Sintering of Lanthanum Zirconate

Abstract

Lanthanum zirconate (La 2 Zr 2 O 7 ) was prepared by coprecipitating lanthanum nitrate and zirconyl oxychloride at pH 10, followed by ethanol washing. The initial high surface area of ∼304 m 2 ؒg −1 decreased very rapidly with increased sintering temperature and decreased to an immeasurably small value after heating at 1200°C for 15 h. The major parameters studied were phase evolution, crystallite size, porosity, surface area reduction, and shrinkage during sintering. Three temperature regions were identified based on these studies: below the crystallization temperature, between the crystallization temperature and ∼1100°C, and above 1100°C. The main contribution of surface area reduction in the region 800°-1100°C was due to surface diffusion; the main contribution above 1100°C was due to grain-boundary diffusion coupled with surface diffusion.

Effects of Y2O3 addition on the phase evolution and thermophysical properties of lanthanum zirconate

“…For samples A0-A4, four Raman bands at 299, 395, 490 and 515 cm −1 are visible. These Raman bands are the characteristics of LZ-type structure, which is consistent with the previous results [18]. One Raman band at 375 cm −1 is also detected in A1-A4, which is the characteristics of LaYO 3 according to the Raman spectrum of pure LaYO 3 .…”

Thermal cycling behavior of La2Zr2O7 coating with the addition of Y2O3 by EB-PVD

“…For the three specimens, four Raman bands at 299, 395, 490 and 515 cm −1 are visible. These Raman bands are the characteristics of LZ-type structure, which is consistent with the previous results [19]. One Raman band at 375 cm −1 is also detected in three specimens, which is the characteristics of LaYO 3 according to the Raman spectrum of pure LaYO 3 .…”

Hot‐Pressed Glass Matrix Composites Containing Pyrochlore Phase Particles for Nuclear Waste Encapsulation

“…The use of sintered glass for the matrix has the important advantage of allowing relatively low processing temperatures (< 700 C), much lower than the sintering temperature required for densification of pyrochlore crystalline ceramics, which is about 1200 C. [32,33] The processing temperature for a glass powder based approach will also be lower than the temperatures required for crystallization of host phases in conventional glass-ceramics, which are usually well above 1000 C. [2,17] Moreover densification by sintering and hotpressing has the additional advantage of avoiding devitrification and phase separation problems occurring in glass melting processes. [2,3] In a previous study, [30] we demonstrated the fabrication of La 2 Zr 2 O 7 pyrochlore-glass composites by powder technology and sintering.…”