View in EDS

Structure and dielectric properties of perovskite ceramics in the system Ba(Ni1/3Nb2/3)O3–Ba(Zn1/3Nb2/3)O3

Saved in:
Bibliographic Details
Title: Structure and dielectric properties of perovskite ceramics in the system Ba(Ni1/3Nb2/3)O3–Ba(Zn1/3Nb2/3)O3
Authors: Barwick, M.1, Azough, F.1, Freer, R. Robert.Freer@manchester.ac.uk
Source: Journal of the European Ceramic Society. Aug2006, Vol. 26 Issue 10/11, p1767-1773. 7p.
Subjects: Ceramics, Powder metallurgy, Sintering, Metallurgy, X-ray diffraction
Abstract: Abstract: Ceramics in the system Ba(Ni1/3Nb2/3)O3–Ba(Zn1/3Nb2/3)O3 (BNN–BZN) were prepared by the mixed oxide route. Powders were mixed and milled, calcined at 1100–1200°C then pressed and sintered at temperatures in the range 1400–1500°C for 4h. Selected samples were annealed or slowly cooled after sintering. Most products were in excess of 96% theoretical density. X-ray diffraction confirmed that all specimens were ordered to some degree and could be indexed to hexagonal geometry. Microstructural analysis confirmed the presence of phases related to Ba5Nb4O15 and Ba8Zn1Nb6O24 at the surfaces of the samples. The end members BNN and BZN exhibited good dielectric properties with quality factor (Qf) values in excess of 25,000 and 50,000GHz, respectively, after rapid cooling at 240°Ch−1. In contrast, mid-range compositions had poor Qf values, less than 10,000GHz. However, after sintering at 1450°C for 4h and annealing at 1300°C for 72h, specimens of 0.35(Ba(Ni1/3Nb2/3)O3)–0.65(Ba(Zn1/3Nb2/3)O3) exhibit good dielectric properties: τ f of +0.6ppm°C−1, relative permittivity of 35 and quality factor in excess of 25,000GHz. The improvement in properties after annealing is primarily due to an increase in homogeneity. [Copyright &y& Elsevier]
Copyright of Journal of the European Ceramic Society is the property of Elsevier B.V. and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
Database: Engineering Source
Description
Abstract:Abstract: Ceramics in the system Ba(Ni1/3Nb2/3)O3–Ba(Zn1/3Nb2/3)O3 (BNN–BZN) were prepared by the mixed oxide route. Powders were mixed and milled, calcined at 1100–1200°C then pressed and sintered at temperatures in the range 1400–1500°C for 4h. Selected samples were annealed or slowly cooled after sintering. Most products were in excess of 96% theoretical density. X-ray diffraction confirmed that all specimens were ordered to some degree and could be indexed to hexagonal geometry. Microstructural analysis confirmed the presence of phases related to Ba5Nb4O15 and Ba8Zn1Nb6O24 at the surfaces of the samples. The end members BNN and BZN exhibited good dielectric properties with quality factor (Qf) values in excess of 25,000 and 50,000GHz, respectively, after rapid cooling at 240°Ch−1. In contrast, mid-range compositions had poor Qf values, less than 10,000GHz. However, after sintering at 1450°C for 4h and annealing at 1300°C for 72h, specimens of 0.35(Ba(Ni1/3Nb2/3)O3)–0.65(Ba(Zn1/3Nb2/3)O3) exhibit good dielectric properties: τ f of +0.6ppm°C−1, relative permittivity of 35 and quality factor in excess of 25,000GHz. The improvement in properties after annealing is primarily due to an increase in homogeneity. [Copyright &y& Elsevier]
ISSN:09552219
DOI:10.1016/j.jeurceramsoc.2005.09.004