ChemInform Abstract: On the Properties of Titanates with Ilmenite Structure. Part 2. Thermodynamics and the Electrical Conductivity of NiTiO3 and Other Phases with Ilmenite Structure.

Abstract

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Synthesis and coloring performance of Ni-geikielite (Ni,Mg)TiO3 yellow pigments: Effect of temperature, Ni-doping and synthesis method

“…As it was to expect, the unit cell parameters and cell volume of (Mg,Ni)TiO 3 ilmenite pigments (in both ceramic and citrate-gel samples) decreased with the increase of Ni-doping (x value) in nominal formulations. This is in agreement with previous reports of MgTiO 3 -NiTiO 3 solid solutions (Mg 1−x Ni x TiO 3 ) showing an almost linear decrease of cell parameters with Ni doping (following Vegard's Law) [32].…”

“…Noteworthy, Lerch and Laqua investigated also the influence of Mg 2+ and Co 2+ doping on the order-disorder transition temperature of NiTiO 3 ilmenite and, in the case of Ni 1−x Mg x TiO 3 solid solutions, they found a strong shift of this transition to higher temperatures if only a small part of the Ni 2+ was replaced by Mg 2+ [32]. For instance, with a 5 mol% of Mg the transition was shown to take place between 1330 and 1355 • C, and with only a 10 mol%-doping of Mg (x = 0.1) the anomalous increase of electrical conductivity with temperature was no longer observed, suggesting the stabilization of the ordered phase (inhibition of order-disorder transition).…”

“…NiTiO 3 , in contrast, is the only binary titanate for which a temperature-driven order-disorder phase transition (from the ordered R-3 to the fully disordered R-3c corundum structure) has been described and analyzed in detail. Indeed, this order-disorder transition has been reported to occur in NiTiO 3 at a temperature around 1287-1290 • C by Lerch et al [32,61] and Boysen and Lerch [62] based on the anomalous increase of the specific electrical conductivity. More recently, Jacob et al have fixed this transition at 1292 • C according to electrochemical EFM measurements [63].…”

“…For instance, Ni titanates (NiTiO 3 ) have been used for many advanced applications, such as high-k dielectrics, antiferromagnetic or multiferroic materials, photocatalysts for organic dyes, solid lubricants, and so on [25,[30][31][32][33][34][35][36][37]. Moreover, NiTiO 3 has been also considered as a traditional yellow pigment and, owing to its high solar (near-IR) radiation reflection efficiency [38], it has been recently postulated as cool pigment for building coatings [39].…”

“…M 2+ Ti IV O 3 titanates with ilmenite structure (M = Mg 2+ or transition divalent metals such as Co, Fe, Mn, Ni, Cu and Zn) have been profusely investigated as functional materials showing a wide variety of electrical, magnetic, optical, gas-sensing and even catalytic properties [22][23][24][25][26][27][28][29][30][31][32][33]. For instance, Ni titanates (NiTiO 3 ) have been used for many advanced applications, such as high-k dielectrics, antiferromagnetic or multiferroic materials, photocatalysts for organic dyes, solid lubricants, and so on [25,[30][31][32][33][34][35][36][37].…”