Crystal structure and electric modulus studies of mixed-alkali (Na+−K+)β- and β″-alumina
1987; Elsevier BV; Volume: 23; Issue: 1-2 Linguagem: Inglês
10.1016/0167-2738(87)90085-3
ISSN1872-7689
AutoresTakaaki Tsurumi, Gurjit Singh, P. Nicholson,
Tópico(s)Microwave Dielectric Ceramics Synthesis
ResumoAbstract The crystal structures of mixed-alkali (Na+-K+) β- and β′' -alumina were refined and the electric modulus of the crystals was measured. The electron density distribution on the conduction planes suggests an attractive interaction exists between the Na+ and K+ on mO sites in the mixed-alkali β-alumina with a K+ mole fraction of 0.80. The thickness of the conduction slab in β′' -alumina is related to the electrical conductivity. The modulus peak shape of the mixed-alkali β′' -alumina was almost identical over the whole composition range but small discrepancies were observed at low frequencies. The modulus peak shape of mixed alkali β-alumina varied with K+ mole fraction, especially at high frequencies. The peak observed for a crystal with 0.25 K+ mole fraction agreed with calculations based on a double log-Gaussian distribution function of relaxation times.
Referência(s)