A bibliographical review of the high pressure studies of ferroelectric phase transitions

A brief review of the various high pressure studies on the phase transitions in ferroelectric crystals carried out over the past two decades is presented. The theoretical framework in which high pressure studies have to be viewed is given. The pressure data of ferroelectric crystals are organized in the form of tables. High pressure spectroscopic and structural studies are included. The review contains a bibliography of over two hundred references.

Adsorption-nucleation/growth based model for electrochemical phase formation and Avrami ansatz for a multicomponent competitive growth process

The existing models describing electrochemical phase formation involving both adsorption and a nucleation/growth process are modified. The limiting cases leading to the existing models are discussed. The characteristic features of the potentiostatic transients are presented. A generalization of the Avrami ansatz is given for two or more competitive irreversibly growing phases.

Disorder-driven electronic localization and phase separation in superconducting Fe1+yTe0.5Se0.5 single crystals

We have investigated the influence of Fe excess on the electrical transport and magnetism of Fe1+yTe0.5Se0.5 (y=0.04 and 0.09) single crystals. Both compositions exhibit resistively determined superconducting transitions (T-c) with an onset temperature of about 15 K. From the width of the superconducting transition and the magnitude of the lower critical field H-c1, it is inferred that excess of Fe suppresses superconductivity. The linear and nonlinear responses of the ac susceptibility show that the superconducting state for these compositions is inhomogeneous. A possible origin of this phase separation is a magnetic coupling between Fe excess occupying interstitial sites in the chalcogen planes and those in the Fe-square lattice. The temperature derivative of the resistivity d(rho)/d(T) in the temperature range T-c < T < T-a with T-a being the temperature of a magnetic anomaly, changes from positive to negative with increasing Fe. A log 1/T divergence of the resistivity above T-c in the sample with higher amount of Fe suggests a disorder-driven electronic localization.

A DC-to-Three-Phase-AC High-Frequency Link Converter With Compensation for Nonlinear Distortion

This paper focuses on a new high-frequency (HF) link dc-to-three-phase-ac power converter. The least number of switching devices among other HF link dc-to-three-phase-ac converters, improved power density due to the absence of devices of bidirectional voltage-blocking capability, simple commutation requirements, and isolation between input and output are the integral features of this topology. The commutation process of the converter requires zero portions in the link voltage. This causes a nonlinear distortion in the output three-phase voltages. The mathematical analysis is carried out to investigate the problem, and suitable compensation in modulating signal is proposed for different types of carrier. Along with the modified modulator structure, a synchronously rotating reference-frame-based control scheme is adopted for the three-phase ac side in order to achieve high dynamic performance. The effectiveness of the proposed scheme has been investigated and verified through computer simulations and experimental results with 1-kVA prototype.

Embedded Storytelling and Gender Negotiations in Githa Hariharan's First Three Novels

This thesis treats Githa Hariharan s first three novels The Thousand Faces of Night (1992), The Ghosts of Vasu Master (1994) and When Dreams Travel (1999) as a trilogy, in which Hariharan studies the effects of storytelling from different perspectives. The thesis examines the relationship between embedded storytelling and the primary narrative level, the impact of character-bound storytelling on personal development and interpersonal relationships. Thus, I assume that an analysis of the instabilities between characters, and tensions between sets of values introduced through storytelling displays the development of the central characters in the novels. My focus is on the tensions between different sets of values and knowledge systems and their impact on the gender negotiations. The tensions are articulated through a resistance and/or adherence to a cultural narrative, that is, a formula, which underlies specific narratives. Conveyed or disputed by embedded storytelling, the cultural narrative circumscribes what it means to be gendered in Hariharan s novels. The analysis centres on how the narratee in The Thousand Faces of Night and the storyteller in The Ghosts of Vasu Master relate to and are affected by the storytelling, and how they perceive their gendered positions. The analysis of the third novel When Dreams Travel focuses on storytelling, and its relationship to power and representation. I argue that Hariharan's use of embedded storytelling is a way to renegotiate and even reconceptualise gender. Hariharan s primary concern in all three novels is the tensions between tradition or repetition, and change, and how they affect gender. Although the novels feature ancient mythical heroes, mice and flies, or are set in a fantasy world of jinnis and ghouls, they are, I argue, deeply concerned with contemporary issues. Whereas the first novel questions the demands set by family and society on the individual, the second strives to articulate an ethical relationship between the self and the other. The third novel examines the relationship between representation and power. These issues could not be more contemporary, and they loom large over both the regional and global arenas.

Phase relations in the system BiO1.5–SrO–CuO at 1123 K

Phase relations in the system Bi-Sr-Cu-O at 1123 K have been investigated using optical microscopy, electron-probe microanalysis (EPMA) and powder X-ray diffraction (XRD) of equilibrated samples. Differential thermal analysis (DTA) was used to confirm liquid formation for compositions rich in BiO1.5. Compositions along the three pseudo-binary sections and inside the pseudo-ternary triangle have been examined. The attainment of equilibrium was facilitated by the use of freshly prepared SrO as the starting material. The loss of Bi2O3 from the sample was minimized by double encapsulation. A complete phase diagram at 1123 K is presented. It differs significantly from versions of the phase diagram published recently.

Potentiometric determination of activities in the two-phase fields of the system Na2O---(α)Al2O3

Three compounds have been found to be stable in the pseudobinary system Na2O---(α)Al2O3 between 825 and 1400 K; two nonstoichiometric phases, β-alumina and β″-alumina, and NaAlO2. The homogeneity of β-alumina ranges from 9.5 to 11 mol% Na2O, while that of β″-alumina from 13.3 to 15.9 mol% Na2O at 1173 K. The activity of Na2O in the two-phase fields has been determined by a solid-state potentiometric technique. Since both β- and β″-alumina are fast sodium ion conductors, biphasic solid electrolyte tubes were used in these electrochemical measurements. The open circuit emf of the following cells were measured from 790 to 980 K: [GRAPHICS] The partial molar Gibbs' energy of Na2O relative to gamma-Na2O in the two-phase regions can be represented as: DELTA-GBAR(Na2O)(alpha- + beta-alumina) = -270,900 + 24.03 T, DELTA-GBAR(Na2O)(beta- + beta"-alumina) = -232,700 + 56.19 T, and DELTA-GBAR(Na2O)(beta"-alumina + NaAlO2) = -13,100 - 4.51 T J mol-1. Similar galvanic cells using a Au-Na alloy and a mixture of Co + CoAl(2+2x)O4+3x + (alpha)Al2O3 as electrodes were used at 1400 K. Thermodynamic data obtained in these studies are used to evaluate phase relations and partial pressure of sodium in the Na2O-(alpha) Al2O3 system as a function of oxygen partial pressure, composition and temperature.

Varistors based on mixed‐phase ceramics containing ZnO and negative temperature coefficient spinels

High nonlinearity coefficients of 60–150 are observed in the current‐voltage (I‐V) curves of the mixed phase ceramics formed by cosintering ZnO with spinel phases having large negative temperature coefficients (NTCs) in resistivity. The region of negative slope in the I‐V curves of the NTC ceramics is progressively made positive with ZnO phase content, wherein ZnO grains function as a built‐in resistor in series to the resistance of the NTC phase. High α depends on the optimum phase content of ZnO as much as its intrinsic conductivity. The studies indicate that the predominent contribution to power dissipation is by way of joule heating from the resistive component of the current.

Jahn-Teller effect induced phase transitions in CsCuCl3

Occurence of the three Jahn-Teller effect induced phase transitions of CsCuCl3 at 423, 510 and 535 K has been established and the nature of the transitions examined by X-ray crystallography, far infrared spectroscopy and other techniques.

Morality and Gender in Jeff Lindsay's Dexter Novels

Tutkimuksessa analysoin neljää Jeff Lindsayn Dexter -dekkaria kahdesta eri näkökulmasta. Ensimmäinen osa keskittyy päähenkilön sosiopaattisen persoonan aiheuttamiin moraalisiin ristiriitoihin, sillä hän on sekä sarjamurhaaja että työskentelee poliisin laboratoriossa silti noudattaen erittäin tiukkaa moraalista ohjenuoraa, joka määrittää kenet hän saa tappaa. Tutkimuksen toinen osa tarkastelee kirjojen naishahmoja ja heidän ongelmiaan. Käsittelen lyhyesti myös kirjasarjan ja niiden pohjalta tehdyn televisiosarjan eroja. Metodeina käytän lähiluentaa, eettistä analyysiä sekä rikoskirjallisuuden alalajien vertailua. Vaikkei rikoskirjallisuudessa olekaan yleistä, että poliisi tai tutkija olisi siviilissä rikollinen, on Dexter hyvin tyypillinen fiktiivinen sosiopaatti ja sarjamurhaaja. Lindsayn kirjojen juonet ja Dexter päähenkilönä noudattavat paikoin lähes kirjaimellisesti Thomas Harrisin Hannibal Lecterille luomaa kaavaa. Kirjojen moraaliset ristiriidat taas aiheutuvat sekä Dexterin roolista lainvartijana ja -rikkojana että hänen noudattamastaan tiukasta moraalisesta ohjenuorasta, joka määrittää kenet saa tappaa. Sosiopaattina hänen pitäisi olla kaikkien yhteiskunnan asettamien lakien ja rajoitusten tavoittamattomissa, mutta silti hänen päätöksentekonsa perustuu täysin kasvatti-isänsä laatimiin ohjeisiin. Tämä on yksi Dexterin hahmon suurimmista ristiriitaisuuksista, joka vahvistaa Heta Pyrhösen esittämän ajatuksen siitä, ettei rikoskirjallisuus tule toimeen ilman vahvaa moraalista selkärankaa. Dexterin tiukka moraalinen ohjenuora ja lukijoiden samaistuminen päähenkilöön ovat kuitenkin todennäköisin syy hänen selviytymiseensä kirjasta toiseen, ja sarjan myötä Dexter muuttuukin inhimillisemmäksi kuin alussa. Toisaalta naishahmojen ongelmien havaitseminen on vaikeaa, sillä ensivaikutelman perusteella voisi kuvitella, että Lindsayn kuvaama yhteiskunta on jo ratkaissut kaikki tasa-arvo-ongelmansa. Sukupuolten ja kansanryhmien välisestä tasa-arvosta ei kirjoissa keskustella, mutta merkittäviä naishahmoja on silti huomattavan vähän, eikä heistäkään ole rakennettu yhtä johdonmukaisia ja mielenkiintoisia kuin päähenkilöstä esimerkiksi. He jäävät pitkälti Dexterin varjoon. Edes Dexterin sisko Deborah ei pysty säilyttämään osaansa kirjojen naispäähenkilönä, sillä hänen ammattitaitoaan poliisina ja olemustaan naisena kuvataan jatkuvan ristiriitaisesti. Kaksi seuraavaksi tärkeintä naishahmoa ovat Dexterin tyttöystävä Rita, joka toimii äitiyden ruumiillistumana, sekä hänen tyttärensä Astor, joka on veljensä ohella samanlainen sosiopaatti kuin Dexter. Naissarjamurhaajien puute ja naishahmojen epäjohdonmukainen kuvaus ovat yksi Lindsayn kirjojen suurimmista ongelmista. Analyysin keskeisimmät johtopäätökset paljastavat, miten omaperäisyydestään huolimatta Dexter muistuttaa huomattavasti muita tunnettuja fiktiivisiä sarjamurhaajia, ja miten Lindsay pohjaa tekstinsä amerikkalaiseen arvomaailmaan ja rikoskirjallisuuden alalajien konventioihin. Vaikka suurin osa lukijoista pystyykin käsittelemään Dexterin tekojen moraalisia ristiriitoja, voi sarjamurhaajan ihannointi aiheuttaa toisille ongelmia. Toisaalta luomalla monipuolisia ja johdonmukaisia naishahmoja, jotka pystyisivät säilyttämään itsenäisyytensä kaikissa tilanteissa, Lindsayn kirjat olisivat sekä ajankohtaisempia että omaperäisempiä kuin nyt.

Infrared spectroscopic study of the phase transitions in CsNO3, RbNO3 and NH4NO3

Phase transitions of CsNO3 (II-I), RbNO3 (IV-III-II) and NH4NO3 (V-IV-III-II-I) have been studied by i.r. spectroscopy. The study has provided useful information on the changes in the dispositions of the ions during the phase transitions.

Infrared and Nuclear Quadrupole Resonance Studies of the Phase Transitions of Para-dichlorobenzene

The α→γ→α→β transitions of para-dichlorobenzene have been studied by employing infrared and n.q.r. spectroscopy as well as differential scanning calorimetry. The γ phase is associated with considerably higher values of some of the intramolecular vibration frequencies. The α→γ transition shows athermal nucleation behaviour as in martensitic transitions. Intermolecular vibration bands around 46 and 85 cm–1 present in γ and α phases disappear in the β phase. The α→β transition seems to be associated with some orientational disorder.