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TiB2, along with MgO and Mg3B2O6, was formed by a thermite reaction between Mg, amorphous B2O3, and TiO2 powders in argon. The mixture 5Mg–TiO2–B2O3 along with binary mixtures and single components were analyzed using differential thermal analysis (DTA) and x-ray diffraction (XRD). Large (25 g) specimens were also ignited in bulk using a resistance-heated nichrome wire. The reaction path in forming TiB2 in the three component mixture was deduced. Mg reduces TiO2 and B2O3 to form Ti and MgB2, respectively, which in turn react to form TiB2. In an oxidizing atmosphere, the significant speed of the reaction permitted solid state reaction to form TiB2 before atmospheric oxygen could diffuse into the powder mass and react to form oxide phases. Thermite reactions in air have the advantage (over furnace heating in air) of not providing time at elevated temperatures for Mg and intermediate products to become consumed in the formation of oxides, nor time for oxidation degradation of TiB2.

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This paper presents for the first time the design, implementation, measurements, reliability data and integration of multiple RF components such as filters, baluns, diplexers, and a combination of the above on Liquid Crystalline Polymer (LCP) based substrates for communication standards such as 802.11 a/b/g, LMDWMMDS, sa1,ellitddigital TV, UWB, cellular and Bluetooth type applications.These components and process technologies are being targeted as a cost-effective high-performance, miniaturized alternative to the primary technologies of choice for multihand RF/wireless applications, namely, low-temperature co-fired ceramic (LTCC), multi-layer ceramic (MLC) and ceramic monoblock technologies.The first examples of this platform substrate technology are very compact 12"' fully packaged SMT 6ont-end filters with center frequencies of2.45, 5.25 and 5.775 GHz. One embodiment of the filter at 2.45 GHz, which is well suited for 802.11 b/g and Bluetooth type applications, provides a passband of 100 MHz with maximum inhand insertion loss less than 1.7dB at 2 5 T , greater than 25dB attenuation at 2700-2800 MHz, greater than lOdB attenuation below ;!.2GHz, greater than 20dB rejection at the second and third harmonic and inhand VSWR less than 1.5 matched to 50 Ohms at the input and output.

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Differential thermal analysis, in air and argon, in concert with x-ray diffraction, was performed on 2-and 3-component mixtures of Al, B 2 O 3 , and TiO 2 , to foster an understanding of the reaction path involved in the TiB 2 -forming thermite reaction. In argon, aluminum reacted with B 2 O 3 to form elemental boron, and reacted with TiO 2 to form AlTi 3 . These two products reacted just after boron was made available at ϳ1060 ± C to form TiB 2 . Formation of Al 18 B 4 O 33 by reaction between B 2 O 3 reactant and Al 2 O 3 product attenuated the yield of TiB 2 , but facilitated its formation by extraction of Al 2 O 3 reaction barriers.Thermite reactions utilize their released thermal energy to be self-sustaining. The reaction is initiated at one end of a powder compact and propagates through its length to completely convert the reactants to products. Use of thermite reactions in formation of advanced ceramics has shown a number of advantages. Low cost raw materials, e.g., ceramic oxides, can be used. High reaction temperatures permit rapid firing without the use of furnaces. Nonoxide ceramic compounds can be formed via rapid reaction and natural temperature quenching in air. 1 A variety of advanced ceramics and composites such as SiC, B 4 C, Al 2 O 3 -SiC, and MgO-B 4 C have been fabricated via thermite reactions. 2 Cutler et al. 3 investigated the feasibility of synthesizing various composite ceramics using aluminum-based thermite reactions. Al 2 O 3 -TiC, Al 2 O 3 -WC, Al 2 O 3 -TiC 0.5 N 0.5 , and Al 2 O 3 -HfB 2 powders were prepared by the aluminothermic reduction of the oxides (i.e., TiO 2 , SiO 2 , WO 3 , or HfO 2 ) in the presence of C, B, and/or N. The effect of TiB 2 additions to the reactant mixture was studied during the synthesis of a titanium diboridealumina composite by thermite reactions. 4 In previous work at Georgia Tech, thermite synthesis involving oxidation-reduction reactions has been used to produce pure TiB 2 and an Al 2 O 3 -TiB 2 composite. 5,6 The effect of aluminum particle size, powder compaction, and reactant preheating on the reaction behavior has been investigated for the Al -B 2 O 3 -TiO 2 system. 5 Logan et al. 6 studied particle-particle interactions during oxidation-reduction types of self-heating synthesis (SHS) reactions using laser exposure. The objective of this study was to determine the reaction path in the TiB 2 -Al 2 O 3 composite formation reaction using differential thermal analysis (DTA) and x-ray diffraction (XRD).The starting powders were aluminum (123-grade, Alcoa), amorphous boron oxide (Fisher Scientific), and titanium oxide (anatase, Fisher Scientific). Average particle sizes (Microtrac II laser particle size analyzer) were measured to be 15 mm for amorphous B 2 O 3 and 0.3 mm for TiO 2 . The particle size of Al was not measured, but the manufacturer's data showed that it was 15 -19 mm. The powders were weighed according to the stoichiometry of reactants to form anticipated products:and then mixed through extensive gentle stirring to ensure homogeneity. The re...