This research investigated the relationship between the quantitative phase crystal structure and mechanical properties of ZrO₂ ceramic addition of Y₂O₃, MgO and BaCO₃ at 0.0, 2.0, 4.0 and 6.0 mol%. Ceramic samples were prepared using mixed oxide method under normal sintering at 1,600 ^oC with dwell time for 120 min . ZrO₂-Y₂O₃ and ZrO₂-MgO ceramics were obtained with bulk densities values between 5.324-5.722 g/cm³ while ZrO₂-BaCO₃ ceramic showed densification values about 4.412-4.827 g/cm³. It was found that ZrO₂-Y₂O₃ and ZrO₂-MgO ceramic showed higher fracture toughness values than ZrO₂-BaCO₃ ceramics. Refinement of lattice parameter using Rietveld analysis in ceramic samples revealed the percentage of fraction phase ratios of m-ZrO₂, t-ZrO₂ and c-ZrO₂. The refinement parameters result in sample ceramic which are Y₂O₃ addition between 4-6 mol% obtained a high ratio of t-ZrO₂ phase and the result supported optimal mechanical properties. ZrO₂-Y₂O₃ ceramic showed a higher lattice stain value compared with the additions of other ZrO₂ oxides and it was found that lattice strain increase with high ratio of t-ZrO₂ phase. Sample ceramics had crystallite size values between 56.65-82.30 nm. SEM micrographs revealed morphology and average grain sizes. All samples grains were spherical in shape combined with irregular shape and were gray in color and were obtained with an average grain size between 0.63 -2.18 µm. It was found that the ZrO₂-Y₂O₃ ceramic showed small crystallize size and size of grains. The optimal condition for addition of oxide were found in ceramics of ZrO₂-Y₂O₃ and ZrO₂-MgO and confirmed that good mechanical properties were obtained from a high ratio of t-ZrO₂ phase and fine grain size

Keywords: ZrO₂, Y₂O₃, MgO, BaCO₃, Rietveld refinement