六方多型钴酸银（III）AgCoO2 + δ的拓扑合成、结构和磁性
Topotactic synthesis, structure and magnetic properties of a new hexagonal polytype of silver cobaltate(III) AgCoO2+δ
摘要：
在AgNO3-NH4NO3熔融体系中，用Na0.75CoO2在175 ℃下进行离子交换，制备了一种新的铜铁矿型AgCoO2 + δ。其结构由XRD数据通过Rietveld精修确定;其为六方晶系，空间群P63/mmc，a = 2.871和c = 12.222 π。它的结构不同于先前报道的AgCoO2（R-3m，3R多型）的堆叠的Co-O层;在新的阶段的2H堆叠的前体Na0.75CoO2，与一个topotactic离子交换的Na银。发现新相含有轻微的氧过剩（δ = 0.06）。磁化率测量表明，没有磁性转变和弱居里项，符合非磁性字符的Co 3+离子。
英文摘要：
A new form of delafossite-type AgCoO2+δwas prepared using ion exchange from Na0.75CoO2 in molten AgNO3-NH4NO3 at 175 degrees C. Its structure was determined by Rietveld refinement from XRD data; it is hexagonal, space group P63/mmc, a = 2.871 and c = 12.222 Å. Its structure differs from previously reported AgCoO2 (R-3m, 3R polytype) by the stacking of Co-O layers; in the new phase the 2H stacking of the precursor Na0.75CoO2, consistent with a topotactic ion exchange of Na by Ag. The new phase is found to contain a slight oxygen excess (δ= 0.06). Magnetic susceptibility measurements show the absence of magnetic transition and a weak Curie term, consistent with the non-magnetic character of Co3+ ions.
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