Geri Dön

Thermoelectric Properties of SrTiO3 Based Oxidesthrough A-site Modifications

Başlık çevirisi mevcut değil.

PDF İndir

  1. Tez No: 630831
  2. Yazar: DURSUN EKREN
  3. Danışmanlar: DOÇ. DANIŞMAN YOK
  4. Tez Türü: Doktora
  5. Konular: Mühendislik Bilimleri, Engineering Sciences
  6. Anahtar Kelimeler: Belirtilmemiş.
  7. Yıl: 2019
  8. Dil: İngilizce
  9. Üniversite: The University of Manchester
  10. Enstitü: Yurtdışı Enstitü
  11. Ana Bilim Dalı: Belirtilmemiş.
  12. Bilim Dalı: Belirtilmemiş.
  13. Sayfa Sayısı: 293

Özet

Özet yok.

Özet (Çeviri)

Donor doped SrTiO3 is one of the most promising thermoelectric oxides, and further improvement in the properties could provide a viable and efficient thermoelectric material that can be utilised to generate electricity from waste heat at elevated temperatures. In this study, the effects of additives, cation vacancies, and processing routes on the thermoelectric properties of ceramics based on SrTiO3 were investigated. High density (typically 95% theoretical) ceramics were prepared by initially calcining the powders with desired compositions for 8 hours in air at 1373-1523 K and then sintering the green bodies for 4-24 hours in either H2-Ar atmosphere or graphite at 1673-1723 K. Minor additives (B2O3 and ZrO2) were utilised for the modification of the structure of Sr0.9Ln0.1TiO3±δ (Ln=Nd and Pr) ceramics at both the atomic and micro scales. B2O3 reduced the sintering temperature required to obtain dense ceramics while ZrO2 improved chemical homogeneity at the atomic scale and homogenised the microstructure. The electrical conductivity and power factor were significantly improved by the substantial increase in charge carrier mobility, while the Seebeck coefficient was maintained. Addition of only 0.5 wt% B2O3 and 0.3 wt% ZrO2 enabled 30-50% improvement in the maximum power factor for both Sr0.9Nd0.1TiO3±δ (~2000 μW/m.K2 ) and Sr0.9Pr0.1TiO3±δ (~2200 μW/m.K2). Moreover, values of the dimensionless figure of merit, ZT (0.37 at 1015 K for Sr0.9Nd0.1TiO3±δ and 0.30 at 800 K for Sr0.9Pr0.1TiO3±δ) were at least comparable to earlier work on these systems. The effect of lanthanide/vacancy doping on the structural and thermoelectric properties of Sr1-xLn2x/3x/3TiO3±δ was studied for Ln=Pr and Nd, and x=0.1-1.0. Increasing cation/vacancy concentration changed the crystal structure from cubic (space group Pm3̅m) to a layered orthorhombic (space group Cmmm) structure. A glass-like thermal conductivity (as low as 2 W/m.K) was achieved with a high level of doping, while low doping resulted in a high thermoelectric power factor (~1800 μW/m.K2 ). The maximum ZT was 0.26 at 865 K for Sr0.60Pr0.267TiO3±δ and 0.28 at 870 K for Sr0.75Nd0.167TiO3±δ samples. Sintering sample by encasing in graphite was an effective processing route. The effect of the lanthanide cation on the thermoelectric properties of Ln0.6Sr0.1TiO3±δ was investigated for Ln=La, Pr and Nd compounds (where RLa>RPr>RNd). The use of La resulted in short-range cation/vacancy ordering (space group Pban) while Pr and Nd containing compositions exhibited long-range ordering (space group Cmmm). Changes of the lanthanide cation changed the unit cell volume and distortion of the TiO6 octahedra. This led to a high thermoelectric power factor (~600 μW/m.K2 ) with the use of larger ionic radius lanthanide (La), while a lower thermal conductivity (~1.88 W/m.K) was achieved with the smaller ionic radius lanthanide (Nd). The maximum ZT was 0.18 at 865 K for compositions with Pr or La regardless of the processing route.

Benzer Tezler

  1. Tez No

    479973

    Effect of grain boundary & interface modification on thermoelectric properties at high temperature

    Tane sınırı ve arayüz modifikasyonun yüksek sıcaklık termoelektrik özelliklerine etkisi

    PINAR KAYA

    Doktora

    İngilizce

    İngilizce

    2017

    EnerjiAnadolu Üniversitesi

    Malzeme Bilimi ve Mühendisliği Ana Bilim Dalı

    PROF. DR. SERVET TURAN

    PROF. DR. JOACHIM MAIER

  2. Tez No

    910162

    Thermoelectric properties of La1/3+xNbO3 perovskite ceramics

    La1/3+xNbO3 perovskit seramiklerinin termoelektrik özellikleri

    DURSUN EKREN

    Yüksek Lisans

    İngilizce

    İngilizce

    2014

    EnerjiThe University of Manchester

    İleri Malzemeler ve Nanoteknoloji Ana Bilim Dalı

    PROF. DR. ROBERT FREER

  3. Tez No

    910903

    Thermoelectric properties of laser-induced graphene based nanocomposites

    Lazer indüklenmiş grafen tabanlı nanokompozitlerin termoelektrik özellikleri

    CEM KINCAL

    Doktora

    İngilizce

    İngilizce

    2024

    Bilim ve Teknolojiİstanbul Teknik Üniversitesi

    Malzeme Bilimi ve Mühendisliği Ana Bilim Dalı

    DR. ÖĞR. ÜYESİ NURİ SOLAK

  4. Tez No

    924365

    Poliselenofen/mangan oksit hibrit kompozitlerin termoelektrik özellikleri

    Thermoelectric properties of polyselenophene/manganese oxide hybride composites

    KEVSER OKCU

    Yüksek Lisans

    Türkçe

    Türkçe

    2025

    Fizik ve Fizik MühendisliğiYıldız Teknik Üniversitesi

    Fizik Ana Bilim Dalı

    PROF. DR. KEMAL ÖZDOĞAN

    DOÇ. DR. AZRA HÜNER

  5. Tez No

    400669

    Thermoelectric properties of Si-based two dimensional structures

    Başlık çevirisi yok

    SEDAT AĞAN

    Doktora

    İngilizce

    İngilizce

    2000

    Fizik ve Fizik MühendisliğiUniversity of Warwick

    Fizik Ana Bilim Dalı

    PROF. T. E. WHALL

    PROF. E. H. C. PARKER

Geri Dön