Electrical Conductivity and Phase Transitions in KDP- And Adp-Porous Glass Nanocomposites

Abstract

The results of dielectric and dilatometric measurements of ADP and KDP-porous glass composites are presented. We stated on dilatometric studies that in ADP-porous glass nanocomposites the phase transition temperature decreases with decreasing of average size of pores. The negative jump of volume at phase transition region in ADP-porous glasses is observed. It was found that for KDP embedded into porous glasses nonmonotonous dependence of phase transition temperature on pores sizes occurs. The conductivity of ADP/KDP composites is significantly higher than in bulk crystals. The obtained values of activation energies are typical for proton movement.

Phase transition in NH4HSO4–porous glasses nanocomposites

“…A recent research of ferroelectric materials embedded in porous glass matrices showed that the new nanocomposites exhibited different properties than those for bulk and increasingly becoming more attractive for wide variety of applications. An embedding of ferroelectric materials into porous glasses either from the melt or from a water solution is one of recommended methods for obtaining the ferroelectric nanoparticles (Colla et al 1997; Dorner et al 2003; Ciżman et al 2012a; Sieradzki et al 2011). …”

“Restricted Geometry” Effect on Phase Transitions in KDP, ADP, and CDP Nanocrystals

“…For example, the experimental study of the dielectric properties of KDP in porous structures with pore dimensions D = 7-100 nm demonstrate that a decrease in the pore diameter leads to a monotonous increase in the TC. At the same time, the nonmonotonic behavior of the TC(D) dependence was revealed in references [10,11] on the basis of dielectric and dilatometric measurement results.…”

“…This is most likely to occur for composites with a high content of embedded matter. The results of dilatometric measurements for composites ADP-PG160 and ADP-PG23 [11] have revealed a significant deformation of glass matrix in the AFE phase transition region, which illustrates this assumption.…”

“…An influence of the pore size on the phase transition temperature in KDP and ADP particles, embedded in porous matrices, has already been discussed [8][9][10][11]13]. However, experimental results obtained by different authors contain some contradictions.…”

“…Alongside this, potassium dihydrogen phosphate [8][9][10][11][12][13], Rochelle salt [14,15], and triglycine sulfate [14,[16][17][18][19], in contrast, are characterized by an increase of ferroelectric phase transition temperature under "restricted geometry" conditions. However the data on the magnitude of T C shifting as a function of the matrix mean that the pore diameter varied significantly for different researchers.…”