Synthesis and Characterization of Leucite Using a Diatomite Precursor

Abstract

Leucite is nowadays an important component in ceramic restoration systems with particular suitability to dental porcelains. The leucite synthesis from a hydrothermally-derived precursor is here presented. A silicate solution was prepared by mixing a naturally derived amorphous silica (diatomitic rock from Crotone, southern Italy) with potassium hydroxide and an aluminate solution was obtained by mixing aluminium hydroxide and potassium hydroxide. Three mixtures of varying ratios of aluminate and silicate solutions were prepared and submitted to hydrothermal treatment at 150 °C for one hour. Subsequently these hydrothermal precursors were subjected to calcination at the temperature of 1000 °C for variable time intervals, thus resulting in 3 series of syntheses. The synthesis run 3 turned out to be the best from the point of view of temporal yield showing the crystallization of the leucite after only 15 hours of heat treatment. The products of synthesis run 3 were fully characterised by Powder X-Ray Diffraction, Inductively Coupled Plasma Optical Emission Spectrometry, Infrared Spectroscopy and Thermal Analysis. The amorphous phase in the synthesis powders was estimated by quantitative phase analysis using the combined Rietveld and reference intensity ratio methods. Density of leucite was also achieved by He-pycnometry. The use of a cost effective starting material such as a diatomite in the experimental route makes the process highly attractive for expansion to an industrial scale especially considering that both the chemical and physical characterizations of our leucite product are highly satisfactory. Last but not least we explain some inferences that can be obtained from this process of synthesis in order to a better understanding of some natural occurrences of leucite in geologic systems related to basaltic magmas.

A Green Method for Synthesis of Silver-Nanoparticles-Diatomite (AgNPs-D) Composite from Pineapple (<i>Ananas comosus</i>) Leaf Extract

“…Leusite is an essential material in Porcelain-Fused-to-Metal (PFM) and all-ceramic restoration systems. This material produces transparency, depth of color, and texture of natural teeth [16]. However, the use of diatomite in the biomedical field is limited because it does not contain antibacterial properties.…”

Synthesis and characterization of Na-P1 (GIS) zeolite using a kaolinitic rock

“…The infrared analysis was performed with a spectrometer FTLA2000, served by a separator of KBr and a DTGS detector; the source of IR radiation was a SiC (Globar) filament. Samples were treated according the method of Novembre et al 39 , 40 using powder pressed pellets (KBr/sample ratio of 1/100, pressure undergone prior determination 15 t/cm 2 ); spectra were processed with the program GRAMS-Al (GRAMS/AI Spectroscopy Software, Thermo Scientific Company).…”

Improvement in the Synthesis Conditions and Studying the Physicochemical Properties of the Zeolite Li-A(BW) Obtained from a Kaolinitic Rock

“…Both the crystalline and amorphous phases in the synthesis powders were estimated using quantitative phase analysis (QPA) applying the combined Rietveld and reference intensity ratio (RIR) methods; corundum NIST 676a was added to each sample, amounting to 10%, and the powder mixtures were homogenized by hand-grinding in an agate mortar 19 . Data for the QPA refinement were collected in the angular range 5-120° 2theta with steps of 0.02° and 10 s step −1 , a divergence slit of 0.5° and a receiving slit of 0.1 mm.…”

“…Li-A(BW) density was calculated by He-picnometry using an ACCUPYC 1330 pycnometer. The specific surface and porosity were obtained by applying the BET (BRUNAUER-EMMETT-TELLER) method with N 2 using a MICROMERITICS ASAP2010 instrument (operating from 10 to 127 kPa) 19 .…”