LATTICE CONSTANTS ANALYSIS OF Ba X Sr 1-X TIO 3 CERAMIC FOR X =0.3; 0.5 AND 0.7 BY VISUAL BASIC PROGRAM

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1 Journal of Nuclear and Related Technology Vol. 4, Special Edition 007, LATTICE CONSTANTS ANALYSIS OF Ba X Sr 1-X TIO 3 CERAMIC FOR X =0.3; 0.5 AND 0.7 BY VISUAL BASIC PROGRAM Z. Jamal 1, M.S. Idris 1, Irzaman, M. Barmawi 3 1 School of Microelectronic Engineering & School of Materials Engineering,Universiti Malaysia Perlis (UniMAP).PO Box 77, Pejabat Pos Kangar, 01007, Kangar, Perlis. zulazhar@kukum.edu.my, sobri@kukum.edu.my Laboratory of Material Physics, Department of Physics, FMIPA IPB,Kampus IPB Darmaga Gedung Wing S Bogor, Indonesia irzaman@yahoo.com, irzaman@dosen.fisika.net 3 Department of Physics, FMIPA ITB, Jl. Ganeca 10 Bandung, Indonesia 4013 ABSTRACT Ceramic of Ba x Sr 1-x TiO 3 (BST) for x =0.3; 0.5 and 0.7 were successfully deposited by solid solution method. The BST ceramic were analyzed by x-ray diffraction (XRD). The XRD spectra was recorded on a Philips type PW 3701 diffractometer using CuK ( co = Å) radiation at 30 KV and 30 ma (900 watt). The spectra shows that BST ceramic are polycrystalline with tetragonal structure. The lattice constants analysis of the grown ceramics was analyzed by visual basic program. Using Cohen s and Cramer s algorithms in visual basic program,, the lattice constants are a = b = Å; c = Å for Ba 0.3 Sr 0.7 TiO 3 ceramic, a = b = Å; c = Å. for Ba 0.5 Sr 0.5 TiO 3 ceramic and a = b = Å; c = Å for Ba 0.7 Sr 0.3 TiO 3 ceramic, respectively. The reform value of the lattice constant of BST ceramic is possibly associated with the anti site defects of Ba and Sr. Keywords: BST, XRD, lattice constants, Cramer s method, Visual Basic Program. INTRODUCTION Ba 0.5 Sr 0.5 TiO 3 films are of considerable interest for a range of applications, including capacitors and high density dynamic random access memory (DRAM), due to its high dielectric constant and high capacity of charge storage (Baumert B. A. et al., 1998; Wang F. et al., 1998). Ba x Sr 1-x TiO 3 films can be formed by various methods, such as Chemical Solution Deposition (CSD) (Baumert B.A. et al., 1998; Wang F. et al., 1998; Cheng J. G. et al., 000), Metal Organic Chemical Vapor Deposition (MOCVD) (Kim S. et al., 1999; Gao Y. et al., 000; Momose S. et al., 000), RF Sputtering (Izuha M. et al., 1997; Kawakubo T. et al., 1997; Cha S. Y. et al., 1999; Lee B. T. et al., 1999; Shin J. C. et al., 1999; Lee J. S. et al., 1999) and Pulsed Laser Ablation Deposition (PLAD) (Yoon K. H. et al., 1999). In this paper we report the fabrication of the Ba 0.3 Sr 0.7 TiO 3, Ba 0.5 Sr 0.5 TiO 3 and Ba 0.7 Sr 0.3 TiO 3 ceramic by solid solution method. The BST ceramics was examined by X-Ray diffraction. The lattice constant was analyzed by visual basic program, and the lattice constants obtained by using Cohen s and Cramer s algorithm are described. 137

2 JOURNAL Of NUCLEAR And Related TECHNOLOGIES, Volume 4, Special Edition, 007 THEORETICAL BACKGROUND The lattice constants analysis of the grown ceramics was analyzed by visual program using Cohen s and Cramer s algorithm. Cohen s method of determining lattice parameter is even more valuable when applied to tetragonal structure. The method provides a direct means of determining these parameters, although the equations are naturally more complex than those needed for tetragonal structure. Tetragonal phase takes on the relatively as Equation (1), (), (3): (Cullity, B.D., 1978; Suryanarayana, C. and Norton, M.G., 1998). d sin, (1) 1 h k l, () d a c sin C B A, (3) sin C B A,. sin C B A, where: d = interplanar spacing; a = the lattice constants; h, k, l = the planes indices; = wave length (( cu = Å)); = the diffraction angle; = h + k + l ; = 10 sin; A = D/10; C = /(4a), A, C = numerator, and D is a constant. The solutions of the numerator A, and C from Equation (3) use Cramer s algorithm (Spiegel M.R., 1983; Arfken G.B. and Weber H.J., 1995) [16,17]. For the case of three equations with three unknowns numerator A and C, Equation (3) become: ac 1 aa a3, (4) bc 1 ba b3 where : a 1 = ; a = b 1 = ; b = ; can be reduced to the previous case by imbedding it in three dimensional space with a solution vector x (A, C) and row vectors a (a 1, a ), c (b 1, b ). EXPERIMENTAL PROCEDURE Ceramic of Ba 0.3 Sr 0.7 TiO 3, Ba 0.5 Sr 0.5 TiO 3 and Ba 0.7 Sr 0.3 TiO 3 ceramics were prepared by solid solution method. The BST ceramic was prepared by mixing barium carbonate [BaCO 3, 99 %], strontium carbonate [SrCO 3, 99.7 %], titanium oxide [TiO, 99.5 %] and 0 ml aceton in a bowl for 1 hour. The mixture was then pressed at MPa for 5 minutes to form a pellet followed by a sintering at 1000 o C for 4 hours in a Furnace. The BST ceramic were analyzed by x-ray diffraction (XRD). The XRD spectra was recorded on Philips type PW 3701 diffractometer using CuK ( cu = Å) radiation at 30 kv and 30 ma (900 watt). The lattice constants analysis of the grown ceramics is analyzed by visual basic program using Cohen s and Cramer s algorithm. The flowchart of this experimental procedure is shown in Fig. 1. RESULTS AND DISCUSSION A search in the ICDD-PDF database using the software available with the diffractometer was identified : BST (JCPDS, 1997). The peak positions of each phase were extracted by means of 138

3 JOURNAL Of NUCLEAR And Related TECHNOLOGIES, Volume 4, Special Edition, 007 single-peak-profile-fittings. The remaining 6 intense peaks corresponding to the phase of interest, BST, were readily indexed in a cubic cell. Table 1 contains the observed X-ray powder diffraction data for Ba0.3Sr0.7TiO3, Ba0.5Sr0.5TiO3 and Ba0.7Sr0.3TiO3. Fig. shows XRD spectra of BST ceramic cubic phase. The presence of intense diffraction peaks that correspond to (110) plane if compared with diffraction peaks from of (100), (111), (00), (10), and (11) planes implied that the BST ceramic assessed a strong preferential orientation. Similar trends were observed in the XRD pattern of BST deposited by solid solution method indicating preferential orientation (Lee B.T. et al., 1999; Lee J.S. et al., 1999; Yoon K.H. et al., 1999). Equation (1), (), (3) using Cohen s algorithm in visual basic program for Ba 0.3 Sr 0.7 TiO 3 ceramic produces numerator A, C as the following: C 36B A C 68B A C B A Table 1: Observed X-ray powder diffraction data of Ba 0.3 Sr 0.7 TiO 3, Ba 0.5 Sr 0.5 TiO 3 and Ba 0.7 Sr 0.3 TiO 3. No h k l ( o ) Ba 0.3 Sr 0.7 TiO 3 Ba 0.5 Sr 0.5 TiO 3 Ba 0.7 Sr 0.3 TiO When Equation (4) was carried out by using Cramer s algorithm in visual basic, we got the lattice constant of Ba 0.3 Sr 0.7 TiO 3 ceramic as the following: a = b = Å; c = Å. The XRD spectra showed that the BST ceramic were tetragonal structure. The calculated lattice constants BST ceramic were given in Table. These values are in good agreement with those observed by other researchers (JCPDS, 1997). The reform value of the lattice constant of BST ceramic is possibly associated with the anti site defects of Ba and Sr. The BST perovskite structure can be simplified with general formula of ABO 3, where A is a monovalent or divalent metal (Ba + or Sr + ) and B is tetravalent (Ti 4+ ), with the Ba and Sr atoms at the tetragonal corners, Ti atom at the body centres, and the oxygen (O) atoms at the face centres. 139

4 JOURNAL Of NUCLEAR And Related TECHNOLOGIES, Volume 4, Special Edition, 007 Barium carbonate (BaCO 3, 99 %] Strontium carbonate [SrCO 3, 99.7 %] Titanium oxide [99.5 %] Mixed with 0 ml aceton in a bowl for 1 hour. BST powder Pelletized with a MPa pressure for 5 minutes and sintered in a furnace at 1000 o C for 4 hours. BST ceramic. Analyzing and characterizing : the structure and lattice constant (by XRD Philips type PW 3701, visual basic program using Cohen s and Cramer s algorithm). STOP Fig. 1. Summary of sample fabrication and characterization. 140

5 JOURNAL Of NUCLEAR And Related TECHNOLOGIES, Volume 4, Special Edition, (110) Intensity (a.u) 500 (100) c (111) (00) (10) (11) b a angle (deg.) Fig.. The XRD spectra of BST ceramic tetragonal phase. (a) Ba0.3Sr0.7TiO3, Ba0.5Sr0.5TiO3, Ba0.7Sr0.3TiO3. Table : The tetragonal structure and the lattice constants of BST ceramic by visual basic program. Ba 0.3 Sr 0.7 TiO 3 Ba 0.5 Sr 0.5 TiO 3 Ba 0.7 Sr 0.3 TiO 3 Lattice constant (tetragonal) a (Å) Å Å Å c (Å) Å Å Å Lattice constant in literature [18] a (Å) Å - - (cubic) CONCLUSIONS We have investigated the lattice constants of BST ceramic by using visual basic program in conjunction with Cohen s and Cramer s algorithm. The ceramic are polycrystalline in tetragonal structure with preferred orientation in (100), (110), (111), (00), (10), (11) crystal planes, and the crystalline quality of the grown ceramic. Using Cohen s and Cramer s algorithms in visual basic program, Using Cohen s and Cramer s algorithms in visual basic program,, the lattice constants are a = b = Å; c = Å or Ba 0.3 Sr 0.7 TiO 3 ceramic, a = b = Å; c = Å. for Ba 0.5 Sr 0.5 TiO 3 ceramic and a =b = Å; c = Å for Ba 0.7 Sr 0.3 TiO 3 ceramic, respectively. The reform value of the lattice constant of BST ceramic is possibly associated with the anti site defects of Ba and Sr. The reform value of the lattice constant of BST ceramic is possibly associated with the anti site defects of Ba and Sr. ACKNOWLEDGMENT This work was supported by RUT XII Project, KMNRT and LIPI, The Republic of Indonesia under contract No. 55/SK/RUT/005 and Short Term Research Grant from Northern Malaysia University College of Engineering, Malaysia under contract No. KUKUM/R&D/ (1)/

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