Iron Phosphate Glass-ceramics

Abstract

Abstract:The crystallization of 40Fe2O3-60P2O5, 10ZnO-30Fe2O3-60P2O5 and (43.3−x)PbO-(13.7+x)Fe2O3-43P2O5, (0 < x < 30), glasses and glassceramic have been investigated. The structural evolution of glasses during heat treatment at various temperatures and the tendency for crystallization for series of glasses with modified composition are characterized by a dendrite-like phase separation in the early stage of crystallization. Such a behavior leads to the formation of randomly dispersed agglomerates which contain the anhedrally shaped crystallites embedded in glass matrix. Therefore, regardless of the type of crystallization, controlled or spontaneous, the formation of crystalline phases in these phosphate glasses and glass-ceramics is attributed to the disordered interfaces between crystalline grains and glassy matrix.

Effect of controlled crystallization on polaronic transport in phosphate‐based glass‐ceramics

“…It should be noted that the heat treatment at higher temperatures causes a massive crystallization, which leads to the presence of all three crystalline phases embedded in a minor residual glassy phase. The appearance of the detected crystalline phase(s) is in accordance with the literature data …”

“…The focus of so far published studies on induced crystallization of iron phosphate glasses was mainly on the structural changes which depend on glass composition and crystallization conditions but less on their influence on the electrical transport . Our recent investigations, however, show that the controlled crystallization appears to be a powerful tool for tailoring electrical properties of these materials .…”

“…Duration of heat treatment at each temperature (530, 560, 590, 620, 670, 720, 770, 800°C) varies from 1, 6, 12, 24 to 48 hours. It was previously reported that the three crystalline phases, namely Fe 3 (P 2 O 7 ) 2 (PDF No: 01‐080‐2315), Fe 4 (P 2 O 7 ) 3 (PDF No: 01‐073‐6768), and minor Fe(PO 3 ) 3 (PDF No: 01‐089‐8524) are created during crystallization. The appearance of each crystalline phase in the glass matrix depends on the time and temperature of heat treatment.…”

“…The appearance of the detected crystalline phase(s) is in accordance with the literature data. [23][24][25]27 The dependence of total crystallinity upon heat-treatment temperatures and times calculated using Rietveld analysis is exhibited in Figure 2. Generally, with increasing heattreatment temperature and time, total amount of crystalline PAVIĆ et Al phase(s) increases.…”

“…7,20 The focus of so far published studies on induced crystallization of iron phosphate glasses was mainly on the structural changes which depend on glass composition and crystallization conditions but less on their influence on the electrical transport. 8,[21][22][23][24][25] Our recent investigations, however, show that the controlled crystallization appears to be a powerful tool for tailoring electrical properties of these materials. 26,27 For instance, our study on the 10ZnO-30Fe 2 O 3 -60P 2 O 5 (mol%) glass system 26 shows that in the initial stage of crystallization, the electrical conductivity decreases, whereas with further crystallization progress it rises as a consequence of an increase in the size of crystal grains and their different distribution within the glass matrix.…”