Origin of the abnormal diffusion of transition metal in rutile

Diffusion of dopants in rutile is the fundamental process that determines the performance of many devices in which rutile is used. The diffusion behavior is known to be highly sample-dependent, but the reasons for this are less well understood. Here, rutile is studied by using first-principles calculations, in order to unravel the microscopic origins of the diverse diffusion behaviors for different doping elements. Anomalous diffusion behavior in the open channel along [001] direction is found: larger atoms include Sc and Zr have lower energy barrier for diffusion via interstitial mechanism, apparently contradicting their known slow diffusion rate. To resolve this, we present an alternate model for the overall diffusion rate of the large-size dopants in rutile, showing that parallel to the [001] channel, it is limited by the formation of the interstitial states, whereas in the direction perpendicular to [001], it proceeds via a kick-out mechanism. By contrast, Co and Ni, prefer to stay in the interstitial site of rutile, and have conventional diffusion with a very small migration barrier in the [001] channel. This leads to highly anisotropic and fast diffusion. The diffusion mechanisms found in the present study can explain the diffusion data measured by experiments, and these findings provide novel understanding for the classic diffusion topic

Data from: How do soil microorganisms respond to N, P and NP additions? Application of the ecological framework of (co‐)limitation by multiple resources

1.Nitrogen, N, and phosphorus, P, often limit biological processes in terrestrial ecosystems. Based on previous studies mainly focusing on plants, the concept of resource limitation has evolved towards a theory of (co)limitations by multiple‐resources. However, this ecological framework has not been applied to analyse how soil microorganisms and plants concurrently respond to N and/or P addition, and whether these responses are constrained by phylogenetic relatedness. 2.Here, we applied this framework to analyse microbial and plant responses at community and taxon levels to different fertilization treatments (4 N levels without P; 4 P levels without N; and 4 NP levels) in Tibetan grasslands. 3.Total plant biomass showed serial limitation by N then P, and most plant species were limited by N only. Total archaeal abundance decreased with P addition, but diverse nutrient limitation types were observed for archaeal taxa. Closely related archaeal taxa tended to similarly respond to N, and functional similarity between distant archaeal groups was observed for response to P, possibly due to functional convergence. In contrast, total bacteria slightly increased with P addition only when plants remained N‐limited, whereas without N limitation plants rather than bacteria benefited from P addition. Most bacterial taxa were limited by other resources than N and P, and no clear phylogenetic signals were observed regarding bacterial responses to N/P additions. 4.Synthesis: We propose a novel approach for characterizing microbial response types to nutrient addition. It demonstrates that in Tibetan meadows, most dominant plant species, archaea and bacteria respectively depend on N, both N and P, and other resources

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Including soil archaeal and bacterial communities, plant community and soil properties

How do soil micro‐organisms respond to N, P and NP additions? Application of the ecological framework of (co‐)limitation by multiple resources

1. Nitrogen (N) and phosphorus (P) often limit biological processes in terrestrial ecosystems. Based on previous studies mainly focusing on plants, the concept of resource limitation has evolved towards a theory of (co) limitations by multiple resources. However, this ecological framework has not been applied to analyse how soil micro-organisms and plants concurrently respond to N and/or P addition, and whether these responses are constrained by phylogenetic relatedness.2. Here, we applied this framework to analyse microbial and plant responses at community and taxon levels to different fertilization treatments (four N levels without P; four P levels without N and four NP levels) in Tibetan grasslands.3. Total plant biomass showed serial limitation by N then P, and most plant species were limited by N only. Total archaeal abundance decreased with P addition, but diverse nutrient limitation types were observed for archaeal taxa. Closely related archaeal taxa tended to similarly respond to N, and functional similarity between distant archaeal groups was observed for response to P, possibly due to functional convergence. In contrast, total bacteria slightly increased with P addition only when plants remained N limited, whereas without N limitation, plants rather than bacteria benefited from P addition. Most bacterial taxa were limited by other resources than N and P, and no clear phylogenetic signals were observed regarding bacterial responses to N/P additions.4. Synthesis. We propose a novel approach for characterizing microbial response types to nutrient addition. It demonstrates that in Tibetan meadows, most dominant plant species, archaea and bacteria, respectively, depend on N, both N and P and other resources