A gear shaft allows a ceramic bearing to be used in environments where gear steel is desirable for driving a gear. The gear shaft includes a gear region and a bearing region. A bearing can be disposed about the bearing region of the gear shaft. A gear can be disposed about the gear region of the gear shaft. The bearing includes a ceramic material. The gear region of the gear shaft includes gear steel, whereas the bearing region of the gear shaft includes a bearing-region material that has a coefficient of thermal expansion (CTE) that is close to the CTE of the ceramic material.