Publication: Production and characterisation of Bi1.5Zn0.92Nb1.5O6.92 Pyrochlore ceramics with precious metal oxide additives
Abstract
DEĞERLİ METAL OKSİT KATKILI Bi1.5Zn0.92Nb1.5O6.92 PİROKLOR SERAMİKLERİNİN ÜRETİMİ VE KARAKTERİZASYONU Bi2O3-ZnO-Nb2O5 sisteminde oluşan Bi1.5Zn0.92Nb1.5O6.92 (BZN) formülüne sahip seramik malzeme kübik piroklor yapısına sahip olup, bu bileşik nonferroelektriktir. Bu bileşik teknolojik olarak faydalı dielektrik özelliklere sahip olup, mikrodalga dielektrik malzeme olarak özellikle kablosuz haberleşmede ve bunun yanında çok katlı seramik kapasitörlerde kullanım alanına sahiptir. BZN piroklor seramiklerin dielektrik sabiti 130-170 arasında değişirken, dielektrik kaybı ise 410-4‘dür. BZN dielektrik malzemenin diğer bir özelliği de relatif olarak düşük sinterlenme sıcaklıklarına (950°C) sahip olmasıdır. Bu ise bu malzemelerin daha düşük maliyete sahip gümüş veya düşük palladyum içerikli gümüş elektrotlarla kullanılmasına imkan sağlar. Bu çalışmada piroklor bileşiklerinin bu özelliklerinden yararlanarak BZN bazlı yeni mikrodalga dielektrik malzemelerin üretilmesi hedeflenmiş olup, bu kapsamda, piroklor yapısına sahip Bi1.5Zn0.92Nb1.5O6.92 (BZN) bileşiğine değerli metal oksitler (Cd, Ta, W, Ir, Hf, Zr ve In) oksitlerin karşımı yöntemiyle ilave edilmiş ve her bir katkının BZN bileşiğindeki çözünürlük sınırı x-ışınları difraktometresiyle saptanmıştır. Üretilen katkılı piroklor seramiklerinin yoğunlukları Arşimed yöntemiyle ölçülmüş ve relatif yoğunlukları %97’nin üzerinde olacak şekilde sinterlenmiştir. Katkı miktarı artıkça ikincil fazlar gözlenmiştir. Ayrıca, her bir katkının BZN seramiğinin dielektrik özelliklerine etkileri de incelenmiş, Cd ve Hf katkıları dielektrik sabitini yükseltirken, Ta, W ve Ir katkıları dielektrik sabitini düşürmüştür. Genel olarak dielektrik sabiti 67 ile 260 değişirken Ir dışındaki bütün katkılarda dielektrik kayıp 100 kHz’in üzerinde 0,001’in altında kalmıştır. Ayrıca Cd haricindeki tüm katkılarda rezonans frekans sıcaklık katsayısında artış saptanmıştır.
PRODUCTION AND CHARACTERISATION OF Bi1.5Zn0.92Nb1.5O6.92 PYROCHLORE CERAMICS WITH PRECIOUS METAL OXIDE ADDITIVES Ceramic compound that forms in Bi2O3-ZnO-Nb2O5 system with a chemical formula of Bi1.5Zn0.92Nb1.5O6.92, (BZN) have a cubic pyrochlore structure and it is nonferroelectric. This compound has important technological dielectric properties, and can be used as microwave dielectric material in wireless communication and multilayer ceramic capacitor. Dielectric constants of BZN pyrochlore ceramics vary between 130-170 and dielectric loss is below 410-4. Having relatively low sintering temperature (950°C) is one of the other property of BZN dielectric material. Low sintering temperature enables the usage of low cost silver and low palladium containing silver electrodes. In this study, by utilizing these properties of BZN pyrochlore compounds, production of a new BZN based microwave dielectric materials was aimed. Some precious metal oxides (Cd, Ta, W, Ir, Hf, Zr and In) were doped into Bi1.5Zn0.92Nb1.5O6.92 compound, and solubility limit of each additive in BZN compound were determined by X-ray diffractometer. Densities of produced pyrochlore ceramics were measured by Archimedes method and ceramics were sintered to have minimum 97 % of relative density. Secondary phases were observed with increasing additive amounts. Besides, effects of each additive on dielectric properties of BZN compounds were examined. Cd, and Hf dopings increased the dielectric constant but on the other hand, dielectric constant decreased with Ta, W, and Ir additives. Generally, dielectric constant varied between 67–260 and dielectric loss for each additive was below 0.001 value at frequencies above 100 kHz except Ir. Also, temperature coefficient of resonant frequency of increased with each doping except Cd.
PRODUCTION AND CHARACTERISATION OF Bi1.5Zn0.92Nb1.5O6.92 PYROCHLORE CERAMICS WITH PRECIOUS METAL OXIDE ADDITIVES Ceramic compound that forms in Bi2O3-ZnO-Nb2O5 system with a chemical formula of Bi1.5Zn0.92Nb1.5O6.92, (BZN) have a cubic pyrochlore structure and it is nonferroelectric. This compound has important technological dielectric properties, and can be used as microwave dielectric material in wireless communication and multilayer ceramic capacitor. Dielectric constants of BZN pyrochlore ceramics vary between 130-170 and dielectric loss is below 410-4. Having relatively low sintering temperature (950°C) is one of the other property of BZN dielectric material. Low sintering temperature enables the usage of low cost silver and low palladium containing silver electrodes. In this study, by utilizing these properties of BZN pyrochlore compounds, production of a new BZN based microwave dielectric materials was aimed. Some precious metal oxides (Cd, Ta, W, Ir, Hf, Zr and In) were doped into Bi1.5Zn0.92Nb1.5O6.92 compound, and solubility limit of each additive in BZN compound were determined by X-ray diffractometer. Densities of produced pyrochlore ceramics were measured by Archimedes method and ceramics were sintered to have minimum 97 % of relative density. Secondary phases were observed with increasing additive amounts. Besides, effects of each additive on dielectric properties of BZN compounds were examined. Cd, and Hf dopings increased the dielectric constant but on the other hand, dielectric constant decreased with Ta, W, and Ir additives. Generally, dielectric constant varied between 67–260 and dielectric loss for each additive was below 0.001 value at frequencies above 100 kHz except Ir. Also, temperature coefficient of resonant frequency of increased with each doping except Cd.