V-ZrSiO4 ceramic pigments synthesis from m-ZrO2 and different amorphous silica sources

Synthesis of zircon pigments from rice husk ash and their performance in ceramic glaze

“…The average particle sizes were 3.2, 3.1, 5.0 and 3.3 µm for V, Pr, Fe and Cr dopants, respectively. These values are in relatively similar ranges with several studies [6,16]. In the backscattering mode (BEI), only a small number of particles of lighter contrast (white) was observed; they were likely of ZrO2 with Zr as a higher atomic number as confirmed by Energy Dispersive Spectroscopy (EDS).…”

“…A careful, slow scan did not reveal an amorphous halo as observed in an amorphous silicate glass (data not shown). Investigations using RHA with NaF as a flux by other researchers did not demonstrate this cristobalite peak but displayed only monoclinic ZrO2 as a secondary phase when fired at or above 1000℃ [15,16]. Pyon et al [15] showed that NaVO3 formed first as an intermediate phase with the reaction between SiO2 and m-ZrO2 starting at 700℃.…”

“…The presence of V 5+ could be ruled out given the fact that no reflectance peak at approximately 530 nm was observed [9]. The characteristic band at 640 nm was attributed to V 4+ with tetrahedral and dodecahedral coordination which is the origin of blue color [9,15,16]. This band is caused by the transition from 2B1 to 2E [15].…”

“…Extraction of pure SiO2 from RHA using alkali and acidic treatment is a laborious and costly process and could have made this alternative source not being advantages to other sources [14]. Several studies on zircon pigment synthesis used RHA without chemical extraction but the chromophores were still limited to vanadium and praseodymium [2,15,16].…”