Investigation of Boro/Carbothermic and Carbothermic Reduction Synthesized Calcium Hexaborides

Year 2018, Volume: 3 Issue: 2, 103 - 108, 05.07.2018

Duygu Yılmaz , Umut Savacı Nurşen Koç , Servet Turan

https://doi.org/10.30728/boron.376549

Cited By: 1

Abstract

In this study, crystal structure and powder morphologies of
CaB₆ synthesized via different synthesis methods were investigated
via Rietveld method and TEM studies. CaB₆ powders were synthesized
via two different methods and to investigate the effect of the synthesis method
on the crystal structure, synthesis temperature and dwell time were kept as
constant for both method. In the first method, CaB₆ was synthesized
via boro/carbothermal reduction of calcium carbonate by in-situ synthesized
boron carbide. In the second method, CaB₆ powders were formed by
carbothermal reduction of calcium hexaborate penthydrate by carbon obtained
from pyrolysis of PVA in PVA-Borate gels. Phase analysis of powders were
studied via X-Ray Diffraction (XRD) and crystal structure refinement was done
using Rietveld method via Maud^TM software. Particle morphologies and
size were studied with Transmission Electron Microscope (TEM) and crystal
structure were analyzed via Selected Area Electron Diffraction (SAED). 

Keywords

CaB6, Hexaboride, Hexaborate, Borocarbothermic Reduction

Boro/Karbotermik ve Karbotermik İndirgeme Yöntemiyle Sentezlenen Kalsiyum Hekzaborürlerin İncelenmesi

Abstract

Bu çalışmada, iki farklı yöntemle sentezlenen CaB₆
kristal yapısı ve toz morfolojisi incelenmiş ve sentez yönteminin, yapı
üzerindeki etkisi Rietveld metodu ve TEM yardımıyla incelenmiştir. CaB₆
tozları iki farklı yöntem kullanılarak sentezlenmiş ve üretim yönteminin
kristal yapı üzerindeki etkisinin incelenmesi için sentez sıcaklığı ve süresi
her iki yöntem için sabit tutulmuştur. İlk yöntemde, CaB₆ tozları,
kalsiyum karbonatın (CaCO₃) boro/karbotermik olarak yerinde
indirgenmesiyle sentezlenmiştir. Diğer yöntemde ise kalsiyum pentaborat
hekzahidrat (CaB₆O₁₀.5H₂O) tozları, PVA-Borat
içeren jelin pirolizinden elde edilen karbonun indirgeyici olarak rol oynamasıyla
ve boratın yerinde indirgenmesiyle sentezlenmiştir. Tozların faz analizi X-Işını
Kırınım (XRD) tekniği ile, kristal yapıya ait detayların belirlenmesi ise Maud^TM
yazılımı kullanılarak Rietveld analizi ve Elektron Kırınımı (SAED) yöntemi ile
gerçekleştirilmiştir. Parçacık morfolojisi ve boyutu, geçirimli elektron
mikroskobu (GEM) kullanılarak incelenmiştir.  

Keywords

CaB6, Hekzaborür, Hekzaborat, Borokarbotermik İndirgeme

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