Materials Literature
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The effects of the dopants, Mg 2+ , Sr 2+ , Sc 3+ , Yb 3+ , Gd 3+ , La 3+ , Ti 4+ , Zr 4+ , Ce 4+ , and Nb 5+ , on the grain boundary mobility of dense Y 2 O 3 have been investigated from 1500° to 1650°C. Parabolic grain growth has been observed in all cases over a grain size from 0.31 to 12.5 μm. Together with atmosp…
The effects of the dopants, Mg 2+ , Ca 2+ , Sr 2+ , Sc 3+ , Yb 3+ , Y 3+ , Gd 3+ , La 3+ , Ti 4+ , Zr 4+ , and Nb 5+ , on the grain boundary mobility of dense CeO 2 have been investigated from 1270° to 1420°C. Parabolic grain growth has been observed in all instances. Together with atmospheric effects, the results sup…
The relevance of algae to the current debate on global biodiversity is assessed. Algal diversity is considered at the levels of richness of species and of higher taxonomic ranks and as the variety of habitats algae dominate and their functional importance in the processes they mediate.The geographical distribution of…
Two user-friendly computer programs are described for use in macromolecular X-ray crystallography, xdlMAPMAN provides an interface for electron-density map exchange between some of the most commonly used phase refinement, structure refinement and model- building programs. In addition, it contains several options to an…
Zinc oxide (ZnO) films have been deposited on 1 μm SiO2/Si (100) substrates by rf magnetron sputtering. Using a sputtering gas of pure oxygen, a pressure regime is found in which the ZnO films grow on room temperature substrates with a single (0001) orientation, small grains (crystallite sizes ∼10–15 nm), and high int…
The aim of this review is to describe many approaches to modulated crystals and quasicrystals developed in two decades after the introduction of higher-dimensional crystallography in a unified way. Much attention is focused on higher-dimensional crystallography of quasi-crystals, which is under development. After disc…
The surfaces of titanium oxide belong to the most-studied oxide systems in the surface science literature. This is in part because TiO2 surfaces and interfaces play a major role in several technological applications, e.g., as promoters in catalysis, as photocatalysts, and as gas sensors. TiO2 is a reducible oxide, i.e…
Abstract The syntheses and properties of novel, extremely strong uncharged polyaminophosphazene bases up to a high level of steric hindrance are described. Most of the systems were readily prepared in up to molar quantities and conveniently recovered from their salts. They are of appreciable to high chemical and therm…
We show that the organic salt 4-N,N-dimethylamino-4′-N′-methyl-stilbazolium tosylate (DAST) is a very interesting material for electro-optic applications in the near infrared. The electro-optic coefficients, namely r111, r221, r331, r113, r223, and r333, were determined in the spectral range of 700 up to 1535 nm using…
Nitinol based shape memory alloys were introduced to Medicine in the late seventies. They possess a unique combination of properties including shape memory, superelasticity, great workability in the martensitic state, resistance to fatigue and corrosion. Despite these exceptional physical, chemical and mechanical prop…
The major methods of mathematical modelling of solidification and melting problems are reviewed in this paper. Different analytical methods, nowadays still used as standard references to validate numerical models, are presented. Various mathematical formulations to numerically solve solidification and melting problems…
Several methods to assess the (dis)similarity of protein structures objectively are described, some of which, when applied to non-crystallographically related protein models, are able to discriminate between significant differences and 'random noise'. Some of these methods have been used to investigate a sample of sev…
Abstract This review focuses on some aspects of the chemistry involved in the preparation of oxides by sol–gel methods. This field is opening interesting possibilities for molecular chemistry and among those presented herein are: (1) the use of precursors containing functional groups for the preparation of solids with…
The origin and interpretation of the Raman features of amorphous (hydrogenated) carbon films deposited at room temperature in the region of 1000–1700 cm−1 is discussed in this paper. Possible interpretations of the linewidths, positions of the ‘‘G’’ graphite peak and ‘‘D’’ disordered peak, and their intensity ratios a…
A model for the doped rare-earth manganites such as ${\mathrm{La}}_{1\ensuremath{-}x}{\mathrm{Sr}}_{x}{\mathrm{MnO}}_{3}$ incorporating the physics of dynamic Jahn-Teller and double-exchange effects is presented and solved via a dynamical mean field approximation. The interplay of these two effects as the electron pho…
Polycrystalline bulk samples of Ti 3 SiC 2 were fabricated by reactively hot‐pressing Ti, graphite, and SiC powders at 40 MPa and 1600°C for 4 h. This compound has remarkable properties. Its compressive strength, measured at room temperature, was 600 MPa, and dropped to 260 MPa at 1300°C in air. Although the room‐temp…
Se analiza la influencia de los tratamientos termomecánicos, en primer lugar, llevados a cabo en laboratorio y, posteriormente, en un proceso industrial, sobre las propiedades mecánicas de aceros microaleados de forja. Se han variado las temperaturas de forja y las velocidades de enfriamiento tras la misma y se ha est…
Department of Chemistry, University of Rajasthan, Jaipur-302 004 <em>Manuscript received 19 November 1993, revised 21 October 1994, accepted 4 November 1994</em> Spectroscopic, Antifungal and Antibacterial Studies of some Manganese Heterochelates.
Experimental and theoretical work on the magnetoacoustics of rare-earth orthoferrites near reorientation phase transitions (RPTs) is reviewed. The temperature and field dependence of magnetoresonant soft-mode frequencies and of the sound velocity and attenuation near various RPTs, as obtained by RF and ultrasonic spec…
Measurements on the anomalous temperature behaviour of the spontaneous magnetisation in various ferrimagnets (N-, M-, and P-type Neel curves) are analysed and summarised. The concept of a 'weak' magnetic sublattice is applied to explain the anomalies as well as manifestations of the 'low-temperature point' TB and the…