In comparison with the ceramic route,citrate-gel samples exhibited a much higher reactivity,yielding well-crystallized
Ni-geikielite free of residual karrooite at much lower temperatures (800 ◦C/3 h),and leading to yellow-orange colors of higher chroma even at lower Ni loadings (L*/a*/b* =80.6/13.0/61.4 for x = 0.2/1200 ◦C).