NiTi substituted hexaferrites for magnetic recording

In order to obtain hexagonal ferrites with improved characteristics for application in the field of the magnetic recording, the ferrimagnetic Sr(NiTi)_x Fe_12-2xO₁₉ system is studied. Preliminary investigations suggested that NI is more effective than Co in reducing the magnetic anisotropy of hexaferrites. The system was analyzed as a function of the degree of substitution x and of the reaction temperature T_R and time τ. The reactivity of the mixtures and their magnetic characteristics (σ, H_c, H_A, T_c) were measured, and from the _χT(H) data it was possible to distinguish between single-domain or polydomain particles. The results are presented. The influence of the extraneous magnetic phases on the coercive field value was also studied and a preliminary investigation of the relation between coercive and anisotropy fields was carried out     

Low-Temperature Synthesis and Properties of LaMnO3±d and La0.67R0.33MnO3±d (R = Ca, Sr, Ba) from Citrate Precursors

LaMn_{1− y} ³⁺Mn _y ⁴⁺O_3±d and La_0.67R_0.33Mn_{1− y} ³⁺Mn _y ⁴⁺O_3±d (R = Ca, Sr, Ba) phases were synthesized at 350°C by using very reactive, amorphous precursors obtained from the stoichiometric citrate solutions. The chemical process was optimized with respect to the solution concentration, pH, and additives. The precursor reactions were investigated as a function of the cation stoichiometry and the additive by simultaneous thermal and thermogravimetric analysis and X-ray diffraction. The reaction pathway was found to be independent of the cation stoichiometry, but related to the acid or base additive. The annealing temperature was systematically increased in the 350–1200°C interval and the La_0.67Sr_0.33MnO_3±d properties (i.e., crystal sizes, Mn average valence, Curie temperature, magnetization, magnetic susceptibility) were measured and found to vary consistently as a function of it.     

Turing’s Imitation Game: Still an Impossible Challenge for All Machines and Some Judges––An Evaluation of the 2008 Loebner Contest

An evaluation of the 2008 Loebner contest