Nuclear spin diffusion in the semiconductor TlTaS3

We report on a 203Tl and 205Tl nuclear magnetic resonance study of the chain ternary semiconductor TlTaS3. We show that spin-lattice relaxation in this compound is driven by two contributions, namely by interactions of nuclear spins with thermally activated carriers and with localized electron spins. The latter mechanism dominates at lower temperature; at that, our measurements provide striking manifestation of the spin-diffusion-limited relaxation regime. The experimental data obtained allow us to estimate the spin diffusion coefficient.Comment: 15 pages, 5 figure

Size-dependent properties of dithallium selenide

We report on size-dependent properties of dithallium selenide, Tl2Se. We have carried out a comparative nuclear magnetic resonance (NMR) study of Tl2Se nanorods and bulk samples, measuring NMR spectra and spin-lattice relaxation rate of 203Tl and 205Tl isotopes. Though bulk Tl2Se was reported to be a metal, the Korringa-like spin-lattice relaxation behavior is observed only at low temperatures and is transformed to an activation regime above ~200 K. This finding is interpreted assuming a two-band model in the semimetallic compound. Our measurements show significant difference in the Knight shift and indirect nuclear exchange coupling for the bulk and nanorod Tl2Se samples, reflecting noticeable distinction in their electronic structure. At that, Tl2Se nanorods are semiconductors and exhibit a characteristic activation behavior in the spin-lattice relaxation rate due to the thermal excitation of carriers to the conduction band. The obtained size dependence of the Tl2Se properties is interpreted in terms of the semimetal-semiconductor transformation due to the quantum confinement.Comment: 15 pages, 4 figure

Electronic properties and phase transitions in low-dimensional semiconductors

We present the first review of the current state of the literature on electronic properties and phase transitions in TlX and TlMX2 (M = Ga, In; X = Se, S, Te) compounds. These chalcogenides belong to a family of the low-dimensional semiconductors possessing chain or layered structure. They are of significant interest because of their highly anisotropic properties, semi- and photoconductivity, non-linear effects in their I-V characteristics (including a region of negative differential resistance), switching and memory effects, second harmonic optical generation, relaxor behavior and potential applications for optoelectronic devices. We review the crystal structure of TlX and TlMX2 compounds, their transport properties under ambient conditions, experimental and theoretical studies of the electronic structure, transport properties and semiconductor-metal phase transitions under high pressure, and sequences of temperature-induced structural phase transitions with intermediate incommensurate states. Electronic nature of the ferroelectric phase transitions in the above-mentioned compounds, as well as relaxor behavior, nanodomains and possible occurrence of quantum dots in doped and irradiated crystals is discussed.Comment: 70 pages, 38 figure

Piezoceramic material based on PZT for use in actuators and hydroacoustics

Исследованы электрофизические и механические свойства сегнетомягкого пьезокерамического материала на основе ЦТС с Ec=6 кВ⁄см и TC=150°C. Полученные данные и пьезоэлектрические характеристики свидетельствуют о возможности применения данного материала для использования в актюаторах и гидроакустиких устройствах.The electrophysical and mechanical properties of a ferrosoft piezoceramic material based on a PZT with Ec = 6 kV/cm and TC = 150°C have een studied. The o tained data and piezoelectric characteristics testify to the possibility of using this material for use in actuators and hydroacoustics

Routledge Handbook of the Archaeology of Indigenous-Colonial Interaction in the Americas

The Routledge Handbook of the Archaeology of Indigenous-Colonial Interaction in the Americas brings together scholars from across the hemisphere to examine how archaeology can highlight the myriad ways that Indigenous people have negotiated colonial systems from the fifteenth century through to today. The contributions offer a comprehensive look at where the archaeology of colonialism has been and where it is heading. Geographically diverse case studies highlight longstanding theoretical and methodological issues as well as emerging topics in the field. The organization of chapters by key issues and topics, rather than by geography, fosters exploration of the commonalities and contrasts between historical contingencies and scholarly interpretations. Throughout the volume, Indigenous and non-Indigenous contributors grapple with the continued colonial nature of archaeology and highlight Native perspectives on the potential of using archaeology to remember and tell colonial histories. This volume is the ideal starting point for students interested in how archaeology can illuminate Indigenous agency in colonial settings. Professionals, including academic and cultural resource management archaeologists, will find it a convenient reference for a range of topics related to the archaeology of colonialism in the Americas.https://scholarcommons.scu.edu/faculty_books/1542/thumbnail.jp

Archaeology for the Seventh Generation

Angela Cavender Wilson\u27s 2004 essay Reclaiming Our Humanity: Decolonization and the Recovery of Indigenous Knowledge provides a useful starting point for considering the role of decolonization in both the academy and in our everyday lives.1 Wilson, as an Indigenous scholar, muses, For what had I been continually seeking an education if not to transform the world around me and create a place where justice for Indigenous people is more than an illusion? 2 For Wilson, the writings of Frantz Fanon and Paulo Freire concerning respectively decolonization and praxis provided, as she says, the language to articulate [her] own struggle. 3 Decolonization as Wilson applies it refers to the process of reversing the colonial structures inherent in both the institutions of colonialism and in the minds of the colonized. In relation to the decolonization of Indigenous peoples, Wilson stresses that Indigenous communities must return to their traditions, reassert these traditional cultural and social values and worldviews into their everyday lives, and begin to rebuild their communities accordingly. But it is through praxis, theoretically informed action, that people are able to decolonize themselves and the structures around them. The concept of praxis situates the power of people, as thinking and knowing individuals, to reflect upon their lives and change them through their actions