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The thernial analyses, therniogravirnetry (TG), and differential thermal analysis (DTA) o f PbOHCI, PbOHBr, and PbOHI reveal that the initial mode of decomposition is via dehydroxylation. Calorimetric measurements along with related enthalpy val~lcs for tlie dcconiposition reaction are givcn.Thc infrared spectra of these conipo~lnds arc interpreted in ternis of folded bands of (PbOH'),, tied together by halide ions consistent with their crystal structures.The kinetics of thermal deconiposition of lead hydroxyhalides follow a diffusion-typc rate equation which is in contrast to tlie simple first-order rate e q~~a t i o n observed for most Cd, Zn, and CLI c o n i p o~~n d s . These two distinct ratcs are interpreted in terms of mobile O H o r H species in the dehydroxylation step.

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This work reports on the result of electrical conductivity measurements carried out on coconut-shell activated carbon. The results suggest that the charge carriers moved by variable-range hopping below 200 K, by hopping among localized energy states between 200 K and 385 K, and by percolation through energy states close to the mobility edge above 385 K. In the latter two conduction processes, significant additional frequency-dependent contributions to the conductivity were observed and are tentatively attributed to polarization of unremovable lignin and/or ionic impurities. These explanations are based on the present trends of the electrical transport theory for amorphous semiconductors.