GB/T 12690.4-2021稀土金属及其氧化物中非稀土杂质化学分析方法 第4部分：氧、氮量的测定 脉冲-红外吸收法和脉冲-热导法Chemical analysis methods for non-rare earth impurities of rare earth metals and their oxides. Part4:Determination of oxygen and nitrogen contents. Impulse-infrared absorption and impulse-

GB/T 12690.4-2021稀土金属及其氧化物中非稀土杂质化学分析方法 第4部分：氧、氮量的测定 脉冲-红外吸收法和脉冲-热导法Chemical analysis methods for non-rare earth impurities of rare earth metals and their oxides. Part4:Determination of oxygen and nitrogen contents. Impulse-infrared absorption and impulse-thermal conductivity method