Electronic Structure of Hydrazinium (2 + ) Ion. A Semiempirical MO Treatment

A simple semiempjrical MO treatment of the electronic structure of hydrazinium (2 + ) ion was carried out on the basis of an extended Htickel method. The electronic population analysis for nitrogen and hydrogen atoms in this ion was calculated to b e (ls) 2 (2s)1 -121 (2px)1 ·3Go (2py)t·3Go (2p z)o .9BG and (ls)0o122, respectively

CHARACTERISATION OF Sr2FeEuO5 BY MÖSSBAUER SPECTRA OF 57Fe

No abstract availabl

Synthesis of Nanocrystalline Nickel-Zinc Ferrites via a Microemulsion Route

ABSTRACT Nanostructured NiZn-ferrites were synthesized using a low-temperature co-precipitation method within the reverse micelles of ternary CTAB/1-hexanol/water microemulsions. The influence of pH on the precipitation reaction was investigated. It was found that a higher pH resulted in more crystalline particles. Subsequent oxidation of the ferrous ions and their precipitation, which leads to the formation of spinel ferrites, is discussed. Diffraction-lines broadening and specific surface area measurements revealed an average particle size of ~ 3 nm. The saturation magnetization of the samples was 20 times smaller than for traditionally synthesized NiZn-ferrites, while the coercivities were 10 -100 times larger than for bulk NiZn-ferrites, which is consistent with the nanocrystalline nature of the synthesized magnetic material. TEM investigations were used to show the agglomerated nature of the synthesized samples, which is the reason why the samples do not show superparamagnetic behavior

THERMAL BEHAVIOR OF NANOCRYSTALLINE CADMIUM SELENIDES AND TELLURIDES

Pseudobinary chalcogenides with the general formula CdSe x Te 1-x exhibit useful physical, chemical and semiconducting properties, which make them promising materials for applications in modern technology. In this article we present a simple and novel method for the preparation of nanocrystalline pseudobinary chalcogenides with the formula CdSe x Te 1-x (x = 0.1 and x = 0.6) by the solvothermal method from elemental precursors in ethylenediamine followed by heating on air or in nitrogen atmosphere. Preparing pseudobinary nanosized CdSe x Te 1-x from binary chalcogenides CdSe and CdTe without solution was not reported yet. By heating the as -prepared mixture of binary chalcogenides to 500 °C, nanosized CdSe 0.1 Te 0.9 was prepared while at higher temperatures and prolonged heating times, the product was CdSe 0.6 Te 0.4 . The products were characterized by X-ray powder diffraction (XRD) and thermal analysis (TGA). The route employed in the present work is simple and controllable and could be used in preparing further semiconducting mixed metal chalcogenides

Effect of Additions and Oxygen Partial Pressure on the Electromagnetic Properties of High Frequency MnZn Ferrites

The effect of dopant and low oxygen partial pressure during sintering on the magnetic properties of MnZn ferrites for use in high frequency power supplies was studied. A low partial pressure of oxygen in the sintering atmosphere and a proper temperature profile during sintering decrease the average grain size, while the dopant, which segregates to the outer grain region, increases the grain boundary resistivity resulting in a lowering of power loss

ORIENTED DRY PRESSING OF STRONTIUM FERRITE MAGNETS

Les aimants céramiques orientés sont mis en forme par pressage sec ou humide. Il est connu que l'on ne peut obtenir un haut degré d'orientation à partir d'une poudre sèche que si les grains n'adhèrent pas entre eux ou ne collent pas ensemble. Puisque des films d'eau ou de lubrifiant accroissent l'adhérence, il est recommandé d'utiliser des poudres soigneusement séchées exemptes de liant ou de lubrifiant. Le pressage de telles poudres sèches en des formes bien définies conduit souvent à des inhomogénéités de densité. Dans ce cas on ne peut éviter l'emploi de poudres agglomérées ou contenant un liant. Dans le présent travail on discute l'influence de la méthode de préparation et des caractéristiques des poudres sur le pressage à sec sous champ magnétique. Les propriétés des aimants fabriqués à partir de poudres spécialement traitées se comparent avantageusement avec celles des aimants mis en forme par méthode humide.Oriented ceramic magnets are shaped either by wet or dry pressing method. It was reported that a high degree of orientation of a dry powder can be achieved only if the powder particles do not stick together or adhere to each other. Since water films or lubricants increase adherence, the use of carefully dried, lubricant-free powders is recommended. Compacting of dry, binder and lubricant free powders into intrinsic shapes often results in inhomogeneous density distribution. In such cases the use of agglomerated powders or binder addition cannot be avoided. In present work, the influence of preparation method and powder characteristics on dry pressing in magnetic field is discussed. The properties of magnets made from specially treated powders compare favourably with the properties of magnets shaped by wet method