The formation of a nano-apatite surface layer is frequently considered a measure of bioactivity, especially for non-phosphate bioceramics. In the present study, strontium-doped calcium sulfate, (Ca,Sr)SO₄, was used to verify the feasibility of this measure. The (Ca,Sr)SO₄ specimen was prepared by mixing 10% SrSO₄ by weight with 90% CaSO₄·½H₂O powder by weight. A solid solution of (Ca,7.6%Sr)SO₄ was then produced by heating the powder mixture at 1100 °C for 1 h. The resulting (Ca,Sr)SO₄ specimen was readily degradable in phosphate solution. A newly formed surface layer in the form of flakes was formed within one day of specimen immersion in phosphate solution. Structural and microstructure–compositional analyses indicated that the flakes were composed of octacalcium phosphate (OCP) crystals. An amorphous interface containing OCP nanocrystals was found between the newly formed surface layer and the remaining (Ca,Sr)SO₄ specimen. The specimen was also implanted into a rat distal femur bone defect. In addition to new bone, fibrous tissue and inflammatory cells were found to interlace the (Ca,Sr)SO₄ specimen. The present study indicated that a more comprehensive evaluation is needed to assess the bioactivity of non-phosphate bioceramics.

纳米磷灰石表面层的形成通常被认为是生物活性的衡量标准，特别是对于非磷酸盐生物陶瓷。本研究采用掺锶硫酸钙(Ca,Sr)SO ₄来验证该措施的可行性。(Ca,Sr)SO ₄试样是通过将10％重量的SrSO ₄与90％重量的CaSO ₄ ·1/2H ₂ O粉末混合来制备的。然后通过将粉末混合物在1100℃加热1小时来制备(Ca,7.6%Sr)SO ₄的固溶体。生成的 (Ca,Sr)SO ₄样品在磷酸盐溶液中很容易降解。在样品浸入磷酸盐溶液后一天内形成了新形成的薄片状表面层。结构和微观结构组成分析表明，薄片由磷酸八钙 (OCP) 晶体组成。在新形成的表面层和剩余的 (Ca,Sr)SO ₄样品之间发现了一个含有 OCP 纳米晶体的非晶界面。该标本也被植入大鼠股骨远端骨缺损处。除了新骨外，还发现纤维组织和炎症细胞与 (Ca,Sr)SO ₄标本交错。本研究表明，需要更全面的评估来评估非磷酸盐生物陶瓷的生物活性。