Submitted by Angela Maria de Oliveira (amolivei@uepg.br) on 2019-02-07T11:30:29Z No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Eliziane Manosso Streiechen.pdf: 3519479 bytes, checksum: bc2afe5b8688c4e6e13ac659934094d6 (MD5) / Made available in DSpace on 2019-02-07T11:30:29Z (GMT). No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Eliziane Manosso Streiechen.pdf: 3519479 bytes, checksum: bc2afe5b8688c4e6e13ac659934094d6 (MD5) Previous issue date: 2018-12-07 / Esta pesquisa teve como objetivo analisar o percurso escolar de um estudante ouvinte, bilíngue e com altas habilidades/superdotação (AH/S), filho de mãe surda, que vive em um contexto familiar, onde há cinco línguas envolvidas: Ucraniana, Portuguesa, Alemã, Inglesa e a Libras. A questão problemática investigada é: quais as implicações que esse contexto multilíngue, bem como as AH/S podem trazer para a escolarização do sujeito? O histórico do percurso escolar analisado inicia-se no 1º ano e segue até o 9º ano do ensino fundamental, que compreende as idades entre seis e quatorze anos do sujeito. A pesquisa foi realizada em duas escolas localizadas em uma cidade do interior do Estado do Paraná, onde o sujeito reside com os pais e avós maternos. Os dados da pesquisa foram coletados por meio de entrevistas com professores, psicólogos, diretores, equipe pedagógica, familiares e com o próprio sujeito. Dados de outros estudos (STREIECHEN, 2014) também serão retomados com a finalidade de discutirmos questões linguísticas e escolares do sujeito em questão. Esta pesquisa é de natureza qualitativa, de cunho etnográfico, apoiada em um estudo de caso. A Análise Textual Discursiva (MORAES; GALIAZZI, 2016) foi a Metodologia utilizada para a análise dos dados, uma vez que esse modelo oferece a oportunidade de o pesquisador mergulhar, de um modo mais profundo, na interpretação dos dados, com o compromisso de gerar novas teorias e/ou pressupostos. A Psicanálise foi a Teoria utilizada para respaldar a análise dos dados, visto que essa abordagem aponta conceitos de interesse para a compreensão da relação professor/aluno, entre os quais está a importância da fala e do desejo do educando na aquisição do conhecimento, bem como da escuta mais atenta por parte dos docentes para conhecer o aluno em sua plenitude. Os resultados da pesquisa indicam, entre outros aspectos que: os desafios de aprendizagem do sujeito, nos anos iniciais, não foram relacionados às AH/S, pelo fato de os professores não as identificarem; seu modo peculiar de escrever não foi associado ao seu contexto multilinguístico e/ou às AH/S, mas tomada como erro, uma vez que os professores desconheciam as línguas que envolviam esse sujeito; a ênfase dos docentes estava mais inclinada às dificuldades e menos às habilidades desse aluno. Isso fez com que as dificuldades se acentuassem cada vez mais, levando o educando a desenvolver repúdio pela escola e um total desinteresse pelos estudos. Nossas conclusões inferem para a dificuldade que alguns docentes encontram ao se depararem com alunos com condições peculiares de aprendizagem, visto que, engessados em suas estratégias tradicionalistas e seculares, ficam impossibilitados de ouvir e conhecer o aluno, desconsiderando a vida que fica além dos muros da escola. Portanto, nossa tese é de que, por não carregarem o estereótipo da deficiência, tanto os alunos com AH/S quanto os filhos de pais surdos, tornam-se invisíveis aos olhos de muitos educadores, ficando à margem e fadados ao ‘fracasso’. Defenderemos, portanto, a importância de esses alunos receberem uma atenção especial, por parte da escola, a fim de que não sejam excluídos de um efetivo processo de ensino e aprendizagem. / This study aimed at analyzing the school trajectory of a hearing student, who: is bilingual with high abilities/giftedness (HA/G); has a deaf mother; lives in a familiar context, in which five languages are involved: Ukrainian, Polish, German, English, and Libras. The research question that guided this study was: what are the implications that this multilingual context, as well as the HA/G may have on the participant's schooling? The participant's school trajectory analyzed encompassed the period from 1st to 9th year of the elementary school, at which the participant’s age varied from six to fourteen years old. The study was conducted in two schools located in countryside of Paraná, where the participant resided with his parents and maternal grandparents. The data were collected through interviews with teachers, psychologists, principals, pedagogical staff, family members and the participant himself. Extra data from other studies (STREIECHEN, 2014) were also used in order to discuss the participant’s linguistic and school issues. This is a qualitative study, ethnographic in nature, supported by a case study. The Discursive Textual Analysis (MORAES; GALIAZZI, 2016) was the methodological framework adopted to analyze data in this study, considering that such framework allows the researcher to interpret the data further, with the commitment to generate new theories and/or assumptions. Psychoanalysis was the theory adopted to support data analysis, since this approach points out concepts of interest for comprehending the relationship between teacher and student, to cite: the importance of student's speech and desire to acquire knowledge, as well as of teacher's most attentive listening to become acquainted with a student in his/her amplitude. Results indicated, among other aspects, that: the participant's learning challenges, in the initial school years, were not related to the HA/G, since teachers did not identify such abilities; the participant's peculiar written style was not associated with his multilingual context and/or with the HA/G, but considered as erroneous, once the teachers were not acquainted with the languages experienced by the participant; the teachers' priority relied on the participant's difficulties rather than his abilities. The aspects aforementioned suggested that the participant' struggles intensified more and more, leading him to develop an antipathy for the school and a total indifference for studying. The conclusions pointed to the difficulty that some teachers encounter when they have to work with students with peculiar learning conditions. Such teachers, due to their traditionalist and secular strategies, are unable to listen and become acquainted with their students, disregarding their lives beyond the school walls. Therefore, the thesis of this study is that, because they do not carry the stereotype of disability, both students with HA/G and children of deaf parents become invisible in the eyes of many educators, being isolated and doomed to failure. This study highlights that these students should receive special attention in the scholar environment, so that they are not excluded from an effective teaching and learning process.

The acquisition and maintenance of human capital are considered key drivers of productivity and economic growth. However, recent literature shows that in the case of Russia, this relationship is not obvious, which raises a question concerning the nature of human capital accumulation, despite the significant expansion of tertiary education in this country. The existing literature, much of it relying on a theory of market imperfections, tends to explain low incidences of training by the lack of employer incentives to invest in the human capital of their employees. This dissertation adds to this view confirming the negative role of ‘bad’ jobs and social origins in obstructing employees from skills development in BRIC-like countries. Skills training in Russia is constrained by stratifying occupational forces comprising jobs with low requirements to skills development, which conserves the working population in generic labour. This reveals the phenomenon of skills polarisation ‘at the bottom’ in a late-industrial country, thus, contributing to the growing critique of the knowledge society theory. For those few workers who occupy ‘good’ jobs, skills training is strongly linked to personal-specific traits, such as qualifications and computer and language skills; and this is common in both Russia and India. However, in contrast to Russia, India is still forming their knowledge society. This is confirmed by the statistically significant impact of socio-demographic origins (e.g. age, household size, marital status, and religion) on the incidence of training, which reveals a crucial role of ascription in human capital acquisition in contemporary India. The present thesis contributes to the growing literature on structural prerequisites for successful advancement and the contradictory development of the BRIC countries.

Text in English with abstracts in English, TshiVenda and Afrikaans / This research sought to propose a personnel selection model encompassing the influence of cognitive intelligence, ability emotional intelligence, trait emotional intelligence, and personality on job performance. Using a quantitative cross-sectional research design, the researcher investigated the interrelationships between the variables relevant to the study using a convenience sample of N = 299 that consisted of Zimbabwean supervisory and professionally qualified and experienced specialists of different ages and genders, and from different job tenures, and job types. To get a true picture of the relationships between the predictor and criterion variables, the interaction (moderating) effects between the sociodemographic variables (age, gender, job tenure, and job type) and the predictor variables (cognitive intelligence, ability emotional intelligence, trait emotional intelligence, and personality) in predicting the criterion of job performance were also examined. The researcher used correlational and inferential multivariate statistical analysis (structural equation modelling, regression analyses, and tests for significant mean differences) to test the research hypotheses. The results from the study indicated that cognitive intelligence was the best predictor of job performance, followed by ability emotional intelligence, and then by personality. Trait emotional intelligence could not account for any variance in job performance. The results showed significant interaction effects between personality and job tenure (judging-perceiving personality types) and job types (extraversion-introversion personality types) in predicting job performance. Significant sociodemographic mean differences in the levels of the predictor variables were also identified. The identified predictive powers of the variables, the interaction effects between the identified sociodemographic and the predictor variables in predicting job performance, and the significant sociodemographic mean differences in the levels of predictor variables need to be considered for personnel selection practices in order to understand the nature of variables that may enhance or inhibit job performance. From a theoretical perspective, the research advanced personnel selection theory by empirically and scientifically identifying the core elements of personnel selection, and proposing a personnel selection model for use by industrial psychologists and organisations. / Ṱhoḓisiso heyi i ṱoḓa u dzinginya tshiedza tsha maitele ane a shumiswa hu tshi tholwa vhashumi ane a katela ṱhuṱhuwedzo ya vhukoni ha muhumbulo nga u angaredza, vhukoni ha u dzhiela nṱha na u langula vhupfiwa, vhukoni ha u dzhiela nṱha na u langula vhupfiwa kha zwithu zwine zwa fana, na vhuḓifari kha kushumele mushumoni. Hu tshi khou shumiswa maitele a ṱhoḓisiso a nḓila yo dzudzanaho ya u kuvhanganya na u saukanya data u bva kha zwiko zwo fhambanaho, u guda zwine zwa khou itea kha tshigwada nga tshenetsho tshifhinga, muṱoḓisisi o ṱoḓisisa vhushaka vhukati ha zwithu zwine zwa fhambana zwo teaho kha ngudo, hu tshi khou shumiswa sambula ya vhathu vhane zwa leluwa u vha swikelela N = 299, i katelaho vhaṱoli na vhathu vha re na ndalukano dza mushumo na vhomakone vha re na tshenzhelo vha vhukale ho fhambanaho, mbeu, tshifhinga tshe vha shuma na tshaka dza mushumo kha vhathu vha Zimbabwe. U wana tshifanyiso tsha vhukuma tsha vhushaka vhukati ha zwithu zwine zwa khou humbulelwa na zwithu zwo ḓisendekaho nga zwiṅwe, ṱhuṱhuwedzo ine ya itea khathihi vhukati ha zwithu zwivhili hune u ṱangana hazwo zwa vha na ndeme khulwane u fhirisa zwipiḓa vhukati ha zwiṱaluli zwa vhathu (vhukale, mbeu, tshifhinga tshe vhashuma, lushaka lwa mushumo) na zwithu zwine zwa khou humbulelwa (vhukoni ha muhumbulo nga u angaredza, vhukoni ha u dzhiela nṱha na u langula vhupfiwa ,vhukoni ha u dzhiela nṱha na u langula vhupfiwa kha zwithu zwine zwa fana, na vhuḓifari) kha u humbulela nḓila dza kushumele mushumoni na dzone dzo ṱoḓuluswa. Muṱoḓisisi o shumisa khoriḽeshinala na siṱatisiṱiki tsha iniferinshiaḽa maḽithivareithi musi a tshi khou saukanya (tshiedza tsha siṱatisisṱika, maitele a siṱatisiṱika a u humbulela vhushaka vhukati ha zwithu, na u linga ndeme ya phambano ya siṱatisiṱika) u linga u vhonela phanḓa kha khonadzeo ya ṱhoḓisiso. Mvelelo u bva kha ngudo dzo sumbedzisa uri vhukoni ha muhumbulo nga u angaredza ho vha tshishumiswa tsha kushumele, ha tevhelwa nga vhukoni ha u dzhiela nṱha na u langula vhupfiwa, ha fhedzisela nga vhuḓifari. Vhukoni ha u dzhiela nṱha na u langula vhupfiwa kha zwithu zwine zwa fana a vhu khwaṱhisedzi phambano kha kushumele mushumoni. Mvelelo dzo sumbedzisa tshanduko ine ya vha hone kha tshithu tshithihi i ḓitika nda ndeme ya tshiṅwe tshithu vhukati ha vhuḓifari na tshifhinga tshe vha shuma (mihumbulo ine ra vha nayo ri tshi sedza zwithu na nḓila ine ra tshilisa ngayo ḓuvha ḽiṅwe na ḽiiṅwe) na tshaka dza mushumo (na tshaka dza vhuḓifari dzo sedzaho nga nnḓa na nga ngomu) kha u humbulela kushumele. Ndeme ya phambano vhukati ha zwigwada zwivhili zwa matshilisano na vhathu kha zwithu zwine zwa khou humbulelwa na zwone zwo dovha zwa topolwa. Zwithu zwo topolwaho zwine zwa khou lavhelelwa, zwithu zwivhili zwo ḓiimisaho nga zwoṱhe zwi tshi ṱangana arali ṱhuṱhuwedzo ya tshithu tshithihi i tshi fhambana yo ḓitika nga vhuimo ha zwiṅwe zwithu vhukati ha zwithu zwa matshilisano na vhathu na zwithu zwine zwa khou humbulelwa, ṱhoḓea dzine dza tea u dzhielwa nṱha kha maitele ane a shumiswa hu tshi tholwa vhashumi u itela u pfesesa lushaka lwa zwithu zwine zwa nga engedza kana u thivhela kushumele. U bva kha mihumbulo ine ya khou ṱoḓisiswa, ṱhoḓisiso yo ṱuṱuwedza thyeori ya maitele ane a shumiswa hu tshi tholwa vhashumi nga u sedza na u topola zwithu zwa ndeme zwa maitele na milayo ya sainthifiki, na u dzinginya tshiedza tsha u thola vhashumi u itela u shumiswa nga vhaḓivhi vha muhumbulo vhane vha shuma na kutshilele na kushumele kha zwiimiswa. / Hierdie navorsing het gepoog om ʼn model vir personeelkeuring te ontwikkel op grond van die invloed van kognitiewe intelligensie, vermoë- emosionele intelligensie; eienskap- emosionele intelligensie en persoonlikheid op werkprestasie. Die navorser het ʼn kwantitatiewe dwarssnitnavorsingsontwerp gebruik, en die onderlinge verbande tussen die toepaslike veranderlikes ondersoek. Die geriefsteekproef van N = 299 het bestaan uit Zimbabwiese toesighoudende, opgeleide en ervare spesialiste van verskillende ouderdomme en uit beide geslagte wat verskillende dienstydperke agter die rug het, en uiteenlopende poste beklee. Om ʼn getroue beeld van die verbande tussen die voorspeller- en kriteriumveranderlikes te kry, is die interaksie- (modererende) effekte tussen die sosiaal-demografiese veranderlikes (ouderdom, geslag, dienstydperk en soort werk) en die voorspellerveranderlikes (kognitiewe intelligensie, vermoë- emosionele intelligensie; eienskap- emosionele intelligensie en persoonlikheid) in die voorspelling van die kriterium van werkprestasie ook ondersoek. Die navorser het ʼn korrelasie- en afgeleide, meerwisselende statistiese ontleding (strukturele vergelykingsmodellering, regressieontledings en toetse vir betekenisvolle gemiddeldeverskille) gedoen om die navorsingshipotese te toets. Die uitslag van die studie toon dat kognitiewe intelligensie die beste voorspeller van werkprestasie is, gevolg deur vermoë- emosionele intelligensie en persoonlikheid. Eienskap- emosionele intelligensie kon geen rekenskap van enige veranderlike in werkprestasie gee nie. Volgens die resultate is daar betekenisvolle interaksie-effekte tussen persoonlikheid en dienstydperk (keurder-waarnemer persoonlikheidstipes) en die soort werk (ekstroversie-introversiepersoonlikheidstipes) in die voorspelling van werkprestasie. Betekenisvolle sosiaal-demografiese gemiddeldeverskille in die vlakke van die voorspellerveranderlikes is ook aangedui. Die voorspellende kragte van die veranderlikes, die interaksie-effekte tussen die sosiaal-demografiese en die voorspellerveranderlikes in die voorspelling van werkprestasie sowel as die beduidende sosiaal-demografiese gemiddeldeverskille in die vlak van voorspellerveranderlikes moet vir personeelkeuringspraktyke in ag geneem word om die aard van veranderlikes wat werkprestasie kan verhoog of inhibeer, te verstaan. Uit ʼn teoretiese oogpunt het die navorsing die persoonkeuringsteorie gevolg deur die kernelemente van personeelkeuring op ʼn empiriese en wetenskaplike wyse aan te toon, en ʼn personeelkeuringsmodel vir bedryfsielkundiges en organisasies aan te bied. / Industrial and Organisational Psychology / D. Phil. (Consulting Psychology)

The parallel active filter (PAF) is the modern solution for harmonic current mitigation and reactive power compensation of nonlinear loads. This thesis is dedicated to detailed analysis, design, control, and implementation of a PAF for a 3- phase 3-wire rectifier load. Specifically, the current regulator and switching ripple filter (SRF) are thoroughly investigated. A novel discrete time hysteresis current regulator with multi-rate current sampling and flexible PWM output, DHCR3, is proposed. DHCR3 exhibits a high bandwidth while limiting the maximum switching frequency for thermal stability and its implementation is simple. In addition to the development of DHCR3, in the thesis state of the art current regulation methods are considered and thoroughly compared with DHCR3. Since the current regulator type determines the SRF topology choice, various SRF topologies are considered and a thorough design study is conducted and SRF topology selection and parameter determination methods are presented via numerical examples. Through a PAF designed for a 10kW diode/thyristor rectifier load, the superior performance of DHCR3 is verified through simulations and experiments and via comparison to other current regulators. The sufficient switching ripple attenuation of the SRF structures for the designed PAF system and the overall performance of the designed and built PAF system are demonstrated via detailed computer simulations and laboratory experiments. This thesis aids the PAF current regulator and SRF selection, design, and implementation.

This study is concerned with the sexual abuse of enslaved women and girls by white men in the antebellum South. Interviews conducted by the Federal Writers’ Project in the 1930s are studied alongside nineteenth-century narratives of the formerly enslaved in order to make calculations of the scale of abuse in the South, but also to discover which conditions, social spaces and situations were, and possibly still are, most conducive to the sexual abuse of women and girls. This thesis is separated into two parts. Part One establishes a methodology for working with testimony of the formerly enslaved and determines the scale of sexual abuse using all available 1930s interviews with people who had lived in Louisiana and Texas under slavery. This systematic quantitative analysis is a key foundation from which to interpret the testimony of abuse that is explored according to different forms of sexual violence in Part Two. It is argued that abuse was endemic in the South, and occurred on a scale that was much higher than has been argued in previous studies. Enslaved people could experience a range of white male sexually abusive behaviours: rape, sexual slavery and forced breeding receive particular attention in this study due to the frequency with which they were mentioned by the formerly enslaved. These abuses are conceptualised as existing on a continuum of sexual violence that, alongside other less frequently mentioned practices, pervaded the lives of all enslaved people. Common features existed along the continuum. Abuse was intergenerational in nature for both the abusers and the abused. Light-skinned enslaved children born of rape were far more likely to become victims of abuse themselves and young enslaved girls were prematurely sexualised. Sexual abuse was brought into the white domestic space through the institution of sexual slavery, white children were thus unconsciously schooled in the abusive sexual mores of southern society from an early age. Abuse was quite open among white male family members. Other institutions existed that normalised and legitimised abuse, such as the fancy-girl trade and sexual interference through forced breeding practices that included eugenic manipulation and the use of ‘studs’. Despite this, enslaved women showed remarkable levels of emotional survival and initial reflections are made on the ways in which women could resist and cope with sexual abuse. Testimony suggests that abuse was discussed amongst the black community, support was rarely denied to victims, and there was no stigma was attached to children born of rape. With recent revelations on the scale of the institutionalised sexual abuse of women and children, as well as vast modern sex-trafficking networks, there are special opportunities presented through the current cultural climate in order to understand the southern experience. The South is reframed as a ‘culture of abuse’ where sexual violence against enslaved people was naturalised and culturally reproduced.

No description available.

Despite its chequered interpretational history, the book of Shîr ha-Shîrîm (Song of Songs) in the Hebrew Bible and Christian Old Testament has still not come to its fullest religious potential. The reason is that it has mainly served relatively closed religious traditions defined by the exclusion of those that have reacted against it. As the text of Song of Songs itself does not explicitly testify to any religiosity, these communities have understood it religiously by projecting their own predetermined needs and beliefs onto it. The text does, however, suggest several layers in the history of its formation, representing different levels of consciousness and stages of religiosity. In the postmodern globalising context where the importance of interfaith understanding is increasingly realised and the nature of human religiosity is constantly redefined in terms of ever-broadening horizons, the religiosity of the book has been stretched as wide as possible by also taking into consideration the ancient contextual influences which could have left their traces on the unconscious mind of its author(s) and redactor(s). To this end, the transpersonal psychological theory of Kenneth Wilber as interpreted by Michael Washburn has been used. Wilber’s inclusive view of religiosity respects all its forms as developmentally appropriate expressions of experiences of the divine which should all be taken seriously. The explicit “absence” of the divine in Song of Songs has been so conspicuous that it has ironically made it more present and led to a greater search for the Ineffable whose whispering and footprints are discernible in relation to the level of consciousness. Exploring the religiosity of Song of Songs in this way then becomes an exercise in being more sensitive to the presence of the divine in all other areas of life as well. Traditional polarities such as sexuality and religiosity are dissolved at the same time and proven to coincide as two aspects of the same experience. Not only does erotic love open one’s eyes to the divine in nature as the body of God, but one also encounters the divine in the body. / Biblical and Ancient Studies / D. Th. (Old Testament)

L'objectif de ce mémoire est d'analyser les différents éléments humoristiques présents dans le roman Dios se lia ido de Javier Garcia Sánchez. Cette œuvre allie la tristesse et l'humour dans des réflexions sur la vie, la solitude, le sexe et le jeu d'échecs dans la vie quotidienne d'un homme solitaire dans la quarantaine, qui devient l'univers exclusif du lecteur. On explore et critique l'évolution de la société espagnole contemporaine qui commence avec la transition démocratique à l'aide, entre autres, du grotesque, des jeux de mots, de la parodie et de l'ironie. On aborde également d'autres thèmes sociaux du point de vue d'un homme ordinaire avec ses préjugés et ses fausses interprétations. Dans ce roman, l'humour possède une fonction récréative mais il mène également à une réflexion sur les valeurs et la vie à une époque de scepticisme et de décadence.

Rare-earth nickel borocarbids RNi2B2C are particularly suitable for investigations on one of the most interesting problems in modern solid-state physics: these compounds display competition and coexistence of superconductivity and magnetism. Depending on the R3+ ion, the transition temperatures are in an experimentally easy accessible range of 1 K to 25 K. This thesis presents experimental studies on the interplay of both ordering phenomena. Neutron diffraction is used to determine the magnetic order and the resulting changes of the crystal structure. Experiments are performed on polycrystalline and single crystal samples in dependence on temperature and external magnetic fields. The Ni-B stoichiometry of the tetragonal RNi2B2C compounds is systematically varied and the magnetic R3+ ions are partially substituted by other magnetic or nonmagnetic R?3+ ions. The experimental results are compared with macroscopic magnetic and electrical properties. For HoNi2B2C three different magnetic structures are found in a narrow temperature range. While for two magnetic structures the Ho3+ moments are modulated along the c axis, a third magnetic structure with a modulation in a direction is observed. Both, partial substitution of Ho3+ ions and variation of the Ni-B stoichiometry, strongly modify the formation of these different types of magnetic order. The comparison with the concomitant changes of the superconducting properties yields the following scenario for HoNi2B2C-based compounds: superconductivity coexists with both magnetic structures with modulations in c direction. However, the onset of magnetic order weakens the superconductivity. For the magnetic structure with modulation along the a axis, components of the magnetic moments arise in c direction. The resulting local magnetic fields on Ni sites yield a strong suppression of the superconductivity. The observed competition between superconductivity and the magnetic structure with modulation along the a axis strongly suggests that the modification of the electronic structure due to the superconducting state influences the magnetic ordering. As a further impact of the magnetism in RNi2B2C compounds with R = Ho, Dy, Tb and Er changes of the crystal structure are investigated. Using high-resolution neutron diffraction, tetragonal-to-orthorhombic lattice distortions are found. They are induced by those magnetic structures with either parallel or anti-parallel alignement of R3+ magnetic moments. The direction of the lattice distortions, the dependence of their size on the square of the effective ordered magnetic moment and on the type of the R3+ ions indicate that the magneto-elastic interactions are determined by crystal-field effects. This fact also facilitates the elucidation of the magnetic phase diagrams by neutron diffraction experiments in external magnetic fields. For a given phase, absence or presence of magneto-elastic lattice distortions restrict the set of possible magnetic structures. For HoNi2B2C the magnetic phases reported in literature are confirmed. The experimental results for DyNi2B2C are interpreted using a simple model to determine the magnetic structures. Based on mean field calculations, the differences in the magnetic structures for increasing and decreasing magnetic fields can be understood as very strong hysteresis effects in connection with first-order phase transitions. / Seltenerd-Nickel-Borkarbid-Verbindungen RNi2B2C sind bestens zur Untersuchung eines der interessantesten Probleme der modernen Festkörperphysik geeignet: Diese Substanzen weisen Konkurrenz und Koexistenz von Supraleitung und Magnetismus auf, wobei die vom R3+-Ion abhängigen Übergangstemperaturen in einem experimentell gut zugänglichen Bereich von 1 K bis 25 K liegen. Die vorliegende Dissertation stellt experimentelle Arbeiten zum Wechselspiel der beiden Ordnungsphänomene vor. Für poly- und einkristalline Proben werden die magnetischen Ordnungen und resultierende Veränderungen der Kristallstruktur mittels Neutronendiffraktion in Abhängigkeit von der Temperatur und vom äußeren Magnetfeld bestimmt und mit den makroskopischen magnetischen und elektrischen Eigenschaften verglichen. Hierbei werden die tetragonalen RNi2B2C-Verbindungen gezielt in ihrer Ni-B-Stöchiometrie variiert sowie die magnetischen R3+-Ionen partiell durch andere magnetische als auch unmagnetische R?3+-Ionen substituiert. Für HoNi2B2C werden in einem engen Temperaturbereich drei verschiedene magnetische Strukturen nachgewiesen. Während in zwei magnetischen Ordnungen die Ho3+-Momente entlang der c-Achse moduliert sind, wird für die dritte magnetische Ordnung eine Modulation in a-Richtung beobachtet. Sowohl durch die partielle Substitution der Ho3+-Ionen als auch durch die Ni-B-Stöchiometrievariation wird die Ausprägung der magnetischen Strukturen stark modifiziert. Der Vergleich mit den ebenfalls veränderten supraleitenden Eigenschaften ergibt das folgende Bild für die HoNi2B2C-Verbindungen: Die Supraleitung koexistiert mit den beiden c-Achsen-modulierten magnetischen Strukturen, das Einsetzen der magnetischen Ordnung führt jedoch zu einer Schwächung der Supraleitung. Die a-Achsen-modulierte magnetische Struktur weist Momentkomponenten in c-Richtung auf, die auf Grund der resultierenden lokalen Magnetfelder an den Ni-Plätzen eine starke Unterdrückung der Supraleitung bewirken. Die beobachtete Konkurrenz zwischen der Supraleitung und der a-Achsen-modulierten magnetischen Struktur gibt andererseits einen starken Hinweis darauf, daß die Modifizierung der elektronischen Struktur im supraleitenden Zustand auf das magnetische System rückwirkt. Als weitere Auswirkung des Magnetismus kommt es in RNi2B2C-Verbindungen mit R = Ho, Dy, Tb und Er zu Veränderungen der Kristallstruktur. Mittels hochauflösender Neutronendiffraktion werden magnetisch induzierte, tetragonal-zu-orthorhombische Gitterverzerrungen für diejenigen magnetischen Ordnungen nachgewiesen, bei denen die magnetischen Momente der R3+-Ionen parallel bzw. antiparallel ausgerichtet sind. Die Richtung der Gitterverzerrung, die Abhängigkeit ihrer Größe vom Quadrat des geordneten magnetischen Momentes als auch von der Art der R3+-Ionen deuten darauf hin, daß die magneto-elastischen Wechselwirkungen durch Kristallfeldeffekte bestimmt werden. Diese Einsicht unterstützt auch die Aufklärung der magnetischen Phasendiagramme mittels magnetfeldabhängiger Neutronenbeugungsexperimente. Für eine magnetische Phase schränkt das Auftreten bzw. Fehlen der magneto-elastischen Effekte die Vielfalt der möglichen magnetischen Strukturen ein. Die aus der Literatur bekannten magnetischen Phasen von HoNi2B2C werden bestätigt. Für DyNi2B2C werden die experimentellen Ergebnisse unter Nutzung eines einfachen Modelles interpretiert und die magnetischen Strukturen bestimmt. Anhand von Molekularfeldrechnungen können die Unterschiede in den magnetischen Strukturen für ansteigendes und für abnehmendes Magnetfeld als sehr starke Hystereseeffekte in Zusammenhang mit Phasenübergängen erster Ordnung gedeutet werden.

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