The phase equilibrium diagram of the CaO-½Ho₂O₃-CoO_z system was determined at 885 °C in air. This diagram offers compatibility relationships in the ternary oxide system that are essential for processing and for the understanding of properties of several thermoelectric phases in the system. Four three-phase regions and three solid solution tie-line regions were determined in the CaO-½Ho₂O₃-CoO_z system. In the CaO-Ho₂O₃ system, while a small solid solution region was identified for (Ho_1-xCa_x)O_(3-z)/2 (0 ≤x ≤ 0.14), Ho was not present in the Ca site of CaO. Neither the reported Ho₂CoO₄ phase in the Ho₂O-CoO_z system nor the Ca-doped (Ho_1+xCa_1-x)CoO_4-z phase was present at 885 °C. No solid solution of the distorted perovskite, (Ho_1-xCa_x)CoO_3-z, was established at this temperature. The CaO-CoO_z system consists of two calcium cobaltate thermoelectric compounds. The 2D thermoelectric oxide, (Ca_3-xHo_x)Co₄O_9-z (0 ≤x ≤ 0.5), has a misfit layered structure, and the 1D Ca₃Co₂O₆ consists of chains of alternating CoO₆ trigonal prisms and CoO₆ octahedra. Ca₃Co₂O₆ was found to be a stoichiometric compound. A comparison of the phase diagrams of the CaO-½R₂O₃-CoO_z (R = La, Nd, Eu, and Ho) systems is given.

CaO-1 / 2Ho ₂ O ₃ -CoO _z系统的相平衡图在空气中于885°C下确定。该图提供了三元氧化物系统中的相容性关系，这对于处理和理解系统中多个热电相的性质至关重要。在CaO-1 / 2Ho ₂ O ₃ -CoO _z系统中确定了四个三相区域和三个固溶联系线区域。在CaO-Ho ₂ O ₃系统中，虽然对（Ho _1-x Ca _x）O _{（3-z）/ 2的}固溶区很小（0≤x≤0.14），在CaO的Ca部位不存在Ho。在Ho ₂ O-CoO _z系统中报道的Ho ₂ CoO ₄相和在885°C下都不存在Ca掺杂（Ho _{1 + x} Ca _1-x）CoO _4-z相。在该温度下未形成变形的钙钛矿（Ho _1-x Ca _x）CoO _3-z的固溶体。CaO-CoO _z系统由两种钴酸钙热电化合物组成。二维热电氧化物（Ca _3-x Ho _x）Co ₄ O _9-z（0≤x≤0.5）具有错配的分层结构，一维Ca ₃ Co ₂ O ₆由交替的CoO ₆三角棱镜和CoO ₆八面体链组成。发现Ca ₃ Co ₂ O ₆是化学计量的化合物。给出了CaO-1 / 2R ₂ O ₃ -CoO _z（R = La，Nd，Eu和Ho）系统的相图的比较。