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For asymmetric digital subscriber line (ADSL) technology applications, new MnZn ferrites are required with not only high initial permeability, but also with low hysteresis material constant [[eta].sub.B]. The effects of calcining and sintering temperatures and oxygen equilibrium partial pressure on the magnetic properties of MnZn ferrites are studied in this work. It was found that raising the calcining temperature required a rise in the sintering temperature to simultaneously achieve maximum permeability and the lowest [[eta].sub.B] value. Both grain size and porosity had an effect on the initial permeability of the samples. Porosity had an even larger effect on the [[eta].sub.B] value than the initial permeability. Oxygen equilibrium partial pressure also had an important effect on the initial permeability and [[eta].sub.B] value. In our testing range, both the initial permeability and the [[eta].sub.B] value decreased with increasing value of A (oxygen parameter). In order to optimize synthesis conditions for the high initial permeability and low [[eta].sub.B] value, it was best to calcine the sample at 950[degrees]C and sinter it at 1370[degrees]C, with A = 7.55. Index Terms--Calcining temperature, grain size, initial permeability, [[eta].sub.B] value, oxygen parameter, porosity, sintering temperature.

Smooth and dense preheated cerium (Ce) and manganese (Mn) codoped barium strontium titanate (CeMn-BST) films with various thicknesses have been prepared by improved sol-gel method. Capacitance-voltage curves show that with increasing film thickness, combination of dielectric properties are significantly improved with optimized values of about 1300 moderate permittivity, less than 0.007 dielectric loss, more than 58% tunability and hence near 180 figure of merit (FOM) for eight-layer CeMn-BST film. The objective of this paper is to study the improved mechanisms for such excellent dielectric properties. XRD shows that the films layered-grow mainly along (110) orientation and exhibit ABO3cubic perovskite structure. As film thickness increases, Ce3+and/or Mn2+ions are showing doping modes from donor doping to acceptor doping, the crystallization of films is enhancing, but the average grain sizes of the films show gradually decreased trend from about 45nm to 25nm in terms of the intensities of (110) diffraction peaks. AFM indicates that the films are getting smoother with smaller roughness with increasing thickness. XPS reveals that the films reveal decreased non-perovskite structure, element core levels and Fermi levels with increasing thickness. Leakage current densities are significantly decreased almost at two orders of magnitude with increasing thickness. Pure BST films are compared. [ABSTRACT FROM AUTHOR]

Manganese (Mn) and yttrium (Y) alternately doped Ba0.6Sr0.4TiO3(BST) films are novelly designed as MnBST/YBST/MnBST/YBST and prepared layer-after-layer on Pt wafer electrodes, and two films where one with the first layer preheated (1Mn/YBST) and the other with four layers preheated (4Mn/YBST) are focused on. XRD shows that two films grow along (110) orientation and reveal ABO3cubic perovskite structures and donor doping, but 4Mn/YBST film shows larger average grain size. SEM demonstrates that 1Mn/YBST film is composed of one 630nm-thick layer with nodular microstructure and the other 570nm-thick surface layer with columnar microstructure, whereas 4Mn/YBST film is 670 nm thick with nodular microstructure. AFM shows that two films are smooth with no cracks, but 4Mn/YBST film is denser with smaller roughness. Two films show more than 55% high tunabilities, but 4Mn/YBST film also reveals low losses of 0.0062∼0.0156 and high figure of merit (FOM) of near 90 at -35V and 100 kHz, fully meeting the needs of tunable microwave applications. [ABSTRACT FROM AUTHOR]

Cerium (Ce) and manganese (Mn) codoped Ba0.6Sr0.4TiO3(BST) films were prepared by improved sol-gel method and the effect of preheating on their dielectric properties was investigated. X-ray diffraction (XRD) reveals that the films grow principally along (110) orientations and show cubic perovskite structures. Preheating corresponds to smaller FWHMs, stronger crystallization and larger grain sizes, and preheating with codoping corresponds to the smallest FWHM, the strongest crystallization and the largest grain size. The prepared film can show tunability of 55.7%, dielectric loss of 0.0074∼0.0175 and approximately 75 FOM, meeting the needs of tunable microwave applications. [ABSTRACT FROM AUTHOR]

Abstract: Mn and Y alternately doped Ba0.6Sr0.4TiO3 film, denoted as Mn/Y-BST film, has been designed and prepared by improved sol–gel method, and the structure and dielectric properties of the film have been studied. Y or Mn doped BST film is also studied. X-ray diffraction reveals that all films grow along (110) orientation and show polycrystalline cubic perovskite structures, and Y3+ and Mn2+ ions enter into B-sites of ABO3 perovskite structure and substitute Ti4+ ions. The Mn/Y-BST film reveals better crystallization with larger crystal grain size. Atomic force microscopy and scanning electron microscopy confirm that the Mn/Y-BST film exhibits better crystallization. X-ray photoelectron spectroscopy shows that the Mn/Y-BST film presents less surface non-perovskite structure. Accordingly, the Mn/Y-BST film exhibits significantly nonlinear improvement in combination of dielectric properties. These results indicate that Mn/Y alternate doping is a novel route to excellent BST films for tunable microwave applications. [Copyright &y& Elsevier]

Abstract: Cerium and manganese codoped Ba0.6Sr0.4TiO3 (CeMn-BST) film and pure BST, Ce-BST and Mn-BST films were prepared. Influence of preheating on film crystallization and growing behavior was studied. X-ray diffraction (XRD) reveals that all films mainly grow along (110) orientation and show cubic ABO3 perovskite structures, and the preheating promotes Ce3+ and Mn4+ ions enter into B-sites and substitute Ti4+ ions. Preheating enhances crystallization and causes the strongest crystallization with CeMn-codoping. Atomic force microscopy (AFM) exhibits that films preheated show layered growth, while those not preheated show island growth, which are related to layer number and doping. Therefore, the films preheated show larger permittivities, higher tunabilities, and lower dielectric losses except the pure BST film and higher figures of merit (FOMs). Preheating with CeMn-codoping causes best dielectric properties with 56% tunability, 0.0037–0.0091 loss and near 150 FOM, meeting the needs of tunable microwave applications. [Copyright &y& Elsevier]