Microwave and electrical characterization of M-type Ba 0.5 Sr 0.5 Co x Ru x Fe (12 À 2x) O 19 hexaferrite for practical applications Rajvir Kaur a,c,n , Naveen Dhillon a , Charanjeet Singh b,c , S. Bindra Narang b , Madhu Chandra d a Department of Electronics and Communication Engineering, Ramgharia Institute of Engineering and Techonology, Phagwara, Punjab, India b Department of Electronics Technology, Guru Nanak Dev University, Amritsar, Punjab, India c Department of Electronics and Communication Engineering, Rayat Bahra Institute of Engineering and Nanotechnology, Hoshiarpur, Punjab, India d Department of Microwave Engineering and Electromagnetic Theory, Chemnitz University of Technology, Chemnitz, Germany article info Article history: Received 13 August 2014 Received in revised form 28 September 2014 Accepted 11 October 2014 by T. Kimura Available online 18 October 2014 Keywords: Ferrites Microwaveproperties Electrical properties abstract The microwave absorption of Ba 0.5 Sr 0.5 Co x Ru x Fe (12À2x) O 19 (x ¼0.0,0.2,0.4,0.8,1.0) ferrite has been inves- tigated as a function of frequency, substitution and thickness. The static I–V characteristics have been studied as a function of substitution. The results exhibit reflection loss of À12.02 dB at 9.0 GHz in x ¼0.2. The electrical current density increases at higher substitution. The microwave and electrical properties show dependence on microstructure. The ferrite compositions for different electromagnetic applications are also suggested. & 2014 Elsevier Ltd. All rights reserved. 1. Introduction With the exponential rise in the development of technology, the study of electromagnetic wave absorbing materials for anti-electro- magnetic interference coatings has attracted attention in recent years. The absorption of electromagnetic signal is required to combat this problem, and ferrites are being used as microwave absorbers/electro- magnetic shield [1,2]. The frequency range of application of exten- sively used spinel ferrites is limited by Snoek’ s law and confines to few gigahertz. However, hexagonal ferrites can be engineered for absorber applications from microwave to higher frequencies [3–5]. M-type hexaferrites are of great interest for microwave devices applications due to an interactive loss mechanisms. In this investigation we are reporting microwave absorption and electrical characterization of Co 2 þ and Ru 4 þ substituted M-type Ba–Sr (Ba 0.5 Sr 0.5 Co x Ru x Fe (12 À2x) O 19 ) ferrite. The expected correlation between microstructure and reported parameters is also discussed. 2. Experimental The microwave characteristics of M-type ferrite, Ba 0.5 Sr 0.5 Co x Ru x Fe (12 À2x) O 19, have been studied as a function substitution and frequency at X-band: synthesis and characterization of this ferrite has been reported elsewhere [6]. The differently substituted samples of ferrite are taken with x ¼ 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0 and reflection loss has been measured by an Absorber Testing Device (ATD) method [7,8]. The microwave frequency source generates X-band frequencies from 8 to 12.4 GHz in the slotted rectangular waveguide. The reflection loss, RL, has been measured by using power meter, Tektronix-Model 3320. The microwave signal interacts with the ferrite composition backed by metallic plate in the waveguide and reflected signal is measured with and without the sample. The reflection loss can be obtained from the difference between the two reflected powers and it is proportional to the power absorbed. The reflection loss, RL, is calculated using following relation: RL dB ð Þ¼ 10 Log 10 P r P i   ð1Þ where P r is reflected power from the sample backed by metal plate and P i is the power reflected from the metallic plate without sample. The large reflection loss corresponds to more absorption and vice versa. The reflection loss of À 10 dB corresponds to 90% absorption. We are reporting the results by selecting the thickness Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/ssc Solid State Communications http://dx.doi.org/10.1016/j.ssc.2014.10.012 0038-1098/& 2014 Elsevier Ltd. All rights reserved. n Corresponding author at: Department of Electronics and Communication Engineering, Ramgharia Institute of Engineering and Technology, Phagwara, Pun- jab, India. E-mail addresses: raj_kaur1989@rediffmail.com (R. Kaur), naveendhillon@rediffmail.com (N. Dhillon), charanjeet2003@rediffmail.com (C. Singh), sukhleen2@yahoo.com (S.B. Narang), Madhu.Chandra@etit.tu-chemnitz.de (M. Chandra). Solid State Communications 201 (2015) 72–75