Current Status of and Recent Results on Group 2 Source Compounds for Vapor Phase Epitaxy of Ferroelectric Thin Films

1993 ◽  
Vol 310 ◽  
Author(s):  
William S. Rees ◽  
Henry A. Luten ◽  
Michael W. Carris ◽  
Celia R. Caballero ◽  
Werner Hesse ◽  
...  

AbstractMuch interest in the area of ferroelectric thin films has been generated by the recent developments in unique property observation for these materials. As deposition methods move toward potential commercialization, the importance of chemically and thermally stable at use temperature, high vapor pressure and purity, readily available and economically competitive sources for the requisite group 2 elements will emerge. This presentation entails an initial overview of the presently utilized compounds, their advantages and disadvantages. New group 2 CVD precursors have been developed based both on inter- and intramolecular stabilization of cyclopentadienides, alkoxides and β-diketonates. Recent results on the coordination environment around the central metal atom have offered insight into the next generation of polydentate, monoanionic ligand design. Specific details are discussed for the metal complexes of “scorpion-tail” β-diketoethers. Results of comparison studies between these new precursors and earlier compounds are presented as a model for designing future sources.

Molecules ◽  
2020 ◽  
Vol 25 (2) ◽  
pp. 244
Author(s):  
Samuel A. Kemp ◽  
Timothy J. Prior ◽  
Huguette Savoie ◽  
Ross W. Boyle ◽  
Benjamin S. Murray

Metallation of biomacromolecular species forms the basis for the anticancer activity of many metallodrugs. A major limitation of these compounds is that their reactivity is indiscriminate and can, in principle, occur in healthy tissue as well as cancerous tissue, potentially leading to side effects in vivo. Here we present pH-dependent intramolecular coordination of an arene-tethered sulfonamide functionality in organometallic ruthenium(II) ethylenediamine complexes as a route to controlling the coordination environment about the central metal atom. Through variation of the sulfonamide R group and the length of the tether linking it to the arene ligand the acidity of the sulfonamide NH group, and hence the pH-region over which regulation of metal coordination occurs, can be modulated. Intramolecular sulfonamide ligation controlled the reactivity of complex 4 within the physiologically relevant pH-region, rendering it more reactive towards 5ʹ-GMP in mildly acidic pH-conditions typical of tumour tissue compared to the mildly alkaline pH-conditions typical of healthy tissue. However, the activation of 4 by ring-opening of the chelate was found to be a slow process relative to the timescale of typical cell culture assays and members of this series of complexes were found not to be cytotoxic towards the HT-29 cell line. These complexes provide the basis for the development of analogues of increased potency where intramolecular sulfonamide ligation regulates reactivity and therefore cytotoxicity in a pH-dependent, and potentially, tissue-dependent manner.


Author(s):  
HARI SINGH NALWA ◽  
SETSUO KOBAYASHI

Third-order non-linear optical susceptibilities of silicon, germanium, tin, aluminum, manganese and vanadium naphthalocyanine derivatives measured by third-harmonic generation technique from 1.05 μm to 2.1 μm are reported. Our results show the dependence of χ(3)(–3ω;ω,ω,ω) values on the variation of the central metal atom associated to different metal-ligand charge-transfer interactions. Silicon naphthalocyanines ( SiNc ) showed the χ(3)(–3ω;ω,ω,ω) values on the order of 10−10 esu at 1.5 μm, this does not appear to be due to a three-photon resonance, instead the increase in χ(3) could be the two-photon resonance lying just above the one-photon state. Degenerate four-wave mixing measurements on thin films of a SiNc derivative yielded the χ(3)(–3ω;ω,ω,ω) value as high as 5.0 × 10−7 esu at 800 nm, enhanced by one-photon resonance near the Q-band peak region. The figure of merit χ(3)/α at 800 nm is quite large corresponding to 4.2 × 10−12 esu cm. Effect of the metal atoms and plausible resonance contribution accounting for large third-order optical non-linearity of naphthalocyanines are discussed.


2007 ◽  
Vol 274 (1) ◽  
pp. 206-212 ◽  
Author(s):  
B. Derkowska ◽  
M. Wojdyła ◽  
R. Czaplicki ◽  
W. Bała ◽  
B. Sahraoui

2009 ◽  
Vol 02 (01) ◽  
pp. 179-200 ◽  
Author(s):  
J. M. Schippers

An overview is given of different techniques of dose delivery applied in currently operating and planned particle therapy systems. Their advantages and disadvantages will be compared and consequences of the methods for the rest of the instrumentation will be discussed. The interrelationship between beam delivery at the patient and the accelerator system is shown by means of several concrete examples. Apart from a description of several subsystems in a particle therapy facility, design rules for optimizing the reliability of an accelerator and beam delivery system will be discussed, as well as some remarks concerning how to deal with future developments.


2004 ◽  
Vol 13 (1-3) ◽  
pp. 15-22 ◽  
Author(s):  
Yohei Otani ◽  
Soichiro Okamura ◽  
Tadashi Shiosaki

1993 ◽  
Vol 335 ◽  
Author(s):  
Harry A. Meinema ◽  
Klaas Timmer ◽  
Hans L. Linden ◽  
Carel I. M. A. Spee

AbstractIn recent years much attention has been given world-wide to the development of suitable MOCVD precursors for the deposition of HTcS thin films. Synthetic research has been and is concentrated on the development of superior Ba-, Sr-, Ca- and Y-precursors. Most emphasis is given to the synthesis of thermally stable volatile barium compounds. Synthetic strategies are based on encapsulating the central metal atom, by use of multidentate ligand systems and/or bulky substituents. Most attention is given to the development of thermally stable volatile ß-diketonate complexes, fluorine-free and fluorine-substituted, with auxiliary ligands. Thermally stable monomeric complexes of fluorine-substituted ß-diketonates with polyethers are by far the most volatile Ba-, Sr-, and Ca-precursors presently available. Low melting Y(thd)3.L complexes where L is 4-Et- or 4-t-Bupyridine- N-oxide can be used as liquid yttrium MOCVD precursors at temperatures above 100°C. This paper gives a survey of the trends in recent research activity and developments in these areas.


1998 ◽  
Vol 08 (PR9) ◽  
pp. Pr9-225-Pr9-228
Author(s):  
J. H. Yi ◽  
P. Thomas ◽  
M. Manier ◽  
J. P. Mercurio ◽  
I. Jauberteau ◽  
...  

2001 ◽  
Vol 11 (PR11) ◽  
pp. Pr11-133-Pr11-137
Author(s):  
J. R. Duclère ◽  
M. Guilloux-Viry ◽  
A. Perrin ◽  
A. Dauscher ◽  
S. Weber ◽  
...  

Sign in / Sign up

Export Citation Format

Share Document