【摘要】 采用可控温、通气氛的杂化微波加热技术,成功合成了Ni3S2、ε-NiS、δ-NiS和NiS2四种化合物。采用XRD和SEM对样品的物相和形貌进行了表征,结果表明此方法容易合成单相的Ni3S2,通过改变烧结条件可获得主相分别为ε-NiS和δ-NiS的样品,合成单相NiS2则比较困难。电磁测量和低温XRD衍射的结果表明,随着温度上升,δ-NiS在260K附近发生顺磁-反铁磁(金属-非金属)转变,同时晶体点阵参数a、c分别减小0.38%和1.4%,在相变温区表现负热膨胀性。Ni3S2单相样品显示顺磁金属性质。更多还原

【Abstract】 A novel temperature-controlled hybrid-microwave method for the synthesis of binary nickel sulfides under argon atmosphere was demonstrated.Using this method,four binary compounds Ni3S2,δ-NiS,ε-NiS and NiS2 were successfully synthesized by adjusting the heating-rate,reaction time and temperature.The products were characterized by means of X-ray powder diffraction and scanning electron microscopy.XRD phase analyses indicate that single-phased Ni3S2 can be prepared easily,while δ-NiS and ε-NiS can be obtained as the major phase by adjusting the preparing condition.It is difficult to prepare single-phased NiS2 sample by the microwave method due to the vaporization of sulfur.The temperature dependence of the electrical resistivity and lattice parameters of the δ-NiS phase were measured in the temperature range of 5-300K.The δ-NiS sample exhibits a paramagnetic to antiferromagnetic(me-tal-nonmetal) phase transition near 260K,accompanied by 0.38% and 1.4% increasing of the lattice parameters a and c,respectively.Ni3S2 shows paramagnetic metal behavior.更多还原