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9楼: Originally posted by xmq135828 at 2016-11-07 22:03:19
104晶面是Li/TM均匀分布的面
是有文献明确提出过吗？
求教...

你用LiCoO2的cif画出来晶体结构图，找到（104）面一看就明白了。

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11楼2016-11-08 08:21:03

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916853152

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低调小弟: 金币+1 2016-11-24 19:15:55

楼上的回答都挺好的，其实（003）/(104)根本上主要是由于I（003）与d(003)相关,由于Ni（56A）的离子半径小于Li（76A），所以当Ni进入Li层，会造成d(003)的降低，表现为I(003)/(014)相对要低，至于>1.2的值，其实是个计算值，实际上这个比值主要在判断材料的结晶性上，当烧制温度较低时，晶体结晶性较低，衍射峰强度弱，层状不完整，Ni分布在锂层，所以材料性能较差。
(006, 102) 和 (108, 110)的分裂也是由于结晶性的问题，但是楼主千万不要以为这些值是个关键问题，当使用光源较强的X衍射仪，衍射峰也会非常符合以上指标，上面的指标只能是个说明层状材料的必要条件（有时候也不是），可以初步判断材料的性能优劣。

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12楼2016-11-08 08:51:22

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lliang157

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低调小弟: 金币+1 2016-11-24 19:15:39

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9楼: Originally posted by xmq135828 at 2016-11-07 22:03:19
104晶面是Li/TM均匀分布的面
是有文献明确提出过吗？
求教...

For the layered rhombohedral structure, if we define foct1 as the average atomic-scattering power at the lithium octahedral sites, foct2 as the average atomic-scattering power at transitionmetal octahedral sites, and fO as the atomic-scattering power of oxygen that builds up the skeleton, then the structural factors for the rhombohedral-(003)R and (104)R peaks can be calculated, respectively, as (3foct1– 3foct2– 1.1fO), and (3foct1 + 3foct2 + 5.8fO). The migration of transition metals from their own layer
to the lithium layer greatly increases foct1 due to the much larger atomic-scattering power of the transition metals. Since
the foct1 and foct2 have opposite signs for the (003)R peak, the increased foct1 will reduce significantly the amplitude square of
Fhkl. In contrast, foct1 and foct2 have the same signs in the structure factor of the (104)R peak, and therefore, the increase of foct1 will engender an increase in the amplitude square of Fhkl for the (104)R peak. This is the origin of using the intensity ratio of the (003) to (104) peaks to indicate the degree of cation mixing (transition metals in lithium-layer sites). During the initial stage of heating, the reducing intensity ratio of the (003)R to (104)R peaks in the TR-XRD patterns clearly denotes the migration of
transition metal cations into the lithium layers where vacancies had been created during the overcharge process

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13楼2016-11-23 14:41:13

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xmq135828

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13楼: Originally posted by lliang157 at 2016-11-23 14:41:13
For the layered rhombohedral structure, if we define foct1 as the average atomic-scattering power at the lithium octahedral sites, foct2 as the average atomic-scattering power at transitionmetal oct ...

您好，能否提供这段话的文献来源，我google了一下，并未找到出处

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14楼2016-11-24 09:23:26

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