水合稀土碳酸盐的红外光谱

IR of Hydrated Rare Earth Carbonates

以碳酸氢铵为沉淀剂合成了十五种稀土碳酸盐晶体。化学分析的结果表明,轻稀土碳酸盐(镧、铈、镨、钕)为八水合正碳酸盐;部分中重稀土碳酸盐(钐、铕、钆、铽、镝、钬、铒、钇)为低水合正碳酸盐;重稀土铥、镱、镥的碳酸盐为碱式盐或碳酸氧化物。红外吸收光谱分析的结果表明,碳酸根离子的非简并振动吸收的频率γ2和γ8发生了分裂,有六个以上的振动吸收峰,这说明稀土碳酸盐晶胞中存在着非等价的碳酸根离子,即双齿配位与单齿配位的碳酸根。

Fifteen crystalline hydrated rare earth carbonates were synthesized using ammonium bicarbonate as precipitant. The results of the chemical analyses suggest that lanthanum, cerous, praseodymium and neodymium carbonates are normal rare earth carbonate octahydrates; samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium and yttrium carbonates are normal rare earth carbonate lowerhydrates; and thulium, ytterbium and lutetium carbonates are hydrated basic carbonates or oxycarbonates. The results of the IR indicate that since there are more than six normal vibrational bands for carbonate group and the non-degenerate Y2 and （or） Y8 is split, there must be two nonequivalent carbonate groups （bidentate and unidentate carbonates） in the unit cell for all rare earth carbonates.