvantages. However, certain methods are generally preferred. Subsequently a detailed account of the method used here for the preparation of amorphous silicon thin films and their hydrogenation is presented. The metal chamber used for the electrical and dielectric measurements is also described. A brief mention is made-on the electrode structure, film area and film geometry. |
Description: | Division of Thin Film, Department of Physics, Cochin University of Science and Technology |
URI: | http://dyuthi.cusat.ac.in/purl/3070 |
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Dyuthi-T1044.pdf | (5.133Mb) |
URI: | http://dyuthi.cusat.ac.in/purl/1707 |
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Dyuthi-T0075.pdf | (3.335Mb) |
Abstract: | In the present thesis a series of exhaustive investigations have been carried out on a number of crystalline samples with special reference tx> the jphase transitions exhibited by them. These include single crystals of pure, doped or deuterated specimens of certain ammonium containing crystals viz., (NH )34H(SO4)2, (NH4)2HPO4, (NH4)2Cr2O7 znui NH4H2PO4. ac/dc electrical conductivity, dielectric constant, ionic thermocurrent as wwifil as photoacoustic measurements have been carried out on most of them over a wide range of temperature. In addition investigations have been carried out in pure and doped single crystals of NaClO3 and NaNO3 using ionic thermocurrent measurements and these are presented here. Special attention has been paid to reveal the mechanism of electrical conduction in various phases of "these crystals and to evaluate the different parameters involved in the conduction as well as phase transition process. The thesis contains ten chapters ‘ |
Description: | Department of Physics, Cochin University of Science and Technology |
URI: | http://dyuthi.cusat.ac.in/purl/3659 |
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Dyuthi-T1579.pdf | (6.801Mb) |
URI: | http://dyuthi.cusat.ac.in/jspui/handle/dyuthi/1713 |
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Dyuthi-T0061.pdf | (4.171Mb) |
Abstract: | The thesis aims to present the results of the experimental investigations on the electrical properties like electrical conductivity, dielectric constant and ionic thermo~ currents in certain ammonium containing ferroelectric crystals viz. LiNH4SO4, (NH4)2SO4 and (NH4)5H(SO4)2. Special attention has been paid in revealing the mechanisms of electrical conduction in the various phases of these crystals and those asso~ ciated with the different phase transitions occurring in them, by making studies on doped, quenched and deuterated crystals. The report on the observation of two new phase transitions in (NH4) S O2 and of a similar one in ( NH4 ) H (2SO4 ) are included. The relaxation mechanisms of the impurity-vacancy complexes and the space charge phenomena in pure and doped crystals of LiNH4SO4 and (NH4)2SO4 and the observation of a new type of ionic thermo-current viz. Protonic Thermo-Current (PTC) in these crystals are also presented here. |
Description: | Department of Physics, Cochin University of Science and Technology |
URI: | http://dyuthi.cusat.ac.in/purl/3643 |
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Dyuthi-T1620.pdf | (15.83Mb) |
Abstract: | This thesis Entitled Electrical switching studies on the thin flims of polyfuran and polyacrylonitrile prepared by plasma polymerisation and vacuum evaporated amorphous silicon.A general introduction to the switching and allied phenomena is presented. Subsequently, developments of switching in thin films are described. The Mott transition is qualitatively presented. The working of a switching transitor is outlined and compared to the switching observed in thin films. Characteristic parameters of switching such as threshold voltage, time response to a, voltage pulse, and delay time are described. The various switching configurations commonly used are discussed. The mechanisms used to explain the switching behaviour like thermal, electrothermal and purely electronic are reviewed. Finally the scope, feasibility and the importance of polymer thin films in switching are highlighted. |
Description: | Department of Physics, Division of Thin Film, Cochin University of Science and Tecnology |
URI: | http://dyuthi.cusat.ac.in/purl/3028 |
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Dyuthi-T1003.pdf | (4.438Mb) |
Abstract: | The primary aim of these investigations was to probe the elecnuchemical and material science aspects of some selected metal phthalocyanines(MPcs).Metal phthalocyanines are characterised by a unique planar molecular structure. As a single class of compounds they have been the subject of ever increasing number of physicochemical and technological investigations. During the last two decades the literature on these compounds was flooded by an outpour of original publications and patents. Almost every branch of materials science has benefited by their application-swface coating, printing, electrophotography, photoelectrochemistry, electronics and medicine to name a few.The present study was confined to the electrical and electrochemical properties of cobalt, nickel, zinc. iron and copper phthalocyanines. The use of soluble Pes as corrosion inhibitor for aluminium was also investigated.In the introductory section of the thesis, the work done so far on MPcs is reviewed. In this review emphasis is given to their general methods of synthesis and the physicochemical properties.In phthalocyanine chemistry one of the formidable tasks is the isolation of singular species. In the second chapter the methods of synthesis and purification are presented with necessary experimental details.The studies on plasma modified films of CoPe, FePc, ZnPc. NiPc and CuPc are also presented.Modification of electron transfer process by such films for reversible redox systems is taken as the criterion to establish enhanced electrocatalytic activity.Metal phthalocyanines are p- type semiconductors and the conductivity is enhanced by doping with iodine. The effect of doping on the activation energy of the conduction process is evaluated by measuring the temperature dependent variation of conductivity. Effect of thennal treatment on iodine doped CoPc is investigated by DSC,magnetic susceptibility, IR, ESR and electronic spectra. The elecnucatalytic activity of such doped materials was probed by cyclic voltammetry.The electron transfer mediation characteristics of MPc films depend on the film thickness. The influence of reducing the effective thickness of the MPc film by dispersing it into a conductive polymeric matrix was investigated. Tetrasulphonated cobalt phthalocyanine (CoTSP) was electrostatically immobilised into polyaniline and poly(o-toluidine) under varied conditions.The studies on corrosion inhibition of aluminium by CoTSP and CuTSP and By virtue of their anionic character they are soluble in water and are strongly adsorbed on aluminium. Hence they can act as corrosion inhibitors. CoTSP is also known to catalyze the reduction of dioxygen.This reaction can accelerate the anodic dissolution of metal as a complementary reaction. The influence of these conflicting properties of CoTSP on the corrosion of aluminium was studied and compared with those of CuTSP.In the course of these investigations a number of gadgets like cell for measuring the electrical conductivity of solids under non-isothermal conditions, low power rf oscillator and a rotating disc electrode were fabricated. |
Description: | Department of Applied Chemistry, Cochin University of Science and Technology |
URI: | http://dyuthi.cusat.ac.in/purl/2647 |
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Dyuthi-T0707.pdf | (6.160Mb) |
URI: | http://dyuthi.cusat.ac.in/purl/1731 |
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Dyuthi-T0126.pdf | (2.482Mb) |
Abstract: | The thesis deals with the preparation of chemical, optical, thermal and electrical characterization of five compounds, namely metal free naphthalocyanine, vanadyl napthalocyanine, zinc naphlocyanine, europium dinaphthalocyanine, and europium diphthalocyanine in the pristine and iodine-doped forms. Two important technological properties of these compounds have been investigated. The electrical properties are important in applications sensors and semiconductor lasers. Opto-thermal properties assume significance for optical imaging and data recording. The electrical properties were investigated by dc and ac techniques. This work has revealed some novel information on the conduction mechanism in five macrocyclic compounds and their iodine-doped forms. Also useful data on the thermal diffusivity of the target compounds have been obtained by optical techniques. |
URI: | http://dyuthi.cusat.ac.in/purl/16 |
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Dyuthi-T0068.pdf | (1.350Mb) |
Abstract: | Metal phthalocyanines have some unique optical properties which are exploited for dyeing fibers and films used in applicationslike dye lasing and optical information storage. Aggregation of dye molecules modifies their absorption and emission spectra with concomitant degradation in their energy transfer characteristics. MPcs as such have poor processability and are seldom used in solid matrices. The finest energy transfer characteristics are shown by the monomers of metal phthalocyanines. In the third chapter of this thesis the studies on two series of metal phthalocyanines are repoted |
Description: | Department of Applied Chemistry, Cochin University of Science And Technology |
URI: | http://dyuthi.cusat.ac.in/purl/3618 |
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Dyuthi-T1597.pdf | (2.258Mb) |
Description: | Division of Marine Biology, Microbiology and Biochemistry, School of Marine Sciences, Cochin University of Science and Technology |
URI: | http://dyuthi.cusat.ac.in/xmlui/purl/2060 |
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Dyuthi-T0405.pdf | (8.939Mb) |
URI: | http://dyuthi.cusat.ac.in/purl/5289 |
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Dyuthi T-2325.pdf | (9.484Mb) |
Abstract: | HINDI |
Description: | Department of Hindi Cochin University of Science & Technology |
URI: | http://dyuthi.cusat.ac.in/purl/4784 |
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Dyuthi-T1881.pdf | (9.024Mb) |
Abstract: | Information and Communication Technologies (ICTs) have a dramatic impact on the tourism industry because they force this sector as a whole to rethink the way in which it organises its business . In the light of such rethinking within the tourism industry, this study has focussed on the Small and Medium Tourism Enterprises (SMTEs) in two island destinations, namely Mauritius and Andaman Islands, India.Suggestions. The findings conceming SMTEs in Mauritius and Andaman Islands have been compared to make some destination-specific inferences. The relevance of the findings has been discussed with reference to the SMTEs in the two destinations as well as the possible acceptability in other comparable settings. Suggestions have been made for further research in SMTEs’ use of the Internet for marketing function. |
Description: | School of Management Studies, Cochin University of Science and Technology. |
URI: | http://dyuthi.cusat.ac.in/purl/2898 |
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Dyuthi-T0894.pdf | (14.55Mb) |
URI: | http://dyuthi.cusat.ac.in/purl/5286 |
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Dyuthi T-2322.pdf | (3.441Mb) |
URI: | http://dyuthi.cusat.ac.in/purl/5284 |
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Dyuthi T-2320.pdf | (4.467Mb) |
Abstract: | Emotional intelligence is very important in organisations and the ability to manage feelings and handle stress is an important aspect of El. Even though a number of studies have been done to prove that E1 is related to organisationally relevant variables like leadership effectiveness, job satisfaction, performance, career success etc., and the theoretical grounding for emotional intelligence-stress-relationship seems sound, only a few studies have been done to establish this linkage. This study is an attempt to measure emotional intelligence and organisational role stress of managers working in industrial organisations and to examine the relationship between Emotional Intelligence and Organisational Role Stress. It also attempts to explore the influence of personal and occupational variables viz., age, education, gender, marital status, experience, department, type of organisation and designation on emotional intelligence. The investigator has also examined the difference in the level of role stress experienced by junior, middle and senior-level managers. The main objective of the study is to examine the relationship between emotional intelligence and organisational role stress. |
Description: | School of Management Studies, Cochin University of Science and Technology |
URI: | http://dyuthi.cusat.ac.in/purl/3228 |
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Dyuthi-T1202.pdf | (2.091Mb) |
URI: | http://dyuthi.cusat.ac.in/purl/5419 |
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Dyuthi T-2460.pdf | (10.30Mb) |
Abstract: | The The The The growing demandgrowing demandgrowing demandgrowing demandgrowing demandgrowing demandgrowing demandgrowing demandgrowing demandgrowing demandgrowing demandgrowing demandgrowing demand for the expansion of for the expansion of for the expansion of for the expansion of for the expansion of for the expansion of for the expansion of for the expansion of for the expansion of for the expansion of for the expansion of for the expansion of for the expansion of for the expansion of for the expansion of for the expansion of for the expansion of for the expansion of for the expansion of for the expansion of for the expansion of the the the the publicly funded system publicly funded system publicly funded system publicly funded system publicly funded system publicly funded system publicly funded system publicly funded system publicly funded system publicly funded system publicly funded system publicly funded system publicly funded system publicly funded system publicly funded system publicly funded system publicly funded system publicly funded system publicly funded system publicly funded system publicly funded system publicly funded system publicly funded system of education as merit and free goodof education as merit and free goodof education as merit and free goodof education as merit and free goodof education as merit and free goodof education as merit and free goodof education as merit and free goodof education as merit and free goodof education as merit and free goodof education as merit and free goodof education as merit and free goodof education as merit and free goodof education as merit and free goodof education as merit and free goodof education as merit and free goodof education as merit and free goodof education as merit and free goodof education as merit and free goodof education as merit and free goodof education as merit and free goodof education as merit and free goodof education as merit and free goodof education as merit and free goodof education as merit and free goodof education as merit and free goodof education as merit and free goodof education as merit and free goodof education as merit and free goodof education as merit and free goodof education as merit and free goodof education as merit and free goodof education as merit and free goodof education as merit and free goods emphasized emphasized emphasized emphasized emphasized emphasized emphasized emphasized emphasized emphasized on large allocation large allocation large allocation large allocation large allocation large allocation large allocation large allocation large allocation large allocation large allocation large allocation large allocation large allocation large allocation large allocation large allocation of funds on of funds on of funds on of funds on of funds on of funds on of funds on of funds on of funds on of funds on of funds for promoting educationfor promoting educationfor promoting educationfor promoting educationfor promoting educationfor promoting educationfor promoting educationfor promoting educationfor promoting educationfor promoting educationfor promoting educationfor promoting educationfor promoting educationfor promoting educationfor promoting educationfor promoting educationfor promoting educationfor promoting educationfor promoting educationfor promoting educationfor promoting educationfor promoting education. 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The presumption of sumption of sumption of sumption of sumption of sumption of sumption of sumption of sumption of sumption of sumption of assured assured assured assured assured assured assured assured and guaranteed and guaranteed and guaranteed and guaranteed and guaranteed and guaranteed and guaranteed and guaranteed and guaranteed and guaranteed and guaranteed and guaranteed and guaranteed and guaranteed and guaranteed employment in employment in employment in employment in employment in employment in employment in employment in employment in employment in employment in employment in the Middle East the Middle East the Middle East the Middle East the Middle East the Middle East the Middle East the Middle East the Middle East the Middle East the Middle East the Middle East the Middle East the Middle East the Middle East the Middle East and also in other and also in other and also in other and also in other and also in other and also in other and also in other and also in other and also in other and also in other and also in other and also in other and also in other and also in other and also in other and also in other and also in other and also in other countries increased furthecountries increased furthecountries increased furthecountries increased furthecountries increased furthecountries increased furthecountries increased furthecountries increased furthecountries increased furthecountries increased furthecountries increased furthecountries increased furthecountries increased furthecountries increased furthecountries increased furthecountries increased furthecountries increased furthecountries increased furthecountries increased furthecountries increased furthecountries increased furthecountries increased furthecountries increased furthecountries increased furthecountries increased further the scope of higher educationthe scope of higher educationthe scope of higher educationthe scope of higher educationthe scope of higher educationthe scope of higher educationthe scope of higher educationthe scope of higher educationthe scope of higher educationthe scope of higher educationthe scope of higher educationthe scope of higher educationthe scope of higher educationthe scope of higher educationthe scope of higher educationthe scope of higher educationthe scope of higher educationthe scope of higher educationthe scope of higher educationthe scope of higher educationthe scope of higher educationthe scope of higher educationthe scope of higher educationthe scope of higher educationthe scope of higher educationthe scope of higher educationthe scope of higher educationthe scope of higher education in KeralaKeralaKeralaKeralaKeralaKerala, particularparticularparticularparticularparticularparticularparticularparticularparticularparticularly the technical educationthe technical educationthe technical educationthe technical educationthe technical educationthe technical educationthe technical educationthe technical educationthe technical educationthe technical educationthe technical educationthe technical educationthe technical educationthe technical educationthe technical educationthe technical educationthe technical educationthe technical educationthe |
URI: | http://dyuthi.cusat.ac.in/purl/5054 |
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Dyuthi-T2117.pdf | (12.98Mb) |
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