Effect of Yttrium (20%) doping on mechanical properties of rare earth nano lanthanum phosphate (LaPO4 ) synthesized by aqueous sol-gel process,

In this study, Nascent Lanthanum Phosphate (LaPO4) and LaPO4 with 20% reinforced Yttria (Y2O3) precursor ceramic powder was synthesized through aqueous Sol-gel route, where theLaPO4 and LaPO4/Y2O3 powder was sourced from Lanthanum chloride (LaCl3) and orthophosphoric acid (H3PO4). By sintering the precursor powder at 1400 °C for 2 h, a relatively high-density composite material of LaPO4 (97.4%) and LaPO4/Y2O3 (98.4%) were fabricated. Through X-ray powder diffraction (XRD) experiment, the results revealed that LaPO4 and LaPO4/ Y2O3 electrolyte samples sintered at 1400 °C for 2 h is impurity free and thereby elemental composition of the
powders is also verified. Further, a small quantity of LaP2 and La2O3elements formed during the synthesis of LaPO4 was found to contribute more on corrosion resistance and high withstanding capacity of the material. 26% of YPO4 formed due to a chemical reaction between Yttrium and Lanthanum made this composite a suitable candidate material for high-temperature applications. Various mechanical characterization tests such as microhardness, flexural strength, and compression capacity were studied, where the microscopic analysis provided
comprehensive information about both transgranular and intergranular types of failure on the fractured regions
of LaPO4 and LaPO4/Y2O3 material. The MicroVicker'shardness of LaPO4 and composite was found to be 5 GPa and 5.2 GPa, respectively. When compared with the nascent sample, on an average, 22% reduction in flexural strength and a 1.05% increase in Young's modulus are observed for the high-density composite.