Journal of Non-Crystalline Solids

Transcription

1 Journal of Non-Crystalline Solids 357 (2011) Contents lists available at ScienceDirect Journal of Non-Crystalline Solids journal homepage: locate/ jnoncrysol Determination of mechanical, electrical and thermal properties of the Sn Bi Zn ternary alloy Emin Çadırlı a,,uğur Böyük b, Hasan Kaya b, Necmettin Maraşlı c a Niğde University, Faculty of Arts and Sciences, Department of Physics, Niğde, Turkey b Erciyes University, Faculty of Education, Department of Science Education, Kayseri, Turkey c Erciyes University, Faculty of Arts and Sciences, Department of Physics, Kayseri, Turkey article info abstract Article history: Received 4 December 2010 Received in revised form 19 March 2011 Available online 7 April 2011 Keywords: Solidification; Microhardness; Tensile stress; Electrical resistivity; Enthalpy The development of lead-free solders has emerged as one of the key issues in the electronics packaging industries. Sn Zn Bi eutectic alloy has been considered as one of the lead-free solder materials that can replace the toxic Pb Sn eutectic solder without increasing soldering temperature. This study investigates the effect of temperature gradient and growth rate on the mechanical, electrical and thermal properties of the Sn Zn Bi eutectic alloy. Sn-23 wt.% Bi-5 wt.% Zn alloy was directionally solidified upward with different growth rates (V= μm/s) at a constant temperature gradient (G=3.99 K/mm) and with different temperature gradients (G= K/mm) at a constant growth rate (V=8.3 μm/s) in the Bridgman-type growth apparatus. The microhardness (HV), tensile stress (σ t ) and compressive stress (σ c ) were measured from directionally solidified samples. The dependency of the HV, σ t and σ c for directionally solidified Sn- 23 wt.% Bi-5 wt.% Zn alloy on the solidification parameters (G, V) were investigated and the relationships between them were obtained by using regression analysis. According to present results, HV, σ t and σ c of directionally solidified Sn-23 wt.% Bi-5 wt.% Zn alloy increase with increasing G and V. Variations of electrical resistivity (ρ) for cast samples with the temperature in the range of 420 K were also measured by using a standard dc four-point probe technique. The enthalpy of fusion (ΔH) and specific heat (C p ) for same alloy was also determined by means of differential scanning calorimeter (DSC) from heating trace during the transformation from eutectic liquid to eutectic solid Elsevier B.V. All rights reserved. 1. Introduction In recent years, increasing environmental and health concerns over the toxicity of lead combined with the strict legislation to ban the use of lead-based solders have provided an inevitable driving force for the development of lead-free solder alloys [1 3]. Among those leadfree solder alloys the Sn-23 wt.% Bi-5 wt.% Zn alloy has received more attention. Sn-23 wt.% Bi-5 wt.% Zn solders possess several fascinating features such as low cost as well as low reflow temperature of 450 K. In addition, Sn-23 wt.% Bi-5 wt.% Zn alloy offers better mechanical properties (high joining strength, good wettability) than the conventional Pb-Sn solders [4 6]. Directionally solidified Sn-23 wt.% Bi-5 wt.% Zn ternary alloy can be a suitable candidate for replacement of Pb-Sn solder due to its convenient mechanical and thermo-physical properties [7 12] and relatively low cost, however it needs more study. Thus the aims of present work were to study the dependency of microhardness, tensile stress and compressive stress on the solidification processing parameters (V and G) for directionally solidified Sn- Corresponding author. Tel.: ; fax: address: ecadirli@gmail.com (E. Çadırlı). 23 wt.% Bi-5 wt.% Zn alloy and the variation of electrical property of Sn-23 wt.% Bi-5 wt.% Zn cast with the temperature in the range of 420 K. 2. Experimental procedures 2.1. Sample preparation and solidification In the present work, Sn-23 wt.% Bi-5 wt.% Zn alloy was prepared in a vacuum furnace [13 17] by using tin, bismuth and zinc of purity of 99.99%. After allowing time for melt homogenization, the molten alloy was poured into 10 graphite crucibles (250 mm in length, 4 mm ID and 6.35 mm OD) held in a specially constructed hot filling furnace at approximately 50 K above the melting point of alloy. The molten metal was then directionally solidified from bottom to top to ensure that the crucible was completely full. Then, each sample was positioned in a Bridgman type furnace in a graphite cylinder ( mm in length 10 mm ID and 40 mm OD). The details of the apparatus and experimental procedures are given in Refs. [13 19]. Unidirectional solidification of the samples with a moderate thermal gradient which is between 1.78 K/mm and 3.99 K/ mm is performed with a maximum furnace temperature of 700 K. In /$ see front matter 2011 Elsevier B.V. All rights reserved. doi: /j.jnoncrysol

2 E. Çadırlı et al. / Journal of Non-Crystalline Solids 357 (2011) the experimental technique, the sample was heated about K above the melting temperature and the sample was then grown by pulling it downwards by means of different speeded synchronous motors after stabilizing the thermal conditions in the furnace under an argon atmosphere. After cm steady state growth, the samples were quenched by rapidly pulling it down into the water reservoir. The melting point of Sn-23 wt.% Bi-5 wt.% Zn alloy is about 448 K. The temperature of water in the reservoir was kept at 283 K with an accuracy of ±0.1 K by using a digital heating/refrigerating circulating bath (model 9102; Poly Science) to obtain a well quenched solid liquid interface in the present work. The sample temperature was also controlled to accuracy of ±0.1 K using a Eurotherm 2604 type controller. Solidification of the samples was carried out with different growth rates (V= μm/s) at a constant temperature gradient (G =3.99 K/mm) and with different temperature gradients (G= K/mm) at a constant growth rate (V=8.3 μm/s) Measurement of growth rate (V) and temperature gradient (G) The temperature in the sample was measured with K-type 0.25 mm in diameter insulated three thermocouples which were fixed within the sample with spacing of mm. In the present work, a 1.2 mm OD 0.8 mm ID alumina tube was used to insulate the thermocouples from the melt. All the thermocouple's ends were then connected the measurement unit consists of data-logger and computer. The cooling rates were recorded with a data-logger via computer during the growth. When the solid/liquid interface was at the second thermocouple, the temperature difference between the first and second thermocouples (ΔT) was read from data-logger record. The time taken for the solid liquid interface phases the thermocouples separated by known distances was read from datalogger record. Thus, the value of growth rate (V=ΔX/Δt) for each sample was determined using the measured value of Δt and known value of ΔX. The temperature gradient (G=ΔT/ ΔX) in the liquid phase for each sample was determined using the measured values of ΔT and ΔX Metallographic examination The quenched samples were removed from the graphite crucible and 3 cm in length from the top and bottom were cropped off and discarded. Then the rest of the samples ground to observe the solidliquid interface and the longitudinal section, which included the quenched interface was separated from the specimen. This part was ground, polished and etched to reveal the quenched interface. Furthermore, the ground specimens were mounted in a cold-setting epoxy-resin. The longitudinal and transverse sections were wetground down to 2500 grit and mechanically polished using 6-μm, 3-μm, 1-μm, and 0.25-μm diamond paste. Finally the samples were etched with an acid solution (1.3 g potassium dichromate, 4.5 ml sulfuric acid, 2.7 ml saturated sodium chloride solution, 17.7 hydrofluoric acid, 8.8 ml nitric acid and 66.3 ml distilled water) to reveal the microstructure. After metallographic process, the microstructures of the samples were revealed. The microstructures of samples were characterized from samples using Olympus BX-51 optical microscopy The measurement of microhardness (HV) One of the purposes of this investigation was to obtain the relationships among solidification processing parameters (G and V) and microhardness hardness for the directionally solidified Sn- 23 wt.% Bi-5 wt.% Zn ternary alloy. The mechanical properties of any solidified materials are usually determined with hardness test, tensile stress test, compressive stress test, ductility test, etc. Since true tensile stress testing of solidified alloys gave inconsistent results with a wide scatter due to the strong dependence on the solidified sample surface quality, the mechanical properties were monitored by hardness testing, which is one of the easiest and most straightforward techniques. The Vickers hardness (HV) is the ratio of a load applied to the indenter to the surface area of the indentation. This is given by HV = 2P sin ð θ = 2 Þ d 2 Microhardness measurements in present work were made with a Future-Tech FM-700 model hardness measuring test device using a (10 50) g load and a dwell time of 10 s giving a typical indentation depth about μm, which is significantly smaller than the original solidified samples. The minimum impression spacing (center to edge of adjacent impression) was about 3 times the diagonal and was located at least 0.5 mm from the edge of sample. The microhardness was the average of at least 30 measurements on the sample. The error in the microhardness measurements has been calculated about 5% The measurement of tensile stress (σ t ) and compressive stress (σ c ) Although many studies on soldering and the interfacial reaction with Sn-23 wt.% Bi-5 wt.% Zn alloys have been performed, there are only a few studies on the mechanical properties of Sn-23 wt.% Bi- 5wt.%Znalloys[4 6]. Mechanical properties, such as tensile stress, compressive stress and ductility are very important factors for the evaluation of the solder joint reliability and necessary for solder joint design, so characterization of these properties is needed. One of the aims of present work is to measure the tensile stress and compressive stress. The tests of tensile and compressive stresses were performed at room temperature with a Shimadzu AG-IS universal testing machine. The data collected from the tensile test can be analysis using the following formula to determine the stress (σ) σ = F A where σ is the stress in N/mm 2 (or MPa), F is the applied force (N), A is the original cross sectional area of the sample. The measurements of tensile and compressive strength were made at room temperature at a strain rate of 10 3 s 1 with a Shimadzu AG-IS universal testing machine. The round rod tensile and compressive samples with diameter of 4 mm and gauge length of 15 mm were prepared from directionally solidified rod samples with different growth rates (V= μm/s) at a constant temperature gradient (G=3.99K/mm) and with different temperature gradients (G= K/mm) at a constant growth rate (V=8.3μm/s). The tensile axis was chosen parallel to the growth direction of the sample. The tensile tests were repeated three times and the average value was taken. It has been found that a standard deviation is approximately 5% The measurement of electrical resistivity The temperature dependence of the electrical resistivity (ρ) for Sn-23 wt.% Bi-5 wt.% Zn cast alloy were measured by the d.c. fourpoint probe method [19]. The four-point probe method is the most widely used technique for electrical profile measurement of materials. In this method, the material's resistivity can be expressed as, ρ = RCF V I where RCF is resistivity correction factor, V is the potential difference measured across the probes and I is the current through the probes. The geometry of the sample determines the correction factors that must be used, additionally the position of the probes on the sample ð1þ ð2þ ð3þ

3 2878 E. Çadırlı et al. / Journal of Non-Crystalline Solids 357 (2011) and the spacings between the probes. The need for correction factors is caused by the proximity of a boundary which limits the possible current paths in the sample. The number of RCF is calculated by diameter of sample divided by probe spacing (probe spacing being the distance between any two adjacent probes). In this study, a 4 mm diameter sample probed with a four point probe with 1 mm tip spacing would have a correction factor of When a constant current was applied on the sample with a Keithley 2400 sourcemeter the potential drops on the samples were measured with a Keithley 2700 multimeter connected to a computer. Platinum wire, 0.5 mm in diameter was used to be the probes of current and potential. Two of the probes are used to source current and the other two probes are used to measure voltage, using four probes eliminates measurement errors due to the probe resistance, the spreading resistance under each probe, and the contact resistance between each metal probe and material [20]. The sizes of samples were measured by using a digital micrometer and have an accuracy of 1 μm. The details of the measurement method have been described in Ref. [21]. The error in the electrical resistivity measurements is calculated about 5%. This error is due to current, voltage and temperature measurements. The electrical resistivity strongly depends on temperature. In metals, electrical resistivity increases with increasing temperature. The temperature coefficient of resistivity (α) is often expressed as a slope in the electrical resistivity versus temperature graph and can be given as α = ρ S ρ S0 ρ S0 ðt T 0 Þ = 1 Δρ ρ S0 ΔT where ρ s is the electrical resistivity at the temperature T and ρ so is the electrical resistivity at the room temperature, T o = K. The temperature of the furnace was controlled with Nabertherm P320 temperature controller and the temperature of the sample was measured with a standard K-type thermocouple. The electrical resistivities of the sample have been measured in the temperature range of 420 K Determination of enthalpy and specific heat The enthalpy of fusion (ΔH)andthespecificheat(C p ) of Sn-23 wt. % Bi-5 wt.% Zn alloy (~10 mg) were determined because they are very important parameters for industrial applications. DSC thermal analysis (Perkin Elmer Diamond model) was performed in the temperature from K to 570 K at a heating rate of 10 K/min under a constant stream of nitrogen at atmospheric pressure. We used a reference material (a sapphire disk) in determining specific heat change. This reference data is used to correct sample data at every temperature. The size of the signal which is used to calculate the specific heat change is proportional to the heating rate, so it follows that faster heating rates will produce larger signals, which would give more accurate data. However, if the heating rate is too high, the temperature gradients in the sample will be large and this may introduce other errors in the measurement. It is normal to use heating rates between 5 K/min and 20 K/min. The heating rate in this study was 10 K/min, which is mostly recommended. The difference between the sample curve and the baseline curve is measured in milliwatts, and converted to specific heat change as follows, ð4þ 3. Results 3.1. The effect of the growth rate, temperature gradient on the microhardness The typical growth morphology of Sn Bi Zn ternary alloy solidified under certain solidification condition (G =3.99 K/mm, V =41.71 μm/s) is shown in Fig. 1. The microstructure of the Sn Bi Zn alloy consists of Sn-rich matrix and Zn phase in the form of both secondary Zn flakes and some relatively coarse needlelike primary Zn flakes dispersed in the Sn-rich matrix. It can be seen from Fig. 1, the Zn phase appears dark and Sn-rich matrix appears grey. Both Zn phase and Sn-rich matrix phase is crystalline form. The size of the primary and secondary flakes in the range of 500 μm and 5 60 μm are determined. The dependence of HV on the G and V can be expressed by the following equations as, HV = kg a HV = kv b where k is a constant, a and b are the exponent values relating to the temperature gradient and growth rate, respectively. The variations of microhardness with the solidification parameters are plotted and given in Fig. 2. As can be seen from Fig. 2a, the microhardness values increase with the increasing G for a given constant V. It is found that increasing temperature gradient from 1.78 K/mm to 3.99 K/mm, microhardness increases from to MPa. The value of the exponent relating to the G is equal to 0.16 for unidirectional solidified Sn-23 wt.% Bi-5 wt.% Zn alloy. This exponent value relating to G obtained in present work is generally in a good agreement with the exponent values relating to the G obtained in previous experimental works [22,23]. Fig. 2b shows the variation of HV as a function of V at a constant G. The value of HV increases with the increasing the value of V. It is found that increasing growth rate from 8.32 μm/s to μm/s, the values of microhardness increase from to MPa The effect of the growth rate, temperature gradient on the tensile and compressive stress Typical stress-strain curves of Sn-23 wt.% Bi-5 wt.% Zn alloy at certain solidification parameters (G=3.99 K/mm, V=153.9 μm/s) ð6þ ð7þ Cp = dq dt 1 mβ ð5þ where dq/dt is heat flow, m is the mass of the sample, and β is the heating rate in K/min. Fig. 1. Growth morphology of directional solidified Sn-23 wt.% Bi-5 wt.% Zn lead-free solder under certain solidification condition (G=3.99 K/mm and V =153.9 μm/s).

4 (a) Microhardness, HV (MPa) (b) Microhardness, HV (MPa) V=8.32 μm/s (constant) 2 G=3.99 K/mm (constant) HV=k 1 G 0.16 k 1 = (N mm K ) r 2 = Temperature gradient, G (K/mm) HV=k 2 V 0.06 k 2 = (N mm s 0.06 ) r 2 = Growth rate, V ( μm/s) E. Çadırlı et al. / Journal of Non-Crystalline Solids 357 (2011) (a) Stress, (MPa) Stress, (MPa) (b) V=8.32 μm/s (constant) G - σ t G - σ c 2 σ t =k 4 G 0.28 G=3.99 K/mm (constant) V - σt V - σc σ =k c 5 G0.32 k 5 =56.17 (N mm K ) r 2 =0.984 k 4 =24.94 (N mm K ) r 2 = Temperature gradient, G (K/mm) σ c =k 7 V 0.19 σ c /σ t =2.30 k 7 = (N mm s 0.19 ) r 2 =0.986 σ c /σ t = σ t =k 6 V k 6 = (N mm s 0.22 ) r 2 = Growth rate, V (μm/s) Fig. 2. Variation of the microhardness with (a) the temperature gradient (b) the growth rate (k: regression coefficient, r 2 : correlation coefficient). Fig. 4. Variation of the tensile stress and compressive stress with (a) the temperature gradient and (b) the growth rate (k: regression coefficient, r 2 : correlation coefficient). are shown in Fig. 3. As can be seen from Fig. 3, the compressive stress values are approximately 2.3 times higher than tensile stress values for Sn-23 wt.% Bi-5 wt.% Zn alloy. Furthermore, the ductility of Sn- 23 wt.% Bi-5 wt.% Zn alloy is very good. Fig. 4a b shows the variation of the stress values (σ t, σ c ) with temperature gradient and growth rate. The dependence of σ t and σ c on the G and V can be represented by equations as follows, ðσ t ; σ c Þ = kg m ð8þ ðσ t ; σ c Þ = kv n ð9þ Fig. 3. Typical stress strain curves for unidirectional solidified Sn-23 wt.% Bi-5 wt.% Zn lead-free solder under certain solidification condition (G =3.99 K/mm and V= μm/s). where k is a constant, m and n are the exponent values relating to the G and V, respectively. Fig. 4a shows the experimental results of tensile stress and compressive stress as a function of temperature gradient. It can be seen that both values of tensile stress and compressive stress increase with increasing temperature gradient. It is found that increasing temperature gradient from 1.78 K/mm to 3.99 K/mm, tensile stress and compressive stress increase from 29.1 to 36.8 and 66.1 to 86.9 MPa, respectively. The ratio of tensile stress to compressive stress, σ c /σ t was calculated to be 2.30 in the temperature gradient range of K/mm for unidirectional solidified Sn-23 wt.% Bi-5 wt.% Zn alloy. The values of the exponent relating to G are equal to 0.28 and 0.32 for tensile stress and compressive stress, respectively. Fig. 4b shows the variation of tensile stress and compressive stress as a function of growth rate. And also it can be seen that both values of tensile stress and compressive stress increase with increasing growth rate. It is found that increasing growth rate from 8.3 μm/s to μm/s, the tensile stress and compressive stress increase from 36.8 to 89.1 MPa

5 2880 E. Çadırlı et al. / Journal of Non-Crystalline Solids 357 (2011) and 86.9 to MPa, respectively. The ratio of tensile stress to compressive stress, σ c /σ t was calculated to be 2.29 in the growth rate range of μm/s The electrical and thermal properties of Sn-23 wt.% Bi-5 wt.% Zn alloy As mentioned above, the variation electrical resistivity with the temperature in the range of 420 K for Sn-23 wt.% Bi-5 wt.% Zn cast alloy were measured and plotted as shown in Fig. 5. The values of ρ were found to be in the range of to Ω m. Fig. 5 shows that the resistivity increases linearly with the increasing temperature. This is because when the alloy is heated, thermal vibration increases. Hence, more vacancies are created leading to disorder in the periodicity, which diffracts and scatters the conduction electrons, thus reducing the conductivity. The DSC curve for Sn-23 wt.% Bi-5 wt.% Zn alloy is shown in Fig. 6. It is clear that sharp peak is observed for melting process as shown in Fig. 6. The enthalpy of fusion was calculated as the area under the peak by numerical integration. The melting temperature of Sn-23 wt.% Bi-5 wt.% Zn alloy was detected to be K. The values of the enthalpy of fusion (ΔH) and the specific heat (C p ) for Sn-23 wt.% Bi-5 wt.% Zn alloy were also calculated to be 54.5 J/g and 0.31 J/g K, respectively from the graph of the heat flow versus temperature. Heat flow, Q (mw) Temperature, T (K) 4. Discussion T peak = K Area=576.3 mj ΔH =54.5 J/g Cp =0.31 J/g K Fig. 6. Heat flow curve versus the temperature for Sn-23 wt.% Bi-5 wt.% Zn alloy with a heating rate of 10 K/min. The microhardness values measured in present work for unidirectional solidified Sn-23 wt.% Bi-5 wt.% Zn alloy are in a good agreement with 255 MPa obtained by Iwanishi et al. [24] for same alloy. The exponent value relating to the growth rate obtained in present work is found to be 0.06 and close to the values of 0.07, 0.08 and 0.10 obtained by Vnuk et al. [25,26] for the Al Si and Sn Zn eutectic alloys and Telli and Kısakürek [27] for the Al Si Sb alloy, respectively, solidified under similar solidification conditions. The values of the exponent relating to the growth rate are equal to 0.22 and 0.19 for tensile stress and compressive stress, respectively. The maximum value of tensile stress of 89.1 MPa obtained in present work is very close to 89 MPa and 72 MPa values obtained by Soares et al. [28] and El-Daly et al. [29], respectively for similar ternary alloy. The values of ρ are slightly higher than data obtained by Kamal et al. [30] for SnZn 9 Bi 1 alloy system. The temperature coefficient of electrical resistivity for Sn-23 wt.% Bi-5 wt.% Zn alloy was determined to be K 1 from the graph of electrical resistivity variation versus temperature. This value is slightly lower than K 1 value obtained by Kamal et al. [30] for SnZn 9 Bi 1 solder. DSC data obtained in present work are in a good agreement with data obtained by Braga et al. [31] for same alloy. 5. Conclusions In present work, the influence temperature and solidification processing parameters on the mechanical, electrical and thermal properties of Sn-23 wt.% Bi-5 wt.% Zn ternary alloy were investigated. The results are summarized as follows: 1. The values of HV for directionally solidified Sn-23 wt.% Bi-5 wt.% Zn alloy have been measured at least 30 regions on the sample. It was found that the values of microhardness increase with increasing the values of V and G. The establishment of the relationships among HV, V and G can be given as HV =kg 0:16 and HV =kv 0:06 Fig. 5. Temperature dependence of (a) the electrical resistivity and (b) the electrical conductivity of Sn-23 wt.% Bi-5 wt.% Zn cast alloy (lines are drawn as guides to the eyes). where the exponent values relating to the temperature gradient and growth rate are 0.16 and These exponent values agree very well with the exponent values relating to the growth rate and temperature gradient obtained in previous works [22 27]. 2. The experimental expressions correlating the values of σ t and σ c with the values of G and V for directional solidified Sn-23 wt.% Bi-

6 E. Çadırlı et al. / Journal of Non-Crystalline Solids 357 (2011) wt.% Zn alloy have shown that both the values of the tensile and compressive stresses increase with increasing the values of G and V. The establishment of the relationships among stresses (σ t, σ c ) and solidification parameters (V and G) can be given as σ t =kg 0:28 ; σ t =kv 0:22 ; σ c =kg 0:32 and σ t =kv 0:19 where the exponent values relating to the temperature gradient and growth rate are 0.28 and 0.22 for tensile stress. Similarly, the exponent values relating to the temperature gradient and growth rate are 0.32 and 0.19 for compressive stress. The maximum value of tensile stress of 89.1 MPa obtained in present work is in a good agreement with the values obtained in previous works [28,29]. Furthermore, the ratio of σ c /σ t was also determined to be 2.30 for directional solidified Sn-23 wt.% Bi-5 wt.% Zn alloy. 3. The electrical resistivity of Sn-23 wt.% Bi-5 wt.% Zn cast alloy increased from to Ω m by increasing temperature. Furthermore, the temperature coefficient of electrical resistivity was determined to be K 1 from the graph of electrical resistivity variation versus temperature. 4. The molten Sn-23 wt.% Bi-5 wt.% Zn alloy was heated with heating rate of 10 K/min from room temperature to 570 K. From the trace of heat flow versus temperature, the melting temperature of Sn- 23 wt.% Bi-5 wt.% Zn alloy was detected to be K. The values of the enthalpy of fusion and the specific heat for Sn-23 wt.% Bi-5 wt.% Zn cast alloy were found to be 54.5 J/g and 0.31 J/gK, respectively. Acknowledgements The authors thank associate professors M. Arı and S. Durmuş for their laboratory facilities. References [1] J. Shen, Y.C. Liu, H.X. Gao, C. Wei, Y.Q. Yang, J. Electron. Mater. 34 (2005) [2] J. Shen, Y.C. Liu, Y.J. Han, P.Z. Zhang, H.X. Gao, J. Mater. Sci. Technol. 21 (2005) 827. [3] J. Shen, Y.C. Liu, Y.J. Han, H.X. Gao, C. Wei, Y.Q. Yang, Trans. Nonferr. Met. Soc. China 16 (2006) 59. [4] Y.S. Kim, K.S. Kim, C.W. Hwang, K. Suganuma, J. Alloy. Compd. 352 (2003) 237. [5] J.M. Song, T.S. Lui, Y.L. Chang, L.H. Chen, J. Alloy. Compd. 403 (2005) 191. [6] R.A. Islam, B.Y. Wua, M.O. Alama, Y.C. Chan, W. Jillek, J. Alloy. Compd. 392 (2005) 149. [7] J. Zhou, Y. Sun, F. Xue, J. Alloy. Compd. 397 (2005) 260. [8] T. El-Ashram, R.M. Shalaby, J. Elect. Mater. 34 (2005) 212. [9] R.M. Shalaby, J. Mater. Sci.: Mater. Electron. 15 (2004) 205. [10] T. El-Ashram, J. Mater. Sci.: Mater. Electron. 16 (2005) 501. [11] C.F. Yang, F.L. Chen, W. Gierlotka, S.W. Chen, K.C. Hsieh, L.L. Huang, Mater. Chem. Phys. 112 (2008) 94. [12] J. Glazer, J. Elect. Mater. 23 (1994) 693. [13] E. Çadırlı, A. Ülgen, M. Gündüz, Mater. Trans. (JIM) 40 (1999) 989. [14] M. Gündüz, H. Kaya, E. Çadırlı, A. Özmen, Mat Sci. Eng. A 369 (2004) 215. [15] E. Çadırlı, H. Kaya, M. Gündüz, Mat. Res. Bull. 38 (2003) [16] E. Çadırlı, M. Gündüz, J. Mat. Proceess. Tech. 97 (2000) 74. [17] E. Çadırlı, İ. Karaca, H. Kaya, N. Maraşlı, J. Cryst. Growth 255 (2003) 190. [18] H. Kaya, E. Çadırlı, M. Gündüz, J. Mat. Eng. Perf. 12 (2003) 456. [19] E. Çadırlı, H. Kaya, N. Maraşlı, U. Böyük, K. Keşlioğlu, S. Akbulut, Y. Ocak, J. Alloy. Compd. 470 (2009) 150. [20] M. Smiths, Bell Sys. Tech. J. 37 (1958) 711. [21] M. Arı, B. Saatçi, M. Gündüz, F. Meydaneri, M. Bozoklu, Mater. Charact. 59 (2008) 624. [22] H. Kaya, E. Çadırlı, U. Böyük, N. Maraşlı, App. Surf. Sci. 255 (2008) [23] H. Kaya, U. Böyük, E. Çadırlı, Y. Ocak, S. Akbulut, K. Keşlioğlu, N. Maraşlı, Met. Mater. Int. 14 (2008) 575. [24] H. Iwanishi, A. Hirose, T. Imamura, K. Tateyama, I. Mori, K.F. Kobayashi, J. Electron. Mater. 32 (2003) [25] F. Vnuk, M. Sahoo, R. Van De Merwe, R.W. Smith, J. Mat. Sci. 14 (1979) 975. [26] F. Vnuk, M. Sahoo, D. Baragor, R.W. Smith, J. Mat. Sci. 15 (1980) [27] A.I. Telli, S.E. Kısakürek, Mat. Sci Tech. 4 (1988) 153. [28] D. Soares, C. Vilarinho, J. Barbosa, R. Silva, M. Pinho, F. Castro, J. Electron. Mater. 27 (1998) 97. [29] A.A. El-Daly, Y. Swilem, M.H. Makled, M.G. El-Shaarawy, A.M. Abdraboh, J. Alloy. Compd. 484 (2009) 134. [30] M. Kamal, M.S. Meikhail, A.B. El-bediwi, E.S. Gouda, Radiat. Eff. Defects Solids 160 (2005) 45. [31] M.H. Braga, J. Vizdal, A. Kroupa, J. Ferreira, D. Soares, L.F. Malheiros, Comput. Coupling Phase Diagrams Thermochemistry 31 (2007) 468.