The unit cell volume of BaZrO3 starts to shrink from 1050 °C until complete intermixing with the matrix is achieved at 1250 °C. This supports the claim that the smaller Ti 4+ -ions diffuse into the BaZrO3 lattice . A small amount of Ca 2+ -ions could possibly also dissolve in this phase, which would shrink the overall cell size , but this effect is deemed to be insignificant. The phase fractions determined from refining the in-situ X-ray diffractograms were summarized in BaZrO3-rich perovskite becomes more crystalline and progressively incorporates more matrix atoms into its structure, leading to homogenization with the BCZT matrix (Figure ).