Microstructure, properties and thermoluminescent response of sintered synthetic topaz (Al2SiO4F1.44 (OH)0.56)/Al2O3 compounds

Thermoluminescent composites of sintered synthetic-topaz/in situ corundum for dosimetry by a novel reversible process

“…The stable synthetic topaz phase (Al 2 SiO 4 F 1·44 (OH) 0.56 ) forms from a heterogeneous reaction between SiF 4(g) and the Al(OH) 3 reactant compact; SiF 4(g) generates from the thermal decomposition of Na 2 SiF 6 at 550 °C [ 29 ]. In parallel, as previously described, the reaction between silicon tetrafluoride and aluminum hydroxide gives rise to aluminum fluoride (AlF 3 ) [ 32 ]. It is postulated that AlF 3 formation during sintering is necessary to obtain the topaz/corundum composite.…”

“…Topaz (Al 2 SiO 4 F 1·44 (OH) 0.56 ) powders were synthesized by the hybrid system chemical vapor deposition (HYSY-CVD) method described previously [ 32 ]. HYSY-CVD is a method developed at CINVESTAV-Saltillo to produce advanced ceramics using solid-gas reaction systems [ 29 , 30 , 37 , [39] , [40] , [41] , [42] ].…”

“…(1) . The porosity of the specimens was evaluated using the ratio of the density of the samples to the theoretical density, as explained in a previous article [ 32 ]. …”

“…Significant progress has been made by developing different materials of natural topaz [ [8] , [9] , [10] , [11] ], synthetic topaz [ [12] , [13] , [14] , [15] , [16] , [17] , [18] , [19] , [20] , [21] ], beach sand-Teflon composites [ 22 , 23 ], wollastonite-Teflon composites [ 24 ], citrine-Teflon [ 25 ], and natural topaz composites [ 1 , 7 , [26] , [27] , [28] ]. Recently, sintered synthetic topaz/corundum compounds – obtained by the hybrid-system chemical vapor deposition or HYSY-CVD route, developed at CINVESTAV-Saltillo [ [29] , [30] , [31] ]– with thermoluminescent behavior were reported [ 32 ]. The primary motivation for proposing composites in dosimetry is the development of materials with thermoluminescence characteristics superior to those obtained with materials of a single constituent.…”

“…In topaz synthesis by HYSY-CVD, when Na 2 SiF 6 is heated, the silicon precursor SiF 4(g) is released and dragged by the inert gas flow throughout the cylindrical reaction chamber. Silicon tetrafluoride (SiF 4 ) gas subsequently reacts with the Al(OH) 3 (aluminum hydroxide) tablet as a substrate, which acts as a nucleation center to produce the stable solid topaz phase [ [12] , [13] , [14] , 32 , 33 , 37 ].…”