Hierarchical Pattern Formation in Thin Film Diblock Copolymers above the Order−Disorder Transition Temperature

1999 ◽  
Vol 32 (24) ◽  
pp. 8167-8172 ◽  
Author(s):  
R. Limary ◽  
P. F. Green
Keyword(s):  
Thin Film ◽  
Transition Temperature ◽  
Pattern Formation ◽  
Diblock Copolymers ◽  
Disorder Transition ◽  
Hierarchical Pattern ◽  
Disorder Transition Temperature

Block Copolymer Thin Films Above and Below the Order-Disorder Transition Temperature

2000 ◽  
Vol 629 ◽  
Author(s):  
Ratchana Limary ◽  
Peter F. Green
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Molecular Weight ◽  
Transition Temperature ◽  
Block Copolymer ◽  
Film Thickness ◽  
Diblock Copolymer ◽  
Diblock Copolymers ◽  
Microphase Separation ◽  
Disorder Transition Temperature

ABSTRACTSymmetric diblock copolymers undergo a disorder to order transition below a microphase separation transition temperature. In this temperature range the structure is characterized by alternating lamellae of thickness L. In thin film geometries, the lamellae are oriented normal to the substrate if there is a preferential interaction between either of the block constituents and the substrate/copolymer or copolymer/vacuum interfaces. Depending on the relation between the film thickness and L, the topography of the film might comprise of holes, islands or spinodal-like structures. We show that in a polystyrene-b-poly(methyl methacrylate) diblock copolymer of molecular weight 20, 000 g/mol, above the microphase separation transition temperature, the topography of the film depends on the thickness. A heirarchy of bicontinuous patterns and holes is observed with increasing film thickness for films thinner than 35 nm.

scholarly journals Alloying effect on the order–disorder transformation in tetragonal FeNi

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Li-Yun Tian ◽  
Oliver Gutfleisch ◽  
Olle Eriksson ◽  
Levente Vitos
Keyword(s):  
Transition Temperature ◽  
High Performance ◽  
Density Functional ◽  
Permanent Magnets ◽  
Positive Impact ◽  
Design Strategies ◽  
Alloying Effect ◽  
Functional Theory ◽  
Disorder Transition ◽  
Disorder Transition Temperature

AbstractTetragonal ($${\hbox{L1}}_{0}$$ L1 0 ) FeNi is a promising material for high-performance rare-earth-free permanent magnets. Pure tetragonal FeNi is very difficult to synthesize due to its low chemical order–disorder transition temperature ($$\approx {593}$$ ≈ 593  K), and thus one must consider alternative non-equilibrium processing routes and alloy design strategies that make the formation of tetragonal FeNi feasible. In this paper, we investigate by density functional theory as implemented in the exact muffin-tin orbitals method whether alloying FeNi with a suitable element can have a positive impact on the phase formation and ordering properties while largely maintaining its attractive intrinsic magnetic properties. We find that small amount of non-magnetic (Al and Ti) or magnetic (Cr and Co) elements increase the order–disorder transition temperature. Adding Mo to the Co-doped system further enhances the ordering temperature while the Curie temperature is decreased only by a few degrees. Our results show that alloying is a viable route to stabilizing the ordered tetragonal phase of FeNi.

Increased Order–Disorder Transition Temperature for a Rod–Coil Block Copolymer in the Presence of a Magnetic Field

2011 ◽  
Vol 44 (19) ◽  
pp. 7503-7507 ◽  
Author(s):  
Bryan McCulloch ◽  
Giuseppe Portale ◽  
Wim Bras ◽  
Rachel A. Segalman
Keyword(s):  
Magnetic Field ◽  
Transition Temperature ◽  
Block Copolymer ◽  
Disorder Transition ◽  
Disorder Transition Temperature

Self-diffusion of an asymmetric diblock copolymer above and below the order-to-disorder transition temperature

1999 ◽  
Vol 111 (6) ◽  
pp. 2789-2796 ◽  
Author(s):  
Gerald Fleischer ◽  
Frank Rittig ◽  
Jörg Kärger ◽  
Christine M. Papadakis ◽  
Kell Mortensen ◽  
...  
Keyword(s):  
Transition Temperature ◽  
Diblock Copolymer ◽  
Disorder Transition ◽  
Self Diffusion ◽  
Disorder Transition Temperature
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