Journal of Interfaces, Thin Films, and Low dimensional systems

Influence of surface alignment on the orientation behavior of a liquid crystal cell near nanoscale grooved surfaces

Document Type : Original Article

Authors

1 Department of Theoretical and Nanophysics, Faculty of Physics, Alzahra University, Tehran, Iran.

2 Department of Physics, University of Qom, Qom, Iran.

Abstract

In this work, we investigate the anchoring energy of a nematic liquid crystal cell with one patterned and one unpatterned surface. Surface reorientation effects are studied both in the absence of an external electric field and under the action of an external field. We consider the contribution of the saddle-splay surface energy and obtain the anchoring energies of the system. Director profiles are determined and the influence of the geometry, as well as the pitch values of the sinusoidal surface, are discussed. The reorientation of liquid crystal molecules in the vicinity of a nano-size grooved surface and the effect of different surface energy terms on the orientational behavior of a liquid crystal near the surfaces are investigated. Our calculations were performed using the Oseen-Frank theory based on nano-scale groove models. Our results reveal the crucial effects of surface and external fields on nematic reorientational behavior near a patterned surface. Also, our findings highlight the importance of the saddle-splay surface energy when comparing the Fukuda and Berreman models. Besides, it turns out that the presence of an external electric field significantly affects the results reported by these models.

Keywords

Main Subjects

Article Title [Persian]

تاثیر تنظیم سطحی بر رفتار سمتگیری یک بلور مایع در نزدیکی سطوح شیاردار نانومقیاس

Authors [Persian]

  • سعیده شعاری نژاد 1
  • زهرا کیکاووسی 1
  • محمد رضا مظفری 2

1 دانشکده فیزیک، دانشگاه الزهرا، تهران، ایران.

2 گروه فیزیک، دانشگاه قم، قم، ایران.

Abstract [Persian]

در این کار، انرژی چنگ زدگی یک سلول بلور مایع نماتیک با یک سطح طرح دار و یک سطح بدون الگو را بررسی می کنیم. اثرات سمت گیری مجدد سطح، هم در غیاب میدان الکتریکی خارجی و هم تحت عمل یک میدان خارجی، مورد مطالعه قرار می گیرد. ما سهم انرژی سطحی زینی را در نظر می گیریم و انرژی های چنگ زدگی سیستم را بدست می آوریم. پروفایل های جهت نما تعیین می شوند و تأثیر هندسه سیستم ، همچنین اثر اندازه گام سطح سینوسی، مورد بحث قرار می گیرند. سمتگیری مجدد مولکول‌های بلورمایع در مجاورت یک سطح شیاردار نانومقیاس و تأثیر جملات مختلف انرژی سطحی بر رفتار سمت‌گیری بلور مایع در نزدیکی سطوح مورد بررسی قرار می‌گیرد. محاسبات ما با استفاده از نظریه اوسین-فرانک بر اساس مدل‌های شیارهای نانومقیاس انجام شده است. نتایج ما اثرات حیاتی میدان‌های سطحی و خارجی را بر رفتار سمتگیری مجدد نماتیک در نزدیکی یک سطح الگودارنانومقیاس نشان می‌دهد. همچنین، یافته‌های ما اهمیت انرژی سطحی زینی را هنگام مقایسه مدل‌های فوکودا و برمن، نشان می‌دهد. علاوه بر این، به نظر می رسد که وجود یک میدان الکتریکی خارجی به طور قابل توجهی بر نتایج گزارش شده توسط این مدل ها تأثیر می گذارد.

Keywords [Persian]

  • بلور مایع نماتیک
  • شیارهای سطحی
  • انرژی چنگ زدگی
  • پروفایل جهت نما
  • گام های شیار
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Journal of Interfaces, Thin Films, and Low dimensional systems
Volume 6, Issue 2
January 2023
Pages 657-668