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A high average power, high figure of merit, X-band, ferrite loaded waveguide phase shifter has been developed. A zinc-doped magnesium manganese ferrite (4πM s =3000 gauss), in combination with a reduced cross-section rectangular waveguide, was used to achieve a figure of merit of 1000 degrees per decibel, which is better than any previously reported mode-free configuration.

The dehydrogenation and dehydration of 2-propanol on manganese ferrite has been studied between 306 and 362 °C. The selectivity for dehydrogenation was constant throughout the temperature range. At...

The influence of long-term milling of a mixture of MnCO3 and alpha-Fe2O3, and of MnO2 and alpha-Fe2O3 powders in a planetary ball mill on the reaction synthesis of nanosized MnFe2O4 ferrites was studied. The mechano-chemical reaction leading to formation of the MnFe2O4 spinel phase was followed by X-ray diffraction. The spinel phase was first observed after 10 h of milling and its formation was completed after 20 h in case of the MnCO3 - alpha-Fe2O3 mixture. The synthesized MnFe2O4 ferrite has a nanocrystalline structure with a crystallite size of about 28 nm. The thermal treatment of the as-milled powder at 400 degrees C for 4 h led to formation of the MnFe2O4 crystalline phase in case of the mixture of MnCO3 and alpha-Fe2O3, but in MnO2 alpha-Fe2O3 case thermal treatment at temperatures of 400 degrees C and higher leads to formation of (Mn,Fe)203 and separation of Mn2O3 and Fe2O3.

It is shown that the value of the magnetic moment of manganese ferrite measured recently by Hastings and Corliss can be explained on the basis of their observations of cation distribution if the Mn in $A$ and $B$ sites is assumed to be ${\mathrm{Mn}}^{2+}$ and ${\mathrm{Mn}}^{3+}$, respectively. This possibility is discussed in relation to the ionic composition found for a single crystal of manganese ferrite grown by the flame fusion method.

The results of microwave resonance measurements of the g factor and the first- and second-order anisotropy fields K1/M and K2/M are summarized for crystals with the nominal composition CoxMn1−xFe2O4, where 0 ≤ x ≤ 0.10. In the region 150°K

Ferrimagnetic resonance experiments have been performed on single-crystal manganese ferrite at high microwave powers. The variation of susceptibility with power level is in good agreement with Suhl's recent theoretical treatment of the saturation process in which scattering of the uniform precession at impurities and imperfections is taken into account. Our results show that the ratio of intrinsic to scattering decay constants is close to zero, so that χ′′ decreases gradually at power levels substantially below the theoretical critical signal level. At very high power levels various anomalous effects appear such as bistabilities, line asymmetries, and flat topped absorption lines.

In this paper, the Effects of different heat treatments on the ferromagnetic resonance of lutecium iron garnet (Lu3Fe5O12) and manganese ferrite (MnFe2O4) single crystals are investigated. The two heat treatments applied are, respectively, 700C in air for one hour and 700C in oxygen for ten hours. It is found that these treatments have no significant effect on the values of K1/Ms and the g-factors, except that the anisotropy of the resonance line width delta H decreases appreciably. Although the effect on delta H of Lu3Fe5O12 is small, the delta H value of MnFe2O4 increases several times after each treatment. The cause for the variation of delta H with heat treatment is discussed. X-ray diffraction patterns show that a small quantity of alpha-Fe2O3 precipitates in the manganese ferrite specimen after the latter is subjected to heat treatment. (Author)