İstanbul Üniversitesi
Research Laboratories Information System
Research Laboratories Information System
Dielektrik Spektroskopi Laboratuvarı
Dielektrik Spektroskopi Laboratuvarı
İstanbul Üniversitesi, Fen Fakültesi, Fizik Bölümü, Genel Fizik Anabilim Dalı, 34134 Vezneciler-Fatih/İstanbul TÜRKİYE
Toplam kullanılan BAP Kaynağı: 824.652,70 TL
1-İnce film formunda termoelektrik ve polimer gibi örnekler farklı kaplama teknikleriyle üretilir.
2-Örneklerin dielektrik sabiti, dielektrik kaybı, elektrik modülü, alternatif iletkenliği gibi parametreleri frekans, sıcaklık ve film kalınlığı gibi değişkenlere bağlı olarak elde edilir.
3-Sıvı örneklerin ölçümlerinde de farklı bir elektrot düzeneği kullanılarak dielektrik spektroskopi cihazı ile ölçümler yapılır.
Mikroişlemcilerin soğutulması, termoelektrik yolla enerji üretimi, ısı yoluyla kaybedilen enerjinin geri dönüştürülmesi gibi bir takım işlemlerde ince film formunda hazırlanmış termoelektrik özellikli malzemelere ihtiyaç duyulmaktadır. Bunların yanında paketleme teknolojisi, biyomedikal malzemelerin kaplanması, kontrollü ilaç salınımı, seçici geçirgenlik gerektiren filtre sistemlerinde polimer tabanlı ve plazma polimer ürünlere ihtiyaç duyulmaktadır.
Dielektrik spektroskopi laboratuvarında kapasitif yapıda ince film örnekler yüksek vakum ortamında termal buharlaştırma, e-beam tekniği ve magnetron sputtering tekniklerinden biri veya birkaçı kullanılarak hazırlanmaktadır. Yüksek vakum sisteminin basıncı turbomoleküler pompa yardımıyla 10-7 Torr seviyesine kadar düşürülebilmektedir.
Hazırlanan kapasitif örnekler dielektrik spektroskopi cihazı ile ölçülerek, ince film örneğin yapısı, yapıdaki polarlanma mekanizması ve yapıdaki etkin iletkenlik mekanizması hakkında bilgiler edinilmektedir.
İstanbul Üniversitesi, Fen Fakültesi, Fizik Bölümü, Genel Fizik Anabilim Dalı, 34134 Vezneciler-Fatih/İstanbul TÜRKİYE
Toplam kullanılan BAP Kaynağı: 824.652,70 TL
Dielectric Spectroscopy Laboratory
Istanbul University, Science Faculty, Physics Department, General Physics Division, 34134, Vezneciler, Fatih, Istanbul TURKEY
Total resource (BAP): 824.652,70 TL
1-Thermoelectric and polymer samples are deposited as thin film by deposition system.
2-Some parameters such as dielectric constant, dielectric loss, electric modulus and alternative conductivity are measured depending on frequency, temperature and film thickness by dielectric spectroscopy system.
3-By making some change on electrodes some liquid measurements are done by dielectric spectroscopy system
Materials with thermoelectric properties as thin film form are needed for some processes such as cooling of microprocessors, thermoelectric energy generation and converting of loss energy to usable energy. Besides, Polymer and plasma polymer materials are used for packaging technology, covering of biomedical materials, controlled drug release and filtering systems.
In Dielectric Spectroscopy Laboratory, thin film samples are deposited by Thermal evaporation, e-beam and magnetron sputtering techniques. The deposited films are measured by Dielectric Spectropy System and their polarization mechanisms, conductivity mechanisms are determined.
Istanbul University, Science Faculty, Physics Department, General Physics Division, 34134, Vezneciler, Fatih, Istanbul TURKEY
Total resource (BAP): 824.652,70 TL
| Görev | Ünvan | Ad | Soyad | Dahili Telefon | AVES Link | |
|---|---|---|---|---|---|---|
| Lab Sorumlusu | DOÇENT | HULUSİ KEMAL | ULUTAŞ | CV |
Cihaz Adı : Dielektrik Spektroskopi Cihazı
Marka : Novocontrol
Model : Alpha-A High Performance Frequency Analyzer
Teknik Özellik : . 3?Hz-20MHz frekans aralığı . (-)130°C-400°C sıcaklık aralığı . tan?: 10^(-5) - 10^4 . kapasite: 1fF - 1F
Miktar : 1
Cihaz Kaynağı : BAP
Alım Tarihi : 30/12/2009Cihaz Adı : Ultra Saf Su Üretici
Marka : ELGA
Model : Purelab Option-S , Purelab Classic
Teknik Özellik : Saf su için: . özdirenç: 15M?.cm . pH: nötr ¬¬¬ Deiyonize su için: . özdirenç: 18,2M?.cm . pH: nötr
Miktar : 1
Cihaz Kaynağı : BAP
Alım Tarihi : 07/10/2009Cihaz Adı : Yüksek Vakumda Kaplama için kombine sistem
Marka : TORR INTERNATIONAL
Model : EB4-TH2-1G2
Teknik Özellik : Termal buharlaştırma E-Beam Magnetron Sputtering
Miktar : 1
Cihaz Kaynağı : BAP
Alım Tarihi : 28/12/2011Cihaz Adı : Vakumlu Fırın
Marka : MTI Corporation
Model : DZF-6020 Bench-Top Vacuum Oven
Teknik Özellik : Çalışma gücü 1000W Sıcaklık aralığı: 50°C-250°C Vakum aralığı:<133Pa Sıcaklık hassasiyeti:?%1
Miktar : 1
Cihaz Kaynağı : BAP
- Makale & Yayın (7)
- Sanayi İşbirliği (0)
- Patent (0)
- Dış Kaynaklı Çalışma (0)
- Faydalı Model (0)
- Ticarileşme (0)
- Proje (1)
- Adı : Synthesis And Characterization Of Anhydrous Conducting Polyimide/Ionic Liquid Copmlex Membranes Via A New Route For High-Tempareture Fuel Cells
Açıklama : The paper deals with the synthesis and characterization of a new series of anhydrous conducting acid?doped complex membranes based on polyimide (PI) and ionic liquid (IL) for high?temperature fuel cells via a new route. For this purpose, three imidazolium?based ILs (RIm+ BF4?) with different alkyl chain lengths (R=methyl, ethyl, and butyl) are added into polyamic acid (PAA) intermediate prepared from the reaction of benzophenonetetracarboxylic dianhydride and diaminodiphenylsulfone in different ?COOH/imidazolium molar ratios (n = 0.5, 1, and 2). Then, the thermally imidized complex membrane was doped with H2SO4. The conductivities of acid?doped PI/IL complex membranes prepared by taking n of 1 are found to be in the range of 10?4 ?10?5 S cm?1 at 180°C, whereas the acid? free PI/IL complex membranes show the conductivity at around 10?9 ?10?10 S cm?1. Thermogravimetric analysis results reveal that the acid?doped PI/IL complex membranes are thermally stable up to 250°C. Dynamic mechanical analysis results of the acid?doped ionically interacted complex membrane show that the mechanical strengths of the PI/IL complex membranes including 1?methyl imidazolium tetrafluoroborate (MeIm?BF4) and 1?ethyl 3?methyl imidazolium tetrafluoroborate (EtIm?BF4) are comparable with those of pristine PI until 200°C. Furthermore, it can be clearly emphasized that the ionic interaction between carboxylic acid groups of PAA?s and IL?s cations offers a positive role in long?term conductivity stability by preventing the IL migration at high temperatures. On the other hand, preliminary methanol permeability tests of the acid?doped membranes show that they can also be considered as an alternative for direct methanol fuel cells.
Ekip : Deligöz H., Yılmazoğlu M., Yılmaztürk S., Şahin Y. , Ulutaş H.K - Adı : Relaxation Spectrum Of The Tlsbse2 Thin Films
Açıklama : The dielectric constant and the dielectric loss of TlSbSe2 thin films, obtained via thermal evaporation of TlSbSe2 crystals grown by Stockber-Bridgman technique, have been measured using ohmic Al electrodes in the frequency range 0.2?100 KHz and within the temperature interval 293?353 K. The capacitance are found to decrease with increasing frequency and increase with increasing temperature. The activation energy values were evaluated too. A good agreement between the activation energy values obtained from capacitance and dielectric loss factor measurements has been observed.
Ekip : Değer Ulutaş D., Ulutaş H.K., Kalkan N., Yildirim S. - Adı : Structural Properties Of In-In2o3 Composite Films
Açıklama : Pure indium metal was thermally evaporated in the presence of oxygen atmosphere, with partial pressure of 6.6x10-2 Pa, onto glass substrates and onto C-Cu grid at room temperature. The structural characteristics of these optically transparent and electrically conducting thin films were investigated using X-ray diffraction (XRD) and transmission electron microscopy (TEM) techniques and the results are discussed on the base of the differences in their morphologies and thicknesses. Cubic In2O3 and tetragonal In phases, with crystal structures and lattice parameters as reported in the literature, have been identified in the thinnest film having 100 nm thickness. The tendency for amorphization of the cubic and tetragonal phases becomes evident as the film thickness increases.
Ekip : Ulutaş H.K., Değer Ulutaş D., Kalkan N., Yildirim S., Çelebi Y.G., Skarlatos Y., Öveçoğlu M. - Adı : Dielectric Polarization In Sb2te3 Thin Films
Açıklama : Dielectric properties of Sb2Te3 films prepared by thermal evaporation technique onto clean glass substrates using ohmic aluminum electrodes have been investigated in the frequency range of 0.01- 100 kHz and within the temperature range of 293K- 373 K. Both the dielectric constant ?1 and dielectric loss factor were found to depend on frequency and temperature. The activation values were evaluated and good agreement between the activation energy values obtained from capacitance and dielectric loss factor measurements were obtained.
Ekip : Ulutaş H.K., Yakut Ş., Değer Ulutaş D - Adı : Ac Conductivity And Dielectric Properties Of Al2o3 Thin Films
Açıklama : Al2O3 thin films of different thicknesses were prepared onto clean glass substrates using ohmic aluminum electrodes. Their dielectric properties and ac conductivity have been investigated in the frequency range 0.1-100KHz and within the temperature range 100- 400K. Oxide-layer thicknesses of the films range between 50-1550 Å. The dielectric constant 1 ? was found to decrease with increasing frequency and increase with temperature in the given intervals. Only ac losses have been investigated due to the smallness of dc losses. The ac conductivity satisfies the power law s ? . Here the s parameter is in the vicinity of 0.8 and it decreases with increasing temperature. This behaviour of s can comply with CBH model. The activation energy values calculated from ac conductivity and dielectric loss factor measurements are in good agreement with each other. The obtained values agree with the model of hopping of charge carriers by thermal activation between two sites having a coulombic potential well. Film thickness dependence of Temperature Coefficient of Capacitance (TCC) and Temperature Coefficient of Permittivity (TCP) of the Al2O3 thin films were also determined.
Ekip : D. DEĞER, K. ULUTAŞ, Ş. YAKUT - Adı : Structure And Dielectric Behavior Of Tlsbs2
Açıklama : A comparison of structure and dielectric properties of TlSbS2 thin films, deposited in different thicknesses (400?4100 Å) by thermal evaporation of TlSbS2 crystals that were grown by the Stockbarger?Bridgman technique and the bulk material properties of TlSbS2 are presented. Dielectric constant ?1 and dielectric loss ?2 have been calculated by measuring capacitance and dielectric loss factor in the frequency range 20 Hz?10 KHz and in the temperature range 273?433 K. It is observed that at 1 kHz frequency and 293 K temperature the dielectric constant of TlSbS2 thin films is ?1 = 1.8?6 and the dielectric loss of TlSbS2 thin films is ?2 = 0.5?3 depending on film thickness. In the given intervals, both of dielectric constant and dielectric loss decrease with frequency, but increase with temperature. The maximum barrier heightWm is calculated from the dielectric measurements. The values of Wm for TlSbS2 films and bulk are obtained as 0.56 eV and 0.62 eV at room temperature, respectively. The obtained values agree with those proposed by the theory of hopping over the potential barrier. The temperature variation of ac conductivity can be reasonably interpreted in terms of the correlated barrier hopping model since it obeys the ?s law with a temperature dependent s (s < 1) and going down as the temperature is increased. The temperature coefficient of capacitance (TCC) and permittivity (TCP) are evaluated for both thin films and bulk material of TlSbS2.
Ekip : M. Parto · D. Deger · K. Ulutas · ¸ S. Yakut - Adı : Thickness Dependence Of The Dielectric Properties Of Thermally Evaporated Sb2te3 Thin Films
Açıklama : Sb2Te3 thin films of different thickness (23 - 350 nm) were prepared by thermal evaporation technique. The thickness dependence of the ac conductivity and dielectric properties of the Sb2Te3 films have been investigated in the frequency range 10 Hz- 100 kHz and within the temperature range 293- 373K. Both the dielectric constant ?1 and dielectric loss factor ?2 were found to depend on frequency, temperature and film thickness. The frequency and temperature dependence of ac conductivity (?ac(?)) has also been determined. The ac conductivity of our samples satisfies the well known ac power law; i.e., ?ac(?) ? s where s<1 and independent of the film thickness. The temperature dependence of ac conductivity and parameter s is reasonably well interpreted by the correlated barrier hopping (CBH) model. The activation energies were evaluated for various thicknesses. The temperature coefficient of the capacitance (TCC) and permitivity (TCP) were determined as a function of the film thickness. The microstructure of the samples were analyzed using X-ray diffraction (XRD). This results are discussed on the base of the differences in their morphologies and thicknesses. The tendency for amorphization of the crystalline phases becomes evident as the film thickness increases.
Ekip : Ulutaş H.K., Değer Ulutaş D., Yakut Ş.
| Adı | Açıklama | Ekip |
|---|---|---|
| No records found. | ||
| Adı | Açıklama | Ekip |
|---|---|---|
| No records found. | ||
| Adı | Açıklama | Ekip |
|---|---|---|
| No records found. | ||
| Adı | Açıklama | Ekip |
|---|---|---|
| No records found. | ||
| Adı | Açıklama | Ekip |
|---|---|---|
| No records found. | ||
| Tip | Adı | Açıklama | Ekip |
|---|---|---|---|
| Proje (BAP) | Enerji verimliliğine yönelik malzemelerin üretimi ve karakteristiklerinin belirlenmesi | Son 5 yıl içerisinde, fosil yakıtlarına alternatif olan enerji kaynaklarının elde edilmesine yönelik olarak oldukça hızlı gelişmeler yaşanmaktadır. Son iki yılda Avrupa ülkeleri, Japonya ve Amerika Birleşik Devletlerinde yer alan özel ve kamu merkezlerinin araştırma laboratuarlarında, bu amaçla yaklaşık 100 milyon dolar civarında harcama yapılmıştır . Nano-teknoloji kullanılarak gerçekleştirilen çalışmalarda çeşitli tip yakıt hücreleri kullanılarak güneş pillerinin ve süper kondansatörlerin geliştirilmesi, elektro-kromik devrelerin yapılması sağlanacaktır. Bu da, otomobil sektöründen inşaat sektörüne kadar çok farklı alanlarda yeni bir teknolojiye yol açacaktır. Bu yeni teknolojide kullanılan malzemelerin üretilmesi ve geliştirilmesine yönelik çalışmalar yoğun bir şekilde devam etmektedir. | Prof. Dr. Deniz Değer ULUTAŞ, Doç. Dr. Nevin KALKAN, Doç. Dr. Hüseyin DELİGÖZ, Doç. Dr. Sedat BALLIKAYA, Yrd. Doç. Dr. Hulusi Kemal ULUTAŞ, Yrd. Doç. Dr. Saffettin YILDIRIM, Arş. Gör. Şahin YAKUT |
© 2019 İstanbul Üniversitesi
Bilgi İşlem Daire Başkanlığı