A preliminary investigation of the molten salt mediated synthesis of Gd2TiO5 ‘stuffed’ pyrochlore

Abstract

Refractory ‘stuffed’ pyrochlores such as Gd2TiO5 are of interest for nuclear applications, including as matrices for actinide disposition and as neutron absorbers in control rods. Here, we report the results of a preliminary comparative investigation of the synthesis of Gd2TiO5 by molten salt and conventional solid-state synthesis. We show that synthesis of Gd2TiO5 proceeds from the pyrochlore phase Gd2Ti2O7 which is first formed as a kinetic product. Molten salt synthesis afforded single phase Gd2TiO5 at 1300 °C in 2 h, via a template growth mechanism, and is effective for the synthesis of these refractory materials. This work demonstrates molten salt mediated synthesis of ‘stuffed’ pyrochlore for the first time. Graphic abstract

Utilizing rare earth titanates to improve performance of solid-state electrochromic device

“…The chemical purity of the sample was confirmed by the XRD [47] pattern (figure 1(b)). The absence of any unaccounted peak in the XRD pattern confirms the sample's high chemical purity and structural integrity [36,48]. To obtain the structural parameters, the FullProf software [49,50] package was used to do the Rietveld refinement of the obtained XRD data.…”

“…The two polyhedral Gd 1 O 7 and Gd 2 O 7 are connected by one standard edge formed by the O2 and O3 atoms (inset: figure 1(b)). The titanium ion forms the distorted Ti-O 5 polyhedral [48,56,57], where five oxygen atoms surround the titanium ion and form the distorted square pyramidal geometry (Inset: figure 1(b)). To further confirm the synthesis of GTO, Raman spectrum have been recorded (figure S2, SI).…”

Low temperature controllable synthesis of transition metal and rare earth borides mediated by molten salt

“…Such a technique is commonly used to synthesise a variety of oxides and non-oxides (borides, carbides, nitrides, alloys, etc.). [47][48][49][50][51][52][53][54][55][56][57][58][59] Figure 3 illustrates schematically the main steps involved in a typical MSS process, 51 including, combining raw materials and salt(s) in appropriate ratios, firing the powder mix in a reaction vessel (e.g. a crucible) to a target temperature above the melting/eutectic point of the salt(s) and holding at the temperature for a requisite time period, water-leaching repeatedly any residual salt(s) in the reacted mass after cooling to room temperature, and collecting and drying the final product.…”

“…Benefiting from all of these, the overall production process is more economical than a conventional synthesis one. [47][48][49][50][51][52][53][54][55][56][57][58][59]…”

“…As well documented in the literature [47][48][49][50][51][52][53][54][55][56][57][58][59] depending on solubility values of the two reactants in molten salt under synthesis conditions, MSS could be dominated by different mechanisms. A 'template-growth' mechanism is dominant when one of the reactants has a much higher solubility than the other, whereas a 'dissolution and precipitation' mechanism is dominant when both reactants have relatively high solubility.…”