Charge carrier mobility and concentration as a function of composition in AgPO3-AgI glasses

Autor(es)

Martins Rodrigues, Ana Candida ^[1] ; Ferreira Nascimento, Marcio Luis ^[2] ; Bragatto, Caio Barca ^[1] ; Souquet, Jean-Louis ^[3]

Afiliação do(s) autor(es)

^[1] Univ Fed Sao Carlos, Dept Mat Engn, Lab Mat Vitreos, BR-13565905 Sao Carlos, SP - Brazil

^[2] Univ Fed Bahia, Inst Humanidades Artes & Ciencias, BR-40170115 Salvador, BA - Brazil

^[3] PHELMA, Lab Electrochim & Physicochim Mat & Interfaces, F-38402 St Martin Dheres - France

• Tipo de documento: Artigo Científico
• Fonte: Journal of Chemical Physics; v. 135, n. 23 DEC 21 2011.
• Citações Web of Science: 16

Resumo

Conductivity data of the xAgI(1-x)AgPO3 system (0 <= x <= 0.5) were collected in the liquid and glassy states. The difference in the dependence of ionic conductivity on temperature below and above their glass transition temperatures (T-g) is interpreted by a discontinuity in the charge carrier's mobility mechanisms. Charge carrier displacement occurs through an activated mechanism below T-g and through a Vogel-Fulcher-Tammann-Hesse mechanism above this temperature. Fitting conductivity data with the proposed model allows one to determine separately the enthalpies of charge carrier formation and migration. For the five investigated compositions, the enthalpy of charge carrier formation is found to decrease, with x, from 0.86 to 0.2 eV, while the migration enthalpy remains constant at approximate to 0.14 eV. Based on these values, the charge carrier mobility and concentration in the glassy state can then be calculated. Mobility values at room temperature (approximate to 10(-4) cm(2) V-1 s(-1)) do not vary significantly with the AgI content and are in good agreement with those previously measured by the Hall-effect technique. The observed increase in ionic conductivity with x would thus only be due to an increase in the effective charge carrier concentration. Considering AgI as a weak electrolyte, the change in the effective charge carrier concentration is justified and is correlated to the partial free energy of silver iodide forming a regular solution with AgPO3. (C) 2011 American Institute of Physics. {[}doi:10.1063/1.3666835] (AU)

• Processo FAPESP: 10/08003-0 - Mecanismos de transporte elétrico em vidros e vitrocerâmicas
• Beneficiário: Ana Candida Martins Rodrigues
• Linha de fomento: Auxílio à Pesquisa - Pesquisador Visitante - Internacional
• Processo FAPESP: 07/08179-9 - Processos cinéticos em vidros e vitrocerâmicas
• Beneficiário: Edgar Dutra Zanotto
• Linha de fomento: Auxílio à Pesquisa - Temático