Muhammad Hikam

Optical Properties of Crystalline Ta2O5 Thin Films

Thin tantalum oxide (Ta 2 O 5 ) films were prepared on Si(100) substrates using the chemical solution deposition (CSD) method. X-ray diffraction (XRD), scanning electron microscopy (SEM), spectrophotometric UV-VIS and ellipsometric measurements were employed to characterize these films. High-quality films of Ta 2 O 5 were obtained by spin coating at 2000, 2250, 2500, 2750 and 3000 rpm during 30 s, and subsequently annealed at 900°C for 15 h. The microstructure and crystallinity of the thin films were analyzed by XRD in preferred (001), (010), (200) orientations, the surface morphology was examined by SEM, and the film thickness was determined by profilometric and ellipsometric measurements, the thin films were heterogeneous. The orthorhombic structure and crystallinity of Ta 2 O 5 thin films on Si(100) substrates were characterized by XRD. The obtained lattice constants are a = 6.117 A, b = 3.716 A, c = 4.114 A. The optical spectrophotometric measurements at λ = 400 nm yielded refractive index values n of 1.81-1.93; from ellipsometric analysis the refractive index values are 1.8-1.94.

Crystallographic and Electrical Properties of Barium Zirconium Titanate Doped by Indium and Lanthanum

Barium Zirconium Titanate (BZT) films doped by Indium and Lanthanum were prepared using Chemical Solution Deposition followed by spin coating method. After deposition, the spesimen was annealed at 800 °C for 3 hours, using 3000 rpm angular spin coating speed. From crystallographic examination we found that the system is perovskite tetragonal with lattice parameters of a = 3.967 Ǻ, c = 3.988 Ǻ. On adding Indium and Lanthanum dopants, their lattice parameters have slightly increased. The spontaneous polarization of BZT is 23.13 µC/cm2, and their spontaneous polarizations increase on adding La dopant. The best spontaneous polarization is at 1 mol % dopant of Lanthanum.

Simple Recipe to Synthesize BaTiO3-BaFe12O19 Nanocomposite Bulk System with High Magnetization

Barium titanate BaTiO3 (BTO) - barium hexaferrite BaFe12O19 (BHF) nanocomposite could be as a raw material of multiferroic. Multiferroic is a class of materials with coupled electric, magnetic and structural order parameters that yield simultaneous effects of ferroelectric, ferromagnetism and ferroelasticity in the same material. This material has potential applications in such as spintronic devices and sensors. This work was an earlier research towards formation of multiferroic material. Knowing magnetic properties that will lead to a better understanding of magnetoelectric coupling in multiferroic material is the objective of this research.The samples were BTO and BHF prepared by sol-gel and then were mixed to synthesize composite in bulk system by a conventional techniques in various of weight fraction between BTO : BHF = 1:1 ; 1:2 and 1:3, then samples were sintered at 925°C for 5, 10 and 15 hours for each fraction respectively. Composite phase study was carried out using X-Ray Diffraction (XRD). MPS Magnet Physik EP3 Permagraph L was used to characterize magnetic properties. No residual phases were identified in the XRD analysis for all parameters. The peaks can be only indexed to BaTiO3 and BaFe12O19 phases for all parameters respectively confirming the formation of a BaTiO3-BaFe12O19 composite system. Barium titanate retains its tetragonal structure while barium hexaferrite exhibits hexagonal structure. For weight fraction of BaFe12O19 until 2 parts there is an increase of intrinsic coersive and saturation magnetization value. The maximum values of intrinsic coersive for samples with 5, 10 and 15 hours sintering are of 361.3 kA/m, 359.0 kA/m and 391.6 kA/m respectively and the maximum values of saturation are of 0.1515 T, 0.1516 T and 0.1414 T respectively leading to good characteristics of multiferroic materials.

Crystallographic Properties of Aluminum-Doped Barium Zirconium Titanate Thin Films by Sol Gel Process

We studied the crystallographic of Barium Zirconium Titanate thin films with Aluminum doped (BZAT). These films were prepared by sol-gel process and followed by spin coating. The sintering temperature is taken at 800°C and 900°C. We found that the crystallographic system of BZAT thin films have tetragonal structure with the lattice parameter slightly changed by various Aluminum partial substitution. When 0.01 Al moles added, the grain size of the films is 29.42 nm at 800°C. The sintering temperature 900°C increased the grain size into 50.95 nm. We also calculated the spontaneous polarization theoretically and we found the optimum value of BZT thin film with 0.01 mole Al heated at 800°C, is 0.143 C/m2. This way, we could predict that the film has ferroelectric phase.

Magnetic Behaviors of BaTiO3-BaFe12O19 Nanocomposite Prepared by Sol-Gel Process Based on Differences in Volume Fraction

Barium titanate BaTiO3 (BTO) - barium hexaferrite BaFe12O19 (BHF) nanocomposite could be as a raw material of multiferroic. Multiferroic is a class of materials with coupled electric, magnetic and structural order parameters that yield simultaneous effects of ferroelectric, ferromagnetism and ferroelasticity in the same material. This material has potential applications in such as spintronic devices and sensors. This work was an earlier research towards formation of multiferroic material. Knowing magnetic properties that will lead to a better understanding of magnetoelectric coupling in multiferroic material is the objective of this research.The samples were BTO and BHF prepared by sol-gel and then were mixed in bulk system by a conventional techniques in various of volume fraction between BTO : BHF = 1:1 ; 1:2 and 2:1, then samples were sintered at 925°C for 5, 10 and 15 hours. Composite phase study was carried out using X-Ray Diffraction (XRD). MPS Magnet Physik EP3 Permagraph L was used to characterize magnetic properties. XRD results confirm that composite with volume fraction of BTO : BHF = 1:1 with sintering at 925°C for 5 hours consists only of 2 phases BTO and BHF. There is impurity phase BaFe2O4 beside BTO and BHF phases at samples with volume fraction BTO:BHF = 1:2 and 2:1 for longer sintering. Composite with volume fraction of BTO:BHF = 1:1 for 5 hours sintering has a high value of remanent magnetization 0.081 T and the lowest value of intrinsic coersive 333.6 kA/m leading to good characteristics of multiferroic materials.

Study of Lead Free Ferroelectric Films for New Solar Cells

We report on the deposition by a sol‐gel process of Ba0.8Sr0.2TiO3 and Ba0.9Sr0.1TiO3 films on platinum coated silicon substrates. X‐Ray diffraction patterns show that the films are (111) preferentially oriented. The surface morphology is smooth, without cracks and the grain size is about 50 nm as determined by AFM and SEM. The dielectric constant measured from 102 to 106 Hz decreases slightly and is around 400 at 104 Hz. The losses are constant in a first approximation for a 1.5 μm thick BST(80/20) film with a value of 0.03 at 10 kHz. The existence of an hysteresis cycle attests that the films, whatever their thickness, are in a ferroelectric state. Pyroelectric coefficients have been determined and the best figure of merit obtained on BST(90/10) at 293 K and 10 kHz is of 149 μC/m3/K. The best dielectric and pyroelectric properties (tgδ = 0.006 at 1 MHz, tunability = 30%, γ = 340 μC/m2/K) were obtained on the 400 nm BST(90/10) film. Work is in progress to characterize the piezoelectric and photovoltaic p...

Intrinsic Ferroelectric Coercive Field Calculation for BZT Films Doped by Indium and Lanthanum

The intrinsic coercive field is predicted by using Landau Ginzburg theory of ferroelectricity. A routine program created on Delphi platform is used to make simulation of the calculation of hysteresis loops and intrinsic coercive field. There are shifting in the values of intrinsic ferroelectric field of BZT on adding the zirconium composition, and the maximum intrinsic coercive field of BZT is found at 0.25 mol zirconium. The calculation shows that the best intrinsic coercive field is found at 1 mol % dopant.

Magnetoelectric Coupling Phenomena Based on the Changes of Magnetic Properties in Multiferroic Nanocomposite BaTiO3-BaFe12O19

Magnetoelectric (ME) coupling effects in multiferroic materials have attracted much attention in recent times because of the intriguing science underpinning this phenomena and being currently intense interest in the implementation of this coupling in an electronic devices. A new multiferroic system comprising of BaTiO3 (BTO) and BaFe12O19 (BHF) has been synthesized as a bulk nanocomposite system in variation of weight fraction of BTO : BHF =1:1, 1:2 and 1:3 and the second sinter temperature was 925°C for 5, 10 and 15 hours. The presence of both phases were confirmed by X-Ray Diffraction (XRD) studies and MPS Magnet Physik EP3 Permagraph L was used to characterize magnetic properties.The morphology and particle size of nanocomposite was characterized by using Transmission Electron Microscope (TEM). No residual phases were identified in the XRD analysis for all parameters confirming the formation of a BTO-BHF composite system. The TEM images show that all samples have particle in nanosize.For weight fraction of BHF until 2 parts there is an increase of intrinsic coersive and magnetization saturation value. If the weight fraction of BHF exceeds from 2 parts, the coersivity and saturation values decrease. Meanwhile in compound of polyvinyl acetate (PVA) and BHF as a compare material, the magnetic properties increase with increasing the content of BHF until 3 parts. From the above results, it presumes that the nanocomposites with weight fraction of BTO : BHF = 1:3 for all time of sintering have ME coupling interaction showing a multiferroic nature. To give evidence of this phenomena, it needs a measurement of ME coupling coefficients for all parameters.

Fixation of chiral smectic liquid crystal (S)-(+)-4-(2-methyl-1-butyloyloxy)phenyl 4-[1-(propenoyloxy) butiloxy] benzoate using UV curing techniques

Chiral Smectic Liquid Crystal (S)-(+)-4-(2-methyl-1-butyloyloxy)phenyl 4-[1-(propenoyloxy) butiloxy] benzoate has been synthesized using method of steglich esterification at room temperature. The mesomorphic behavior of chiral smectic at 55°C that showed schlieren texture in POM analysis. Fixation of structure chiral smectic liquid crystal by means of photopolymerization of monomer (S)-(+)-4-(2-methyl-1-butyloyloxy)phenyl 4-[1-(propenoyloxy) butiloxy] benzoate under UV irradiation which called UV curing techniques. The curing process using UV 3 lamps 100 volt at 60°C for an hour. The product of photopolymerization could be seen by analysis of FTIR spectra both monomer and polymer. FTIR spectra of monomer, two peaks for ester carbonyl and C-C double bond groups appeared at 1729.09 cm-1and 3123.46 cm−1. After UV curing process, peak for the carbonyl group at 1729.09 cm−1 decreased and a new peak at 1160.21 cm−1 appeared due to the carbonyl group attached to a C-C bond group and then peak at 3123.46 cm−1 for...

Nanosize Effects on Magnetic Properties and Peak Shifting of X-Ray Diffraction Pattern of BaFe12O19 Produced by Sol Gel Method

The formation of barium hexaferrite, BaFe12O19 single phase with nanosize crystalline is very important to get the best performance especially magnetic properties. The samples were prepared by sol gel method in citric acid-metal nitrates system. Hence the mole ratios of Ba2+/Fe3+ were varied at 1:12 and 1:11.5 with pH of 7 in all cases using ammonia solution. The solution was then heated at 80-90°C for 3 to 4 hours. Then it was kept on a pre-heated oven at 150°C. The samples were then heat treated at 450°C for 24 hours. Sintering process was done at 850°C and 1000°C for 10 hours.Crystallite size was calculated by X-Ray Diffraction (XRD) peaks using scherrer formula. To confirm the formation of a single phase, XRD analyses were done by comparing the sample patterns with standard pattern. The peak shifting of pattern could be seen from XRD pattern using rocking curves at extreme certain 2θ. It was used MPS Magnet Physik EP3 Permagraph L to know magnetic characteristics. This method can produce BaFe12O19 nanosize powder, 22-34 nm for crystallite size and 55.59-78.58 nm for particle size. A little diference in nanosize affects the peak shifting of XRD pattern significantly but shows a little difference in magnetic properties especially for samples at 850°C and 1000°C with mole ratio of 1:12 respectively. The well crystalline powder is formed at mole ratio of 1:11.5 at 850°C since it has the finest particle (55.59 nm) and crystalline (21 nm), the highest remanent magnetization (0.161 T) and the lowest intrinsic coersive (275.8 kA/m). It is also fitting exactly to the standard diffraction pattern with the highest value of best Figure of Merit (FoM), 90%. XRD peak position of this sample is almost same with XRD peak position of another sample with sinter temperature 1000°C at same mole ratio.